WO2025049152A1

WO2025049152A1 - Li metal battery cycle life improvement by interface metal/dielectric stack

Info

Publication number: WO2025049152A1
Application number: PCT/US2024/042946
Authority: WO
Inventors: Kashish SHARMA; Thomas Humphreys; Girish Kumar Gopalakrishnan Nair; Subramanya P. Herle
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2023-08-31
Filing date: 2024-08-19
Publication date: 2025-03-06
Anticipated expiration: 2026-02-28

Abstract

Alkali metal containing devices and methods for manufacturing alkali metal containing devices are provided. In one aspect, an anode electrode structure is provided. The anode electrode structure includes a current collector including copper and/or stainless steel, a lithium metal film formed over the current collector, and a protective film stack formed on the lithium metal film. The protective film stack includes a metallic film formed over the lithium metal film and a lithium salt film formed on the metallic film. The metallic film is selected from a bismuth film, a tin film, a silver film, or a combination thereof. The lithium salt film is formed on the metallic film, the lithium salt film selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

Description

LI METAL BATTERY CYCLE LIFE IMPROVEMENT BY INTERFACE METAL/DIELECTRIC STACK

BACKGROUND

Field

[0001 ] The present disclosure generally relates to alkali metal containing devices and methods for manufacturing alkali metal containing devices. More particularly, the disclosure relates to device stacks including lithium metal anodes and pre-lithiated anodes for energy storage devices and methods for manufacturing the same.

Description of the Related Art

[0002] Rechargeable electrochemical storage systems are currently becoming increasingly essential for many fields of everyday life. High-capacity electrochemical energy storage devices, such as lithium-ion (Li-ion) batteries, are used in a growing number of applications, including portable electronics, medical, transportation, grid- connected large energy storage, renewable energy storage, and uninterruptible power supply (UPS). Traditional lead/sulfuric acid batteries often lack the capacitance and are often inadequately cyclable for these growing applications. Lithium-ion batteries, however, are thought to provide the best solution.

[0003] Therefore, there is a need for methods and systems for the deposition and processing of lithium metals used in energy storage devices.

SUMMARY

[0004] The present disclosure generally relates to alkali metal containing devices and methods for manufacturing alkali metal containing devices. More particularly, the disclosure relates to device stacks including lithium metal anodes and pre-lithiated anodes for energy storage devices and methods for manufacturing the same.

[0005] In one aspect, an anode electrode structure is provided. The anode electrode structure includes a current collector including copper and/or stainless steel, a lithium metal film formed over the current collector, and a protective film stack formed on the lithium metal film. The protective film stack includes a metallic film formed over the lithium metal film and a lithium salt film formed on the metallic film. The metallic film is selected from a bismuth film, a tin film, a silver film, or a combination thereof. The lithium salt film is formed on the metallic film, the lithium salt film selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

[0006] Implementations may include one or more of the following. The protective film stack further includes a lithium carbonate film, the lithium carbonate film formed on the lithium metal film and the metallic film formed on the lithium carbonate film. The anode electrode structure further includes an anode film, the anode film formed on the current collector and the lithium metal film formed on the anode film. The metallic film is the silver film. The metallic film has a thickness in a range from about 50 nanometers to about 500 nanometers. The lithium salt film is a lithium fluoride film having a thickness in a range from about 100 nanometers to about 500 nanometers. The current collector includes a polymer substrate and a copper film formed over the polymer substrate.

[0007] In another aspect an energy storage device is provided. The energy storage device includes the aforementioned anode electrode structure, a cathode electrode structure, and a separator film or solid electrolyte film formed between the anode electrode structure and the cathode electrode structure.

[0008] In yet another aspect, a method of forming an anode electrode structure is provided. The method includes forming a protective film stack over a lithium metal film, the lithium metal film formed over a substrate. Forming the protective film stack includes forming a metallic film over the lithium metal film and forming a lithium salt film on the metallic film. The metallic film is selected from a bismuth film, a tin film, a silver film, or a combination thereof. The lithium salt film is selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydrides, or a combination thereof.

[0009] Implementations may include one or more of the following. The method further includes forming a lithium carbonate film on the lithium metal film prior to forming the protective film stack over the lithium salt film, the lithium carbonate film formed on the lithium salt film and the metallic film formed on the lithium carbonate film. Forming the lithium carbonate film includes exposing the lithium metal film to CO2 gas in a first processing region defined by a first processing chamber. The method further includes transferring the substrate from the first processing region to a second processing region in a second processing region defined by a second processing chamber, wherein the protective film stack is formed in the second processing chamber. The substrate is a current collector having an anode film formed thereon. Forming the metallic film includes a thermal evaporation process. Forming the lithium salt film includes a thermal evaporation process. The substrate is a webbased substrate. The metallic film is the silver film. The metallic film has a thickness in a range from about 50 nanometers to about 500 nanometers. The lithium salt film is a lithium fluoride film having a thickness in a range from about 100 nanometers to about 500 nanometers. The substrate includes a polymer substrate and a copper film formed over the polymer substrate.

