[go: up one dir, main page]

WO1998000877A1 - Preparation et utilisation de minces cathodes flexibles dans des elements d'accumulateurs electrochimiques en metal alcalin - Google Patents

Preparation et utilisation de minces cathodes flexibles dans des elements d'accumulateurs electrochimiques en metal alcalin Download PDF

Info

Publication number
WO1998000877A1
WO1998000877A1 PCT/US1997/004975 US9704975W WO9800877A1 WO 1998000877 A1 WO1998000877 A1 WO 1998000877A1 US 9704975 W US9704975 W US 9704975W WO 9800877 A1 WO9800877 A1 WO 9800877A1
Authority
WO
WIPO (PCT)
Prior art keywords
current collector
electrochemical cell
cathode
metal
active material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1997/004975
Other languages
English (en)
Inventor
Esther S. Takeuchi
William C. Thiebolt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Greatbatch Ltd
Original Assignee
Greatbatch Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Greatbatch Ltd filed Critical Greatbatch Ltd
Priority to AU25913/97A priority Critical patent/AU2591397A/en
Publication of WO1998000877A1 publication Critical patent/WO1998000877A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • 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
    • H01M10/052—Li-accumulators
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0409—Methods of deposition of the material by a doctor blade method, slip-casting or roller coating
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0416—Methods of deposition of the material involving impregnation with a solution, dispersion, paste or dry powder
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • H01M4/0435—Rolling or calendering
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/049—Manufacturing of an active layer by chemical means
    • H01M4/0492—Chemical attack of the support material
    • 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
    • H01M4/06—Electrodes for primary cells
    • H01M4/08—Processes of manufacture
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/581—Chalcogenides or intercalation compounds thereof
    • H01M4/5815—Sulfides
    • 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
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/626—Metals
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H01M4/662—Alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M6/00—Primary cells; Manufacture thereof
    • H01M6/14—Cells with non-aqueous electrolyte
    • H01M6/16—Cells with non-aqueous electrolyte with organic electrolyte
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/40—Alloys based on alkali metals
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/669—Steels
    • 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 generally relates to the conversion of chemical energy to electrical energy, and more particularly, to an alkali metal electrochemical cell having an electrode formed by casting a slurry of electrode active material to a metal foil followed by pressing the laminate.
  • the resulting electrode active componer.t is thinner than conventional pressed powder electrodes while maintaining acceptable flexibility characteristics. Thinner electrodes benefit electrode surface area which in turn results in increased discharge capacity.
  • the anhydrous, dry powder form of the active materials described in these prior art patents are typically mixed with a conductive diluent and a binder material, and layers of the dry powder active mixture are pressed onto opposed sides of a conductive, current collector screen. It is believed that the resulting electrode maintains its mechanical integrity during manufacture into various cell configurations by the active mixture locking to itself through the screen perforations.
  • pressed powder electrodes of the prior art have limited, if any, flexibility and are generally incapable of being formed at thickness less than approximately 0.013 inches.
  • Improved electrode thickness characteristics result in an increased electrode surface area for a given volume casing which is believed to increase the current capacity of cells incorporating the electrodes.
  • the present invention is directed to a thin, flexible electrode comprising an electrode active material contacted to a conductive substrate serving as the current collector.
  • the present invention is also directed to a method of manufacturing such an electrode.
  • the thusly formed electrode is preferably a cathode for use in an alkali metal, organic electrolyte cell.
  • the preferred conductive substrate is comprised of an aluminum or aluminum alloy in the form of a screen or a foil. In the latter case, the foil can be roughened or etched using an acid solution, or the foil can be used in a cleaned but untreated condition.
  • electrode active material preferably including a conductive diluent and a binder material is first formed into a slurry by mixing with a solvent, and then the active slurry is cast or otherwise contacted to the conductive substrate, followed by pressing.
  • Fig. 1 is a photograph showing the surface condition of an untreated aluminum alloy substrate.
  • Fig. 2 is a photograph showing the surface condition of an aluminum alloy substrate similar to that shown in Fig. 1 but after treatment in the sulfuric acid solution according to the present invention.
