WO2025235585A1 - Cyclic organosulfur additive containing electrolyte formulations used to derive sei layers, electrodes, systems and formation protocols - Google Patents
Cyclic organosulfur additive containing electrolyte formulations used to derive sei layers, electrodes, systems and formation protocolsInfo
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- WO2025235585A1 WO2025235585A1 PCT/US2025/028105 US2025028105W WO2025235585A1 WO 2025235585 A1 WO2025235585 A1 WO 2025235585A1 US 2025028105 W US2025028105 W US 2025028105W WO 2025235585 A1 WO2025235585 A1 WO 2025235585A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0567—Liquid materials characterised by the additives
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0568—Liquid materials characterised by the solutes
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/621—Binders
- H01M4/622—Binders being polymers
- H01M4/623—Binders being polymers fluorinated polymers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the present invention relates to the field of lithium-ion batteries and electrolyte formulations, methods of forming robust solid electrolyte interphase (SEI) layers on electrodes formed with fibrillatable polytetrafluoroethylene (PTFE) or tetrafluoroethylene (TFE) copolymers and the resulting electrode.
- SEI solid electrolyte interphase
- Electrodes for lithium-ion batteries e.g., anode or cathode, can be prepared using a variety of binders. Commercially used anode binders are generally relatively reductively stable and, there should be no, or very minimal loss in coulombic efficiency from electrochemical processes related to binder degradation (Nagai, A.
- PTFE and many TFE-based ‘fluoropolymer’ binders possess the remarkable ability to fibrillate when shear stress is applied to the polymer. This allows the fibrillatable polymer to be used in a dry, solvent-less processes to form an electrode with electroactive components, e.g., carbon black and the polymer. These electrodes can be used in lithium-ion batteries.
- the PTFE and TFE-based copolymer binders are reductively or electrochemically unstable when used as an anode in lithium-ion batteries or other electrochemical devices.
- the initial coulombic efficiency value (ICE) in fully batter design determines the utilization rate of active materials and the total weight of an assembled battery (see U.S. Patent No.4,304,825 to Basu, S., incorporated herein by reference in its entirety).
- the present invention disclosed herein relates to solid electrolyte interphase (SEI) layers for electrodes formed by using fibrillatable PTFE and TFE polymers and copolymer binders (collectively fibrillatable “TFE containing polymers” including PTFE homopolymers, modified PTFE, and fibrillatable TFE-based polymers such as TFE- copolymers or terpolymers), and in certain embodiments electrodes formed using dry processing methodology (a solvent-free process, involving dry mixing of materials, forming a film, and lamination onto a current collector (Lu et al., Matter (5) 876-898 (2022)).
- SEI solid electrolyte interphase
- One aspect of the present invention relates to electrolyte formulations and methods of forming robust SEI layers on electrodes formed with PTFE or TFE copolymers.
- the ICE of electrode materials can be calculated from the ratio of the ions that participated in the faradaic reactions to the total ions input into the electrode during the initial cycle, which highly depends on the reversibility of electrode materials, irreversible decomposition of electrolyte, the formation of solid electrolyte interface (SEI) and other side reactions.
- SEI solid electrolyte interface
- the electrolyte is crucial in determining the electrochemical performance of electrode materials, including ICE, cycle life and rate performance, etc. Therefore, improving the ICE by the electrolyte optimization is required.
- Electrodes which comprise one or more solid electrolyte interphase (SEI) layers formed by subjecting an electrode and its fibrillatable TFE-containing polymers (i.e. PTFE homopolymer, modified PTFE, and TFE-based copolymers/terpolymers) in contact with an electrolyte to a sequence of different current rates.
- SEI solid electrolyte interphase
- electrodes comprise one or more solid electrolyte interphase (SEI) layers formed by subjecting an electrode and its fibrillated binder in contact with a cyclic organosulfur stabilizing electrolyte to a C/40 current rate to 0.2V and switching to a C/10 rate down to 0.01 V, and then C/10 rate up to 1.5 volts.
- SEI solid electrolyte interphase
- an SEI formation process is applied based on an overall slower lithiation process similar to C/40 from an open cell voltage to 0.8 V vs. Li/Li + or lower voltage, but just before the lithiation in the active anode material takes place.
- the SEI formation cycle involves a slow lithiation current of C/40 from open cell voltage to 0.2 V vs Li/Li + which is applied prior to faster the lithiation current of C/10 for the rest of lithiation and delithiation steps of the formation cycle.
- electrodes comprise a first C/40 current rate solid electrolyte interphase (SEI) layer, a second C/10 current rate solid SEI layer, and a third C/10 current rate SEI layer.
- SEI formation protocols comprising subjecting an electrode in contact with an electrolyte to a first C/40 current rate down to 0.2 volts, a second C/10 rate down to 0.01 V, and a third C/10 rate up to 1.5 volts.
- SEI formation protocols comprising applying a first C/40 current rate down to 0.2 volts, a second C/10 rate down to 0.01 V, and a third C/10 rate up to 1.5 volts to an electrode in contact with a cyclic organosulfur electrolyte.
- Several embodiments disclosed herein relate to SEI formation protocols comprising subjecting an electrode in contact with a cyclic organosulfur containing non- aqueous electrolyte to a first C/10 rate or slower (for example, C/50) rate down 0.2V, a second C/10 rate from 0.2 V to > 0 (0.01 V), and a C/10 de-lithiation rate up to 1.5 volts.
- a first C/10 rate or slower (for example, C/50) rate down 0.2V for example, C/50) rate down 0.2V
- a second C/10 rate from 0.2 V to > 0 (0.01 V
- a C/10 de-lithiation rate up to 1.5 volts.
- lithiation rates comprising subjecting an electrode in contact with a non-aqueous electrolyte to one of more lithiation rates, e.g., a rate slower than C/10 might be down 0.2V, a second C/10 rate from 0.2 V to > 0 (0.01 V), and a C/10 de-lithiation rate up to 1.5 volts.
- Several embodiments disclosed herein relate to SEI formation involving stepped lithiation protocols comprising subjecting an electrode, formed from conductive material and a TFE fibrillated binder, which is in contact with a non-aqueous, cyclic organosulfur additive containing electrolyte, to increasing current rates from a rate slower or than C/10 or slower rate down 0.2 V vs. Li/Li + via one or more increasing current rates to a last lithiation step comprising a C/10 rate from 0.2 V to > 0 (0.01 V), followed by a C/10 de-lithiation rate up to 1.5 volts.
- a delithiation step which is preceded by a rest period with a duration ranging from which ranges from > 10 seconds up to ⁇ 60 minutes.
- Several embodiments disclosed herein relate to non-aqueous electrolytes comprising a solvent formed from (1) one or more linear carbonates including, but not limited, to ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), cyclic carbonates such as ethylene carbonate (EC), (2) at least one lithium halide salt, including, but not limited, to lithium hexafluorophosphate (LiPF6), lithium bis (trifluoromethyl) tetrafluorophosphate (LiPF4(CF3)2), lithium bis(fluorosulfonyl)imide LiFSI, lithium bis (trifluoromethanesulfonyl) imide LiTFSI, lithium difluoro oxalate borate(LiDF
- cyclic organosulfur compound includes, but is not limited to heterocyclic compounds containing carbon, oxygen and sulfur comprising a C2-C8 cyclic sulfate, sulfite or sulfone.
- Non-aqueous electrolytes comprising at least one linear carbonate selected from one or more of ethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate, lithium halide salts selected from one of lithium difluoro oxalate borate (LiDFOB), lithium bis(oxalate) borate (LiBOB), lithium bi(fluorosulfonyl) imide (LiFSI) and a cyclic organosulfur additive comprising, consisting essentially of or consisting of a C2-C8 cyclic sulfate, sulfite or sultone.
- LiDFOB lithium difluoro oxalate borate
- LiBOB lithium bis(oxalate) borate
- LiFSI lithium bi(fluorosulfonyl) imide
- a cyclic organosulfur additive comprising, consisting essentially of or consisting of a C2-C8 cyclic sul
- Non-aqueous electrolytes comprising at least one linear carbonate selected from one or more of ethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate, and one of lithium difluoro oxalate borate (LiDFOB), lithium bis(oxalate) borate (LiBOB), lithium bi(fluorosulfonyl) imide (LiFSI) and stabilizing additives comprising cyclic organosulfur compounds and fluorocarbonates.
- LiDFOB lithium difluoro oxalate borate
- LiBOB lithium bis(oxalate) borate
- LiFSI lithium bi(fluorosulfonyl) imide
- stabilizing additives comprising cyclic organosulfur compounds and fluorocarbonates.
- Electrodes comprising a fibrillated fluoropolymer binder bearing an electrochemically induced interface layer derived from an electrolyte comprising at least a lithium salt compound containing lithium, fluorine and one of a carbonate, borate, chlorate, oxalate, or sulfonyl group, and at least one cyclic organosulfur compound.
- One or more embodiments disclosed herein also relates to systems, half- cells, and full-cells containing anode electrodes having one or more SEI layers in contact with a non-aqueous electrolyte
- the anode electrode comprises a conductive material, a fibrillated fluoropolymer binder
- the non-aqueous electrolyte comprises at least one linear carbonate, at least one lithium halide salt compound containing lithium, fluorine/chlorine and one of a carbonate, borate, chlorate, oxalate, sulfonyl group, and sulfide, and a heterocyclic compound containing carbon, sulfur and multiple oxygen atoms
- the SEI layers are electrochemically derived from the non-aqueous electrolyte, and methods of forming the anode of the systems, half-cells, and full-cells.
- One or more embodiments disclosed herein also relates to systems, half- cells, and full-cells containing anode electrodes having one or more SEI layers in contact with a non-aqueous electrolyte
- the anode electrode comprises a conductive material, a fibrillated fluoropolymer binder
- the non-aqueous electrolyte comprises linear or cyclic carbonates selected from at least one of ethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or dimethyl carbonate
- anode of systems, half-cells, and full-cells in which the anode comprises a fibrillated fluoropolymer binder bearing first and second electrochemically produced interface layers derived from a non- aqueous solvent containing a linear carbonate, at least one lithium salt compound containing lithium, fluorine and one of a carbonate, borate, chlorate, oxalate, sulfonyl group or a sulfide, and at least a cyclic, dicyclic and tricyclic organosulfur compound, and methods of forming the anode of the systems, half-cell, and full-cell.
- the anode comprises a fibrillated fluoropolymer binder bearing first and second electrochemically produced interface layers derived from a non- aqueous solvent containing a linear carbonate, at least one lithium salt compound containing lithium, fluorine and one of a carbonate, borate, chlorate, oxalate, sulfonyl group or
- non-aqueous electrolytes comprising, consisting essentially of, or consisting of one or more non-aqueous solvents comprising linear carbonates, and at least one additive comprises a heterocyclic sulfur compound defined by one of the following formulae:
- non-aqueous electrolytes comprising, consisting essentially of, or consisting of one or more non-aqueous solvents comprising linear carbonates, and at least one additive comprises a heterocyclic sulfur compound defined by one of the following formulae (II), (III), (V) or (VI), wherein A and A’ are defined above.
- the number of carbon atoms in the heterocyclic sulfur compound or cyclic organosulfur additive compound comprises 2, 3, 4, 5, 6, 7 and up to 8 carbon atoms, preferably between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms.
- the C, S, O heterocyclic compound or cyclic organosulfur additive compound comprises at least one C, S, O heterocyclic substituent, each substituent preferably having between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms, most preferably 2 carbon atoms.
- an additive system comprising a first C, S, O heterocyclic compound or cyclic organosulfur compound with at least one C, S, O heterocyclic substituent, each substituent preferably having between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms and a fluorinated cyclic carbonate.
- Certain embodiments disclosed herein relate to non-aqueous electrolytes containing one or more additives, wherein at least one additive comprises, consists essentially of, or consists of a compound containing linked C, S, O heterocyclic substituents preferably having between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms and a fluorinated cyclic carbonate.
- an additive system comprising a first C, S, O heterocyclic compound or cyclic organosulfur compound with at least one C, S, O heterocyclic substituent, each substituent preferably having between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms and a fluorinated cyclic carbonate, and the additive system amounts to about >0 to ⁇ 10 wt % of the total amount of stabilizing electrolyte.
- first and second stabilizers amount to about >0 to ⁇ 10 wt % of the total amount of stabilizing electrolyte.
- the present invention also relates to systems including electrolyte formulations and electrodes with a fibrillated fluoropolymer binder and SEI surface layer formed by electrochemical reduction and interaction of at least a surface of the fibrillated fluoropolymer binder and at least one cyclic organosulfur compound comprising, consisting essentially, or consisting of one or more cyclic sulfate, sulfite or sultone components which are capable for forming an SEI layer with electrolyte components to form one or more SEI layers which o stabilize the electrode.
- the electrolyte includes a cyclic sulfur additive including, but not limited to sulfite, sulfate or sultone compounds having 2-8, preferably 2-4 ring carbons in the main ring, such as ethylene sulfite (1,3,2- dioxathiolan-2-oxide), ethylene sulfate (1,3,2-dioxathiolane 2,2-dioxide), 1,3-propylene sulfite, 1,3-propylene sulfate, 1,3 propane sultone, and 1-propene-1,3 sultone.
- a cyclic sulfur additive including, but not limited to sulfite, sulfate or sultone compounds having 2-8, preferably 2-4 ring carbons in the main ring, such as ethylene sulfite (1,3,2- dioxathiolan-2-oxide), ethylene sulfate (1,3,2-dioxathiolane 2,2-dioxide), 1,3-
- the organo- sulfate, sulfite or sultone additives/compounds includes but is not limited to compounds having one of the following formula, O O O O O A ' preferably one of formula (II), (III), (V), or (VI) wherein each A and A’ is independently a hydrogen or optionally acyclic ethers include without limitation vinyl, allyl, acetylenic, propargyl or C1–C3 alkyl.
- the number of carbon atoms in the cyclic sulfur include 2, 3, 4, 5, 6, 7, and up to 8 carbons, preferably between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms.
- the non-aqueous electrolyte comprises at least a first additive selected from a C2-C4 cyclic sulfite, sulfate or sultone and optionally, a second additive which comprises a fluorinated cyclic carbonate component, in additive quantities, e.g., less than 10 weight %, preferably less than 5 weight %, most preferably between > 0.1 weight % and 5 weight %.
- the non-aqueous electrolyte comprises at least a first additive selected from a C2-C4 cyclic sulfite, sulfate or sultone and optionally, a second additive which comprises a fluorinated cyclic carbonate selected from a first fluorinated cyclic carbonate component, such as fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoropropylene carbonate, (TFPC), 4-((2,2,3,3-tetrafluoropropoxy)methyl)-1,3-dioxolan-2-one (HFEEC), and 4- (2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolan-2-one (NFPEC), illustrated below: (DFEC)
- FEC fluoroethylene carbonate
- DFEC difluoroethylene carbonate
- TFPC trifluoropropylene carbonate
- HFEEC 4-(2,2,3,3-tetra
- the non-aqueous linear carbonate electrolyte comprises at least a first additive selected from a C2-C4 cyclic sulfite, sulfate or sultone comprising a 2 or 3 carbons atoms in the ring, and defined by anyone of the formula below: preferably one of formula (II), (III), (V), or (VI)
- each A or A’ is independently a hydrogen or optionally acyclic ethers include without limitation vinyl , allyl, acetylenic, propargyl or C1–C3 alkyl.
- a or A’ could be joined to another cyclic organo structure similar to formula (I)-(VI), preferably (II), (III), (V) or (VI) or other C, S, O heterocyclic structures having 2-8 carbon atoms and substituted as above.
- the non-aqueous electrolyte comprises at least a first additive selected from a C2-C4 cyclic sulfite, sulfate or sultone comprising a 2 or 3 carbons atoms in the ring, and defined by anyone of the formula below: O O O O O A ' preferably one of formula (II), (III), (V), or (VI) wherein each A or A’ is independently a hydrogen or optionally acyclic ethers include without limitation vinyl, allyl, acetylenic, propargyl or C1–C3 alkyl.
- FEC fluoroethylene carbonate
- DFEC difluoroethylene carbonate
- TFPC trifluoropropylene carbonate
- HFEEC 4-(2,2,3,3,4,4,5,5,5-n
- the cyclic organosulfur compound comprises, consists essentially of, or consists of a cyclic sulfate or cyclic sulfite. [0043] In certain embodiments disclosed herein the cyclic organosulfur compound comprises, consists essentially of, or consists of a cyclic sulfite. [0044] In certain embodiments disclosed herein the cyclic organosulfur compound comprises, consists essentially of, or consists of a compound defined by formula (III) or (VI).
- the cyclic organosulfur compound comprises, consists essentially of, or consists of a compound defined by formula (II), (III), (V), or (VI).
- the first cyclic sulfur additive in the electrolyte unexpectedly provides improved performance, e.g., coulombic efficiency, relative to electrolyte formulations which lack the cyclic sulfur additive.
- inclusion of the first cyclic organosulfur additive in combination with a second fluorinated cyclic carbonate additive in the non-aqueous electrolyte forms one or more layers upon a series of lithiation and delithiation steps which unexpectedly improved stability of TFE-containing fibrillated fluoropolymer binders of the electrode, preferably wherein the binder comprises, consists essentially of, or consists of fibrillatable PTFE homopolymers, fibrillatable modified PTFE, fibrillatable TFE copolymers/terpolymers, and combinations thereof, which is believed to result from synergy between the fluorinated cyclic carbonate and cyclic organosulfur additive and other electrolyte components.
- a second fluorinated cyclic carbonate additive unexpectedly improved stability of the electrode containing a fibrillated fluoropolymer binder, preferably wherein the binder comprises, consists essentially of, or consists of PTFE homopolymers or TFE-based polymers (including modified PTFE where the total comonomer content is 1 wt% or less of the modified PTFE) having at least one comonomer of hexafluoropropylene (HFP), and/or perfluoro(alkyl vinyl ether) (PAVE) in which the linear or branched alkyl group contains 1 to 5 carbon atoms, FEP (TFE/HFP copolymer and TFE/HFP/PAVE copolymer), PFA (TFE/PAVE copolymer), wherein PAVE is most preferably perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(
- Embodiments of the invention disclosed herein relate to half-cells and full cells comprising (1) electrodes formed with fibrillated fluoropolymer binder, such as PTFE and TFE containing copolymers, preferably wherein the binder comprises, consists essentially of, or consists of PTFE, or TFE copolymers (including modified PTFE) formed with one of hexafluoropropylene (HFP), and/or perfluoro(alkyl vinyl ether) (PAVE) in which the linear or branched alkyl group contains 1 to 5 carbon atoms, FEP (TFE/HFP copolymer and TFE/HFP/PAVE copolymer), PFA (TFE/PAVE copolymer), wherein PAVE is most preferably perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE), or the combination of perfluoro(methyl vinyl ether)(PMVE) and PPVE
- TFE/PMVE/PPVE copolymer (2) electrolytes containing at least a first cyclic organosulfur compound, e.g., a sulfite, sulfate, or sultone compounds having a 4 to 10 member ring
- a first cyclic organosulfur compound e.g., a sulfite, sulfate, or sultone compounds having a 4 to 10 member ring
- the binder comprises, consists essentially of, or consists of PTFE, modified PTFE or TFE copolymers formed with one of hexafluoropropylene (HFP), and/or perfluoro(alkyl vinyl ether) (PAVE) in which the linear or branched alkyl group contains 1 to 5 carbon atoms, FEP (TFE/HFP copolymer and TFE/HFP/PAVE copolymer), PFA (TFE/PAVE copolymer),
- One embodiment disclosed herein relates to a process comprising contacting a surface of a graphite electrode containing a fibrillated fluoropolymer binder with a LiPF6-EC/DEC solution containing at least one cyclic organosulfur compounds, e.g., a sulfite, sulfate or sultone compound having a 4-to-10-member ring under slow lithiation similar to C/40 to 0.2V and then faster lithiation below 0.2V .
- electrochemical evaluations include half-cell evaluations using lithium metal counter electrodes examined galvanostatically.
- SEI layer formation depends on the anode material, its microstructure, electrolyte salt and electrolyte solvent in the system.
- the formation protocol for SEI electrode layers is modified to further enhance SEI formation from the electrolyte formulations with an initial slow lithiation current of C/40 to 0.2V, and improvements in the coulombic efficiency when the modified formation protocols are used occur.