[0010] In yet another aspect, a method of forming a film stack for an energy storage device is provided. The method includes forming a protective film stack over a flexible support layer stack. Forming the protective film stack includes forming a lithium salt film over the release layer, forming a metallic film on the lithium salt film, the metallic film selected from a bismuth film, a tin film, a silver film, or a combination thereof, and forming a lithium metal film on the metallic film. The method further includes laminating the lithium metal film to a flexible substrate stack. The method further includes separating the protective film stack from the flexible support layer stack to form an anode film stack. The lithium salt film is selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

[0011 ] Implementations may include one or more of the following. The flexible support layer stack includes a polymer substrate having a release layer formed thereon and the protective film stack is formed on the release layer. The flexible support layer stack includes a polymer substrate and the protective film stack is formed on the polymer substrate. The flexible substrate stack includes a current collector including copper. The flexible substrate stack further includes an anode film formed over the current collector and the lithium metal film contacts the anode film. Forming the metallic film includes a thermal evaporation process. Forming the lithium salt film includes a thermal evaporation process. The metallic film is the silver film.

[0012] In yet another aspect, an anode stack is provided. The anode stack includes a copper substrate configured to act as a current collector, a lithium layer disposed on the copper substrate and configured to act as an anode, a silver layer disposed on the lithium layer, and a lithium salt layer disposed on the silver layer, the lithium salt layer selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

[0013] Implementations may include one or more of the following. A passivation layer is disposed between the lithium layer and the silver layer. The passivation layer includes lithium carbonate and is formed by passivating the lithium layer with carbon dioxide. The lithium salt layer includes lithium fluoride. The lithium salt layer has a thickness of 50 nm to 600 nm. The silver layer has a thickness of 40 nm to 600 nm.

[0014] In yet another aspect, a method of forming an anode stack is provided. The method includes depositing a lithium layer on a copper substrate using a roll to roll physical vapor deposition (PVD) tool, depositing a silver layer on the lithium layer using thermal evaporation, and depositing a lithium salt on the silver layer using thermal evaporation, the lithium salt layer selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

[0015] Implementations may include one or more of the following. The method further includes passivating the lithium layer prior to depositing the silver layer with an in-situ carbon dioxide passivation process. Depositing of the lithium layer and passivating the lithium layer are done in the roll to roll PVD tool and the depositing of the silver layer and lithium salt layer are done in a different chamber. The method is done in the roll to roll PVD tool. The lithium salt layer includes lithium fluoride. The lithium salt layer has a thickness of 50 nm to 600 nm. The silver layer has a thickness of 40 nm to 600 nm. The method further includes integrating the anode stack with a separator and cathode structure to form an energy storage device.

[0016] In yet another aspect, a method of forming an anode structure is provided. The method includes forming a release layer on a polymer substrate, depositing a lithium salt layer on the release layer disposed on the polymer substrate, depositing a silver layer on the lithium salt layer, depositing a lithium layer on the silver layer forming an anode, and transferring the anode from the polymer substrate to a copper substrate forming an anode structure, the lithium salt layer selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

[0017] Implementations may include one or more of the following. The lithium salt layer includes lithium fluoride. The lithium salt layer has a thickness of 50 nm to 600 nm. The silver layer has a thickness of 40 nm to 600 nm. The lithium layer has a thickness of 2 microns to 25 microns. The method further includes integrating the anode stack with a separator and cathode structure to form an energy storage device.

[0018] In another aspect, a non-transitory computer readable medium has stored thereon instructions, which, when executed by a processor, causes the process to perform operations of the above apparatus and/or method.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments.

[0020] FIG. 1 illustrates a schematic cross-sectional view of an energy storage device incorporating an anode structure having a protective film stack formed according to one or more implementations described herein.

[0021 ] FIG. 2 illustrates a cross-sectional view of a dual-sided anode electrode structure having a protective film stack formed according to one or more implementations described herein.

[0022] FIG. 3 illustrates a flowchart showing selected operations of a method of forming an energy storage device in accordance with one or more implementations of the present disclosure.

[0023] FIGS. 4A-4D illustrate views of various stages of manufacturing an energy storage device according to the method of FIG. 3 in accordance with one or more implementations of the present disclosure. [0024] FIG. 5 illustrates a flowchart showing selected operations of a method of forming an energy storage device in accordance with one or more implementations of the present disclosure.

[0025] FIGS. 6A-6F illustrate views of various stages of manufacturing an energy storage device according to the method of FIG. 5 in accordance with one or more implementations of the present disclosure.

[0026] FIG. 7 illustrates SEM images of a lithium surface passivated with different protective film stacks and control samples with no passivation in accordance with one or more implementations of the present disclosure.

[0027] FIG. 8 illustrates a plot of impedance data for various protective film stacks in accordance with one or more implementations of the present disclosure.