  • Fig. 3 is a graph showing the voltage under background load and pi minima and p4 minima pulse train voltages versus amp hours of a cell having a cathode comprising a silver vanadium oxide admixture slurry cast and pressed to a surface treated aluminum substrate.
  • Fig. 4 is a graph showing the voltage versus amp hours of a cell having a cathode comprising a silver vanadium oxide admixture slurry cast and pressed to a surface treated conductive substrate and subjected to pulses 1.5 A in amplitude.
  • Fig. 5 is a graph showing the voltage versus amp hours of a cell having a cathode comprising a silver vanadium oxide admixture slurry cast and pressed to a surface treated conductive substrate and subjected to pulses 2.0 A in amplitude.
  • Fig. 6 is a graph showing the average voltage versus amp hours of five cells similar to those discharged to construct Figs. 4 and 5.
  • Fig. 7 to 9 are graphs showing the voltage versus amp hours of cells having a cathode comprising a silver vanadium oxide admixture slurry cast and pressed to a surface treated conductive substrate and subjected to pulses 1.5 A, 1.75 A and 2.0 A in amplitude, respectively.
  • Fig. 10 is a graph showing the voltage versus amp hours of a cell having a cathode comprising a silver vanadium oxide admixture slurry cast and pressed to an untreated aluminum substrate.
  • the electrochemical cell of the present invention comprises an anode of a metal selected from Group IA of the Periodic Table of the Elements, including lithium, sodium, potassium, etc., and their alloys and intermetallic compounds including, for example, Li -Si, Li-Al, Li-B and Li-Si-B alloys and intermetallic compounds.
  • the preferred anode comprises lithium, and the more preferred anode comprises a lithium alloy such as a lithium-aluminum alloy. However, the greater the amount of aluminum present by weight in the alloy the lower the energy density of the cell.
  • the form of the anode may vary, but preferably the anode is a thin metal sheet or foil of the anode metal, pressed or rolled on a metallic anode current collector, i.e., preferably comprising nickel, to form an anode component.
  • the anode component has an extended tab or lead of the same material as the anode current collector, i.e., preferably nickel, integrally formed therewith such as by welding and contacted by a weld to a cell case of conductive metal in a case-negative electrical configuration.
  • the anode may be formed in some other geometry, such as a bobbin shape, cylinder or pellet to allow an alternate low surface cell design.
  • the electrochemical reaction at the cathode involves conversion of ions which migrate from the anode to the cathode in atomic or molecular forms.
  • the solid cathode material may comprise a metal element, a metal oxide, a mixed metal oxide and a metal sulfide, and combinations thereof.
  • the metal oxide or the mixed metal oxide can be formed by the chemical addition, reaction, or otherwise intimate contact of various metal oxides and/or metal elements, preferably during thermal treatment, sol -gel formation, chemical vapor deposition or hydrothermal synthesis in mixed states.
  • the active materials thereby produced contain metals, oxides and sulfides of Groups IB, IIB, IIIB, IVB, VB, VIB, VIIB and VIII which includes the noble metals and/or other oxide and sulfide compounds.
  • readily decomposable compounds consisting of metals from Groups IB, IIB, IIIB, IVB, VB, VIB, VIIB, as well as similarly decomposable compounds from Group VIII, are thermally treated so as to effect the rapid preparation of the oxides or the respective metal elements themselves to be utilized further in the preparation of suitable cathode materials.
  • readily decomposable materials include, but are not limited to, those classes of compounds known as nitrates, nitrites, carbonates and/or ammonium salts.
  • the precursor materials may be decomposed in a combined state or individually decomposed and thereafter combined in an oxide/decomposable metal salt compound and subsequently decomposed to form the cathode active material comprising a mixed metal oxide.
  • Preferred mixed metal oxides are prepared by thermally decomposing a vanadium salt, suitably ammonium meta-vanadate to produce vanadium pentoxide.
  • a decomposable metal salt suitably the nitrates of a second metal and possibly a third metal, are then added to the vanadium pentoxide, thoroughly mixed therewith and thereafter thermally treated.
  • the second and third metals are most preferably silver and copper.
  • One preferred mixed metal oxide has the general formula SM_.V 2 0 y wherein SM is a metal selected from the Groups IB to VIIB and VIII of the Periodic Table of elements and x is about 0.30 to 2.0 and y is about 4.5 to 6.0 in the general formula.
  • SVO silver vanadium oxide
  • this composite cathode active material may be described as a metal oxide-metal oxide-metal oxide, a metal -metal oxide -metal oxide, or a metal -metal -metal oxide and the range of material composition found for Cu x Ag y V 2 Oi, is preferably about 0.01 ⁇ x ⁇ 1.0, about 0.01 ⁇ y ⁇ 1.0 and about 5.01 ⁇ z ⁇ 6.5.