- Another aspect of this invention is the unusual synergy and combination of the electrolyte with these formation protocols.
- galvanostatic current used can be very low C rate ⁇ C/10, e.g., C/40 at voltages above the lithium intercalation voltage of the graphitic anode or any other anode.
- the effective SEI layer is formed before (above or positive of) the decomposition potential of the PTFE or TFE copolymer binder in the graphite anode. Because of the robust SEI formation before the decomposition potential of the PTFE or TFE co-polymer binder there is less loss of cyclable lithium through a PTFE reduction process thereby providing higher coulombic efficiency of Graphite/Li half cells. This approach provides an SEI formation protocol for half cells. The duration of this C/40 formation significantly lowers the formation time compared to both charge current and discharge current of C/25 in the formation protocol and also substantially improves the 1 st cycle Coulombic Efficiency.
- the C/40 formation protocol generates effective (probably thinner) SEI layers such that there is more lithium delithiation or less lithium loss from the graphite anode providing higher delithiation capacity.
- the C rate can be diminished so that the voltage varies little above 0.8 V versus Li/Li + , before resuming the discharge of the half-cell battery to lower voltages vs Li/Li + .
- These procedures are beneficial establishing a protective SEI layer before the voltage is realized at which the PTFE or TFE copolymer will decompose (about 0.6- 0.8 V versus Li/Li+). This strategy can be translated to the formation protocol of full cells.
- the charge-discharge potential window of the full cells depends on what type of anode and cathode are utilized. SEI formation takes place in the initial stage of the 1 st Charge in a full cell while this happens in the initial stage of discharge in half cell.
- LiNi0.8Mn0.1Co0.1O2 cathode vs Graphite anode is utilized in the commercial lithium-ion battery.
- the safe and efficient charge-cut off potential is 4.2V (Eldesoky, A. et al., 2022, J. Electrochem. Soc. 169010501; Vidal Laveda et al., ACS Appl. Energy Mater.2019, 2(10), 7036–7044.
- Formation protocols in a half cell, with a lithium counter electrode also include C/40 lithiation to 0.2V vs Li/Li+, C/10 lithiation to 0.01V vs Li/Li+, and C/10 delithiation to an upper cut off voltage can range from 1.2 to 1.5V vs Li/Li+.
- the inventive formation protocols start with applying lower current of C/40 at the voltage of the open circuit (which can be over 2.0 V). The voltage decreases during the lithiation process of the graphite electrode.
- This formation is performed galvanostatically at a rate of C/40 down to 0.2 V. Afterwards, the C rate (current) is increased to C/10 until 0.01 V versus Li/Li+. Thereafter, the lithiation is reversed (or the graphite electrode is delithiated) at a current of C/10 to 1.25 up to 1.5 V versus Li/Li+.
- the presence of effective amounts of cyclic organosulfur compounds in the electrolyte allows for the formation of several SEI layers which stabilize the electrode and allows for high coulombic efficiency.
- the solid electrolyte interphase layer (SEI) formed during the formation cycle using the electrolyte component in the electrolyte formulation stabilized the fibrillated fluoropolymer binder (i.e., fibrillatable TFE copolymers and/or PTFE binders) components of the electrode with respect to electrochemical reduction.
- the electrolyte is stabilized against reduction over other components of the anode surface. Decomposition of the PTFE or TFE copolymer binder is believed to generate high surface area carbon-type products. Applicants believe the electrolyte additives described herein form SEI layers which prevent reduction on these newly formed surfaces during the formation cycle.
- the net result is that the coulombic efficiency of the cell during the first formation cycle is substantially improved.
- the coulombic efficiency (CE) is the ratio of the charge (delithiation of graphite in a half cell) capacity to discharge (lithiation of graphite in half cell) capacity during the formation cycle; this is typically monitored to determine initial cell performance.
- the initial coulombic efficiency is substantially increased, in some cases, to > 90 %.
- Electrolyte formulations without these additives show much lower initial coulombic efficiency of 55- 57 %, indicating significant side reactions which lead to the loss of cyclable lithium. These reactions can include the electrochemical reduction of the binder, electrolyte reduction on the anode surface, and electrolyte reduction on surfaces generated by any reduced binder.
- electrodes will include electroactive components, which can be selected from one of or more of silicon, SiOx, lithium alloys such as lithium - aluminum alloy, lithium - lead alloy, lithium - silicon alloy, and lithium - tin alloy; carbon materials such as carbon black, graphite, graphene, carbon nanotubes, mesocarbon microbeads (MCMB ), carbon nanotubes, conductive carbon,; phosphorus -containing materials such as conductive black phosphorus, metal oxides such as SnO2, SnO and TiO2; nanocomposites containing antimony or tin, for example nanocomposites containing antimony, oxides of aluminum, titanium, or molybdenum.
- electroactive components can be selected from one of or more of silicon, SiOx, lithium alloys such as lithium - aluminum alloy, lithium - lead alloy, lithium - silicon alloy, and lithium - tin alloy
- carbon materials such as carbon black, graphite, graphene, carbon nanotubes, mesocarbon microbeads (
- the anode active material comprises graphite, graphene, silicon or SiOx or mixtures thereof.
- the anode-additive containing electrolyte is assemble in suitable container to provide electrochemical cell components and a cathode.
- Housing materials are well-known in the art and can include, for example, metal and polymeric housings. While the shape of the housing is not particularly important, suitable housings can be fabricated in the shape of a small or large cylinder, a prismatic case, or a pouch.
- the anode and the cathode may be comprised of any suitable conducting material depending on the type of electrochemical cell.
- the porous separator serves to prevent short circuiting between the anode and the cathode.
- the porous separator typically consists of a single- ply or multi-ply sheet of a microporous polymer such as polyethylene, polypropylene, polyamide, polyimide or a combination thereof.
- the pore size of the porous separator is sufficiently large to permit transport of ions to provide ionically conductive contact between the anode and the cathode, but small enough to prevent contact of the anode and cathode either directly or from particle penetration or dendrites which can form on the anode and cathode. Examples of porous separators suitable for use herein are disclosed in U.S.
- cathode materials include, but are not limited to graphite, graphene, aluminum, platinum, palladium, electroactive transition metal oxides comprising lithium or sodium, indium tin oxide, and conducting polymers such as polypyrrole and polyvinyl ferrocene.
- Suitable cathodes include those disclosed in U.S.
- rare earth element is meant the lanthanide elements from La to Lu, and Y and Sc.
- NMC cathode that is, a LiNiMnCoO cathode, more specifically, cathodes in which the atomic ratio of Ni: Mn: Co is 1:1:1 (LiaNia
- the cathode comprises a material of the formula LiaMnbJcO4Zd, wherein J is Ni, Co, Mn, Cr, Fe, Cu, V, Ti, Zr, Mo, B, Al, Ga, Si, Li, Mg, Ca, Sr, Zn, Sn, a rare earth element, or a combination thereof; Z is F, S, P, or a combination thereof; and 0.9 ⁇ a ⁇ 1.2, 1.3 ⁇ b ⁇ 2.2, 0 ⁇ c ⁇ 0.7, 0 ⁇ d ⁇ 0.4.
- the cathode is a stabilized manganese cathode comprising a lithium-containing manganese composite oxide having a spinel structure as cathode active material.
- the lithium-containing manganese composite oxide in a cathode suitable for use herein comprises oxides of the formula LixNiyMzMn2-y-zO4-d, wherein x is 0.03 to 1.0; x changes in accordance with release and uptake of lithium ions and electrons during charge and discharge; y is 0.3 to 0.6; M comprises one or more of Cr, Fe, Co, Li, Al, Ga, Nb, Mo, Ti, Zr, Mg, Zn, V, and Cu; z is 0.01 to 0.18; and d is 0 to 0.3.
- FIG. 1 illustrates comparative properties of commercially available binders from density functional theory (DFT) calculations (see Nagai, A., supra).
- FIG. 2 illustrates an SEI formation protocol.
- FIG. 1 illustrates comparative properties of commercially available binders from density functional theory (DFT) calculations (see Nagai, A., supra).
- FIG. 2 illustrates an SEI formation protocol.
- FIG. 3 illustrates the inventive SEI formation protocol.
- FIG. 4 illustrates a typical half-cell.
- FIG. 5 illustrates a typical full cell.
- FIGs 6A through 6C illustrates a series of X-ray photoelectron spectrometer (XPS) spectra corresponding to the binding energy of sulfur species within the solid electrolyte interphase.
- FIG.6A illustrates the XPS spectra for Example 8b.
- FIG.6B illustrates the XPS spectra for Example 4a.
- FIG.6C illustrates the XPS spectra for the comparative example.
- FIGs 7A thorough 7D are the XPS spectra corresponding to carbon structures with the peak that represents a carbon-carbon double bond specifically highlighted.
- FIG. 7A thorough 7D are the XPS spectra corresponding to carbon structures with the peak that represents a carbon-carbon double bond specifically highlighted.
- FIG. 7A thorough 7D are the XPS spectra corresponding to carbon structures with the peak that represents
- FIG. 7A illustrates the XPS spectra for Example 8b before cycling while FIG.7B is the XPS spectra for Example 8b after cycling.
- FIG.7C is the XPS spectra for the comparative example while FIG.7D is the XPS spectra for Example 4a after cycling.
- DETAILED DESCRIPTION [0077] The present invention relates to anode electrodes containing TFE copolymer or PTFE binders which are stabilized with electrolyte formulations containing electrolyte additives. Cyclic sulfite, sulfite or sultone additive-containing electrolyte formulation help stabilize the electrolyte against reduction on these newly formed surfaces during the formation cycle (i.e.
- the coulombic efficiency is the ratio of the charge (delithiation of graphite in a half cell) capacity to discharge (lithiation of graphite in a half cell) capacity during the formation cycle; this is typically monitored to determine initial cell performance.
- the initial coulombic efficiency is substantially increased, in some cases, to > 90 %. Lithium-ion battery cells containing electrolyte formulations without these additives show an initial coulombic efficiency of 55-57 %.
- the electrolyte formulation which form the solid electrolyte interphase (SEI) layer(s) on the electrode, comprise a cyclic additive containing sulfur.
- the cyclic sulfur containing compound can be a cyclic sulfite, sulfate or sultone represented by formulas below: preferably one of formula (II), (III), (V), or (VI),
- each A and A’ is independently a hydrogen, optionally acyclic ethers including without limitation vinyl, allyl, acetylenic, propargyl or C1–C3 alkyl.
- one or more layers on a fibrillated polymer substrate surface or a reduced polymer substrate surface comprises one or more films independently the same or different chemically, and each independently continuous, non-continuous, and/or fragmented.
- electrolyte composition refers to a chemical composition that includes at a minimum a solvent for an electrolyte salt and an electrolyte salt, wherein the composition is suitable as an electrolyte in an electrochemical cell.
- An electrolyte composition can include other components to enhance the performance of the battery in safety, reliability, and or efficiency.
- electrolyte salt refers to an ionic salt that is at least partially soluble in the solvent of the electrolyte composition and that at least partially dissociates into ions in the solvent of the electrolyte composition to form an ionically conductive electrolyte composition.
- An “electrolyte solvent” as defined herein, is a solvent or a solvent mixture for an electrolyte composition that can comprise, for example and without limitation, linear carbonates such as diethyl carbonate, ethyl methyl carbonate, or dimethyl carbonate, cyclic carbonates such as ethylene carbonate, and fluorinated carbonates, esters, or ethers or their combination.
- fluorinated and non-fluorinated solvents can be used, for example, non-fluorinated ethers such as the cyclic ether tetrahydrofuran, and fluorinated solvents such as 2,2 difluoroethyl acetate, a fluorinated ester, or 2,2 difluoroethyl methyl carbonate or a fluorinated carbonate.
- the electrolyte can comprise more than one solvent, and in many cases, two or more solvents.
- the solvent can participate in reactions to create a solid electrolyte interphase.
- the term "anode” refers to the electrode of an electrochemical cell. In a secondary (i.e., rechargeable ) battery.
- the anode is the electrode at which oxidation occurs during discharge and reduction occurs during charging.
- the term “cathode” refers to the electrode of an electrochemical cell. In a secondary (i.e., rechargeable ) battery. The cathode is the electrode at which reduction occurs during discharge and oxidation occurs during charging.
- the term “ lithium-ion battery ” refers to a type of rechargeable battery in which lithium ions move from the anode to the cathode during discharge and from the cathode to the anode during charge.
- the phrase “lithium intercalation voltage of the graphitic anode” is meant to cover a voltage range which is approximately 0.2 to 0.01 V versus Li/Li + .
- product, film, layer or deposit “derived from” and “generated from” is meant to include products, films, layers or deposits formed from, inter alia, decomposition, absorption, assimilation, infusion, incorporation, polymerization, reaction, co-polymerization with other electrolyte additives and components, co-polymerization with a partially reduced polymer of a polymer substrate or polymeric component of an electrode, or combinations of the above.
- the “derived/generated” product, film, layer or deposit is one or more continuous or discontinuous films/layers on the polymer which may be different than another layer on other electrode components.
- the derived/generated product, film, layer or deposit may comprise one or more layers or films, wherein each layer or film of a multiple layer or film is independently continuous or discontinuous.
- the polymer substrate or the polymeric component of the electrode optionally includes a structure comprising fibrils.
- the polymer substrate or polymeric component of the electrode include a structure comprising a plurality of fibrils (i.e., a fibrillated polymer structure).
- Coulombic efficiency (CE) of an anode as used herein is the percentage ratio of specific charge (delithiation in a half cell) capacity to specific discharge (lithiation in a half cell) capacity.
- SEI solid electrolyte interface layer formed during the initial cycle of discharge-charge cycle as a result of electrolyte components undergoing electrochemical reaction on the surface of anode components which are conductive.
- the formed SEI protects the anode components from forming new surfaces and it also protects electrolyte from further decomposing; in some cases, this includes prevention of volatile products that contribute to gassing.
- the “equilibrium potential between lithium and lithium ion” is the potential of a reference electrode using lithium metal in contact with the non- aqueous electrolyte containing lithium salt at a concentration sufficient to give about 1 mole/liter of lithium ion concentration and subjected to sufficiently small currents so that the potential of the reference electrode is not significantly altered from its equilibrium value (Li/Li + ).
- a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
- “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present), and B is false (or not present), A is false (or not present), and B is true (or present), and both A and B is true (or present). [0100]
- PTFE binder or TFE copolymer binder is meant to mean a PTFE homopolymer formed from polymerizing tetrafluoroethylene monomers or a TFE containing copolymer contains tetrafluoroethylene (TFE) copolymerized with other monomers.
- the binder comprises a fibrillatable PTFE homopolymer or fibrillatable TFE copolymer; wherein the binder partially or completely fibrillates upon application of sufficient shear.
- One concept of the present invention is to provide a lithium battery with a graphite-carbon electrode containing a PTFE or TFE copolymer binder that is resistant to or resistive of destabilization of the fibrillated binder to substantially maintain the integrity of the fibril structure, binder and electrode.
- the binder comprises a tetrafluoroethylene homopolymer, consisting essentially of repeating units arising from the tetrafluoroethylene monomer, as disclosed in U.S.
- the tetrafluoroethylene polymer is a “modified” PTFE, referring to copolymers of tetrafluoroethylene with such a small concentration of comonomer that the molecular weight of the resultant polymer is not substantially reduced below that of homopolymer PTFE.
- the concentration of such comonomer in modified PTFE is less than 1 wt %, preferably less than 0.5 wt % based on the total weight of the modified PTFE copolymer.
- a minimum amount of at least about 0.05 wt % is generally used to have significant effect.
- comonomers in modified PTFE include perfluoroolefins, notably hexafluoropropylene (HFP) or perfluoro(alkyl vinyl ether) (PAVE), where the alkyl group contains 1 to 5 carbon atoms, with perfluoro(ethyl vinyl ether) (PEVE) and perfluoro(propyl vinyl ether) (PPVE) being preferred, chlorotrifluoroethylene (CTFE), perfluorobutyl ethylene (PFBE), or other similar monomers that introduce relatively sterically bulky side groups into the PTFE polymer chain.
- HFP hexafluoropropylene
- PAVE perfluoro(alkyl vinyl ether)
- CTFE chlorotrifluoroethylene
- PFBE perfluorobutyl ethylene
- the tetrafluoroethylene polymer or copolymer is fibrillatable.
- fibrillatable is meant that the tetrafluoroethylene polymer is capable of forming nanosized (in at least one-dimension (i.e. ⁇ 100 nm width) fibrils which can vary in length from submicrometer, to several, to tens of micrometers in length when the tetrafluoroethylene polymer/copolymer is subjected to sufficient shear forces.
- P-1 Polymer Preparation Polymer 1
- the fluoropolymer binder (polymer 1) is commercially available from Chemours FC LLC (Wilmington, DE) or can be prepared from aqueous dispersions of tetrafluoroethylene homopolymer using known methods.
- Polymer 2 [0112] A modified tetrafluoroethylene polymer, containing 0.128 wt% of copolymerized PPVE (perfluoro(propyl vinyl ether)) as modifier, was manufactured by Chemours FC LLC having a melt creep viscosity of 1.47 x 10 10 poise.
- MCV Melt creep viscosity
- the copolymer contains vinylidene fluoride (VDF) and hexafluoropropylene (HFP), with the HFP content 40% weight percent and having a Dv (50), 215 nm, measured from the Malvern Particle Sizer, Nano Series - ZS. Polymer 4: (P-4) [0114]
- a copolymer was manufactured by Chemours FC, LLC.
- the copolymer contains tetrafluoroethylene (TFE) and perfluoro(propyl vinyl ether) (PPVE), with the PPVE content of 4 weight percent relative to the entire polymer weight.
- the final copolymer has a melt flow rate (MFR) of 15 g/10 minute, as measured according to ASTM D-1238 and ASTM D 3307-93, at 372° C using a 5 kg weight on the molten PFA.
- the PFA is fluorine-treated so as to have the stable -CF3 end group as the predominate end group and less than 50, preferably less than 25, total thermally unstable end groups, for example, -CONH2, -COF, -CH2OH and -COOH per 10 6 carbon atoms as the most common end groups resulting from the aqueous dispersion polymerization process used to make the PFA.
- Processes for fluorination are known in the art, for example, in U.S. Pat.
- the PFA is not fluorine treated, whereby its end groups, about 200 or more per 10 6 carbon atoms, are the unstable end groups mentioned above arising from aqueous dispersion polymerization to form the PFA.
- the two agitators were separated by 6 cm on the shaft and comprised of four blades (blades are 1.5 cm wide and 4.5 cm long) with a 45-degree pitch. The rotation was in the direction to create an upward flow of fluid.
- the contents of the coagulator were stirred at 800 rpm with a Caframo BDC3030 motor (Caframo Lab Solutions, Georgian Bluffs, Ontario, CA) until the solid co-coagulated polymer was sufficiently separated from the water. After decanting, the wet powder was washed with 1000 mL of demineralized water then filtered through cheesecloth.
- Polymer 6 (P-6) [0116] The polymer 6 fluoropolymer composition was prepared according to the procedure for the synthesis of polymer 5 described above. Demineralized water (1159 mL) was combined with 636 mL of an aqueous dispersion containing polymer 2 (having a polymer solids of 39.73%) and 62 mL of an aqueous dispersion containing polymer 4 (having a polymer solids of 21.47%).
- Polymer 7 (P-7): [0117] Polymer 7 is a PVDF binder for Li-ion Battery Electrodes is purchased from MTI Corporation Richmond, CA. The product was in white powder form with purity >99.5% and has a molecular weight is reported to be approximately 600,000 according to ASTM D 5296-05 Testing. Electrode Preparation Polymer 5 (P-5)- Electrode 1: [0118] Electrode 1 Procedure: Test anodes were prepared using the present fluoropolymer compositions by the following procedures: Approximately 10 g of a powder mixed was created using 97.5 % graphite (Amsted Graphite Materials, Anmoore, VA), 1.0 % Super P carbon black, and 1.5 wt % of the polymer binder.
- the graphite and super P carbon black were combined in a mortar and pestle and mixed for approximately 15 minutes.
- This mixture was combined with the fluoropolymer binder into a 250-mL plastic bottle with approximately ten ZrO2 (10 mm in diameter) milling media and rolled for about 30 minutes.
- the powder was separated from the milling media.
- a free-standing film was created by placing 3 g of the mixture onto a small glass mortar and pestle. This material was manually ground until the powder formed a solid flake.