[0028] FIG. 9 illustrates a plot of voltage versus time demonstrating lithium plating/stripping behavior of Li/Li symmetric cells including various protective film stacks in accordance with one or more implementations of the present disclosure.

[0029] FIG. 10 illustrates a plot demonstrating the discharge and charge capacity against cycle numbers collected for the Li/Li symmetric cells in accordance with one or more implementations of the present disclosure.

[0030] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

[0031 ] The present disclosure generally relates to an alkali metal containing devices and methods for manufacturing alkali metal containing devices. More particularly, the disclosure relates to device stacks including lithium metal anodes and pre-lithiated anodes for energy storage devices and methods for manufacturing the same.

[0032] Energy storage devices, for example, Li-ion batteries and sodium-ion batteries, typically include a positive electrode (e.g., cathode), and a negative electrode separated by a polymer separator with a liquid electrolyte. Solid-state batteries also typically include a positive electrode (e.g., cathode) and a negative electrode (e.g., anode) but replace both the polymer separator and the liquid electrolyte with an ion-conducting material. Lithium metal is considered to be one of the most attractive candidates due to its high capacity and low potential than traditionally used graphite but cycle life is a challenge due to lithium dendrite formation during charging/discharging. The ability to use alkali metals such as lithium and sodium in next generation batteries including Li-ion batteries, sodium-ion batteries, and solid-state batteries becomes increasingly substantial. However, alkali metal technology presents significant device integration challenges such as handling lithium in dry room ambient, suitable surface protection technology, and the need to suppress or eliminate lithium metal dendrite during battery cycling. For example, lithium metal is very reactive with ambient gases like O2, N2, and H2O under normal atmospheric conditions. From the electrochemical device perspective, an interface material should not only help prevent oxidation of the lithium surface but also should help in improving device performance is desirable.

[0033] Using the implementations described herein, the deposited lithium metal, either single-sided or dual-sided, can be protected during winding and unwinding of the reels downstream. Deposition of one or more thin protective films as described herein has several advantages. In some implementations, the one or more protective films described herein provide adequate surface protection for shipping, handling, and storage as well as avoiding surface reactions of lithium during device integration. In some implementations, the one or more protective films described herein are compatible with lithium ions and reduce impedance for ions to move across. In some implementations, the one or more protective films described herein are ion-conducting and thus may be incorporated into the formed energy storage device. In some implementations, the one or more protective films described herein can also help suppress or eliminate lithium dendrites, especially at high current density operation. In some implementations, the use of protective films described herein reduces the complexity of manufacturing systems and is compatible with current manufacturing systems.

[0034] As described herein, flexible substrates can be considered to include among other things, films, foils, webs, strips of plastic material, metal, paper, or other materials. Typically, the terms “web,” “foil,” “strip,” “substrate” and the like are used synonymously.

[0035] FIG. 1 illustrates a schematic cross-sectional view of one implementation of an energy storage device 100 incorporating an anode electrode structure having a protective film stack formed according to implementations described herein. The energy storage device 100 may be a solid-state energy storage device, a sodium-ion based storage device, or a lithium-ion based energy storage device. The energy storage device 100, even though shown as a planar structure, may also be formed into a cylinder by rolling the stack of layers; furthermore, other cell configurations (e.g., prismatic cells, button cells, or stacked electrode cells) may be formed. The energy storage device 100 includes an anode electrode structure 110 and a cathode electrode structure 120 with a separator film 130 positioned therebetween. In implementations where the energy storage device 100 is a solid-state energy storage device, the separator film 130 is replaced with a solid-electrolyte film. The cathode electrode structure 120 includes a cathode current collector 140 and a cathode film 150. The anode electrode structure 110 includes an anode current collector 160, an anode film 170, and the protective film stack 180. The protective film stack 180 includes at least one or more of a lithium salt film, a sodium salt film, a metallic film (e.g., a bismuth film, a tin film, a silver film), and a lithium carbonate film.

[0036] The cathode electrode structure 120 includes the cathode current collector 140 with the cathode film 150 formed on the cathode current collector 140. It should be understood that the cathode electrode structure 120 may include other elements or films.

[0037] The separator film 130 may include, a cellulose based substrate, for example, a blend of cellulose nanofibers and aramid fibers, by way of non-limiting example. The separator film 130 may include, a microporous polymeric separator including a polyolefin, by way of non-limiting example. The polyolefin may be a homopolymer (derived from a single monomer constituent) or a heteropolymer (derived from more than one monomer constituent), which may be either linear or branched. If a heteropolymer is derived from two monomer constituents, the polyolefin may assume any copolymer chain arrangement, including those of a block copolymer or a random copolymer. Similarly, if the polyolefin is a heteropolymer derived from more than two monomer constituents, it may likewise be a block copolymer or a random copolymer. In certain implementations, the polyolefin may be polyethylene (PE), polypropylene (PP), or a blend of PE and PP, or multi-layered structured porous films of PE and/or PP. Commercially available polyolefin porous membranes include CELGARD® 2500 (a monolayer polypropylene separator) and CELGARD® 2320 (a tri-layer polypropylene/polyethylene/polypropylene separator) available from Celgard LLC. The separator film 130 may be or include a web-based substrate.