  • Typical forms of CSVO are Cu 0 ⁇ 6 Ag 067 V 2 O z with z being about 5.5 and
  • the oxygen content is designated by z since the exact stoichiometric proportion of oxygen in CSVO can vary depending on whether the cathode material is prepared in an oxidizing atmosphere such as air or oxygen, or in an inert atmosphere such as argon, nitrogen and helium.
  • cathode active materials include manganese dioxide, lithium cobalt oxide, lithium nickel oxide, copper oxide, titanium disulfide, copper sulfide, iron sulfide, iron disulfide, copper vanadium oxide, and mixtures thereof.
  • the cathode active material is preferably present in the cathode at about 80 to 99 weight percent.
  • the above described active materials are formed into an electrode for incorporation into an electrochemical cell by mixing one or more of them with up to about 5 weight percent of a conductive additive such as acetylene black, carbon black and/or graphite.
  • a conductive additive such as acetylene black, carbon black and/or graphite.
  • a preferred carbonaceous diluent is Ketjenblack carbon.
  • Metallic powders such as nickel, aluminum, titanium and stainless steel in powder form are also useful as conductive diluents when mixed with the above listed active materials.
  • the electrode further comprises up to about 10 weight percent of a binder material which is preferably a fluoro- resin powder such as powdered polytetrafluoroethylene (PTFE) or powdered polyvinylidene fluoride (PVDF) .
  • PTFE powdered polytetrafluoroethylene
  • PVDF powdered polyvinylidene fluoride
  • a preferred cathode active admixture comprises, by weight, about 94% SVO in any one of its many phases, or mixtures thereof, and/or CSVO mixed with about 3 weight percent of a binder material and about 3 weight percent of a conductive diluent.
  • the thusly formed electrode active admixture is converted into a slurry by mixing with a high permittivity solvent such as a cyclic amide, a cyclic carbonate or a cyclic ester.
  • a high permittivity solvent such as a cyclic amide, a cyclic carbonate or a cyclic ester.
  • Suitable high permittivity solvents include propylene carbonate, ethylene carbonate, ⁇ -butyrolactone, N- methyl -pyrrolidinone, dimethyl sulfoxide, acetonitrile, dimethyl formamide and dimethyl acetamide, and mixtures thereof .
  • the active slurry is then cast or otherwise applied or contacted to a conductive foil substrate which serves as the current collector for the electrode.
  • Suitable materials for the current collector substrate include nickel, aluminum, stainless steel, mild steel and titanium with aluminum being preferred.
  • the foil prior to being contacted with the active slurry the foil is roughened to increase its surface area by immersion in an acidic etchant solution such as a sulfuric acid solution.
  • a preferred etchant solution is designated a P2 solution and comprises sulfuric acid (H 2 S0 4 ) having ferrous sulfate (Fe 2 (S0 4 ) 3 -5H 2 0) dissolved therein. If surface roughening is desired, the foil is immersed in the sulfuric acid solution for about 8 to 12 minutes at about 50°C to 70°C to provide the substrate with a pitted or honeycombed surface texture.
  • the foil substrate is preferably cleaned of surface contamination such as dirt, grease, oil and the like and then used in its cleaned but untreated condition. After drying to remove all residual water from the slurry, contacted to the conductive substrate, the resulting anhydrous active admixture is calendared under a pressure of about 40 tons/inch 2 to laminate the active admixture to either the etched or unetched current collector foil, as the case may be, to thereby form the electrode according to the present invention.
  • the substrate can be a screen comprised of one or more of the enumerated conductive materials.
  • Cathodes prepared as described above are flexible and may be in the form of one or more plates operatively associated with at least one or more plates of anode material, or in the form of a strip wound with a corresponding strip of anode material in a structure similar to a "jellyroll" .
  • conventional electrodes fabricated from dry powder active mixtures pressed onto a perforated conductive screen generally are limited to total thicknesses not less than 0.013 inches (measured electrode thickness includes the first and second active layers or plates pressed onto the opposed sides of the intermediate conductive screen) .
  • the electrode comprising the active admixture cast and pressed onto the opposed sides of the conductive foil ranges between about 0.002 to 0.009 inches.
  • the conductive foil itself typically is 0.001 inches thick which means that castings as thin as 0.0005 inches can be applied or contacted to the foil without compromising mechanical integrity. Decreasing electrode thickness beneficially increases electrode surface area which in turn benefits discharge current capacity.
  • the cathode is separated from the Group IA anode material by a suitable separator material .
  • the separator is of electrically insulative material, and the separator material also is chemically unreactive with the anode and cathode active materials and both chemically unreactive with and insoluble in the electrolyte.