- the flakes were placed onto a hot plate with a piece of Kapton ® film, heated to 100° C. Using a manual steel roller, the flake was rolled at 100° C until a film was formed which was uniform.
- Electrode 2 Procedure The same Electrode 1 procedure was used except Polymer 6 was used instead of P-5.
- Electrode 3 Procedure The same Electrode 1 procedure was used except Polymer 1 was used instead of P-5. The same procedure was also used to prepare electrodes using Polymer 3.
- Electrode 4 Procedure PVDF electrode (electrode 4) SP Carbon (0.05 gm) and 4.75 gm of Graphite Active Anode material were mixed on mortar and pestle for 15 minutes and they were mixed in roller mixer with zirconia balls (1 balls per gm of powder material) for additional 30 minutes. N-methyl-2-pyrrolidone (NMP) and polyvinylidene fluoride (PVDF) were mixed separately and obtained 10 weight % PVDF/NMP thick solution.2 gm of NMP/PVDF solution is added to the powder mixture and additional 3.5 gm of NMP is also added. The final mixture is mixed at 2000 revolutions per minute (RPM) for 2 minutes three times with an interval of few minutes.
- NMP N-methyl-2-pyrrolidone
- PVDF polyvinylidene fluoride
- Electrode disks (14 mm in diameter) were punched from a free-standing (self- supporting) film formed from fibrillatable fluoropolymer binder, graphite, and Super P carbon black. The assembly was performed in an inert, Argon atmosphere drybox with ⁇ 0.01 ppm H2O and O2.
- Coin cells type 2032 were assembled with a lithium metal counter electrode (15 mm in diameter), Celgard 2325 separator (16 mm in diameter) and electrolyte compositions described herein below.0.5 mm thick stainless-steel spacers were used. Formation protocols: [0123] The assembled coin cells were allowed to rest for about 2 hours in the electrolyte to wet the electrode and separator before starting the discharge-charge process. The initial cycle of discharge-charge is called the cell formation step. The cell formation and discharge-charge cycles were performed with a Neware battery tester BT-4008EN-5V-10mA-164-U (Neware Lab, San Jose, CA).
- FIGs 2-5 relate to formation protocols, and half- and full cells.
- FIG.2 illustrates an existing protocol 1, wherein C/10 lithiation to 0.01V is followed by C/10 delithiation to between 1.25V and 1.5V, preferably one of 1.25V, 1.30V, 1.35V, to 1.5V and all values and fractions there between .
- Formation Protocol 3 is a stepped lithiation protocol and illustrated in FIG. 3. According to the present invention the lithiation involves FIG.3 illustrates stepped, e.g., two step lithiation at C/40 and then C/10 followed by a delithiation at C/10, although more than two, three, four, etc., steps can be involved.
- At least the first lithiation step is conducted at much slower/lower rates than the second step or subsequent steps, e.g., C/50, C/40, C/30, C/20 or C/15.
- the rate lower/slower than C/10, e.g. C/20, C/30, C/40, C/50, up to C/100 is continued down 0.2V, then followed by a second C/10 rate from 0.2 V to > 0 (0.01 V), and then a C/10 de-lithiation rate up to between 1.25 and 1.5 volts.
- FIG. 4 illustrates a half-cell of a stacked spacer, anode electrode, separator containing a non-aqueous electrolyte including at least the cyclic organosulfur compounds disclosed herein, a cathode electrode, spacer and spring arranged between bottom and top enclosers.
- FIG.5 is similar that of FIG.4, but a lithium electrode is used in place of the anode electrode of FIG.4.
- Formation protocol A is a regular baseline formation protocol. It includes a discharge (lithiation) from an open circuit voltage (OCV) to lower cut off voltage of 0.01V vs Li/Li+ at C/10 constant current rate (over 10 hours) and a charge (delithiation) cycle from lower cut off voltage of 0.01V vs Li/Li/Li+ to upper cut off voltage of 1.25V vs Li/Li+ at the same C/10 constant current rate.
- OCV open circuit voltage
- delivery charge
- formation protocols are modified by first using a slow discharge (lithiation) of C/40 (over 40 hours) from open circuit voltage (OCV) to 0.2V vs Li/Li+ plus faster discharge of C/10 from 0.2V vs Li/Li+ to lower cut off voltage of 0.01V vs Li/Li+ and faster charge of C/10 from lower cut off voltage of 0.01V vs Li/Li+ to upper cut off voltage of 1.25V.
- OCV open circuit voltage
- Constant current discharging and charging current are applied and a rest of 5 minutes in between the discharge and charge cycle in the case of the modified formation protocol.
- the 1 st cycle lithiation capacity, delithiation capacity and coulombic efficiency are measured from the formation step.
- Comparative Examples [0129] Examples C1-C3 :1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC, electrode 1, formation protocol 3. Coin cell evaluations used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the Table 2 below. [0130] Examples C4-C5 : CMC-6:1.2 M LiPF6 + EC/DEC (3:7 by volume) electrode 1, formation protocol 3.
- Examples 2A, 2B, 2C 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC, 1 wt % ethylene sulfite, electrode 1, formation protocol 3.0.1546 grams of ethylene sulfite (Sigma Aldrich) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox.
- Coin cell evaluations used electrode 1, formation protocol 3.
- the final data (coulombic efficiency) is shown in the table below.
- Example 3A, 3B 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC, 1 wt % ethylene sulfite, 1 wt % LiFSI, electrode 1, formation protocol 3- 0.1563 grams of ethylene sulfite (Sigma Aldrich), 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials), 0.1563 of lithium bis(fluorosulfonyl) imide (LIFSI, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox.
- a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA)
- Example 6A, 6B 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC 1 wt % ethylene sulfite 0.5 wt % vinylene carbonate, electrode 1, formation protocol 3- 0.1554 grams of ethylene sulfite (Sigma Aldrich), 0.3109 g of fluoroethylene carbonate (FEC, Gotion, battery materials), 0.0777 g of vinylene carbonate ( Aldrich) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox.
- Example 7A, 7B, 7C 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC, 1 wt % 1,3 propane sultone, electrode 1, formation protocol 3- 0.1546 grams of 1,3 propane sultone (Sigma Aldrich) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox.
- Example 8A, 8B 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC+ 1 wt % ethylene sulfite, electrode 3, formation protocol 1 0.1546 grams of ethylene sulfite (Sigma Aldrich) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox.
- Coin cell evaluations used electrode 3, formation protocol 1.
- Coin cell evaluations used electrode 2 formation protocol 1.
- Example 11A, 11B 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC+ 1 wt % ethylene sulfite, electrode 2, formation protocol 3 0.1546 grams of ethylene sulfite (Sigma Aldrich) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox.
- Coin cell evaluations used electrode 2, formation protocol 3.
- Example 14A, 14B, 14C 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 1 wt % ethylene sulfate, electrode 1, formation protocol 3 0.1515 grams of ethylene sulfate (Sigma Aldrich) was combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox.
- Coin cell evaluations used electrode 1, formation protocol 3
- the final data (coulombic efficiency) is shown in the table below.
- Example 15A, 15B 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 1 wt % ethylene sulfate, 1 wt % LiFSI, electrode 1, formation protocol 3 0.1531 grams of ethylene sulfate (Sigma Aldrich) and 0.1531 of lithium bis(fluorosulfonyl) imide (LIFSI, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox.
- Coin cell evaluations used electrode 1, formation protocol 3.
- the final data (coulombic efficiency) is shown in the table below.
- Example 16A, 16B, 16C 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt FEC, 1 wt % ethylene sulfate, 1 wt % LiFSI, electrode 1, formation protocol 3 0.1563 grams of ethylene sulfate (Sigma Aldrich), 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials), 0.1563 of lithium bis(fluorosulfonyl) imide (LIFSI, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox.
- a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA)
- Example 18A, 18B, 18C 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 1 wt % ethylene sulfite, electrode 1, formation protocol 1 0.1515 grams of ethylene sulfite (Sigma Aldrich) was combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 1. The final data (coulombic efficiency) is shown in the table below. TABLE 2 EXAMPLES Examples 20-43 and Comparative Example C6-C16 are listed in Table 2.
- Electrode 1 was fabricated with Polymer 5
- Electrode 2 with Polymer 6 was fabricated with Polymer 1.
- the electrolyte compositions are indicated in Table 2.
- the procedures to form the electrolytes were the same as described in the previous examples, except that the composition of the additives were adjusted as indicated in the Table 2.
- multiple coin cell evaluations were used and are replicates.
- C1, C2, C 3 are separate coin cell experiments using the same combination of electrode, electrolyte and the same electrochemical formation protocol.
- Electrolyte additive Coulombic Polymer Formation (combined with 1.2 M Capacity on Efficiency E l l P l LiPF E DE 7 l h Ahg TABLE 1 (continued) Electrolyte additive Coulombic Polymer Formation (combined with 1.2 M Capacity on Efficiency E l l P l LiPF E DE 7 l h Ahg TABLE 1 (continued) Electrolyte additive Coulombic Polymer Formation (combined with 1.2 M Capacity on Efficiency E l l P l LiPF E DE 7 l h Ahg TABLE 1 (continued) Electrolyte additive Coulombic Polymer Formation (combined with 1.2 M Capacity on Efficiency E l l P l LiPF E DE 7 l h Ahg TABLE 1 (continued) Electrolyte additive Coulombic Polymer Formation (combined with 1.2 M Capacity on Efficiency E l l P l LiPF E DE 7 l h Ahg
- the improvement in initial coulombic efficiency is shown in table 1 using the formation protocol “C/40 to 0.2V, C/10 to 0.01V, C/10 to 1.25”, and shows an initial coulombic efficiency for the comparative examples C4 and C5 of 55-57 % compared to much as 92-94% for examples 2A, 3A, 4B and 4C of this invention.
- Tables 1 and 2 for the examples of this invention, an improvement is realized of 5, 10, 15, 20, 25, 35 % in the absolute value of the initial coulombic efficiency in half cell electrochemical evaluations.
- the relative improvement is as much as 10, 20, 30, 40, 50, 60 %.
- XPS measurements of the electrode surface were performed using a Thermo Scientific K-alpha XPS which utilizes an aluminum k-alpha monochromatic source, a 180-degree focused hemispherical analyzer, and a 128-channel detector. All investigations utilized a 400 ⁇ m spot size and all presented data is an average of 20 scans.
- the solid electrolyte interphase (SEI) of the electrode was examined. This technique provides information regarding the chemical species on the surface of a sample to a depth of approximately 10nm. To prepare the samples for measurement, the coin cells were decrimped and the electrodes were separated from the separator.
- the electrode was gently rinsed with dimethyl carbonate in an Argon atmosphere drybox and allowed to dry.
- XPS analysis of electrode surface [0150]
- the coin cell batteries of examples 8b and 4a of Table 1 were mounted into a vacuum transfer module within a glovebox and transferred into the instruments vacuum environment without any exposure to air.
- SEI solid electrolyte interphase
- FIGs 6A through 6C illustrate a series of XPS spectra corresponding to the binding energy of sulfur species within the solid electrolyte interphase.
- FIGs 7A through 7D are the XPS spectra corresponding to carbon structures with the peak that represents a carbon-carbon double bond specifically highlighted. The fact that a carbon-carbon double bond is still visible in Examples 4a and 8b suggests that the SEI formed in these examples is much thinner than the SEI in the comparison.
- Significant differences in the SEI between Example 8b, Example 4a, and a comparative example using a CMC electrolyte were documented and are shown in FIGs 6A, 6B, and 6C and FIGs 7A, 7B, 7C, and 7D.
- FIGs 6A-C show that the electrolyte system used in Examples 8b (FIG.6A) and 4a (FIG.6B) resulted in an SEI that contains both reduced and oxidized sulfur species. Whereas the comparative example (FIG.6C) is only populated by a Phosphorus 2P satellite peak, thereby indicating no significant sulfur species in the SEI.
- the sulfur species of the SEI layer is derived from the cyclic organosulfur compound and can be either a reduced form of sulfur species or an oxidized form of sulfur. By a reduced form, it is meant the formal oxidation state of the sulfur itself.
- the reduced sulfur species containing sulfur derived from the cyclic organosulfur compound is in a formal oxidation state lower than 0, up to -2, or a mixture of oxidation states.
- sulfur is also observed to be in another form, with a formal oxidation state 2+ or greater or mixtures thereof, and represents an “oxidized form”, more precisely as sulfur species derived from a cyclic organosulfur compound containing sulfur in a positive formal oxidation state.
- FIGs 7A through 7D show XPS analysis in the region corresponding to carbon species.
- the XPS data for a pristine (non- cycled) electrode has a large peak corresponding to a carbon-carbon double bond.
- this double bond is due to the significant amount of graphite on the surface of the electrode (i.e., there is no SEI present to cover up this graphite).
- This figure also shows that the comparative example shows no such graphite peaks.
- An electrode comprising: a fibrillated fluoropolymer binder, and one of: i. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer derived from an electrolyte formulation containing at least one cyclic organosulfur additive; ii. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer containing a sulfur species, wherein the sulfur species is derived from a cyclic organosulfur compound; iii.
- SEI solid-electrolyte interface
- At least one solid-electrolyte interface (SEI) layer said at least one SEI layer containing a reduced sulfur species; wherein the sulfur is derived from a cyclic organosulfur compound and has a formal oxidation state lower than 0, up to -2, or a mixture of oxidation states; iv. at least one solid-electrolyte interface (SEI) layer, said at least o ne SEI layer containing an oxidized sulfur species derived from a cyclic organosulfur compound containing sulfur in a positive formal oxidation state; v.
- SEI solid-electrolyte interface
- At least one solid-electrolyte interface (SEI) layer said at least o ne SEI layer containing an oxidized sulfur species derived from a cyclic organosulfur compound containing sulfur in a positive formal oxidation state of +2 up to +6, or a mixture of oxidation states; vi. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer derived from electrochemical interaction of (i) a linear (and/or) cyclic carbonate, (ii) a lithium halide salt, (iii) at least one a cyclic organosulfur additive, and (iv) optionally, at least one cyclic carbonate containing fluorine; and vii.
- SEI solid-electrolyte interface
- At least one solid-electrolyte interface (SEI) layer said at least one SEI layer is derived from electrochemical interaction of (i) at least one a cyclic organosulfur additive, and (ii) at least one cyclic carbonate containing fluorine.
- SEI solid-electrolyte interface
- the sulfur species is derived from the at least one cyclic organosulfur additive.
- the at least one cyclic organosulfur additive comprises between 2 and 8 carbons, preferably between 2 and 6 carbon atoms, more preferably 2-4 carbon atoms, and most preferably 2-3 carbon atoms.
- the at least one cyclic organosulfur additive comprises one of formula (I), (II), (III), (IV), (V) or (VI): preferably one of , , , or
- the electrode of claim 1 wherein the linear or cyclic carbonate is selected from at least one of ethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and dimethyl carbonate.
- the lithium halide is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium bis (trifluoromethyl) tetrafluorophosphate (LiPF4(CF3)2), lithium bis(fluorosulfonyl)imide LiFSI, lithium bis (trifluoromethanesulfonyl) imide LiTFSI, lithium perchlorate, lithium hexafluoroarsenate, and lithium trifluoromethanesulfonate.
- the electrode according to any of the preceding claims comprising a conductive component selected from at least one of graphite, graphene, mesocarbon microbeads (MCMB ), silicon, or SiOx or mixtures thereof, silicon/carbon/graphite composites, SiOx/carbon/graphite composite, lithiated tin oxide, conductive black phosphorus, MnP4, CoPz; SnO2, SnO, nanocomposites containing antimony, and oxides of aluminum, titanium, and molybdenum.
- a conductive component selected from at least one of graphite, graphene, mesocarbon microbeads (MCMB ), silicon, or SiOx or mixtures thereof, silicon/carbon/graphite composites, SiOx/carbon/graphite composite, lithiated tin oxide, conductive black phosphorus, MnP4, CoPz; SnO2, SnO, nanocomposites containing antimony, and oxides of aluminum, titanium, and molybden
- the electrode of claim 1 comprising, graphite, conductive carbon and a fibrillated polymer selected from one of a polytetrafluoroethylene (PTFE) homopolymer, a TFE copolymer formed with one of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), fluorinated ethylene propylene (FEP), perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE), and co-coagulated TFE-containing polymers and copolymers.
- PTFE polytetrafluoroethylene
- a fibrillated polymer of a PTFE homopolymer b. a fibrillated polymer of a TFE co-polymer formed with one of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), FEP, perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE); and c. a fibrillated co-coagulated polymer.
- HFP hexafluoropropylene
- PAVE perfluoro(alkyl vinyl ether)
- FEP perfluoro(ethyl vinyl ether)
- PEVE perfluoro(propyl vinyl ether)
- PPVE perfluoro(propyl vinyl ether)
- the electrode according to claim 1 comprising a conductive component comprising one of graphite, graphene, mesocarbon microbeads (MCMB ), silicon, or SiOx or mixtures thereof, silicon/carbon/graphite composites, SiOx/carbon/graphite composite, lithiated tin oxide, conductive black phosphorus, MnP4, CoPz; SnO2, SnO, nanocomposites containing antimony, and oxides of aluminum, titanium, and molybdenum. [0174] 16.
- the electrode according to claim 12 further comprising carbon black. [0175] 17.
- the electrode of claim 1 wherein the fluorinated cyclic carbonate is selected from one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoropropylene carbonate, (TFPC), 4-((2,2,3,3-tetrafluoropropoxy)methyl)- 1,3-dioxolan-2-one (HFEEC), and 4-(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolan-2- one (NFPEC).
- FEC fluoroethylene carbonate
- DFEC difluoroethylene carbonate
- TFPC trifluoropropylene carbonate
- HFEEC 4-(2,2,3,3-tetrafluoropropoxy)methyl)- 1,3-dioxolan-2-one
- NFPEC 4-(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolan-2- one
- the fibrillated fluoropolymer comprises one of (i) a fibrillated polymer of a PTFE homopolymer, (ii) a fibrillated polymer of a TFE co-polymer formed with one of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), FEP, perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE); and (iii) a fibrillated co-coagulated polymer.
- HFP hexafluoropropylene
- PAVE perfluoro(alkyl vinyl ether)
- FEP perfluoro(ethyl vinyl ether)
- PEVE perfluoro(propyl vinyl ether)
- PPVE perfluoro(propyl vinyl ether)
- the cyclic organosulfur additive comprises a cyclic sulfite, a cyclic sulfate or a cyclic sultone.
- cyclic organosulfur additive comprises a cyclic sulfite.
- an electrode and at least one solid-electrolyte interface (SEI) layer comprising a conductive material and a fibrillatable fluoropolymer binder and the layer comprising an electrochemically formed reaction substance between a non-aqueous electrolyte composition containing a solvent, and at least two additives, said additives comprising: (i) a first a cyclic sulfur compound, and (ii) optionally at least a cyclic carbonate containing fluorine.
- SEI solid-electrolyte interface
- a process comprising, a) providing a half cell electrochemical cell containing an anode electrode comprising at least one of graphite, graphene, mesocarbon microbeads (MCMB ), silicon, or SiOx or mixtures thereof, silicon/carbon/graphite composites, SiOx/carbon/graphite composite, lithiated tin oxide, conductive black phosphorus, MnP4, CoPz; SnO2, SnO, nanocomposites containing antimony, oxides of aluminum titanium and molybdenum with a fibrillated PTFE or TFE co-polymer binder, a lithium metal counter-electrode, and an electrolyte comprising a non-aqueous solvent, at least one lithium halide salt, and at least one additive comprising a cyclic organosulfur compound, and b) applying a galvanostatic current at voltages above the lithium intercalation voltage of the electrode and before the decomposition potential of the PTFE or TFE co-pol
- a method for producing an electrode comprising: a. exposing a conductive electrode formed with a fibrillated PTFE or TFE co- polymer binder to a non-aqueous electrolyte comprising a lithium halide salt and cyclic organo- sulfur additive, b. applying a first lithiation current density between C/100 and less than C/10to form a first SEI layer, c. applying an ultimate lithiation current density C/10 from 0.2V to .01V form another SEI layer, and d. applying a delithiation current density for form a stabilized electrode. [0185] 27.
- An SEI formation protocol comprising, a. contacting a conductive electrode having a fibrillated binder with an electrolyte comprising at least a cyclic organosulfur compound, b. applying a first constant current rate lower than C/10 to the electrode and the electrolyte to form a first SEI layer, c.