[0038] The current collectors 140, 160, on the cathode film 150 and the anode film 170, respectively, can be identical or different electronic conductors. In some implementations, at least one of the current collectors 140, 160 is a flexible substrate. In some implementations, the flexible substrate is a CPP film (i.e., a casting polypropylene film), an OPP film (i.e., an oriented polypropylene film), or a PET film (i.e., an oriented polyethylene terephthalate film). Alternatively, the flexible substrate may be a pre-coated paper, a polypropylene (PP) film, a PEN film, a poly lactase acetate (PLA) film, or a PVC film. Examples of metals that the current collectors 140, 160 may be comprised of include aluminum (Al), copper (Cu), zinc (Zn), nickel (Ni), cobalt (Co), manganese (Mn), chromium (Cr), stainless steel, clad materials, alloys thereof, and a combination thereof. In one or more implementations, which can be combined with other implementations, at least one of the current collectors 140, 160 is perforated. In one implementation, at least one of the current collectors 140, 160 is a metallized plastic substrate including a polymer substrate (e.g., polyethylene terephthalate (“PET”)) coated with a metallic material. In one or more implementations, which can be combined with other implementations, the anode current collector 160 is a polymer substrate (e.g., a PET film) coated with copper. In another implementation, the anode current collector 160 is a multi-metal layer on a polymer substrate. The multi-metal layer can be combinations of copper, chromium, nickel, etc. In one or more implementations, which can be combined with other implementations, the anode current collector 160 is a multi-layer structure that includes a copper-nickel cladding material. In one or more implementations, which can be combined with other implementations, the multi-layer structure includes a first layer of nickel or chromium, a second layer of copper formed on the first layer, and a third layer including nickel, chromium, or both formed on the second layer. In one or more implementations, which can be combined with other implementations, the anode current collector 160 is nickel coated copper. Furthermore, current collectors may be of any form factor (e.g., metallic foil, mesh foil, sheet, or plate), shape and micro/macro structure.

[0039] Generally, in prismatic cells, tabs are formed of the same material as the current collector and may be formed during fabrication of the stack, or added later. In some implementations, the current collectors extend beyond the stack and the portions of the current collector extending beyond the stack may be used as tabs. In one or more implementations, which can be combined with other implementations, the cathode current collector 140 is aluminum. In one or more implementations, which can be combined with other implementations, the cathode current collector 140 comprises aluminum deposited on a polymer substrate (e.g., a PET film). In one implementation, the cathode current collector 140 has a thickness below 50 pm more specifically, 5 pm or, even more specifically 2 pm. In one implementation, the cathode current collector 140 has a thickness from about 0.5 pm to about 20 pm (e.g., from about 1 pm to about 20 pm; from about 6 pm to about 18 pm; or from about 5 pm to about 10 pm). In one or more implementations, which can be combined with other implementations, the anode current collector 160 is or includes copper. In one implementation, the anode current collector 160 is stainless steel. In one implementation, the anode current collector 160 has a thickness below 50 pm more specifically, 5 pm or, even more specifically 2 pm. In one implementation, the anode current collector 160 has a thickness from about 0.5 pm to about 20 pm (e.g., from about 1 pm to about 10 pm; from about 2 pm to about 8 pm; from about 6 pm to about 18 pm; or from about 5 pm to about 10 pm).

[0040] The cathode film 150 or cathode may be any material compatible with the anode and may include an intercalation compound, an insertion compound, or an electrochemically active polymer. Suitable intercalation materials include, for example, lithium-containing metal oxides, M0S2, FeS2, BiFs, Fe2OF4, MnO2, TiS2, NbSes, LiCoO2, LiNiC>2, LiMnC , LiMn2O4, VeO and V2O5. Suitable polymers include, for example, polyacetylene, polypyrrole, polyaniline, and polythiophene. The cathode film 150 or cathode may be made from a layered oxide, such as lithium cobalt oxide, an olivine, such as lithium iron phosphate, or a spinel, such as lithium manganese oxide. Exemplary lithium-containing oxides may be layered, such as lithium cobalt oxide (LiCoC ), or mixed metal oxides, such as LiNixCoi-2xMnO2, LiNiMnCoC (“NMC”), LiNio.5Mm.5O4, Li(Nio.8Coo.i5Alo.o5)02, LiMri2O4, and doped lithium rich layered-layered materials, wherein x is zero or a non-zero number. Exemplary phosphates may be iron olivine (LiFePO4) and it is variants (such as LiFe(i-x)Mg_xPO4), LiMoPO4, LiCoPO4, LiNiPCM, Li3V2(PO4)3, LiVOPO4, LiMP2O?, or LiFei.sP2O7, wherein x is zero or a non-zero number. Exemplary fluorophosphates may be LiVPO4F, LiAIPO4F, LisV(PO4)2F2 LisCr(PO4)2F2 U2COPO4F, or Li2NiPO4F. Exemplary silicates may be Li2FeSiO4, Li2MnSiO4, or Li2VOSiO4. An exemplary non-lithium compound is Na₅V2(PO4)2F₃.