  • the separator material has a degree of porosity sufficient to allow flow therethrough of the electrolyte during the electrochemical reaction of the electrochemical cell.
  • Illustrative separator materials include fabrics woven from fluoropolymeric fibers including polyvinylidene fluoride, polyethylenetetrafluoroethylene, and polyethylenechlorotrifluoroethylene used either alone or laminated with a fluoropolymeric microporous film, non- woven glass, polypropylene, polyethylene, glass fiber materials, ceramics, polytetrafluoroethylene membrane commercially available under the designation ZITEX (Chemplast Inc.), polypropylene membrane commercially available under the designation CELGARD (Celanese Plastic Company, Inc.) and a member commercially available under the designation DEXIGLAS (C.H. Dexter, Div. , Dexter Corp.).
  • fluoropolymeric fibers including polyvinylidene fluoride, polyethylenetetrafluoroethylene, and polyethylenechlorotrifluoroethylene used either alone or laminated with a fluoropolymeric microporous film, non- woven glass, polypropylene, poly
  • the electrochemical cell of the present invention further includes a nonaqueous, ionically conductive electrolyte which serves as a medium for migration of ions between the anode and the cathode electrodes during the electrochemical reactions of the cell.
  • the electrochemical reaction at the electrodes involves conversion of ions in atomic or molecular forms which migrate from the anode to the cathode.
  • nonaqueous electrolytes suitable for the present invention are substantially inert to the anode and cathode materials, and they exhibit those physical properties necessary for ionic transport, namely, low viscosity, low surface tension and wettability.
  • a suitable electrolyte has an inorganic, ionically conductive salt dissolved in a nonaqueous solvent, and more preferably, the electrolyte includes an ionizable alkali metal salt dissolved in a mixture of aprotic organic solvents comprising a low viscosity solvent and a high permittivity solvent.
  • the inorganic, ionically conductive salt serves as the vehicle for migration of the anode ions to intercalate into the cathode active material, and has the general formula MM'F 6 or MM' F 4 wherein M is an alkali metal similar to the alkali metal comprising the anode and M' is an element selected from the group consisting of phosphorous, arsenic, antimony and boron.
  • salts yielding M'F 6 are: hexafluorophosphate (PF 6 ) , hexafluoroarsenate (AsF 6 ) and hexafluoroantimonate (SbF 6 ) while tetrafluoroborate (BF 4 ) is exemplary of salts yielding M'F 4 .
  • the alkali metal salt comprises lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium hexafluoroantimonate or lithium tetrafluoroborate dissolved in a suitable solvent mixture.
  • the corresponding sodium or potassium salts may be used.
  • inorganic salts useful with the present invention include LiC10 4 , LiAlCl 4 , LiGaCl 4 , LiC (S0 2 CF 3 ) 3 , LiN (S0 2 CF 3 ) 2 , LiS0 3 F, LiB(C 6 H 5 ) 4 and LiCF 3 S0 3 , and mixtures thereof.
  • Low viscosity solvents include tetrahydrofuran (THF) , methyl acetate (MA) , diglyme, triglyme, tetraglyme, dimethyl carbonate (DMC) , diethyl carbonate, 1, 2 -dimethoxyethane (DME) and mixtures thereof
  • high permittivity solvents include cyclic carbonates, cyclic esters and cyclic amides such as propylene carbonate (PC) , ethylene carbonate (EC) , acetonitrile, dimethyl sulfoxide, dimethyl formamide, dimethyl acetamide, ⁇ -butyrolactone (GBL) and N-methyl -pyrrolidinone (NMP) and mixtures thereof.
  • the anode is preferably lithium metal and the preferred electrolyte is 1.0M to 1.4M LiAsF 6 dissolved in an aprotic solvent mixture comprising a 50/50 mixture (by volume) of propylene carbonate (PC) and dimethoxyethane (DME) .
  • PC propylene carbonate
  • DME dimethoxyethane
  • the preferred form of the electrochemical cell is a case-negative design wherein the anode/cathode couple is inserted into a conductive metal casing such that the casing is connected to the anode current collector in a case-negative configuration, as is well known to those skilled in the art.
  • a preferred material for the casing is titanium although stainless steel, mild steel, nickel -plated mild steel and aluminum are also suitable.
  • the casing header comprises a metallic lid having an opening to accommodate the glass-to-metal seal/terminal pin feedthrough for the cathode electrode.
  • the anode electrode is preferably connected to the case or the lid. An additional opening is provided for electrolyte filling.
  • the casing header comprises elements having compatibility with the other components of the electrochemical cell and is resistant to corrosion.
  • the cell is thereafter filled with the electrolyte solution described hereinab ⁇ ve and hermetically sealed such as by close-welding a stainless steel plug over the fill hole, but not limited thereto.
  • the cell of the present invention can also be constructed in a case-positive design.
  • SVO Silver vanadium oxide
  • DMF dimethyl formamide