- the binder comprises one of (i) a fibrillated polymer of a PTFE homopolymer, (ii) a fibrillated polymer of a TFE co- polymer formed with one of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), FEP, perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE); and (iii) a fibrillated co-coagulated polymer. [0192] 34.
- HFP hexafluoropropylene
- PAVE perfluoro(alkyl vinyl ether)
- FEP perfluoro(ethyl vinyl ether)
- PEVE perfluoro(propyl vinyl ether)
- PPVE perfluoro(propyl vinyl ether)
- cyclic organo sulfur compound comprises one of ethylene sulfite (1,3,2-dioxathiolan-2-oxide), ethylene sulfate (1,3,2- dioxathiolane 2,2-dioxide), 1,3-propylene sulfite, 1,3-propylene sulfate, 1,3 propane sultone, and 1-propene-1,3 sultone.
- first and second SEI layers each comprising different electrochemical reaction products formed from a lithium halide salt, a linear or carbonate, a cyclic organo sulfur additive, and optionally a fluorinated cyclic carbonate.
- An SEI layer comprising electrochemically reacted (i) linear or cyclic carbonates selected from one or more ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC) and ethylene carbonate (EC), (ii) one or more lithium halides salts selected from lithium hexafluorophosphate (LiPF6), lithium bis (trifluoromethyl) tetrafluorophosphate (LiPF4(CF3)2), lithium bis(fluorosulfonyl)imide LiFSI, lithium bis (trifluoromethanesulfonyl) imide LiTFSI, lithium difluoro oxalate borate(LiDFOB), lithium bis(oxalate)borate (LiBOB), lithium perchlorate, lithium hexafluoroarsenate, or lithium trifluoromethanesulfonate, and (iii) a cyclic organo sulfur compound selected from one of ethylene
- An SEI composite layer comprising at least first and second layer comprising electrochemically reacted linear or cyclic carbonates selected from one or more ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC) and ethylene carbonate (EC), one or more lithium halides salts selected from lithium hexafluorophosphate (LiPF6), lithium bis (trifluoromethyl) tetrafluorophosphate (LiPF4(CF3)2), lithium bis(fluorosulfonyl)imide LiFSI, lithium bis (trifluoromethanesulfonyl) imide LiTFSI, lithium difluoro oxalate borate(LiDFOB), lithium bis(oxalate)borate (LiBOB), lithium perchlorate, lithium hexafluoroarsenate, or lithium trifluoromethanesulfonate, and a cyclic organo sulfur compound selected from one of
- the SEI composite layer of claim 41 wherein the cyclic organo sulfur comprises 1,3 propane sultone.
- the SEI composite layer of claim 41 wherein the cyclic organo sulfur comprises 1-propene-1,3 sultone.
- An SEI composite layer comprising derived from at least one electrolyte comprising a cyclic organo sulfur compound, optionally a fluorinated cyclic carbonate component layers, and a reduced fibrillated fluoropolymer binder.
- the SEI composite layer of claim 48 wherein the cyclic organo sulfur compound comprises one of comprises one of ethylene sulfite (1,3,2-dioxathiolan-2- oxide), ethylene sulfate (1,3,2-dioxathiolane 2,2-dioxide), 1,3-propylene sulfite, 1,3- propylene sulfate, 1,3 propane sultone, and 1-propene-1,3 sultone. [0211] 53. The SEI layer of claim 40 formed under a constant current rate lower than C/10. [0212] 54. The SEI layer of claim 50 wherein the SEI is ⁇ nm thick. [0213] 55.
- the electrode of claim 9 wherein the cyclic organo sulfur compound comprises, consists essentially of, or consists of a cyclic sulfate or cyclic sulfite. [0214] 56. The electrode of claim 9 wherein the cyclic organo sulfur compound comprises, consists essentially of, or consists of a cyclic sulfite. [0215] 57. The electrode of claim 9 wherein the cyclic organo sulfur compound comprises, consists essentially of, or consists of a compound defined by formula (III) or (VI). [0216] 58. An electrochemical device comprising the electrode of any one of the preceding claims. [0217] 59. A secondary lithium-ion battery comprising the electrode of any one of the preceding claims.
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Abstract
The present invention disclosed herein relates to electrode and solid electrolyte interphase (SEI) layers thereof using fibrillatable PTFE and TFE copolymer binders. The electrode and solid electrolyte interface layers are particularly suitable when preparing electrodes and resulting batteries using dry processing methodology ("dry batter electrode" processing).
Description
TITLE OF THE INVENTION CYCLIC ORGANOSULFUR ADDITIVE CONTAINING ELECTROLYTE FORMULATIONS USED TO DERIVE SEI LAYERS, ELECTRODES, SYSTEMS AND FORMATION PROTOCOLS CROSS REFERENCE TO RELATED APPLICATIONS [0001] This Application claims the priority benefit of US provisional patent application No.63/644,153, filed on May 8, 2024, the disclosure of which is incorporated by reference in its entirety. FIELD [0002] The present invention relates to the field of lithium-ion batteries and electrolyte formulations, methods of forming robust solid electrolyte interphase (SEI) layers on electrodes formed with fibrillatable polytetrafluoroethylene (PTFE) or tetrafluoroethylene (TFE) copolymers and the resulting electrode. BACKGROUND [0003] Electrodes for lithium-ion batteries, e.g., anode or cathode, can be prepared using a variety of binders. Commercially used anode binders are generally relatively reductively stable and, there should be no, or very minimal loss in coulombic efficiency from electrochemical processes related to binder degradation (Nagai, A. in Lithium-ion batteries, Yoshio M., Brodd R.J., Kozawa A. (eds.) (Springer Science, 2009, Berlin/Heidelberg, Germany, Chapter 6, pp.155-161). Two commercially used anode binders are CMC (carboxymethylcellulose) and SBR (styrene butadiene rubber). Polyvinylidene fluoride (PVDF) is another binder frequently evaluated and cited in the literature. These binders are reductively stable, and it has been determined the reductive stability of PVDF and SBR is about the same as polyethylene itself, which is an anodically stable material (FIG.1 and Figure 6.1 of Nagai, A., supra). The calculated lowest unoccupied molecular orbitals (LUMO) of PVDF and SBR are almost the same as that of polyethylene (PE), and thus these compounds may be used as an [anode] binder. As such, “the LUMO of polyethylene (PE) is high would be expected to be
stable in an anodic environment” (Nagai, A., supra). As shown in FIG.1, CMC is also essentially reductively stable. However, FIG.1 also shows that PTFE is the least stable, based on the apparent magnitude of the darkened bar above the x-axis. Unlike many of the binders identified in FIG.1, PTFE and many TFE-based ‘fluoropolymer’ binders possess the remarkable ability to fibrillate when shear stress is applied to the polymer. This allows the fibrillatable polymer to be used in a dry, solvent-less processes to form an electrode with electroactive components, e.g., carbon black and the polymer. These electrodes can be used in lithium-ion batteries. However, the PTFE and TFE-based copolymer binders are reductively or electrochemically unstable when used as an anode in lithium-ion batteries or other electrochemical devices. It is believed the electrochemical reduction of the binder leads to a loss of cell capacity (loss of lithium due to lithiation of the polymer) as well as loss of mechanical cohesion in the electrode. This can lower the cycle life durability of the battery and lead to poorer electrochemical performance. [0004] The initial coulombic efficiency value (ICE) in fully batter design determines the utilization rate of active materials and the total weight of an assembled battery (see U.S. Patent No.4,304,825 to Basu, S., incorporated herein by reference in its entirety). Low ICE values unavoidably lead to unsatisfactory energy density and increased cost of LIBs, which generally originate from the decomposition of electrolyte, poor reversibility of the lithiation/delithiation process, and unknown side reaction[s] (H. Yoshitake, Battery and Power Supply in Techno-Frontier Symposium, Makuhari, Japan (1999)). Although substantial efforts continue to be made to electrode design to improve the ICE of LIBs and achieve obviously improved electrochemical performance, including surface modification, structure engineering, pre-lithiation, and binder optimization (See H. Yoshitake, Functional Electrolyte in Lithium-Ion Batteries (in Japanese), M. Yoshio, A. Kozawa, Eds., Nikkan Kougyou Shinbunsha, Japan, 2000, pp.73–82. The electrolytes remain a key component of lithium-ion batteries which can have a major impact on the initial coulombic efficiency. The reductive instability of the PTFE or TFE-based copolymer binders often results in a diminution of the ICE. Thus, a need still exists to develop electrolyte formulations which form solid electrolyte interphase (SEI) layers
which can stabilize the electrodes containing the fibrillated PTFE and TFE-based copolymer binders when they are used in batteries, especially as anode electrodes. SUMMARY [0005] The present invention disclosed herein relates to solid electrolyte interphase (SEI) layers for electrodes formed by using fibrillatable PTFE and TFE polymers and copolymer binders (collectively fibrillatable “TFE containing polymers” including PTFE homopolymers, modified PTFE, and fibrillatable TFE-based polymers such as TFE- copolymers or terpolymers), and in certain embodiments electrodes formed using dry processing methodology (a solvent-free process, involving dry mixing of materials, forming a film, and lamination onto a current collector (Lu et al., Matter (5) 876-898 (2022)). One aspect of the present invention relates to electrolyte formulations and methods of forming robust SEI layers on electrodes formed with PTFE or TFE copolymers. [0006] The ICE of electrode materials can be calculated from the ratio of the ions that participated in the faradaic reactions to the total ions input into the electrode during the initial cycle, which highly depends on the reversibility of electrode materials, irreversible decomposition of electrolyte, the formation of solid electrolyte interface (SEI) and other side reactions. [0007] As shown in FIG. 2, during the initial charging process, Li+ from the cathode will be inevitably consumed due to the formation of the SEI on the anode and other side reactions (such as the oxidation of solvents, the reaction with current collector), which leads to a lower actual discharge capacity. So, the ICE is closely related to the energy density of full cells due to the limited and single Li+ supply from cathode materials. [0008] The electrolyte is crucial in determining the electrochemical performance of electrode materials, including ICE, cycle life and rate performance, etc. Therefore, improving the ICE by the electrolyte optimization is required. [0009] Certain embodiments of the invention disclosed herein relate to electrodes which comprise one or more solid electrolyte interphase (SEI) layers formed by
subjecting an electrode and its fibrillatable TFE-containing polymers (i.e. PTFE homopolymer, modified PTFE, and TFE-based copolymers/terpolymers) in contact with an electrolyte to a sequence of different current rates. [0010] In other embodiments of the invention disclosed herein, electrodes comprise one or more solid electrolyte interphase (SEI) layers formed by subjecting an electrode and its fibrillated binder in contact with a cyclic organosulfur stabilizing electrolyte to a C/40 current rate to 0.2V and switching to a C/10 rate down to 0.01 V, and then C/10 rate up to 1.5 volts. [0011] In other certain embodiments of the invention disclosed herein, an SEI formation process is applied based on an overall slower lithiation process similar to C/40 from an open cell voltage to 0.8 V vs. Li/Li+ or lower voltage, but just before the lithiation in the active anode material takes place. [0012] In other certain embodiments of the invention disclosed herein, the SEI formation cycle involves a slow lithiation current of C/40 from open cell voltage to 0.2 V vs Li/Li+ which is applied prior to faster the lithiation current of C/10 for the rest of lithiation and delithiation steps of the formation cycle. [0013] In still other embodiments of the invention disclosed herein, electrodes comprise a first C/40 current rate solid electrolyte interphase (SEI) layer, a second C/10 current rate solid SEI layer, and a third C/10 current rate SEI layer. [0014] Several embodiments disclosed herein relate to SEI formation protocols comprising subjecting an electrode in contact with an electrolyte to a first C/40 current rate down to 0.2 volts, a second C/10 rate down to 0.01 V, and a third C/10 rate up to 1.5 volts. [0015] Several embodiments disclosed herein relate to SEI formation protocols comprising applying a first C/40 current rate down to 0.2 volts, a second C/10 rate down to 0.01 V, and a third C/10 rate up to 1.5 volts to an electrode in contact with a cyclic organosulfur electrolyte.
[0016] Several embodiments disclosed herein relate to SEI formation protocols comprising subjecting an electrode in contact with a cyclic organosulfur containing non- aqueous electrolyte to a first C/10 rate or slower (for example, C/50) rate down 0.2V, a second C/10 rate from 0.2 V to > 0 (0.01 V), and a C/10 de-lithiation rate up to 1.5 volts. [0017] Several embodiments disclosed herein relate to SEI formation protocols comprising subjecting an electrode in contact with a non-aqueous electrolyte to one of more lithiation rates, e.g., a rate slower than C/10 might be down 0.2V, a second C/10 rate from 0.2 V to > 0 (0.01 V), and a C/10 de-lithiation rate up to 1.5 volts. [0018] Several embodiments disclosed herein relate to SEI formation involving stepped lithiation protocols comprising subjecting an electrode, formed from conductive material and a TFE fibrillated binder, which is in contact with a non-aqueous, cyclic organosulfur additive containing electrolyte, to increasing current rates from a rate slower or than C/10 or slower rate down 0.2 V vs. Li/Li+ via one or more increasing current rates to a last lithiation step comprising a C/10 rate from 0.2 V to > 0 (0.01 V), followed by a C/10 de-lithiation rate up to 1.5 volts. In several SEI formation protocol embodiments disclosed herein relate to a delithiation step which is preceded by a rest period with a duration ranging from which ranges from > 10 seconds up to ≤60 minutes. [0019] Several embodiments disclosed herein relate to non-aqueous electrolytes comprising a solvent formed from (1) one or more linear carbonates including, but not limited, to ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), cyclic carbonates such as ethylene carbonate (EC), (2) at least one lithium halide salt, including, but not limited, to lithium hexafluorophosphate (LiPF6), lithium bis (trifluoromethyl) tetrafluorophosphate (LiPF4(CF3)2), lithium bis(fluorosulfonyl)imide LiFSI, lithium bis (trifluoromethanesulfonyl) imide LiTFSI, lithium difluoro oxalate borate(LiDFOB), lithium bis(oxalate)borate (LiBOB), lithium perchlorate, lithium hexafluoroarsenate, or lithium trifluoromethanesulfonate, and (3) a cyclic organosulfur compound, and an optional fluoroalkyl salt, wherein the cyclic organosulfur compound includes, but is not limited to, a heterocyclic compound containing carbon, oxygen and sulfur, dimers and trimers thereof.
[0020] Several embodiments disclosed herein relate to non-aqueous electrolytes comprising a solvent, lithium halide salt(s), a cyclic organosulfur compound, and an optional fluoroalkyl salt, wherein the cyclic organosulfur compound includes, but is not limited to heterocyclic compounds containing carbon, oxygen and sulfur comprising a C2-C8 cyclic sulfate, sulfite or sulfone. [0021] Several embodiments disclosed herein relate to non-aqueous electrolytes comprising at least one linear carbonate selected from one or more of ethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate, lithium halide salts selected from one of lithium difluoro oxalate borate (LiDFOB), lithium bis(oxalate) borate (LiBOB), lithium bi(fluorosulfonyl) imide (LiFSI) and a cyclic organosulfur additive comprising, consisting essentially of or consisting of a C2-C8 cyclic sulfate, sulfite or sultone. [0022] Several embodiments disclosed herein relate to non-aqueous electrolytes comprising at least one linear carbonate selected from one or more of ethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate, and one of lithium difluoro oxalate borate (LiDFOB), lithium bis(oxalate) borate (LiBOB), lithium bi(fluorosulfonyl) imide (LiFSI) and stabilizing additives comprising cyclic organosulfur compounds and fluorocarbonates. [0023] One or more embodiments disclosed herein also relate to electrodes comprising a fibrillated fluoropolymer binder bearing an electrochemically induced interface layer derived from an electrolyte comprising at least a lithium salt compound containing lithium, fluorine and one of a carbonate, borate, chlorate, oxalate, or sulfonyl group, and at least one cyclic organosulfur compound. [0024] One or more embodiments disclosed herein also relates to systems, half- cells, and full-cells containing anode electrodes having one or more SEI layers in contact with a non-aqueous electrolyte, the anode electrode comprises a conductive material, a fibrillated fluoropolymer binder, the non-aqueous electrolyte comprises at least one linear carbonate, at least one lithium halide salt compound containing lithium, fluorine/chlorine and one of a carbonate, borate, chlorate, oxalate, sulfonyl group, and sulfide, and a heterocyclic compound containing carbon, sulfur and multiple oxygen
atoms, and the SEI layers are electrochemically derived from the non-aqueous electrolyte, and methods of forming the anode of the systems, half-cells, and full-cells. [0025] One or more embodiments disclosed herein also relates to systems, half- cells, and full-cells containing anode electrodes having one or more SEI layers in contact with a non-aqueous electrolyte, the anode electrode comprises a conductive material, a fibrillated fluoropolymer binder, the non-aqueous electrolyte comprises linear or cyclic carbonates selected from at least one of ethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or dimethyl carbonate, a lithium halide selected from one or more of lithium hexafluorophosphate (LiPF6), lithium bis (trifluoromethyl) tetrafluorophosphate (LiPF4(CF3)2), lithium bis(fluorosulfonyl)imide LiFSI, lithium bis (trifluoromethanesulfonyl) imide LiTFSI, lithium perchlorate, lithium hexafluoroarsenate, or lithium trifluoromethanesulfonate, and a compound containing one or more heterocyclic substituents each containing carbon, sulfur and oxygen atoms, wherein one or more of the heterocyclic substituents independently include between 2 and 8 carbon atoms, and optionally a fluorinated cyclic carbonate. [0026] Other embodiments disclosed herein relate to anode of systems, half-cells, and full-cells in which the anode comprises a fibrillated fluoropolymer binder bearing first and second electrochemically produced interface layers derived from a non- aqueous solvent containing a linear carbonate, at least one lithium salt compound containing lithium, fluorine and one of a carbonate, borate, chlorate, oxalate, sulfonyl group or a sulfide, and at least a cyclic, dicyclic and tricyclic organosulfur compound, and methods of forming the anode of the systems, half-cell, and full-cell. [0027] Other embodiments disclosed herein relate to non-aqueous electrolytes comprising, consisting essentially of, or consisting of one or more non-aqueous solvents comprising linear carbonates, and at least one additive comprises a heterocyclic sulfur compound defined by one of the following formulae:
wherein the heterocyclic sulfur compounds can be substituted with A and A’, each A and A’ is independently a hydrogen, fluorine, or optionally acyclic ethers including without limitation vinyl, allyl, acetylenic , propargyl , or C1–C3 alkyl, wherein the vinyl (H2C=CH ), allyl ( H2C=CH-CH2-), acetylenic ( =C- ), propargyl (HC=C-CH2–), or C1-C3 alkyl group is, unsubstituted, partially, or totally fluorinated; wherein A and A’ are also independently a hydrocarbon substituent having one or more fluorine atoms, or one of compounds defined by formula (I), (II), (III), (IV), (V), or (VI). [0028] Other embodiments disclosed herein relate to non-aqueous electrolytes comprising, consisting essentially of, or consisting of one or more non-aqueous solvents comprising linear carbonates, and at least one additive comprises a heterocyclic sulfur compound defined by one of the following formulae (II), (III), (V) or (VI), wherein A and A’ are defined above.