[0041 ] The anode electrode structure 110 includes the anode current collector 160 with the anode film 170 formed on the anode current collector 160. The anode electrode structure 110 comprises the protective film stack 180, which includes at least one or more of a lithium salt film, a sodium salt film, a metallic film, and a lithium carbonate film. In some implementations, the one or more protective film(s) are ionconducting films.

[0042] The anode film 170 may be any material compatible with the cathode film 150. The anode film 170 can be or include alkali metals, alkaline earth metals, and alloys thereof. The anode film 170 may have an energy capacity greater than or equal to 372 mAh/g, preferably > 700 mAh/g, and most preferably > 1000 mAh/g. The anode film 170 may be constructed from graphite, silicon, silicon-containing graphite, silicon oxide, alkali metals, for example, alkali metal foil or an alkali metal alloy foil (e.g. lithium aluminum alloys or sodium aluminum alloys), or a mixture of an alkali metal and/or an alkali metal alloy and materials such as carbon (e.g. coke, graphite), nickel, copper, tin, indium, silicon, oxides thereof, or a combination thereof. The alkali metal or alloy includes an alkali metal, for example, lithium metal, sodium, potassium, rubidium, cesium, francium, an alloy including the alkali metal, or a combination thereof. The already formed anode material can include or be, but is not limited to, graphite, silicon, silicon graphite, silicon oxide graphite, silicon, tin, hard carbon, metal oxide, or combinations thereof. The alloy including the alkali metal can include an alloy of the alkali metal and the anode material. Suitable lithium-containing metal films include lithium metal, lithium metal foil or a lithium alloy foil (e.g. lithium aluminum alloys), or a mixture of a lithium metal and/or lithium alloy and materials such as carbon (e.g. coke, graphite), nickel, copper, tin, indium, silicon, oxides thereof, or a combination thereof. Suitable sodium-containing metal films include sodium metal, sodium metal foil or a sodium alloy foil (e.g. sodium aluminum alloys), or a mixture of a sodium metal and/or sodium alloy and materials such as carbon (e.g. coke, graphite), nickel, copper, tin, indium, tellurium, silicon, oxides thereof, or a combination thereof. The anode film 170 can include intercalation compounds containing lithium, sodium, or insertion compounds containing lithium or sodium. In one or more implementations, which can be combined with other implementations, the anode film is a lithium metal film or a sodium metal film. In some implementations, wherein the anode film 170 includes lithium metal or sodium metal, the lithium metal or sodium metal may be deposited using the methods described herein.

[0043] In one implementation, the anode film 170 has a thickness from about 10 pm to about 200 pm (e.g., from about 1 pm to about 100 pm; from about 10 pm to about 30 pm; from about 20 pm to about 30 pm; from about 4 pm to about 20 pm; or from about 50 pm to about 100 pm).

[0044] In one or more implementations, which can be combined with other implementations, the anode electrode structure further includes a film of lithium activated tellurium. The film of lithium activated tellurium can be used in place of the anode film 170 to form an anode-free energy storage device. The film of lithium activated tellurium can be an ultrathin lithium activated tellurium film.

[0045] In some implementations, the protective film stack 180 is formed on the anode film 170. In some implementations, the one or more protective film(s) are ionconducting films. In some implementations, the protective film stack 180 are permeable to at least one of lithium ions and lithium atoms. The protective film stack 180 provide surface protection of the anode film 170, which allows for handling of the anode film in a dry room. In some implementations where the energy storage device 100 is a solid-state energy storage device, the protective film stack 180 contributes to the formation of an improved SEI layer and thus improve device performance. The protective film stack 180 can be directly deposited on the anode film 170 by Physical Vapor Deposition (PVD), such as evaporation (e.g., thermal or e-beam) or sputtering, atomic layer deposition (ALD), a slot-die process, dip coating, planar flow melt-spin process, a thin-film transfer process, gravure coating or a three-dimensional lithium printing process. [0046] In some implementations, the protective film stack 180 include one or more metal film(s). Suitable metal film(s) include but are not limited to tin films, bismuth films, gallium films, germanium films, copper films, silver films, gold films, bismuth alloy films, gallium alloy films, germanium alloy films, copper alloy films, silver alloy films, gold alloy films, or a combination thereof. The one or more metal film(s) may be an ultra-thin metal seed film.