  • Aluminum alloy foil designated as 1145-0 was etched using a sulfuric acid solution designated as a P2 solution which was made by bringing 210 ml of concentrated sulfuric acid (H 2 S0 4 ) and 183.76 grams of ferrous sulfate (Fe 2 (S0 4 ) 3 5H 2 0) to 1 liter with water.
  • a sulfuric acid solution designated as a P2 solution which was made by bringing 210 ml of concentrated sulfuric acid (H 2 S0 4 ) and 183.76 grams of ferrous sulfate (Fe 2 (S0 4 ) 3 5H 2 0) to 1 liter with water.
  • Figs. 1 and 2 show lOOOx magnification scanning electron microscope photos of untreated and P2 etched 1145-0 aluminum alloy foil, respectively.
  • the SVO slurry was shaken and transferred using a scoopula to the etched aluminum foil.
  • the slurry was spread using a doctor blade with a gap of 0.008 inches to provide a uniform coating thereon.
  • the casting was allowed to dry in a flowing air hood overnight before a coupon of 5.2cm 2 was cut from the laminate. Drying generally reduces the thickness of the active mixture by about one-half. In this example, the dried active casting had a thickness of about 0.004 inches.
  • a 0.125 x 0.125 inch area was cleared from one corner of the coupon before it was pressed at 6.15 tons/cm 2 . Pressing further reduced the thickness of the active casting to about 0.0015 to 0.002 inches.
  • a 0.125 x 6 inch aluminum lead was resistance spot welded to the cleared area of the coupon.
  • the cathode laminate was wrapped in two layers of CELGARD 4560 polypropylene separator material, and a piece of lithium metal of a similar dimension was placed against the SVO coated side of the cathode followed by a screen with a lead to serve as the current collector for the lithium anode.
  • the electrode assembly was held together between glass slides using a metal clip and positioned in a glass vessel of suitable dimension with the leads allowed to hang over the rim of the vessel.
  • the vessel was filled with 1M LiAsF 6 in 1:1, by volume, propylene carbonate and dimethoxyethane.
  • a rubber stopper provided a lid for the vessel.
  • Fig. 3 is a graph showing the discharge of the above described cell constructed in this example according to the present invention, wherein curve 30 was constructed from the prepulse voltage and curves 32 and 34 were constructed from the PI Min. and P4 Min. discharge voltages versus delivered capacity, respectively.
  • the cell delivered 0.028 Ah to a 2.0 V cutoff as defined by a pulse four minimum at or below 2.0 V.
  • Silver vanadium oxide was ball milled for 2 hours using 1/2 x 1/2 inch cylindrical ceramic media in a polytetrafluoroethylene jar. This material was then baked at 375°C for 65 hours prior to being sieved to remove particles larger than 0.0041 inches. 47 grams of the resulting sample of SVO was mixed with 1.5 grams of Ketjenblack carbon (3% by weight) using a mortar and pestle. The resulting admixture was added to 7.5 grams of a 17.3 wt% solution of Kynar 711 polyvinylidene fluoride in dimethyl formamide and made less viscous with about 45 ml of additional DMF.
  • This cathode active mixture was spread on one side of a P2 etched 1145-0 aluminum foil using a doctor blade having a gap of about 0.008 inches, and allowed to dry to a thickness of about 0.004 inches, as described in Example I.
  • the second side of the aluminum foil was then coated in a similar manner to provide samples comprising the SVO cathode active material contacted to both sides of the P2 surface treated foil collector. The samples were about 5 x 12 inches. From these large samples, smaller ribbons were cut to 0.695 inches in width. Cathodes of 13.25 inches in length were fabricated from smaller pieces by clearing areas of
  • Both the anodes and the cathodes were wrapped in one layer of CELGARD 2400 polypropylene separator before being wound together in a jellyroll configuration and placed in a stainless steel vessel of 0.551 x 0.708 x 0.998 inch dimension.
  • the anode leads were welded to the side of the vessel and the cathode leads were welded to a glass- o-metal hermetic feedthrough in the vessel lid.
  • the cells were then activated with an electrolyte of 1 M LiAsF 6 in 1:1, by volume, propylene carbonate and dimethoxyethane. Open circuit voltages of the cells were 3.45 to 3.47 V. Thirty cells were made.
  • Fig. 5 is a graph showing the discharge of a typical one of these nine cells wherein curve 50 was constructed from the prepulse voltage and curves 52 and 54 were constructed from the PI Min. and P4 Min. discharge voltages versus delivered capacity, respectively.
  • Fig. 6 is a graph showing the average discharge of five of these cells wherein curve 60 was constructed from the average prepulse voltage and curves 62 and 64 were constructed from the average PI Min. and P4 Min. discharge voltages versus delivered capacity, respectively.
  • Silver vanadium oxide was attrited for 1 hour using 1/4 inch spherical steel media to reduce its average particle size.
  • 9 grams of the resulting ground SVO was mixed with 0.5 grams of Ketjenblack carbon (5% by weight) using a mortar and pestle.
  • the resulting admixture was added to 2.86 grams of a 17.3 wt % solution of Kynar 711 polyvinylidene fluoride in dimethyl formamide and made less viscous by the addition of more DMF.