[0029] In certain embodiments disclosed herein the number of carbon atoms in the heterocyclic sulfur compound or cyclic organosulfur additive compound comprises 2, 3, 4, 5, 6, 7 and up to 8 carbon atoms, preferably between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms. [0030] In certain embodiments disclosed herein the C, S, O heterocyclic compound or cyclic organosulfur additive compound comprises at least one C, S, O heterocyclic substituent, each substituent preferably having between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms, most preferably 2 carbon atoms. [0031] In certain embodiments relate to an additive system comprising a first C, S, O heterocyclic compound or cyclic organosulfur compound with at least one C, S, O heterocyclic substituent, each substituent preferably having between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms and a fluorinated cyclic carbonate. [0032] Certain embodiments disclosed herein relate to non-aqueous electrolytes containing one or more additives, wherein at least one additive comprises, consists essentially of, or consists of a compound containing linked C, S, O heterocyclic
substituents preferably having between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms and a fluorinated cyclic carbonate. [0033] In certain embodiments disclosed herein relate to an additive system comprising a first C, S, O heterocyclic compound or cyclic organosulfur compound with at least one C, S, O heterocyclic substituent, each substituent preferably having between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms and a fluorinated cyclic carbonate, and the additive system amounts to about >0 to ≤10 wt % of the total amount of stabilizing electrolyte. [0034] In certain embodiments disclosed herein relate to stabilizing non-aqueous electrolytes comprising a first C, S, O heterocyclic compound or cyclic organosulfur compound with at least one C, S, O heterocyclic substituent, each substituent preferably having between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms and a second fluorinated cyclic carbonate, and first and second stabilizers amount to about >0 to ≤10 wt % of the total amount of stabilizing electrolyte. [0035] The present invention also relates to systems including electrolyte formulations and electrodes with a fibrillated fluoropolymer binder and SEI surface layer formed by electrochemical reduction and interaction of at least a surface of the fibrillated fluoropolymer binder and at least one cyclic organosulfur compound comprising, consisting essentially, or consisting of one or more cyclic sulfate, sulfite or sultone components which are capable for forming an SEI layer with electrolyte components to form one or more SEI layers which o stabilize the electrode. [0036] In one embodiment of the present invention the electrolyte includes a cyclic sulfur additive including, but not limited to sulfite, sulfate or sultone compounds having 2-8, preferably 2-4 ring carbons in the main ring, such as ethylene sulfite (1,3,2- dioxathiolan-2-oxide), ethylene sulfate (1,3,2-dioxathiolane 2,2-dioxide), 1,3-propylene sulfite, 1,3-propylene sulfate, 1,3 propane sultone, and 1-propene-1,3 sultone. [0037] In other embodiments of the present invention the organo- sulfate, sulfite or sultone additives/compounds includes but is not limited to compounds having one of the following formula,
O O O O O A'
preferably one of formula (II), (III), (V), or (VI)
wherein each A and A’ is independently a hydrogen or optionally acyclic ethers include without limitation vinyl, allyl, acetylenic, propargyl or C1–C3 alkyl. The vinyl (H2C=CH-),
allyl ( H2C=CH-CH2-), acetylenic ( =C-), propargyl (HC=C-CH2–) or C1-C3 alkyl groups, can be unsubstituted or partially or totally fluorinated. In certain embodiments the number of carbon atoms in the cyclic sulfur include 2, 3, 4, 5, 6, 7, and up to 8 carbons, preferably between 2 and 4 carbon atoms, more preferably 2-3 carbon atoms. [0038] In certain embodiments disclosed herein the non-aqueous electrolyte comprises at least a first additive selected from a C2-C4 cyclic sulfite, sulfate or sultone and optionally, a second additive which comprises a fluorinated cyclic carbonate component, in additive quantities, e.g., less than 10 weight %, preferably less than 5 weight %, most preferably between > 0.1 weight % and 5 weight %. [0039] In certain embodiments disclosed herein the non-aqueous electrolyte comprises at least a first additive selected from a C2-C4 cyclic sulfite, sulfate or sultone and optionally, a second additive which comprises a fluorinated cyclic carbonate selected from a first fluorinated cyclic carbonate component, such as fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoropropylene carbonate, (TFPC), 4-((2,2,3,3-tetrafluoropropoxy)methyl)-1,3-dioxolan-2-one (HFEEC), and 4- (2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolan-2-one (NFPEC), illustrated below:
(DFEC)
uoopopye e - , , , -e a- - , , , , , , , , - carbonate (TFPC) fluoropropoxy)methyl)-1,3- nonafluoropentyl)-1,3- dioxolan-2-one (HFEEC) dioxolan-2-on (NFPEC) [0040] In certain embodiments disclosed herein the non-aqueous linear carbonate electrolyte comprises at least a first additive selected from a C2-C4 cyclic sulfite, sulfate or sultone comprising a 2 or 3 carbons atoms in the ring, and defined by anyone of the formula below:
preferably one of formula (II), (III), (V), or (VI)
wherein each A or A’ is independently a hydrogen or optionally acyclic ethers include without limitation vinyl , allyl, acetylenic, propargyl or C1–C3 alkyl. The vinyl (H2C=CH-), allyl ( H2C=CH-CH2-), acetylenic ( =C- ), propargyl (HC=C-CH2–) or C1-C3 alkyl groups, can be unsubstituted or partially or totally fluorinated. In addition, A or A’ could be joined to another cyclic organo structure similar to formula (I)-(VI), preferably (II), (III), (V) or (VI) or other C, S, O heterocyclic structures having 2-8 carbon atoms and substituted as above. [0041] In certain embodiments disclosed herein the non-aqueous electrolyte comprises at least a first additive selected from a C2-C4 cyclic sulfite, sulfate or sultone comprising a 2 or 3 carbons atoms in the ring, and defined by anyone of the formula below:
O O O O O A'
preferably one of formula (II), (III), (V), or (VI)
wherein each A or A’ is independently a hydrogen or optionally acyclic ethers include without limitation vinyl, allyl, acetylenic, propargyl or C1–C3 alkyl. The vinyl (H2C=CH-),
allyl ( H2C=CH-CH2-), acetylenic ( =C- ) , propargyl (HC=C-CH2–), or C1-C3 alkyl groups, can be unsubstituted or partially or totally fluorinated and a second additive including, but not limited to, fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoropropylene carbonate, (TFPC), 4-((2,2,3,3-tetrafluoropropoxy)methyl)-1,3- dioxolan-2-one (HFEEC), and 4-(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolan-2-one (NFPEC). [0042] In certain embodiments disclosed herein the cyclic organosulfur compound comprises, consists essentially of, or consists of a cyclic sulfate or cyclic sulfite. [0043] In certain embodiments disclosed herein the cyclic organosulfur compound comprises, consists essentially of, or consists of a cyclic sulfite. [0044] In certain embodiments disclosed herein the cyclic organosulfur compound comprises, consists essentially of, or consists of a compound defined by formula (III) or (VI). [0045] In certain embodiments disclosed herein the cyclic organosulfur compound comprises, consists essentially of, or consists of a compound defined by formula (II), (III), (V), or (VI). [0046] In several embodiments disclosed herein the first cyclic sulfur additive in the electrolyte unexpectedly provides improved performance, e.g., coulombic efficiency, relative to electrolyte formulations which lack the cyclic sulfur additive. [0047] In several embodiments disclosed herein inclusion of the first cyclic organosulfur additive in combination with a second fluorinated cyclic carbonate additive in the non-aqueous electrolyte forms one or more layers upon a series of lithiation and delithiation steps which unexpectedly improved stability of TFE-containing fibrillated fluoropolymer binders of the electrode, preferably wherein the binder comprises, consists essentially of, or consists of fibrillatable PTFE homopolymers, fibrillatable modified PTFE, fibrillatable TFE copolymers/terpolymers, and combinations thereof, which is believed to result from synergy between the fluorinated cyclic carbonate and cyclic organosulfur additive and other electrolyte components.
[0048] In several embodiments disclosed herein inclusion of the first cyclic sulfur additive in combination a second fluorinated cyclic carbonate additive unexpectedly improved stability of the electrode containing a fibrillated fluoropolymer binder, preferably wherein the binder comprises, consists essentially of, or consists of PTFE homopolymers or TFE-based polymers (including modified PTFE where the total comonomer content is 1 wt% or less of the modified PTFE) having at least one comonomer of hexafluoropropylene (HFP), and/or perfluoro(alkyl vinyl ether) (PAVE) in which the linear or branched alkyl group contains 1 to 5 carbon atoms, FEP (TFE/HFP copolymer and TFE/HFP/PAVE copolymer), PFA (TFE/PAVE copolymer), wherein PAVE is most preferably perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE), or the combination of perfluoro(methyl vinyl ether)(PMVE) and PPVE, i.e., TFE/PMVE/PPVE copolymer (MFA), which is believed to result from synergy between the fluorinated cyclic carbonate and cyclic organosulfur additive. [0049] In several embodiments disclosed herein including both a fluorinated cyclic carbonate additive and a cyclic organosulfur additive an unexpected improvement in the electrochemical performance of the electrode is obtained and believe to be due to the formation of solid electrolyte interphase layers on the anode electrode comprising fibrillatable fluoropolymer binders described herein. [0050] Embodiments of the invention disclosed herein relate to half-cells and full cells comprising (1) electrodes formed with fibrillated fluoropolymer binder, such as PTFE and TFE containing copolymers, preferably wherein the binder comprises, consists essentially of, or consists of PTFE, or TFE copolymers (including modified PTFE) formed with one of hexafluoropropylene (HFP), and/or perfluoro(alkyl vinyl ether) (PAVE) in which the linear or branched alkyl group contains 1 to 5 carbon atoms, FEP (TFE/HFP copolymer and TFE/HFP/PAVE copolymer), PFA (TFE/PAVE copolymer), wherein PAVE is most preferably perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE), or the combination of perfluoro(methyl vinyl ether)(PMVE) and PPVE, i.e. TFE/PMVE/PPVE copolymer (MFA), (2) electrolytes containing at least a first cyclic organosulfur compound, e.g., a sulfite, sulfate, or sultone compounds having a 4 to 10 member ring
[0051] Certain embodiment disclosed herein relate to half-cells and full cells comprising (1) electrodes formed with fibrillated fluoropolymer binder, such as PTFE and TFE containing copolymers, preferably wherein the binder comprises, consists essentially of, or consists of PTFE, modified PTFE or TFE copolymers formed with one of hexafluoropropylene (HFP), and/or perfluoro(alkyl vinyl ether) (PAVE) in which the linear or branched alkyl group contains 1 to 5 carbon atoms, FEP (TFE/HFP copolymer and TFE/HFP/PAVE copolymer), PFA (TFE/PAVE copolymer), wherein PAVE is most preferably perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE), or the combination of perfluoro(methyl vinyl ether)(PMVE) and PPVE, i.e., TFE/PMVE/PPVE copolymer (MFA), (2) an LiPF6-EC/DEC electrolyte solution containing at least one organosulfur compounds, e.g., a sulfite, sulfate, or sultone compound having a 4 to 10 member ring, and (3) at least first and second SEI layers formed from the components of the electrolyte solution by slow lithiation similar to C/40 to 0.2V and then faster lithiation to 0.01V. [0052] One embodiment disclosed herein relates to a process comprising contacting a surface of a graphite electrode containing a fibrillated fluoropolymer binder with a LiPF6-EC/DEC solution containing at least one cyclic organosulfur compounds, e.g., a sulfite, sulfate or sultone compound having a 4-to-10-member ring under slow lithiation similar to C/40 to 0.2V and then faster lithiation below 0.2V . [0053] As disclosed herein, electrochemical evaluations include half-cell evaluations using lithium metal counter electrodes examined galvanostatically. The galvanostatic data clearly show the significant impact that electrolyte formulations have on the initial coulombic efficiency with the electrolyte formulations which produce the SEI (solid electrolyte interphase) layers of this invention. SEI layer formation depends on the anode material, its microstructure, electrolyte salt and electrolyte solvent in the system. [0054] The formation protocol for SEI electrode layers is modified to further enhance SEI formation from the electrolyte formulations with an initial slow lithiation current of C/40 to 0.2V, and improvements in the coulombic efficiency when the modified formation protocols are used occur.
[0055] Another aspect of this invention is the unusual synergy and combination of the electrolyte with these formation protocols. [0056] The protocol modified to increase the time the cell/anode will be exposed to voltages higher than the decomposition potential of the TFE copolymer electrode binder such that robust SEI gets formed on the anode surface which protects from further decomposition at the lower voltages. [0057] In one embodiment, in a half cell electrochemical cell containing a graphite electrode and a lithium metal counter-electrode, galvanostatic current used can be very low C rate < C/10, e.g., C/40 at voltages above the lithium intercalation voltage of the graphitic anode or any other anode. The effective SEI layer is formed before (above or positive of) the decomposition potential of the PTFE or TFE copolymer binder in the graphite anode. Because of the robust SEI formation before the decomposition potential of the PTFE or TFE co-polymer binder there is less loss of cyclable lithium through a PTFE reduction process thereby providing higher coulombic efficiency of Graphite/Li half cells. This approach provides an SEI formation protocol for half cells. The duration of this C/40 formation significantly lowers the formation time compared to both charge current and discharge current of C/25 in the formation protocol and also substantially improves the 1st cycle Coulombic Efficiency. While not being bound by any theory the C/40 formation protocol generates effective (probably thinner) SEI layers such that there is more lithium delithiation or less lithium loss from the graphite anode providing higher delithiation capacity. [0058] Alternatively, the C rate can be diminished so that the voltage varies little above 0.8 V versus Li/Li+, before resuming the discharge of the half-cell battery to lower voltages vs Li/Li+. These procedures are beneficial establishing a protective SEI layer before the voltage is realized at which the PTFE or TFE copolymer will decompose (about 0.6- 0.8 V versus Li/Li+). This strategy can be translated to the formation protocol of full cells. The charge-discharge potential window of the full cells depends on what type of anode and cathode are utilized. SEI formation takes place in the initial stage of the 1st Charge in a full cell while this happens in the initial stage of discharge in half cell. For example, LiNi0.8Mn0.1Co0.1O2 cathode vs Graphite anode is utilized in the
commercial lithium-ion battery. The safe and efficient charge-cut off potential is 4.2V (Eldesoky, A. et al., 2022, J. Electrochem. Soc. 169010501; Vidal Laveda et al., ACS Appl. Energy Mater.2019, 2(10), 7036–7044. In order to apply this formation strategy, lower charging current in the potential region before lithium intercalation is used in the graphite anode. [0059] Formation protocols in a half cell, with a lithium counter electrode, also include C/40 lithiation to 0.2V vs Li/Li+, C/10 lithiation to 0.01V vs Li/Li+, and C/10 delithiation to an upper cut off voltage can range from 1.2 to 1.5V vs Li/Li+. Specifically, the inventive formation protocols start with applying lower current of C/40 at the voltage of the open circuit (which can be over 2.0 V). The voltage decreases during the lithiation process of the graphite electrode. This formation is performed galvanostatically at a rate of C/40 down to 0.2 V. Afterwards, the C rate (current) is increased to C/10 until 0.01 V versus Li/Li+. Thereafter, the lithiation is reversed (or the graphite electrode is delithiated) at a current of C/10 to 1.25 up to 1.5 V versus Li/Li+. [0060] As demonstrated herein, the presence of effective amounts of cyclic organosulfur compounds in the electrolyte allows for the formation of several SEI layers which stabilize the electrode and allows for high coulombic efficiency. While not being bound by any theory, the solid electrolyte interphase layer (SEI) formed during the formation cycle using the electrolyte component in the electrolyte formulation stabilized the fibrillated fluoropolymer binder (i.e., fibrillatable TFE copolymers and/or PTFE binders) components of the electrode with respect to electrochemical reduction. In addition, the electrolyte is stabilized against reduction over other components of the anode surface. Decomposition of the PTFE or TFE copolymer binder is believed to generate high surface area carbon-type products. Applicants believe the electrolyte additives described herein form SEI layers which prevent reduction on these newly formed surfaces during the formation cycle. The net result is that the coulombic efficiency of the cell during the first formation cycle is substantially improved. The coulombic efficiency (CE) is the ratio of the charge (delithiation of graphite in a half cell) capacity to discharge (lithiation of graphite in half cell) capacity during the formation cycle; this is typically monitored to determine initial cell performance. The initial
coulombic efficiency is substantially increased, in some cases, to > 90 %. Electrolyte formulations without these additives show much lower initial coulombic efficiency of 55- 57 %, indicating significant side reactions which lead to the loss of cyclable lithium. These reactions can include the electrochemical reduction of the binder, electrolyte reduction on the anode surface, and electrolyte reduction on surfaces generated by any reduced binder. [0061] In all of the forgoing embodiments electrodes will include electroactive components, which can be selected from one of or more of silicon, SiOx, lithium alloys such as lithium - aluminum alloy, lithium - lead alloy, lithium - silicon alloy, and lithium - tin alloy; carbon materials such as carbon black, graphite, graphene, carbon nanotubes, mesocarbon microbeads (MCMB ), carbon nanotubes, conductive carbon,; phosphorus -containing materials such as conductive black phosphorus, metal oxides such as SnO2, SnO and TiO2; nanocomposites containing antimony or tin, for example nanocomposites containing antimony, oxides of aluminum, titanium, or molybdenum. [0062] In one embodiment disclosed herein, the anode active material comprises graphite, graphene, silicon or SiOx or mixtures thereof. [0063] In certain embodiment disclosed herein the anode-additive containing electrolyte is assemble in suitable container to provide electrochemical cell components and a cathode. Housing materials are well-known in the art and can include, for example, metal and polymeric housings. While the shape of the housing is not particularly important, suitable housings can be fabricated in the shape of a small or large cylinder, a prismatic case, or a pouch. The anode and the cathode may be comprised of any suitable conducting material depending on the type of electrochemical cell. [0064] The porous separator serves to prevent short circuiting between the anode and the cathode. The porous separator typically consists of a single- ply or multi-ply sheet of a microporous polymer such as polyethylene, polypropylene, polyamide, polyimide or a combination thereof. The pore size of the porous separator is sufficiently large to permit transport of ions to provide ionically conductive contact between the anode and the cathode, but small enough to prevent contact of the anode and cathode
either directly or from particle penetration or dendrites which can form on the anode and cathode. Examples of porous separators suitable for use herein are disclosed in U.S. Patent No.8,518,525, incorporated herein by reference in its entirety. [0065] In some embodiments, suitable examples of cathode materials include, but are not limited to graphite, graphene, aluminum, platinum, palladium, electroactive transition metal oxides comprising lithium or sodium, indium tin oxide, and conducting polymers such as polypyrrole and polyvinyl ferrocene. [0066] Suitable cathodes include those disclosed in U.S. Patent NOs 5,962,166; 6,680,145; 6,964,828; 7,026,070; 7,078,128; 7,303,840; 7,381,496; 7,468,223; 7,541,114; 7,718,319; 7,981,544; 8,389,160; 8,394,534; and 8,535,832, each incorporated herein by reference in its entirety. By "rare earth element" is meant the lanthanide elements from La to Lu, and Y and Sc. [0067] In another embodiment, the cathode material is an NMC cathode; that is, a LiNiMnCoO cathode, more specifically, cathodes in which the atomic ratio of Ni: Mn: Co is 1:1:1 (LiaNia-b-cCobRcO2-dZd where 0.98 < a < 1.05, 0 < d < 0.05, b = 0.333, c = 0.333, where R comprises Mn) or where the atomic ratio of Ni: Mn: Co is 5:3:2 (LiaNia-b- cCobRcO2-dZd where 0.98 < a < 1.05, 0 < d < 0.05, c = 0.3, b = 0.2, where R comprises Mn). [0068] In another embodiment, the cathode comprises a material of the formula LiaMnbJcO4Zd, wherein J is Ni, Co, Mn, Cr, Fe, Cu, V, Ti, Zr, Mo, B, Al, Ga, Si, Li, Mg, Ca, Sr, Zn, Sn, a rare earth element, or a combination thereof; Z is F, S, P, or a combination thereof; and 0.9 < a < 1.2, 1.3 < b < 2.2, 0 < c < 0.7, 0≤d < 0.4. [0069] In another embodiment, the cathode is a stabilized manganese cathode comprising a lithium-containing manganese composite oxide having a spinel structure as cathode active material. The lithium-containing manganese composite oxide in a cathode suitable for use herein comprises oxides of the formula LixNiyMzMn2-y-zO4-d, wherein x is 0.03 to 1.0; x changes in accordance with release and uptake of lithium ions and electrons during charge and discharge; y is 0.3 to 0.6; M comprises one or more of Cr, Fe, Co, Li, Al, Ga, Nb, Mo, Ti, Zr, Mg, Zn, V, and Cu; z is 0.01 to 0.18; and d
is 0 to 0.3. In one embodiment in the above formula, y is 0.38 to 0.48, z is 0.03 to 0.12, and d is 0 to 0.1. In one embodiment in the above formula, M is one or more of Li, Cr, Fe, Co, and Ga. Stabilized manganese cathodes may also comprise spinel-layered composites which contain a manganese-containing spinel component and a lithium rich layered structure, as described in U.S. Patent No.7,303,840. BRIEF DESCRIPTION OF THE DRAWINGS [0070] FIG. 1 illustrates comparative properties of commercially available binders from density functional theory (DFT) calculations (see Nagai, A., supra). [0071] FIG. 2 illustrates an SEI formation protocol. [0072] FIG. 3 illustrates the inventive SEI formation protocol. [0073] FIG. 4 illustrates a typical half-cell. [0074] FIG. 5 illustrates a typical full cell. [0075] FIGs 6A through 6C illustrates a series of X-ray photoelectron spectrometer (XPS) spectra corresponding to the binding energy of sulfur species within the solid electrolyte interphase. FIG.6A illustrates the XPS spectra for Example 8b. FIG.6B illustrates the XPS spectra for Example 4a. FIG.6C illustrates the XPS spectra for the comparative example. [0076] FIGs 7A thorough 7D are the XPS spectra corresponding to carbon structures with the peak that represents a carbon-carbon double bond specifically highlighted. FIG. 7A illustrates the XPS spectra for Example 8b before cycling while FIG.7B is the XPS spectra for Example 8b after cycling. FIG.7C is the XPS spectra for the comparative example while FIG.7D is the XPS spectra for Example 4a after cycling. DETAILED DESCRIPTION [0077] The present invention relates to anode electrodes containing TFE copolymer or PTFE binders which are stabilized with electrolyte formulations containing electrolyte additives. Cyclic sulfite, sulfite or sultone additive-containing electrolyte formulation help
stabilize the electrolyte against reduction on these newly formed surfaces during the formation cycle (i.e. stabilizing against decomposition of PTFE or TFE-copolymer binders that generate high surface area carbon type products). As a result, the initial coulombic efficiency of the cell during the first formation cycle is substantially improved. The coulombic efficiency is the ratio of the charge (delithiation of graphite in a half cell) capacity to discharge (lithiation of graphite in a half cell) capacity during the formation cycle; this is typically monitored to determine initial cell performance. The initial coulombic efficiency is substantially increased, in some cases, to > 90 %. Lithium-ion battery cells containing electrolyte formulations without these additives show an initial coulombic efficiency of 55-57 %. [0078] In one embodiment, the electrolyte formulation, which form the solid electrolyte interphase (SEI) layer(s) on the electrode, comprise a cyclic additive containing sulfur. The cyclic sulfur containing compound can be a cyclic sulfite, sulfate or sultone represented by formulas below:
preferably one of formula (II), (III), (V), or (VI),
wherein each A and A’ is independently a hydrogen, optionally acyclic ethers including without limitation vinyl, allyl, acetylenic, propargyl or C1–C3 alkyl. The vinyl (H2C=CH), allyl (H2C=CH-CH2-), acetylenic ( =C ), propargyl (HC=C-CH2–), C1-C3 alkyl groups, unsubstituted or partially or totally fluorinated, another C, O, S heterocyclic as defined by Formula (II), (III), (V) or (VI). [0079] In certain embodiments disclosed herein, the cyclic organosulfur compound comprises, consists essentially of, or consists of a cyclic sulfate or cyclic sulfite. [0080] In certain embodiments disclosed herein, the cyclic organosulfur compound comprises, consists essentially of, or consists of a cyclic sulfite. [0081] In certain embodiments disclosed herein, the cyclic organosulfur compound comprises, consists essentially of, or consists of a compound defined by formula (III) or (VI). [0082] In electrode embodiments disclosed herein, one or more layers on a fibrillated polymer substrate surface or a reduced polymer substrate surface comprises one or more films independently the same or different chemically, and each independently continuous, non-continuous, and/or fragmented.