[0047] In some implementations, the protective film stack 180 includes one or more lithium salt films. Lithium salt films can include or be lithium salt containing electrolytes, lithium salt anode coatings, or a combination thereof. The electrolytes can be in a gel or polymer matrix medium. Lithium salt films can include or be lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof. Suitable lithium halide films can include or be lithium chloride films, lithium iodide films, lithium fluoride films, and lithium bromide films. Suitable examples of lithium halide films can be or include Li F, LiCI, Li Br, Lil, Li2BeF4, Li3AIF6, Li3YBr6, Li3lnCI6, Li3ScCI6, Li6PS5l, Li6PS5Br, Sr2LiCBr3N2, Li3lnCI6, LiErCI6, Li6PS5CI, LiAICW, LiGaBr4, LiGaCW, LiBiF4, Li6AsS5l, LiSbF4, LiHoGe2(O4F)2, LiBF4, or a combination thereof. Suitable examples of lithium oxide films can be or include Li7La3Zr2O12 (LLZO), Li7La3Hf2O12, LiErO2, LiYO2, LiLaO2, Li5AIO4, Li6PCIO5, Li3AsO4, Li3PO4, Li4GeO4, Li5GaO4, Li2CO3, LiAIB2O5, Li3BiO3, LiZr2(PO4)3, LiTi2(PO4)3, Li2O, Li2HIO, Li10SiP2O12 (LiSiPO), LSnPO, or a combination thereof. Suitable examples of lithium sulfide films can be or include Li9S3N, LiAIS2, Li10Si(PS6)2, Li10SiP2S12, Li3AsS3, Li4GeS4, Li3PS4, Li3BS3, Li4TiS4, LiZnPs4, Li7P3S11 , Li3PS4, Li4GeS4, Li10GeP2S12, Li2S, SrLi(BS2)3, Li5B7S13, LiSO3F, Li2BS3, Li2B2S5, LiSmS2, KLiS, RbLiS, BaLiS3, Li2GePbS4, LiErS2, LiHoS2, LiDyS2, LSiPS, lithium phosphorous sulfide (75Li2S-25P2S5/[3- Li3PS4), crystalline LPS (c-LPS), amorphous lithium phosphorous sulfide LPS (a- LPS), or a combination thereof. Suitable examples of lithium chalcogenide films can be or include Li2Se, LiGaSe2, Li4SnSe4, LilnSe2, LiErSe2, or a combination thereof. Suitable lithium borohydride films can be or include LiBH4 CH3NH2, LiBH4 NH3, LiBH4 NH3BH3, [Li(CH3NH2)(BH4)3], 0.7Li(CB9H10)-0.3Li(CB11 H12), or a combination thereof. Other suitable examples of lithium metal salts include Li3BN2, Sr4Li(BN2)3, Li5SiP3, LiMgB3(H9N)2, Lithium Bis(fluorosulfonyl)imide (LiFSI), Lithium Bis(trifluoromethanesulfonyl)imide, Lithium Bis(oxalate) Borate (LiBOB), Lithium hexafluorophosphate (LiPF6), or a combination thereof.

[0048] In one or more examples, LiTFSI can be incorporated in a flexible solid electrolyte (CSE) membrane composed of poly(vinylidene fluoride) (PVDF) matrix, high-concentration lithium salt (LiTFSI), solvent (DMF), and ceramic filler Li1.3AI0.3Ti1.7 (LATP) PVDF-xLiTFSI, HFP/LiTFSI.

[0049] In one or more implementations, which can be combined with other implementations, the lithium metal salt film may be formed directly on the substrate stack, for example, directly on the current collector to form an anode-free energy storage device.

[0050] In some implementations, the protective film stack 180 includes one or more sodium salt films. In one or more implementations, which can be used with other implementations, the lithium metal salt film can be replaced with or used in combination with sodium salt containing electrolytes, sodium salt anode coatings, or a combination thereof. Sodium salt films can be or include cto-Borate/C/oso-Borate Mixed Anion Electrolytes. Suitable examples of cto-Borate/C/oso-Borate Mixed Anion Electrolytes can be or include NaB11 H14, Na(B11 H14)(B12H12)2, Nax+2y(B11 H14)x(B12H12)y, Na5(B11 H14)(B12H12)2, Na4(B11 H14)2(B12H12), Na3(B11 H14)(B12H12), Na2B12H12, or a combination thereof.

[0051 ] In some implementations, each layer of the protective film stack 180 is a coating or a discrete film having a thickness in a range of 1 nanometer to 3,000 nanometers (e.g., in the range of 10 nanometers to 600 nanometers; in the range of 50 nanometers to 100 nanometers; in the range of 50 nanometers to 200 nanometers; in the range of 100 nanometers to 150 nanometers). In some implementations, each layer of the protective film stack 180 is a coating or discrete film having a thickness of 500 nanometers or less (e.g., from about 1 nm to about 400 nm; from about 25 nm to about 300 nm; from about 50 nm to about 200 nm; from about 100 nm to about 150 nm; from about 10 nm to about 80 nm; or from about 30 to about 60 nanometers). In some implementations, each layer of the protective film stack 180 is a coating or discrete film having a thickness of 100 nanometers or less (e.g., from about 5 nanometers to about 100 nanometers; from about 5 nanometers to about 40 nanometers; from about 10 nanometers to about 20 nanometers; or from about 50 nanometers to about 100 nanometers).