  • This cathode active admixture was spread on one side of a P2 etched 1145-0 aluminum foil (0.008 inches in thickness) and dried to a thickness of about 0.004 inches thick, as described in Example I.
  • the second side of the aluminum foil was then coated in a similar manner so that a sample having both sides coated resulted.
  • the sample was about 5 x 12 inches. From this large sample, smaller ribbons were cut to 0.695 inches in width.
  • Cathodes of 15.5 inches in length were fabricated from smaller pieces by clearing areas of 0.125 inches from the ribbon ends, pressing the pieces at 6.15 tons/cm 2 to a thickness of about 0.0015 to 0.002 inches, and resistance spot welding the pieces together. Leads were welded to the cathodes in the cleared areas .
  • Lead placement was at positions about was one-quarter of the total length of the cathode from each of its ends.
  • Anodes of 16.5 x 0.605 x 0.008 inches were fabricated by applying 0.0012 thick lithium to a 0.580 inch thick expanded nickel metal screen. The anodes had leads at one end and at a position about 3/4 along their lengths .
  • Both the anodes and the cathodes were wrapped in one layer of CELGARD 2400 separator before being wound together in a jellyroll configuration and placed in a stainless steel vessel of 0.551 x 0.708 x 0.998 inch dimension.
  • the anode leads were welded to the side of the vessel and the cathode leads were welded to a glass - to-metal hermetic feedthrough in the vessel lid.
  • FIG. 7 is a graph showing the discharge of the cell subjected to 1.5 A pulses wherein curve 70 was constructed from the prepulse voltage and curves 72 and 74 were constructed from the PI Min. and P4 Min. discharge voltages versus delivered capacity, respectively.
  • Fig. 8 is a graph showing the discharge of the cell subjected to 1.75 A pulses wherein curve 80 was constructed from the prepulse voltage and curves 82 and 84 were constructed from the Pi Min. and P4 Min. discharge voltages versus delivered capacity, respectively.
  • Fig. 9 is a graph showing the discharge of the cell subjected to the 2.0 A pulses wherein curve 90 was constructed from the prepulse voltage and curves 92 and 94 were constructed from the PI Min. and P4 Min. discharge voltages versus delivered capacity, respectively.
  • Table 3 shows the capacity delivered by each cell to the specified cutoffs:
  • cathodes prepared according to the present invention from a slurry of an electrode active material, exemplified by silver vanadium oxide, contacted to a surface- treated foil collector can be wound about a 1/8 inch metal rod while maintaining their mechanical integrity, even after several windings and unwindings .
  • the electrodes comprising a cathode active material contacted to a surface treated conductive foil according to the present invention exhibit improved structural integrity even when tightly wound with an anode in a jellyroll configuration while maintaining high current densities typically associated with an alkali metal/mixed metal oxide electrical couple.
  • Silver vanadium oxide was sieved to less than 140 mesh and, 4.25 grams of the sieved material was combined with 10 grams of graphite #38 and 15 grams of Ketjenblack carbon using a mortar and pestle. The resulting mixture was added to a solution of 50 grams Kynar 461 polyvinylidene fluoride in 800 grams of dimethyl formamide and 10 grams of propylene carbonate. The resulting slurry was milled/mixed and transfered to untreated Reynolds, heavy duty aluminum foil of 0.001 inches in thickness using a scoopula. The slurry was spread using a doctor blade with a gap of 0.015 inches such that a uniform coating resulted.
  • the casting was allowed to dry to a thickness of about 0.008 inches in a heated chamber before a coupon of 5.2 cm 2 was cut from the laminate.
  • a 0.125 x 0.125 inch area was cleared from one corner of the coupon before it was pressed at 6.15 tons/cm 2 to provide the coupon having an active material thickness of about 0.004 inches.
  • a 0.125 x 6 inch aluminum lead was resistance spot welded to the cleared area of the cathode active coupon laminate.
  • the cathode laminate was wrapped in two layers of CELGARD 4560 polypropylene separator material, and a coupon of lithium metal of the same dimension was placed against the SVO coated side of the cathode as was a screen with a lead to serve as a current collector for the lithium anode.
  • the electrode assembly was held together using a metal clip and positioned in a glass vessel of suitable dimension with the leads allowed to hang over the rim of the vessel.
  • the vessel was filled by 1M LiAsF 6 in 1:1, by volume, propylene carbonate and 1, 2 -dimethoxyethane.
  • a rubber stopper provided a lid for the vessel.
  • the cell was discharged using semi -hourly applied pulse trains comprising four, 10 second, 0.094 A (0.018A/cm 2 ) pulses with 15 seconds rest between each pulse.
  • a plot of the discharge curves are present in Fig. 10.
  • curve 100 was constructed from the prepulse voltage of the cell constructed according to this example, and curves 102 and 104 were constructed from the PI Min. and P4 Min. discharge voltages versus delivered capacity, respectively of this cell.
  • the cell delivered 0.0075 Ah to a 2 V cutoff as defined by a pulse minimum at or below 2 V.