[0083] Before addressing details of embodiments described herein, some terms are defined or clarified as follows. [0084] The term “ electrolyte composition" as used herein, refers to a chemical composition that includes at a minimum a solvent for an electrolyte salt and an electrolyte salt, wherein the composition is suitable as an electrolyte in an electrochemical cell. An electrolyte composition can include other components to enhance the performance of the battery in safety, reliability, and or efficiency. [0085] The term “ electrolyte salt ” as used herein, refers to an ionic salt that is at least partially soluble in the solvent of the electrolyte composition and that at least partially dissociates into ions in the solvent of the electrolyte composition to form an ionically conductive electrolyte composition. [0086] An “electrolyte solvent” as defined herein, is a solvent or a solvent mixture for an electrolyte composition that can comprise, for example and without limitation, linear carbonates such as diethyl carbonate, ethyl methyl carbonate, or dimethyl carbonate, cyclic carbonates such as ethylene carbonate, and fluorinated carbonates, esters, or ethers or their combination. Additionally, fluorinated and non-fluorinated solvents can be used, for example, non-fluorinated ethers such as the cyclic ether tetrahydrofuran, and fluorinated solvents such as 2,2 difluoroethyl acetate, a fluorinated ester, or 2,2 difluoroethyl methyl carbonate or a fluorinated carbonate. In all cases, the electrolyte can comprise more than one solvent, and in many cases, two or more solvents. The solvent can participate in reactions to create a solid electrolyte interphase. [0087] The term "anode” refers to the electrode of an electrochemical cell. In a secondary (i.e., rechargeable ) battery. The anode is the electrode at which oxidation occurs during discharge and reduction occurs during charging. [0088] The term "cathode” refers to the electrode of an electrochemical cell. In a secondary (i.e., rechargeable ) battery. The cathode is the electrode at which reduction occurs during discharge and oxidation occurs during charging.
[0089] The term “ lithium-ion battery ”refers to a type of rechargeable battery in which lithium ions move from the anode to the cathode during discharge and from the cathode to the anode during charge. [0090] As used herein, the phrase “lithium intercalation voltage of the graphitic anode” is meant to cover a voltage range which is approximately 0.2 to 0.01 V versus Li/Li+ . [0091] As used herein, the phrase “decomposition potential of the PTFE or TFE co- polymer” is defined as the voltage range where the majority of the PTFE or TFE co- polymer decomposition occurs, which is about 0.3- 0.8 volts vs Li/Li+. [0092] As used herein the terms product, film, layer or deposit “derived from” and “generated from” is meant to include products, films, layers or deposits formed from, inter alia, decomposition, absorption, assimilation, infusion, incorporation, polymerization, reaction, co-polymerization with other electrolyte additives and components, co-polymerization with a partially reduced polymer of a polymer substrate or polymeric component of an electrode, or combinations of the above. [0093] The “derived/generated” product, film, layer or deposit is one or more continuous or discontinuous films/layers on the polymer which may be different than another layer on other electrode components. The derived/generated product, film, layer or deposit may comprise one or more layers or films, wherein each layer or film of a multiple layer or film is independently continuous or discontinuous. The polymer substrate or the polymeric component of the electrode optionally includes a structure comprising fibrils. In a further embodiment, the polymer substrate or polymeric component of the electrode include a structure comprising a plurality of fibrils (i.e., a fibrillated polymer structure). [0094] Coulombic efficiency (CE) of an anode as used herein is the percentage ratio of specific charge (delithiation in a half cell) capacity to specific discharge (lithiation in a half cell) capacity. The 1st cycle CE indicates the loss of capacity during SEI formation and robustness of SEI to provide the reversibility of lithium intercalation and deintercalation.
[0095] A used herein “SEI” is meant to describe a solid electrolyte interface layer formed during the initial cycle of discharge-charge cycle as a result of electrolyte components undergoing electrochemical reaction on the surface of anode components which are conductive. The formed SEI protects the anode components from forming new surfaces and it also protects electrolyte from further decomposing; in some cases, this includes prevention of volatile products that contribute to gassing. A robust SEI formation due to the interaction of electrolyte and anode component in the initial cycle of discharge-charge cycle is crucial for superior performance of lithium-ion battery for many reversible charge discharge cycles. Such lithium-ion batteries are needed to increase the lifetime of electrical vehicles, laptop computers, and other electrical devices that contain batteries. [0096] As used herein, the “equilibrium potential between lithium and lithium ion” is the potential of a reference electrode using lithium metal in contact with the non- aqueous electrolyte containing lithium salt at a concentration sufficient to give about 1 mole/liter of lithium ion concentration and subjected to sufficiently small currents so that the potential of the reference electrode is not significantly altered from its equilibrium value (Li/Li+). The potential of such a Li / Li+ reference is assigned here the value of 0.0 V. [0097] As used herein “voltage” means the potential difference between the cathode and the anode of a cell, neither electrode of which may be operating at a potential of 0.0 V. [0098] As used herein the term “about” in certain embodiments can be quantified to mean ± 1%, ± 2%, ± 3% up to and including ±10% of the stated value, and all whole numbers and fractions therebetween. [0099] As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to
an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present), and B is false (or not present), A is false (or not present), and B is true (or present), and both A and B is true (or present). [0100] The transitional phrase “consisting of” excludes any element, step, or ingredient not specified. If in the claim such would close the claim to the inclusion of materials other than those recited except for impurities ordinarily associated therewith. When the phrase “consists of” appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole. [0101] The transitional phrase “consisting essentially of” is used to define a composition, method that includes materials, steps, features, components, or elements, in addition to those literally disclosed provided that these additional included materials, steps, features, components, or elements do not materially affect the basic and novel characteristic(s) of the claimed invention, especially the mode of action to achieve the desired result of any of the processes of the present invention. The term ‘consisting essentially of’ occupies a middle ground between “comprising” and ‘consisting of.’ [0102] Where an invention or a portion thereof is defined with an open-ended term such as “comprising,” it should be readily understood that (unless otherwise stated) the description should be interpreted to also include such an invention using the terms “consisting essentially of” or “consisting of.” [0103] Also, use of “a” or “an” are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise. [0104] Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range. Moreover, all ranges set forth herein are
intended to include not only the particular ranges specifically described, but also any combination of values therein, including the minimum and maximum values recited. [0105] When an amount, concentration, or other value or parameter is given as either a range, preferred range or a list of upper preferable values and/or lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. [0106] Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. [0107] As used herein the terms “PTFE” binder or “TFE copolymer” binder is meant to mean a PTFE homopolymer formed from polymerizing tetrafluoroethylene monomers or a TFE containing copolymer contains tetrafluoroethylene (TFE) copolymerized with other monomers. In another embodiment, the binder comprises a fibrillatable PTFE homopolymer or fibrillatable TFE copolymer; wherein the binder partially or completely fibrillates upon application of sufficient shear. One concept of the present invention is to provide a lithium battery with a graphite-carbon electrode containing a PTFE or TFE copolymer binder that is resistant to or resistive of destabilization of the fibrillated binder to substantially maintain the integrity of the fibril structure, binder and electrode. [0108] In one embodiment, the binder comprises a tetrafluoroethylene homopolymer, consisting essentially of repeating units arising from the tetrafluoroethylene monomer, as disclosed in U.S. Provisional Application No.63/411,777, filed September 30, 2022, entitled, “DRY FRIABLE FLUOROPOLYMER AGGLOMERATE COMPOSITIONS FOR USE AS BINDER IN LITHIUM-ION SECONDARY BATTERY ELECTRODES”. [0109] In other embodiments the tetrafluoroethylene polymer is a “modified” PTFE, referring to copolymers of tetrafluoroethylene with such a small concentration of comonomer that the molecular weight of the resultant polymer is not substantially reduced below that of homopolymer PTFE. The concentration of such comonomer in modified PTFE is less than 1 wt %, preferably less than 0.5 wt % based on the total
weight of the modified PTFE copolymer. A minimum amount of at least about 0.05 wt % is generally used to have significant effect. Examples of comonomers in modified PTFE include perfluoroolefins, notably hexafluoropropylene (HFP) or perfluoro(alkyl vinyl ether) (PAVE), where the alkyl group contains 1 to 5 carbon atoms, with perfluoro(ethyl vinyl ether) (PEVE) and perfluoro(propyl vinyl ether) (PPVE) being preferred, chlorotrifluoroethylene (CTFE), perfluorobutyl ethylene (PFBE), or other similar monomers that introduce relatively sterically bulky side groups into the PTFE polymer chain. [0110] The tetrafluoroethylene polymer or copolymer is fibrillatable. By fibrillatable is meant that the tetrafluoroethylene polymer is capable of forming nanosized (in at least one-dimension (i.e. <100 nm width) fibrils which can vary in length from submicrometer, to several, to tens of micrometers in length when the tetrafluoroethylene polymer/copolymer is subjected to sufficient shear forces. EXAMPLES Polymer Preparation Polymer 1 (P-1): [0111] The fluoropolymer binder (polymer 1) is commercially available from Chemours FC LLC (Wilmington, DE) or can be prepared from aqueous dispersions of tetrafluoroethylene homopolymer using known methods. The dispersion processes for polymerizing fluorinated monomers in aqueous media are known and prepared using established commercial technology, for example, as taught in U.S. Patent No. 4,576,869 granted to Malhotra, the disclosure of which is incorporated herein by reference in its entirety. Polymer 2 (P-2): [0112] A modified tetrafluoroethylene polymer, containing 0.128 wt% of copolymerized PPVE (perfluoro(propyl vinyl ether)) as modifier, was manufactured by Chemours FC LLC having a melt creep viscosity of 1.47 x 1010 poise. Melt creep viscosity (MCV) is measured by the method described in Ebnesajjad, Sina, (2015),
Fluoroplastics, Volume 1 - Non-Melt Processible Fluoropolymers - The Definitive User's Guide and Data Book (2nd Edition), William Andrew Publishing, Norwich, NY, Appendix 5, “Melt Creep Viscosity of Polytetrafluoroethylene”, pp.660-661, with reference to US patent No.3,819,594. Polymer 3: (P-3) [0113] A copolymer (FKM) manufactured by Chemours FC, LLC. The copolymer contains vinylidene fluoride (VDF) and hexafluoropropylene (HFP), with the HFP content 40% weight percent and having a Dv (50), 215 nm, measured from the Malvern Particle Sizer, Nano Series - ZS. Polymer 4: (P-4) [0114] A copolymer was manufactured by Chemours FC, LLC. The copolymer contains tetrafluoroethylene (TFE) and perfluoro(propyl vinyl ether) (PPVE), with the PPVE content of 4 weight percent relative to the entire polymer weight. The final copolymer has a melt flow rate (MFR) of 15 g/10 minute, as measured according to ASTM D-1238 and ASTM D 3307-93, at 372° C using a 5 kg weight on the molten PFA. In one embodiment, the PFA is fluorine-treated so as to have the stable -CF3 end group as the predominate end group and less than 50, preferably less than 25, total thermally unstable end groups, for example, -CONH2, -COF, -CH2OH and -COOH per 106 carbon atoms as the most common end groups resulting from the aqueous dispersion polymerization process used to make the PFA. Processes for fluorination are known in the art, for example, in U.S. Pat. No.4,743,658 and U.S. Pat. No.6,838,545. According to one embodiment, the PFA is not fluorine treated, whereby its end groups, about 200 or more per 106 carbon atoms, are the unstable end groups mentioned above arising from aqueous dispersion polymerization to form the PFA. Polymer (P-5): [0115] Polymer 5 was co-coagulated from a dispersion containing polymer 2 and polymer 3. The final, dried product contains 95% polymer 2 and 2 wt% of polymer 3. The co-coagulation procedure is as follows. Polymers 2 and 3 are added to a 3-liter glass vessel equipped with four stainless steel baffles to form Polymer 5. Specifically,
953 mL of demineralized water, 844 mL of a dispersion containing polymer 2 (39.73% solids), 60 mL of polymer 3 FKM aqueous dispersion with a polymer solids of 11.4%, and 43 mL of a 20% ammonium carbonate solution are added. A mechanical stirrer equipped with two 4-blade turbine agitators attached to a central shaft, was added to complete the apparatus. The 3-L glass container had an inner diameter of 13 cm. The baffles were attached with a thin metal ring and have a height of 13 cm and a width of 1.5 cm. The two agitators were separated by 6 cm on the shaft and comprised of four blades (blades are 1.5 cm wide and 4.5 cm long) with a 45-degree pitch. The rotation was in the direction to create an upward flow of fluid. With the lid in place (through which the agitator shaft runs), the contents of the coagulator were stirred at 800 rpm with a Caframo BDC3030 motor (Caframo Lab Solutions, Georgian Bluffs, Ontario, CA) until the solid co-coagulated polymer was sufficiently separated from the water. After decanting, the wet powder was washed with 1000 mL of demineralized water then filtered through cheesecloth. The powder was dried at a temperature of 150° C in a tray oven to yield the co-coagulated fluoropolymer composition. Polymer 6 (P-6): [0116] The polymer 6 fluoropolymer composition was prepared according to the procedure for the synthesis of polymer 5 described above. Demineralized water (1159 mL) was combined with 636 mL of an aqueous dispersion containing polymer 2 (having a polymer solids of 39.73%) and 62 mL of an aqueous dispersion containing polymer 4 (having a polymer solids of 21.47%). Polymer 7 (P-7): [0117] Polymer 7 is a PVDF binder for Li-ion Battery Electrodes is purchased from MTI Corporation Richmond, CA. The product was in white powder form with purity >99.5% and has a molecular weight is reported to be approximately 600,000 according to ASTM D 5296-05 Testing.
Electrode Preparation Polymer 5 (P-5)- Electrode 1: [0118] Electrode 1 Procedure: Test anodes were prepared using the present fluoropolymer compositions by the following procedures: Approximately 10 g of a powder mixed was created using 97.5 % graphite (Amsted Graphite Materials, Anmoore, VA), 1.0 % Super P carbon black, and 1.5 wt % of the polymer binder. The graphite and super P carbon black were combined in a mortar and pestle and mixed for approximately 15 minutes. This mixture was combined with the fluoropolymer binder into a 250-mL plastic bottle with approximately ten ZrO2 (10 mm in diameter) milling media and rolled for about 30 minutes. The powder was separated from the milling media. A free-standing film was created by placing 3 g of the mixture onto a small glass mortar and pestle. This material was manually ground until the powder formed a solid flake. The flakes were placed onto a hot plate with a piece of Kapton® film, heated to 100° C. Using a manual steel roller, the flake was rolled at 100° C until a film was formed which was uniform. A heated two-roll calendar was used (TMAX, Dongguan City, China). The calendering gap was reduced by 50-micron steps. For each step, the film was passed through the calendaring rollers two times. Eventually, the film will stick to the rolls, and the film was run through the calendaring device in this manner. The calendared gap was continually lowered in 50 micron increments until a final thickness of 70-80 microns was reached. [0119] Electrode 2 Procedure: The same Electrode 1 procedure was used except Polymer 6 was used instead of P-5. [0120] Electrode 3 Procedure: The same Electrode 1 procedure was used except Polymer 1 was used instead of P-5. The same procedure was also used to prepare electrodes using Polymer 3.