[0052] FIG. 2 illustrates a cross-sectional view of one implementation of an anode electrode structure 200 formed according to implementations described herein. Note in FIG. 2 that the anode current collector 160 is shown to extend beyond the stack, although it is not necessary for the anode current collector 160 to extend beyond the stack, the portions extending beyond the stack may be used as tabs. Although the anode electrode structure 200 is depicted as a dual-sided electrode structure, it should be understood that the implementations described herein also apply to single-sided electrode structures.

[0053] The anode electrode structure 200 has the anode current collector 160 and anode film stack 110a-b formed on opposing sides of the anode current collector 160. In one or more implementations, which can be combined with other implementations, the anode film stack 110a-b includes an anode film 170a-b and the protective film stack 180a-b formed on each of the anode films 170a-b.

[0054] FIG. 3 illustrates a flow chart of a method 300 for manufacturing an anode electrode structure 400 in accordance with one or more implementations of the present disclosure. FIGS. 4A-4D illustrate views of various stages of manufacturing an anode electrode structure 400 in accordance with one or more implementations of the present disclosure. Although FIGS. 4A-4D are described in relation to the method 300, it will be appreciated that the structures disclosed in FIGS. 4A-4D are not limited to the method 300, but instead may stand alone as structures independent of the method 300. Similarly, although the method 300 is described in relation to FIGS. 4A- 4D, it will be appreciated that the method 300 is not limited to the structures disclosed in FIGS. 4A-4D but instead may stand alone independent of the structures disclosed in FIGS. 4A-4D. It should be understood that FIGS. 4A-4D illustrate only partial schematic views of the anode electrode structure 400, and the anode electrode structure 400 may contain any number of additional layers and/or additional materials common to energy storage devices, which are not shown for the sake of brevity. It should also be noted that although the method 300 illustrated in FIG. 3 is described sequentially, other process sequences that include one or more operations that have been omitted and/or added, and/or have been rearranged in another desirable order, fall within the scope of the implementations of the disclosure provided herein.

[0055] Referring to FIG. 4A, at operation 310 a flexible substrate stack 402 is provided. The flexible substrate stack 402 can include one or more layers. In some implementations, for example, for a lithium metal anode device, the flexible substrate stack 402 can include a current collector such as the current collector 160. In some implementations, for example, for a pre-lithiation process, the flexible substrate stack 402 can include an anode material. In other implementations, for a pre-lithiation process, the flexible substrate stack 402 can include both a current collector and an anode material. In yet other implementations, the flexible substrate stack 402 can be or include a separator, for example, the separator film 130 as shown in FIG. 1. The flexible substrate stack 402 can be or include a current collector or a current collector having anode material formed thereover. The flexible substrate stack 402 can further include interface layers, solid electrolyte interface (SEI) layers, or both interface layers and SEI layers. In one or more implementations, which can be combined with other implementations, the flexible substrate stack 402 includes a web-based substrate, for example, the current collector can be a web-based substrate.

[0056] Referring to FIG. 4A, at operation 320, a lithium metal film 404 is formed on the substrate. The lithium metal film 404 can be the anode film 170. In one implementation, the lithium metal film 404 is the anode film and the flexible substrate stack 402 is the anode current collector. In one implementation, the lithium metal film 404 is formed on a copper current collector. In some implementations, if an anode film is already present on the substrate, the lithium metal film 404 is formed on the anode film. If the anode film is not present, the lithium metal film 404 may be formed directly on the flexible substrate stack 402. Any suitable lithium metal film deposition process for depositing thin films of lithium metal may be used to deposit the thin film of lithium metal. Deposition of the thin film of lithium metal may be by PVD processes, such as evaporation (e.g., thermal evaporation or e-beam), a slot-die process, a transfer process, a spin spray coating process followed by optional melt reflow, or a three-dimensional lithium printing process. The chamber for depositing the thin film of lithium metal may include a PVD system, such as an electron-beam evaporator, a thermal evaporator, or a sputtering system, a thin film transfer system (including large area pattern printing systems such as gravure printing systems) or a slot-die deposition system. The lithium metal film 404 may be deposited under vacuum. The lithium metal film 404 may be deposited under vacuum in a roll-to-roll deposition system.

[0057] Referring to FIG. 4B, optionally, at operation 330, a first protective film 410 is formed on or over the lithium metal film 404. The first protective film 410 may be part of the protective film stack 180 and the lithium metal film 404 may be the anode film 170. In one or more implementations, which can be combined with other implementations, the first protective film 410 is a passivation film. The passivation film can serve as a protective film for the lithium metal film 404. For example, the passivation layer can protect the lithium metal film 404 from oxidation and damage during storage and shipping. In one or more implementations, which can be combined with other implementations, the first protective film 410 is or includes a lithium carbonate film. In some implementations, where the lithium metal film 404 is formed in a first processing chamber and then transferred to a second processing chamber for forming additional films in the stack, the lithium carbonate film serves as a passivation layer, which protects the underlying lithium metal film 404 from exposure to atmosphere. In some implementations, where the lithium metal film 404 is not exposed to atmosphere, the first protective film 410 may not be present. In some implementations, the first protective film 404 has a thickness of 100 nanometers or less (e.g., from about 5 nanometers to 100 nanometers; from about 10 nanometers to about 20 nanometers; or from about 50 nanometers to about 100 nanometers). The lithium carbonate film may be formed by exposing the lithium metal film 404 to carbon dioxide in the processing chamber where the lithium metal film 404 is formed.