Landscapes

  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Cell Electrode Carriers And Collectors (AREA)
  • Secondary Cells (AREA)

Abstract

Cette invention se rapporte à un procédé pour former des électrodes flexibles, telles que de préférence des cathodes. Ce procédé consiste à couler une suspension épaisse d'un matériau actif d'électrodes, de préférence mélangée à un matériau liant et à un diluant conducteur, sur un substrat conducteur, puis à presser le stratifié ainsi produit. Le substrat conducteur peut être soumis à une opération visant à le rendre rugueux ou à une opération d'attaque au moyen d'une solution acide, ou ledit substrat peut être utilisé à l'état nettoyé mais non traité. Les cathodes ainsi obtenues sont utiles pour être déchargées dans des éléments d'accumulateurs électrochimiques non aqueux en métal alcalin.
PCT/US1997/004975 1996-07-02 1997-03-25 Preparation et utilisation de minces cathodes flexibles dans des elements d'accumulateurs electrochimiques en metal alcalin Ceased WO1998000877A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU25913/97A AU2591397A (en) 1996-07-02 1997-03-25 Preparation and use of thin flexible cathodes in alkali metal electrochemical cells

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US67456396A 1996-07-02 1996-07-02
US08/674,563 1996-07-02

Publications (1)

Publication Number Publication Date
WO1998000877A1 true WO1998000877A1 (fr) 1998-01-08

Family

ID=24707096

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/004975 Ceased WO1998000877A1 (fr) 1996-07-02 1997-03-25 Preparation et utilisation de minces cathodes flexibles dans des elements d'accumulateurs electrochimiques en metal alcalin

Country Status (2)

Country Link
AU (1) AU2591397A (fr)
WO (1) WO1998000877A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0969539A1 (fr) * 1998-06-30 2000-01-05 Wilson Greatbatch Ltd. Nitrites organiques comme additifs dans l'électrolyte nonaqueux de piles électrochimiques contenant un métal alcalin
EP1217674A3 (fr) * 2000-12-15 2004-10-20 Wilson Greatbatch Ltd. Céllule électrochimique avec un électrode à l'oxide d'argent et vanadium enduit sur un collecteur de courant
US7790009B2 (en) 2001-06-15 2010-09-07 Replisaurus Technologies Ab Method and electrode for defining and replicating structures in conducting materials