[0121] Electrode 4 Procedure: PVDF electrode (electrode 4) SP Carbon (0.05 gm) and 4.75 gm of Graphite Active Anode material were mixed on mortar and pestle for 15 minutes and they were mixed in roller mixer with zirconia balls (1 balls per gm of powder material) for additional 30 minutes. N-methyl-2-pyrrolidone (NMP) and polyvinylidene fluoride (PVDF) were mixed separately and obtained 10 weight % PVDF/NMP thick solution.2 gm of NMP/PVDF solution is added to the powder mixture and additional 3.5 gm of NMP is also added. The final mixture is mixed at 2000 revolutions per minute (RPM) for 2 minutes three times with an interval of few minutes. Then finely mixed viscous slurry was obtained. The slurry was casted on the carbon coated copper foil current collector by utilizing a doctor blade manually. The wet lamination was transferred to the hot air furnace at 130° F and kept for at least 2 hours to obtain dry Anode Electrode sheet. Circular electrodes (14 mm) disks were punched and dried at 120° C overnight before assembling the cells. Cell fabrication: [0122] Electrode disks (14 mm in diameter) were punched from a free-standing (self- supporting) film formed from fibrillatable fluoropolymer binder, graphite, and Super P carbon black. The assembly was performed in an inert, Argon atmosphere drybox with <0.01 ppm H2O and O2. Coin cells (type 2032) were assembled with a lithium metal counter electrode (15 mm in diameter), Celgard 2325 separator (16 mm in diameter) and electrolyte compositions described herein below.0.5 mm thick stainless-steel spacers were used. Formation protocols: [0123] The assembled coin cells were allowed to rest for about 2 hours in the electrolyte to wet the electrode and separator before starting the discharge-charge process. The initial cycle of discharge-charge is called the cell formation step. The cell formation and discharge-charge cycles were performed with a Neware battery tester BT-4008EN-5V-10mA-164-U (Neware Lab, San Jose, CA). Without being bound by any theory or explanation it is believed that during the cell formation step, electrolyte components undergo electrochemical reduction and form SEI layers on the surface of
the anode components which are conductive, e.g., between conductive component and the binder. The SEI protects the anode components by permitting the formation of new surfaces layers and protects electrolyte from further decomposition and gassing. Therefore, robust SEI formation due to the interaction of electrolyte and anode components in the initial cycle of discharge-charge cycle is crucial for superior performance of lithium-ion battery. Formation Protocol 1 (A) and Formation Protocol 3 (B). [0124] FIGs 2-5 relate to formation protocols, and half- and full cells. FIG.2 illustrates an existing protocol 1, wherein C/10 lithiation to 0.01V is followed by C/10 delithiation to between 1.25V and 1.5V, preferably one of 1.25V, 1.30V, 1.35V, to 1.5V and all values and fractions there between . [0125] Formation Protocol 3 is a stepped lithiation protocol and illustrated in FIG. 3. According to the present invention the lithiation involves FIG.3 illustrates stepped, e.g., two step lithiation at C/40 and then C/10 followed by a delithiation at C/10, although more than two, three, four, etc., steps can be involved. At least the first lithiation step is conducted at much slower/lower rates than the second step or subsequent steps, e.g., C/50, C/40, C/30, C/20 or C/15. The rate lower/slower than C/10, e.g. C/20, C/30, C/40, C/50, up to C/100 is continued down 0.2V, then followed by a second C/10 rate from 0.2 V to > 0 (0.01 V), and then a C/10 de-lithiation rate up to between 1.25 and 1.5 volts. In several SEI formation protocol embodiments disclosed herein, the delithiation step is preceded a rest period which ranges from > 10 seconds up to ≤60 minutes, including but not limited to 20 seconds, 60 seconds, 5 minutes, ten minutes up to ≤60 minutes and all values and ranges therebetween. [0126] FIG. 4 illustrates a half-cell of a stacked spacer, anode electrode, separator containing a non-aqueous electrolyte including at least the cyclic organosulfur compounds disclosed herein, a cathode electrode, spacer and spring arranged between bottom and top enclosers. FIG.5 is similar that of FIG.4, but a lithium electrode is used in place of the anode electrode of FIG.4. In either case the electrode is preferably formed from a conductive material, a fibrillatable fluoropolymer binder containing
PTFE/TFE, and ultimately at least one SEI layer formed using a rate slower than C/10, or a slower lithiation rate. [0127] Formation protocol A is a regular baseline formation protocol. It includes a discharge (lithiation) from an open circuit voltage (OCV) to lower cut off voltage of 0.01V vs Li/Li+ at C/10 constant current rate (over 10 hours) and a charge (delithiation) cycle from lower cut off voltage of 0.01V vs Li/Li/Li+ to upper cut off voltage of 1.25V vs Li/Li+ at the same C/10 constant current rate. There is a 5-minute rest step in between discharge and charge. To calculate the discharge and charge current, the specific capacity of graphite (350 mAh/g) is used. [0128] As disclosed herein formation protocols are modified by first using a slow discharge (lithiation) of C/40 (over 40 hours) from open circuit voltage (OCV) to 0.2V vs Li/Li+ plus faster discharge of C/10 from 0.2V vs Li/Li+ to lower cut off voltage of 0.01V vs Li/Li+ and faster charge of C/10 from lower cut off voltage of 0.01V vs Li/Li+ to upper cut off voltage of 1.25V. Constant current discharging and charging current are applied and a rest of 5 minutes in between the discharge and charge cycle in the case of the modified formation protocol. The 1st cycle lithiation capacity, delithiation capacity and coulombic efficiency are measured from the formation step. Comparative Examples [0129] Examples C1-C3 :1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC, electrode 1, formation protocol 3. Coin cell evaluations used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the Table 2 below. [0130] Examples C4-C5 : CMC-6:1.2 M LiPF6 + EC/DEC (3:7 by volume) electrode 1, formation protocol 3. A standard electrolyte 1.2 M LiPF6 -EC/DEC obtained from Gotion (Fremont, CA) was used. Coin cell evaluations used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the Table 2 below.
TABLE 1 EXAMPLES Examples 1A, 1B, 1C: 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC, 1 wt % ethylene sulfate, electrode 1, formation protocol 3. A cell containing electrode 1 and an electrolyte described below was used. The formation protocol B is used for the electrochemical measurements and the calculation of the formation cycle coulombic efficiency. 0.1546 grams of ethylene sulfate (Sigma Aldrich, St. Louis, MO) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the Table 1 below. [0131] Examples 2A, 2B, 2C: 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC, 1 wt % ethylene sulfite, electrode 1, formation protocol 3.0.1546 grams of ethylene sulfite (Sigma Aldrich) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the table below. [0132] Example 3A, 3B: 1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC, 1 wt % ethylene sulfite, 1 wt % LiFSI, electrode 1, formation protocol 3- 0.1563 grams of ethylene sulfite (Sigma Aldrich), 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials), 0.1563 of lithium bis(fluorosulfonyl) imide (LIFSI, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the table below. [0133] Example 4A, 4B, 4C:1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC, 1 wt % ethylene sulfite, electrode 1, formation protocol 1-
0.1546 grams of ethylene sulfite (Sigma Aldrich) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 1. The final data (coulombic efficiency) is shown in the table below. [0134] Example 5A, 5B, 5C:1.2 M LiPF6 + EC/DEC (3:7 by volume) 1 wt % FEC + 1 wt % ethylene sulfite, electrode 1, formation protocol 3- 0.1531 grams of ethylene sulfite (Sigma Aldrich) and 0.1531 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the table below. [0135] Example 6A, 6B :1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC 1 wt % ethylene sulfite 0.5 wt % vinylene carbonate, electrode 1, formation protocol 3- 0.1554 grams of ethylene sulfite (Sigma Aldrich), 0.3109 g of fluoroethylene carbonate (FEC, Gotion, battery materials), 0.0777 g of vinylene carbonate ( Aldrich) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the table below. [0136] Example 7A, 7B, 7C :1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC, 1 wt % 1,3 propane sultone, electrode 1, formation protocol 3- 0.1546 grams of 1,3 propane sultone (Sigma Aldrich) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the table below.
[0137] Example 8A, 8B:1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC+ 1 wt % ethylene sulfite, electrode 3, formation protocol 1 0.1546 grams of ethylene sulfite (Sigma Aldrich) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 3, formation protocol 1. The final data (coulombic efficiency) is shown in the table below. [0138] Examples 9A, 9B:1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC+ 1 wt % ethylene sulfite, electrode 3, formation protocol 3 0.1546 grams of ethylene sulfite (Sigma Aldrich) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 3, formation protocol 3. The final data (coulombic efficiency) is shown in the table below. [0139] Example 10A, 10B, 10C:1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC+ 1 wt % ethylene sulfite, electrode 2, formation protocol 1 0.1546 grams of ethylene sulfite (Sigma Aldrich) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 2, formation protocol 1. The final data (coulombic efficiency) is shown in the table below. [0140] Example 11A, 11B:1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt % FEC+ 1 wt % ethylene sulfite, electrode 2, formation protocol 3 0.1546 grams of ethylene sulfite (Sigma Aldrich) and 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 2, formation protocol 3. The final data (coulombic efficiency) is shown in the table below.
[0141] Example 14A, 14B, 14C :1.2 M LiPF6 + EC/DEC (3:7 by volume) + 1 wt % ethylene sulfate, electrode 1, formation protocol 3 0.1515 grams of ethylene sulfate (Sigma Aldrich) was combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 3 The final data (coulombic efficiency) is shown in the table below. [0142] Example 15A, 15B :1.2 M LiPF6 + EC/DEC (3:7 by volume) + 1 wt % ethylene sulfate, 1 wt % LiFSI, electrode 1, formation protocol 3 0.1531 grams of ethylene sulfate (Sigma Aldrich) and 0.1531 of lithium bis(fluorosulfonyl) imide (LIFSI, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the table below. [0143] Example 16A, 16B, 16C :1.2 M LiPF6 + EC/DEC (3:7 by volume) + 2 wt FEC, 1 wt % ethylene sulfate, 1 wt % LiFSI, electrode 1, formation protocol 3 0.1563 grams of ethylene sulfate (Sigma Aldrich), 0.3093 g of fluoroethylene carbonate (FEC, Gotion, battery materials), 0.1563 of lithium bis(fluorosulfonyl) imide (LIFSI, Gotion, battery materials) were combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the table below. [0144] Example 17A, 17B, 17C, 17D :1.2 M LiPF6 + EC/DEC (3:7 by volume) + 1 wt % ethylene sulfite, electrode1, formation protocol 3 0.1515 grams of ethylene sulfite (Sigma Aldrich) was combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations
used electrode 1, formation protocol 3. The final data (coulombic efficiency) is shown in the table below. [0145] Example 18A, 18B, 18C :1.2 M LiPF6 + EC/DEC (3:7 by volume) + 1 wt % ethylene sulfite, electrode 1, formation protocol 1 0.1515 grams of ethylene sulfite (Sigma Aldrich) was combined with 15 grams of a standard electrolyte 1.2M LiPF6 EC/DEC obtained from Gotion (Fremont, CA) to prepare the electrolyte mixture in an inert atmosphere drybox. Coin cell evaluations used electrode 1, formation protocol 1. The final data (coulombic efficiency) is shown in the table below. TABLE 2 EXAMPLES Examples 20-43 and Comparative Example C6-C16 are listed in Table 2. [0146] In all cases, the electrodes and the polymers as indicated in Table 2 were used for Examples 20-43 and Examples C6-C16. Electrode 1 was fabricated with Polymer 5, Electrode 2 with Polymer 6, and Electrode 3 was fabricated with Polymer 1. [0147] The electrolyte compositions are indicated in Table 2. The procedures to form the electrolytes were the same as described in the previous examples, except that the composition of the additives were adjusted as indicated in the Table 2. In many cases, multiple coin cell evaluations were used and are replicates. Hence, for example C1, C2, C 3 are separate coin cell experiments using the same combination of electrode, electrolyte and the same electrochemical formation protocol.
TABLE 1 Electrolyte additive Coulombic Polymer Formation (combined with 1.2 M Capacity on Efficiency E l l P l LiPF E DE 7 l h Ahg
TABLE 1 (continued) Electrolyte additive Coulombic Polymer Formation (combined with 1.2 M Capacity on Efficiency E l l P l LiPF E DE 7 l h Ahg
TABLE 1 (continued) Electrolyte additive Coulombic Polymer Formation (combined with 1.2 M Capacity on Efficiency E l l P l LiPF E DE 7 l h Ahg
TABLE 1 (continued) Electrolyte additive Coulombic Polymer Formation (combined with 1.2 M Capacity on Efficiency E l l P l LiPF E DE 7 l h Ahg
TABLE 2 Electrolyte additive (combined with 1.2 M LiPF6 Polymer Formation EC:DEC (3:7 vol ratio)) Capacity on
TABLE 2 (continued) Electrolyte additive (combined with 1.2 M LiPF6 Polymer Formation EC:DEC (3:7 vol ratio)) Capacity on
[0148] The improvement in initial coulombic efficiency is shown in table 1 using the formation protocol “C/40 to 0.2V, C/10 to 0.01V, C/10 to 1.25”, and shows an initial coulombic efficiency for the comparative examples C4 and C5 of 55-57 % compared to much as 92-94% for examples 2A, 3A, 4B and 4C of this invention. As shown in Tables 1 and 2, for the examples of this invention, an improvement is realized of 5, 10, 15, 20, 25, 35 % in the absolute value of the initial coulombic efficiency in half cell electrochemical evaluations. Compared to the coulombic efficiency without the electrolyte of this invention, the relative improvement is as much as 10, 20, 30, 40, 50, 60 %. X-ray photoelectron spectrometer (XPS) Investigation [0149] XPS measurements of the electrode surface were performed using a Thermo Scientific K-alpha XPS which utilizes an aluminum k-alpha monochromatic source, a 180-degree focused hemispherical analyzer, and a 128-channel detector. All investigations utilized a 400 µm spot size and all presented data is an average of 20 scans. The solid electrolyte interphase (SEI) of the electrode was examined. This technique provides information regarding the chemical species on the surface of a sample to a depth of approximately 10nm. To prepare the samples for measurement, the coin cells were decrimped and the electrodes were separated from the separator. The electrode was gently rinsed with dimethyl carbonate in an Argon atmosphere drybox and allowed to dry. XPS analysis of electrode surface [0150] The coin cell batteries of examples 8b and 4a of Table 1 were mounted into a vacuum transfer module within a glovebox and transferred into the instruments vacuum environment without any exposure to air. [0151] The solid electrolyte interphase (SEI) of the electrode was examined. This technique provides information regarding the chemical species on the surface of a sample to a depth of approximately 10nm. Should the SEI layer thickness be greater than the depth capability of XPS testing, then the C=C bond of the underlying electrode
will not be detected. Alternatively, if the C=C bond is detected the thickness of the SEI layer would be < about 10 nm. [0152] FIGs 6A through 6C illustrate a series of XPS spectra corresponding to the binding energy of sulfur species within the solid electrolyte interphase. [0153] FIGs 7A through 7D are the XPS spectra corresponding to carbon structures with the peak that represents a carbon-carbon double bond specifically highlighted. The fact that a carbon-carbon double bond is still visible in Examples 4a and 8b suggests that the SEI formed in these examples is much thinner than the SEI in the comparison. [0154] Significant differences in the SEI between Example 8b, Example 4a, and a comparative example using a CMC electrolyte were documented and are shown in FIGs 6A, 6B, and 6C and FIGs 7A, 7B, 7C, and 7D. FIGs 6A-C show that the electrolyte system used in Examples 8b (FIG.6A) and 4a (FIG.6B) resulted in an SEI that contains both reduced and oxidized sulfur species. Whereas the comparative example (FIG.6C) is only populated by a Phosphorus 2P satellite peak, thereby indicating no significant sulfur species in the SEI. [0155] The sulfur species of the SEI layer is derived from the cyclic organosulfur compound and can be either a reduced form of sulfur species or an oxidized form of sulfur. By a reduced form, it is meant the formal oxidation state of the sulfur itself. Therefore, the reduced sulfur species containing sulfur derived from the cyclic organosulfur compound is in a formal oxidation state lower than 0, up to -2, or a mixture of oxidation states. Sulfur can also adopt oxidation states to form species such as Li2S2 (this is S2=2-) or Li2S (this is S=2-) or non-stoichiometric intermediate solid solutions or mixtures of phases. [0156] From XPS, sulfur is also observed to be in another form, with a formal oxidation state 2+ or greater or mixtures thereof, and represents an “oxidized form”, more precisely as sulfur species derived from a cyclic organosulfur compound containing sulfur in a positive formal oxidation state. Sulfur can also adopt oxidation states to form that are non-stoichiometric intermediate solid solutions or mixtures of phases.
[0157] FIGs 7A through 7D show XPS analysis in the region corresponding to carbon species. Within this figure it can be seen that the XPS data for a pristine (non- cycled) electrode has a large peak corresponding to a carbon-carbon double bond. [0158] In this case this double bond is due to the significant amount of graphite on the surface of the electrode (i.e., there is no SEI present to cover up this graphite). This figure also shows that the comparative example shows no such graphite peaks. This can be taken to mean that a thick (>10nm) SEI layer has formed on the surface of the graphite therefore the x-rays cannot penetrate deep enough into the SEI to see a carbon-carbon double bond. In Examples 8b (FIGs 7A and 7B) and 4a (FIG.7D) small amounts of signal corresponding to carbon-carbon double bonds still exist, although the peaks are much smaller than in the non-cycled case. This suggests that some of the x- rays can penetrate through the SEI in these examples reaching the graphite. This suggests that a much thinner (<10nm) SEI has formed in the case of Examples 8b and 4a, when compared to the comparative example (FIG.7C). Other embodiments: [0159] 1. An electrode comprising: a fibrillated fluoropolymer binder, and one of: i. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer derived from an electrolyte formulation containing at least one cyclic organosulfur additive; ii. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer containing a sulfur species, wherein the sulfur species is derived from a cyclic organosulfur compound; iii. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer containing a reduced sulfur species; wherein the sulfur is derived from a cyclic organosulfur compound and has a formal oxidation state lower than 0, up to -2, or a mixture of oxidation states;
iv. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer containing an oxidized sulfur species derived from a cyclic organosulfur compound containing sulfur in a positive formal oxidation state; v. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer containing an oxidized sulfur species derived from a cyclic organosulfur compound containing sulfur in a positive formal oxidation state of +2 up to +6, or a mixture of oxidation states; vi. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer derived from electrochemical interaction of (i) a linear (and/or) cyclic carbonate, (ii) a lithium halide salt, (iii) at least one a cyclic organosulfur additive, and (iv) optionally, at least one cyclic carbonate containing fluorine; and vii. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer is derived from electrochemical interaction of (i) at least one a cyclic organosulfur additive, and (ii) at least one cyclic carbonate containing fluorine. [0160] 2. The electrode of claim 1 having multiple SEI layers. [0161] 3. The electrode of claim 1 having two or more SEI layers [0162] 4. The electrode of claim 3 wherein the two or more layers are chemically or dimensionally different. [0163] 5. The electrode of 4 wherein the electrode comprises a graphitic material, a first SEI layer dimensioned to permit detection of a C=C bond of the electrode. [0164] 6. The electrode of claim 5 wherein the first SEI layered dimensioned to permit detection of a C=C bond of the electrode by XPS (X-ray photoelectron spectroscopy).
[0165] 7. The electrode of claim 1 wherein the sulfur species is derived from the at least one cyclic organosulfur additive. [0166] 8. The electrode of claim 1 wherein the at least one cyclic organosulfur additive comprises between 2 and 8 carbons, preferably between 2 and 6 carbon atoms, more preferably 2-4 carbon atoms, and most preferably 2-3 carbon atoms. [0167] 9. The electrode of claim 7 wherein the at least one cyclic organosulfur additive comprises one of formula (I), (II), (III), (IV), (V) or (VI):
preferably one of , , , or
wherein each A and A’ is: (1) independently a hydrogen, an acyclic ether selected form vinyl, allyl, acetylenic, propargyl, or C1–C3 alkyl, and wherein the vinyl (H2C=CH ), allyl (H2C=CH-CH2-), acetylenic ( =C- ) , propargyl (HC=C-CH2–), or C1-C3 alkyl groups, unsubstituted, partially or totally fluorinated, (2) one of formula (I), (II), (III), (IV), (V) or (VI) or preferably one of formula (I), (II), (V) or (VI) and each additional A or A’ is identified above. [0168] 10. The electrode of claim 1 wherein the linear or cyclic carbonate is selected from at least one of ethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and dimethyl carbonate. [0169] 11. The electrode of claim 1 wherein the lithium halide is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium bis (trifluoromethyl) tetrafluorophosphate (LiPF4(CF3)2), lithium bis(fluorosulfonyl)imide LiFSI, lithium bis (trifluoromethanesulfonyl) imide LiTFSI, lithium perchlorate, lithium hexafluoroarsenate, and lithium trifluoromethanesulfonate. [0170] 12. The electrode according to any of the preceding claims comprising a conductive component selected from at least one of graphite, graphene, mesocarbon
microbeads (MCMB ), silicon, or SiOx or mixtures thereof, silicon/carbon/graphite composites, SiOx/carbon/graphite composite, lithiated tin oxide, conductive black phosphorus, MnP4, CoPz; SnO2, SnO, nanocomposites containing antimony, and oxides of aluminum, titanium, and molybdenum. [0171] 13. The electrode of claim 1 comprising, graphite, conductive carbon and a fibrillated polymer selected from one of a polytetrafluoroethylene (PTFE) homopolymer, a TFE copolymer formed with one of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), fluorinated ethylene propylene (FEP), perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE), and co-coagulated TFE-containing polymers and copolymers. [0172] 14. The electrode of claim 1 comprising, (1) one of silicon, silicon oxide, combinations of silicon and silicon oxide, and graphite, and (2) one of a. a fibrillated polymer of a PTFE homopolymer, b. a fibrillated polymer of a TFE co-polymer formed with one of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), FEP, perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE); and c. a fibrillated co-coagulated polymer. [0173] 15. The electrode according to claim 1 comprising a conductive component comprising one of graphite, graphene, mesocarbon microbeads (MCMB ), silicon, or SiOx or mixtures thereof, silicon/carbon/graphite composites, SiOx/carbon/graphite composite, lithiated tin oxide, conductive black phosphorus, MnP4, CoPz; SnO2, SnO, nanocomposites containing antimony, and oxides of aluminum, titanium, and molybdenum. [0174] 16. The electrode according to claim 12 further comprising carbon black. [0175] 17. The electrode of claim 1 wherein the fluorinated cyclic carbonate is selected from one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoropropylene carbonate, (TFPC), 4-((2,2,3,3-tetrafluoropropoxy)methyl)-
1,3-dioxolan-2-one (HFEEC), and 4-(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolan-2- one (NFPEC). [0176] 18. The electrode of claim 1 wherein the fibrillated fluoropolymer comprises one of (i) a fibrillated polymer of a PTFE homopolymer, (ii) a fibrillated polymer of a TFE co-polymer formed with one of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), FEP, perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE); and (iii) a fibrillated co-coagulated polymer. [0177] 19. The electrode of claim 14 wherein the cyclic organosulfur additive comprises a cyclic sulfite, a cyclic sulfate or a cyclic sultone. [0178] 20. The electrode of claim 16, wherein the cyclic organosulfur compound comprises one of formula (I)-(VI):
preferably one of , , or independently a hydrogen, optionally acyclic ethers include without limitation vinyl , allyl, acetylenic , propargyl , or C1–C3 alkyl, wherein the vinyl (H2C=CH), allyl (H2C=CH-CH2-), acetylenic ( =C ) , propargyl (HC=C-CH2–), or C1-C3 alkyl groups, is unsubstituted or partially or totally fluorinated, or each A and A’ comprises one or more C, O, S heterocyclic
compounds optionally selected from formula (I)-(VI) to form dimers, trimers or oligomers. [0179] 21. The electrode of claim 16 wherein the cyclic organosulfur additive comprises a cyclic sulfite. [0180] 22. An SEI comprising first and second layers, said first and second layers each containing sulfur, each layer derived from electrochemical reaction amongst (i) a linear or cyclic carbonate, (ii) a lithium halide salt, (iii) at least one a cyclic organosulfur additive, and (iv) optionally at least one cyclic carbonate containing fluorine, wherein the additive comprises between 2 and 8 carbons, is unsubstituted or substituted with a hydrogen, an acyclic ether selected from vinyl , allyl, acetylenic , propargyl , or C1–C3 alkyl, and the vinyl (H2C=CH), allyl (H2C=CH-CH2-), acetylenic ( =C ) , propargyl (HC=C-CH2–), or C1-C3 alkyl groups are unsubstituted or partially or totally fluorinated. [0181] 23. An SEI comprising first and second layers, said first and second layers each containing sulfur, each layer derived from electrochemical reaction amongst (i) a linear or cyclic carbonate, (ii) a lithium halide salt, (iii) at least one a cyclic organosulfur additive, and (iv) optionally at least one cyclic carbonate containing fluorine, wherein the additive comprises between 2 and 8 carbons and is substituted with one or more C,O,S heterocyclic groups, each of which is unsubstituted or substituted with a hydrogen, an acyclic ether selected from vinyl, allyl, acetylenic, propargyl, C1–C3 alkyl, and the vinyl (H2C=CH), allyl (H2C=CH-CH2-), acetylenic (=C), propargyl (HC=C-CH2–), and C1-C3 alkyl groups are unsubstituted or partially or totally fluorinated. [0182] 24. In combination, an electrode and at least one solid-electrolyte interface (SEI) layer, the electrode comprising a conductive material and a fibrillatable fluoropolymer binder and the layer comprising an electrochemically formed reaction substance between a non-aqueous electrolyte composition containing a solvent, and at least two additives, said additives comprising: (i) a first a cyclic sulfur compound, and (ii) optionally at least a cyclic carbonate containing fluorine.
[0183] 25. A process comprising, a) providing a half cell electrochemical cell containing an anode electrode comprising at least one of graphite, graphene, mesocarbon microbeads (MCMB ), silicon, or SiOx or mixtures thereof, silicon/carbon/graphite composites, SiOx/carbon/graphite composite, lithiated tin oxide, conductive black phosphorus, MnP4, CoPz; SnO2, SnO, nanocomposites containing antimony, oxides of aluminum titanium and molybdenum with a fibrillated PTFE or TFE co-polymer binder, a lithium metal counter-electrode, and an electrolyte comprising a non-aqueous solvent, at least one lithium halide salt, and at least one additive comprising a cyclic organosulfur compound, and b) applying a galvanostatic current at voltages above the lithium intercalation voltage of the electrode and before the decomposition potential of the PTFE or TFE co-polymer binder. [0184] 26. A method for producing an electrode comprising: a. exposing a conductive electrode formed with a fibrillated PTFE or TFE co- polymer binder to a non-aqueous electrolyte comprising a lithium halide salt and cyclic organo- sulfur additive, b. applying a first lithiation current density between C/100 and less than C/10to form a first SEI layer, c. applying an ultimate lithiation current density C/10 from 0.2V to .01V form another SEI layer, and d. applying a delithiation current density for form a stabilized electrode. [0185] 27. An electrode formed by the method of claim 23, wherein the electrolyte comprises one or more linear and/or cyclic carbonates, a Li halide salt and the cyclic organosulfur additive comprises a cyclic sulfite, cyclic sulfate or cyclic sultone, and optionally a second additive comprising a fluorinated cyclic carbonate.
[0186] 28. An SEI formation protocol comprising, a. contacting a conductive electrode having a fibrillated binder with an electrolyte comprising at least a cyclic organosulfur compound, b. applying a first constant current rate lower than C/10 to the electrode and the electrolyte to form a first SEI layer, c. applying a second higher C/10 constant current rate to the electrode and the electrolyte to form a second SEI layer over the first SEI layer, and d. applying a third constant delithiation current to form a third SEI layer. [0187] 29. The formation protocol of claim 25, wherein the current rate lower than C/10 is selected from one of C/50, C/40, C/30, C/20, and C/15. [0188] 30. The formation protocol of claim 25, wherein the current rate lower than C/10 is applied from OCV to 0.2V. [0189] 31. The formation protocol of claim 25, wherein the current rate lower than C/10 is applied from OCV to 0.0.1V. [0190] 32. The formation protocol of claim 25 wherein the electrode comprises a fibrillatable binder. [0191] 33. The formation protocol of claim 29 wherein the binder comprises one of (i) a fibrillated polymer of a PTFE homopolymer, (ii) a fibrillated polymer of a TFE co- polymer formed with one of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), FEP, perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE); and (iii) a fibrillated co-coagulated polymer. [0192] 34. The formation protocol of claim 25 wherein the electrolyte comprises LiPF6, EC, DEC, and optionally a fluorinated cyclic carbonate. [0193] 35. The formation protocol of claim 25 wherein cyclic organo sulfur compound comprises one of ethylene sulfite (1,3,2-dioxathiolan-2-oxide), ethylene sulfate (1,3,2-
dioxathiolane 2,2-dioxide), 1,3-propylene sulfite, 1,3-propylene sulfate, 1,3 propane sultone, and 1-propene-1,3 sultone. [0194] 36. The formation protocol of claim 32 wherein the electrolyte includes ethylene sulfite (1,3,2-dioxathiolan-2-oxide). [0195] 37. The protocol of claim 32 wherein the electrolyte includes ethylene sulfate (1,3,2-dioxathiolane 2,2-dioxide). [0196] 38. The protocol of claim 32wherein the electrolyte includes 1,3-propylene sulfite. [0197] 39. The protocol of claim 32 wherein the electrolyte includes 3-propylene sulfate. [0198] 40. The protocol of claim 32 wherein the electrolyte includes 1,3 propane sultone. [0199] 41. The protocol of claim 32 wherein the electrolyte includes 1-propene-1,3 sultone. [0200] 42. In combination, first and second SEI layers each comprising different electrochemical reaction products formed from a lithium halide salt, a linear or carbonate, a cyclic organo sulfur additive, and optionally a fluorinated cyclic carbonate. [0201] 43. An SEI layer comprising electrochemically reacted (i) linear or cyclic carbonates selected from one or more ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC) and ethylene carbonate (EC), (ii) one or more lithium halides salts selected from lithium hexafluorophosphate (LiPF6), lithium bis (trifluoromethyl) tetrafluorophosphate (LiPF4(CF3)2), lithium bis(fluorosulfonyl)imide LiFSI, lithium bis (trifluoromethanesulfonyl) imide LiTFSI, lithium difluoro oxalate borate(LiDFOB), lithium bis(oxalate)borate (LiBOB), lithium perchlorate, lithium hexafluoroarsenate, or lithium trifluoromethanesulfonate, and (iii) a cyclic organo sulfur compound selected from one of ethylene sulfite (1,3,2-dioxathiolan-2-oxide), ethylene sulfate (1,3,2-dioxathiolane 2,2-dioxide), 1,3-propylene sulfite, 1,3-propylene sulfate, 1,3 propane sultone, and 1-propene-1,3 sultone, and optionally (iv) a fluorinated cyclic
carbonate selected from one of one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoropropylene carbonate, (TFPC), 4-((2,2,3,3- tetrafluoropropoxy)methyl)-1,3-dioxolan-2-one (HFEEC), and 4-(2,2,3,3,4,4,5,5,5- nonafluoropentyl)-1,3-dioxolan-2-one (NFPEC). [0202] 44. An SEI composite layer comprising at least first and second layer comprising electrochemically reacted linear or cyclic carbonates selected from one or more ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC) and ethylene carbonate (EC), one or more lithium halides salts selected from lithium hexafluorophosphate (LiPF6), lithium bis (trifluoromethyl) tetrafluorophosphate (LiPF4(CF3)2), lithium bis(fluorosulfonyl)imide LiFSI, lithium bis (trifluoromethanesulfonyl) imide LiTFSI, lithium difluoro oxalate borate(LiDFOB), lithium bis(oxalate)borate (LiBOB), lithium perchlorate, lithium hexafluoroarsenate, or lithium trifluoromethanesulfonate, and a cyclic organo sulfur compound selected from one of ethylene sulfite (1,3,2-dioxathiolan-2-oxide), ethylene sulfate (1,3,2-dioxathiolane 2,2- dioxide), 1,3-propylene sulfite, 1,3-propylene sulfate, 1,3 propane sultone, and 1- propene-1,3 sultone, and optionally a fluorinated cyclic carbonate selected from one of one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoropropylene carbonate, (TFPC), 4-((2,2,3,3-tetrafluoropropoxy)methyl)-1,3- dioxolan-2-one (HFEEC), and 4-(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolan-2-one (NFPEC). [0203] 45. The SEI composite layer of claim 41wherein the cyclic organo sulfur comprises ethylene sulfite (1,3,2-dioxathiolan-2-oxide). [0204] 46. The SEI composite layer of claim 41 wherein the cyclic organo sulfur comprises ethylene sulfate (1,3,2-dioxathiolane 2,2-dioxide). [0205] 47. The SEI composite layer of claim 41 wherein the cyclic organo sulfur comprises 1,3-propylene sulfite. [0206] 48. The SEI composite layer of claim 41 wherein the cyclic organo sulfur comprises 3-propylene sulfate.
[0207] 49. The SEI composite layer of claim 41 wherein the cyclic organo sulfur comprises 1,3 propane sultone. [0208] 50. The SEI composite layer of claim 41 wherein the cyclic organo sulfur comprises 1-propene-1,3 sultone. [0209] 51. An SEI composite layer comprising derived from at least one electrolyte comprising a cyclic organo sulfur compound, optionally a fluorinated cyclic carbonate component layers, and a reduced fibrillated fluoropolymer binder. [0210] 52. The SEI composite layer of claim 48 wherein the cyclic organo sulfur compound comprises one of comprises one of ethylene sulfite (1,3,2-dioxathiolan-2- oxide), ethylene sulfate (1,3,2-dioxathiolane 2,2-dioxide), 1,3-propylene sulfite, 1,3- propylene sulfate, 1,3 propane sultone, and 1-propene-1,3 sultone. [0211] 53. The SEI layer of claim 40 formed under a constant current rate lower than C/10. [0212] 54. The SEI layer of claim 50 wherein the SEI is ≤nm thick. [0213] 55. The electrode of claim 9 wherein the cyclic organo sulfur compound comprises, consists essentially of, or consists of a cyclic sulfate or cyclic sulfite. [0214] 56. The electrode of claim 9 wherein the cyclic organo sulfur compound comprises, consists essentially of, or consists of a cyclic sulfite. [0215] 57. The electrode of claim 9 wherein the cyclic organo sulfur compound comprises, consists essentially of, or consists of a compound defined by formula (III) or (VI). [0216] 58. An electrochemical device comprising the electrode of any one of the preceding claims. [0217] 59. A secondary lithium-ion battery comprising the electrode of any one of the preceding claims. [0218] Although certain aspects, embodiments and principals have been described above, it is understood that this description is made only way of example and not as
limitation of the scope of the invention or appended claims. The foregoing various aspects, embodiments and principals can be used alone and in combinations with each other.
Claims
CLAIMS What is claimed is: 1. An electrode comprising: a fibrillated tetrafluoroethylene (TFE) containing binder, and one of: i. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer derived from an electrolyte formulation containing at least one cyclic organosulfur additive; ii. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer containing a sulfur species, wherein the sulfur species is derived from a cyclic organosulfur compound; iii. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer containing a reduced or oxidized sulfur species derived from a cyclic organosulfur compound; iv. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer containing a reduced sulfur species; wherein the sulfur is derived from a cyclic organosulfur compound and has a formal oxidation state lower than 0, up to -2, or a mixture of oxidation states; v. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer containing an oxidized sulfur species derived from a cyclic organosulfur compound containing sulfur in a positive formal oxidation state of +2 up to +6, or a mixture of oxidation states; vi. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer derived from electrochemical interaction of (i) a linear (and/or) cyclic carbonate, (ii) a lithium halide salt, (iii) at least one a cyclic organosulfur additive, and (iv) optionally, at least one cyclic carbonate containing fluorine; and vii. at least one solid-electrolyte interface (SEI) layer, said at least one SEI layer is derived from electrochemical interaction of (i) at least one a cyclic organosulfur additive, and (ii) at least one cyclic carbonate containing fluorine.
2. The electrode of claim 1 comprising, graphite, conductive carbon and a fibrillated polymer selected from one of a polytetrafluoroethylene (PTFE) homopolymer, a tetrafluoroethylene (TFE) copolymer formed with one of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), fluorinated ethylene propylene (FEP), perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE), and co-coagulated TFE- containing polymers and copolymers. 3. The electrode of claim 1 comprising, (1) one of silicon, silicon oxide, combinations of silicon and silicon oxide, and graphite, and (2) one of: i. a fibrillated polymer of a PTFE homopolymer; ii. a fibrillated polymer of a TFE copolymer formed with one of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), FEP, perfluoro(ethyl vinyl ether) (PEVE) or perfluoro(propyl vinyl ether) (PPVE); and iii. a fibrillated co-coagulated polymer. 4. The electrode of claim 1 wherein the at least one cyclic organosulfur additive comprises a C2-C3 cyclic or sulfite. 5. The electrode of claim 1 wherein the at least one cyclic organosulfur additive comprises a C2-C3 cyclic sulfite. 6. The electrode of claim 1 having at least one SEI layer containing sulfur derived from the cyclic organo sulfate or sulfite. 7. The electrode of claim 3 wherein two or more layers are present and are chemically or dimensionally different. 8. The electrode of claim 4 wherein C=C bonds of the electrode by XPS are detected through a first SEI layer. 9. The electrode of claim 1 wherein the sulfur species is derived from at least one cyclic organosulfur additive.
10. The electrode of claim 1 wherein the at least one cyclic organosulfur additive comprises between 2 and 8 carbons, preferably between 2 and 6 carbon atoms, more preferably 2-4 carbon atoms, and most preferably 2-3 carbon atoms. 11. The electrode of claim 8 wherein the at least one cyclic organosulfur additive comprises one of formula (I), (II), (III), (IV), (V), and (VI):
preferably one of formula (II), (III), (V) or (VI),more preferably wherein each A and A’ is: (1) independently a hydrogen, an acyclic ether selected form vinyl, allyl, acetylenic, propargyl, or C1–C3 alkyl, and wherein the vinyl (H2C=CH ), allyl (H2C=CH-CH2-), acetylenic, propargyl (HC=C-CH2–), or C1-C3 alkyl groups, unsubstituted, partially or totally fluorinated, or (2) one of formula (I), (II), (III), (IV), (V) or (VI), preferably one of formula (II), (III), (V) or (VI), and each additional A or A’ is identified above. 12. The electrode of claim 1 wherein the linear or cyclic carbonate is selected from at least one of ethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and dimethyl carbonate. 13. The electrode of claim 1 wherein the lithium halide is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium bis (trifluoromethyl) tetrafluorophosphate
(LiPF4(CF3)2), lithium bis(fluorosulfonyl)imide LiFSI, lithium bis (trifluoromethanesulfonyl) imide LiTFSI, lithium perchlorate, lithium hexafluoroarsenate, and lithium trifluoromethanesulfonate. 14. The electrode according to any of the preceding claims comprising a conductive component selected from at least one of graphite, graphene, mesocarbon microbeads (MCMB ), silicon, SiOx or mixtures thereof, silicon/carbon/graphite composites, SiOx/carbon/graphite composite, lithiated tin oxide, conductive black phosphorus, MnP4, CoPz; SnO2, SnO, nanocomposites containing antimony, and oxides of aluminum, titanium, and molybdenum. 15. The electrode according to claim 1 comprising a conductive component comprising one of graphite, graphene, mesocarbon microbeads (MCMB ), silicon, SiOx or mixtures thereof, silicon/carbon/graphite composites, SiOx/carbon/graphite composite, lithiated tin oxide, conductive black phosphorus, MnP4, CoPz; SnO2, SnO, nanocomposites containing antimony, and oxides of aluminum, titanium, and molybdenum. 16. The electrode according to claim 12 further comprising carbon black. 17. The electrode of claim 1 wherein the fluorinated cyclic carbonate is selected from one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoropropylene carbonate, (TFPC), 4-((2,2,3,3-tetrafluoropropoxy)methyl)-1,3- dioxolan-2-one (HFEEC), and 4-(2,2,3,3,4,4,5,5,5-nonafluoropentyl)-1,3-dioxolan-2-one (NFPEC). 18. The electrode of claim 1 wherein the fibrillated fluoropolymer comprises one of (i) a fibrillated polymer of a PTFE homopolymer, (ii) a fibrillated polymer of a TFE copolymer formed with one of hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), FEP, perfluoro(ethyl vinyl ether)(PEVE) or perfluoro(propyl vinyl ether)(PPVE); and (iii) a fibrillated co-coagulated polymer. 19. The electrode of claim 14 wherein the cyclic organosulfur additive comprises a cyclic sulfite or cyclic sulfate.
20. The electrode of claim 16, wherein the cyclic organosulfur compound comprises one of formula (I)-(VI): preferably one of
, , is independently a hydrogen, optionally acyclic ethers include without limitation vinyl , allyl, acetylenic , propargyl , or C1–C3 alkyl, wherein the vinyl (H2C=CH), allyl (H2C=CH-CH2-), acetylenic ( =C ) , propargyl (HC=C-CH2–), or C1-C3 alkyl groups, is unsubstituted or partially or totally fluorinated, or each A and A’ comprises one or more C, O, S heterocyclic compounds optionally selected from formula (I)-(VI), preferably one of formula to form dimers, trimers or oligomers. 21. The electrode of claim 18 wherein the cyclic organosulfur additive comprises a cyclic sulfite. 22. In combination, an electrode and at least one solid-electrolyte interface (SEI) layer, the electrode comprising a conductive material and a fibrillatable fluoropolymer binder and the layer comprising an electrochemically formed reaction substance between a non-aqueous electrolyte composition containing a solvent, and at least two
additives, said additives comprising: (i) a first a C2-C3 cyclic sulfur compound, and (ii) optionally at least a cyclic carbonate containing fluorine. 23. The electrode of any of claims 14-20 wherein the cyclic carbonate containing fluorine is fluoroethylene carbonate (FEC). 24. The electrode of claim 1 where the sulfur is one of (i) a reduced sulfur species and has a formal oxidation state lower than 0, up to -2, or a mixture of oxidation states and (ii) an oxidized sulfur species derived from a cyclic organosulfur compound containing sulfur in a positive formal oxidation state. 25. An electrochemical device comprising the electrode of any of the preceding claims. 26. A secondary lithium-ion battery comprising the electrode of any of the preceding claims.
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