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5424151A (en) * 1993-08-04 1995-06-13 Valence Technology, Inc. Cathode composition and method of making same
US5436091A (en) * 1989-05-11 1995-07-25 Valence Technology, Inc. Solid state electrochemical cell having microroughened current collector
US5580683A (en) * 1993-11-01 1996-12-03 Wilson Greatbatch Ltd. high pulse power cell
US5616366A (en) * 1994-04-20 1997-04-01 Valence Technology, Inc. Method for producing low porosity electrode

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5436091A (en) * 1989-05-11 1995-07-25 Valence Technology, Inc. Solid state electrochemical cell having microroughened current collector
US5424151A (en) * 1993-08-04 1995-06-13 Valence Technology, Inc. Cathode composition and method of making same
US5580683A (en) * 1993-11-01 1996-12-03 Wilson Greatbatch Ltd. high pulse power cell
US5616366A (en) * 1994-04-20 1997-04-01 Valence Technology, Inc. Method for producing low porosity electrode

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0969539A1 (fr) * 1998-06-30 2000-01-05 Wilson Greatbatch Ltd. Nitrites organiques comme additifs dans l'électrolyte nonaqueux de piles électrochimiques contenant un métal alcalin
EP1217674A3 (fr) * 2000-12-15 2004-10-20 Wilson Greatbatch Ltd. Céllule électrochimique avec un électrode à l'oxide d'argent et vanadium enduit sur un collecteur de courant
US7790009B2 (en) 2001-06-15 2010-09-07 Replisaurus Technologies Ab Method and electrode for defining and replicating structures in conducting materials

Also Published As

Publication number Publication date
AU2591397A (en) 1998-01-21

Similar Documents

Publication Publication Date Title
CA2346601C (fr) Empilement efficace de cellules pour piles avec cathode sandwich collectrice double
US6228534B1 (en) Annealing of mixed metal oxide electrodes to reduce polarization resistance
US6790561B2 (en) Process for fabricating continuously coated electrodes on a porous current collector and cell designs incorporating said electrodes
EP0698934B1 (fr) Méthode de fabrication d'une électrode négative pour pile secondaire au lithium
US6511772B2 (en) Electrochemical cell having an electrode with a phosphate additive in the electrode active mixture
US5695892A (en) Preparation of silver vanadium oxide using nitric acid with oxide starting materials
AU756839B2 (en) Chemically machined current collector design
US6673493B2 (en) Double current collector cathode design using the same active material in varying formulations for alkali metal or ion electrochemical cells
US5807645A (en) Discharge promoter mixture for reducing cell swelling in alkali metal electrochemical cells
US7820328B1 (en) Electrochemical cell electrode with improved particle-to-particle contact and method of manufacturing
US6743547B2 (en) Pellet process for double current collector screen cathode preparation
US20030096169A1 (en) Powder process for double current collector screen cathode preparation
EP1221732A2 (fr) Electrode contenant un liant traité thermiquement consistant d'un mélange d'acide polyamique et PVDF
JP2960834B2 (ja) リチウム二次電池
JPH11265722A (ja) アルカリ金属電気化学電池の膨潤の制御
US20070059599A1 (en) Sandwich Cathode Electrochemical Cell With Wound Electrode Assembly
CA2361030A1 (fr) Cathode double collectrice de courant pour cellules electrochimiques a metal alcalin ayant des dispositifs de securite pour les courts-circuits
EP0989624A1 (fr) Batterie secondaire au lithium fabriquée avec des matériaux à basse susceptibilité magnétique
US6767670B2 (en) Carbon-coated titanium current collectors for use in alkali metal electrochemical cells
JP2002198061A (ja) 二重集電体カソード構造を用いた短絡安全特性を有するアルカリ金属電気化学セル
EP1207570A2 (fr) Structure cathodique sandwich utilisant une matière active chimiquement identique pour cellules électrochimiques à métal alcalin
CA2376895A1 (fr) Processus de fabrication d'electrodes a revetement en continu sur un collecteur de courant poreux et modeles de cellules contenant lesdits electrodes
US6528207B2 (en) Electrochemical cell having an electrode with a nitrite additive in the electrode active mixture
JPH117962A (ja) 非水電解質二次電池
WO1998000877A1 (fr) Preparation et utilisation de minces cathodes flexibles dans des elements d'accumulateurs electrochimiques en metal alcalin

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU JP

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: JP

Ref document number: 98504087

Format of ref document f/p: F

122 Ep: pct application non-entry in european phase