[0058] Referring to FIG. 4C, at operation 340, a second protective film 420 is formed on or over the lithium metal film 404. The second protective film 420 may be part of the protective film stack 180. The second protective film 420 may be formed over or on the first protective film 410 if present. In one or more implementations, where the first protective film 410 is not present, the second protective film 420 may be formed directly on the lithium metal film 404. In one or more implementations, the second protective film 420 is or includes a metallic film. In one or more implementations, which can be combined with other implementation, the metallic film is a bismuth film, a tin film, a silver film, or a combination thereof. In some implementations, the metallic film is an ultra-thin metal film. Any suitable metallic film deposition process for depositing thin films of metal may be used to deposit the metallic film. Deposition of the metallic film may be by a PVD process, such as evaporation (e.g., thermal or e-beam), a CVD process, a slot-die process, a transfer process, or a three-dimensional lithium printing process. The chamber for depositing the metallic film may include a PVD system, such as an electron-beam evaporator, a thermal evaporator, or a sputtering system, a thin film transfer system (including large area pattern printing systems such as gravure printing systems) or a slot-die deposition system. In particular implementations, the second protective film 420 is a bismuth film formed by a thermal evaporation process.

[0059] In some implementations, the second protective film 420 has a thickness of 500 nanometers or less (e.g., from about 10 nm to about 500 nm; from about 25 nm to about 500 nm; from about from about 50 nm to about 500 nm; from about 50 nm to about 300 nm; from about 100 nm to about 150 nm; from about 10 nm to about 80 nm; or from about 30 to about 60 nanometers). In some implementations, the second protective film 620 has a thickness of 100 nanometers or less (e.g., from about 5 nanometers to 100 nanometers; from about 10 nanometers to about 20 nanometers; or from about 50 nanometers to about 100 nanometers).

[0060] Referring to FIG. 4D, at operation 350, a third protective film 430 is formed on or over the second protective film 420. The third protective film 430 may be part of the protective film stack 180. In one or more implementations, the third protective film 430 is an alkali-metal containing salt film, for example, a lithium salt film or a sodium salt film. Any suitable alkali metal salt film deposition process for depositing thin films of alkali metal salts may be used to deposit the alkali metal salt film. Deposition of the metallic film may be by a PVD process, such as evaporation (e.g., thermal or e-beam), a CVD process, a slot-die process, a transfer process, or a three- dimensional lithium printing process. The chamber for depositing the metallic film may include a PVD system, such as an electron-beam evaporator, a thermal evaporator, or a sputtering system, a thin film transfer system (including large area pattern printing systems such as gravure printing systems) or a slot-die deposition system. In particular implementations, the third protective film 430 is a lithium fluoride film formed by a thermal evaporation process. [0061 ] In one or more implementations, which can be combined with other implementations, the third protective film 430 be formed directly on the flexible substrate stack 402, for example, directly on the current collector to form an anode- free energy storage device.

[0062] In some implementations, the third protective film 430 has a thickness of 500 nanometers or less (e.g., from about 10 nm to about 500 nm; from about 25 nm to about 500 nm; from about from about 50 nm to about 500 nm; from about 50 nm to about 300 nm; from about 100 nm to about 150 nm; from about 10 nm to about 80 nm; or from about 30 to about 60 nanometers). In some implementations, the third protective film 430 has a thickness of 100 nanometers or less (e.g., from about 5 nanometers to 100 nanometers; from about 10 nanometers to about 20 nanometers; or from about 50 nanometers to about 100 nanometers).

[0063] The anode electrode stack may be integrated with a cathode structure, for example, the cathode electrode structure 120, a separator, for example, the separator film 130, or both a cathode structure and a separator to form an energy storage device, for example, the energy storage device 100 shown in FIG. 1 .

[0064] FIG. 5 illustrates a flow chart of a method 500 for manufacturing an energy storage device 600 in accordance with one or more implementations of the present disclosure. FIGS. 6A-6F illustrate views of various stages of manufacturing an energy storage device 600 in accordance with one or more implementations of the present disclosure. Although FIGS. 6A-6F are described in relation to the method 500, it will be appreciated that the structures disclosed in FIGS. 6A-6F are not limited to the method 500, but instead may stand alone as structures independent of the method 500. Similarly, although the method 500 is described in relation to FIGS. 6A-6F, it will be appreciated that the method 500 is not limited to the structures disclosed in FIGS. 6A-6F but instead may stand alone independent of the structures disclosed in FIGS. 6A-6F. It should be understood that FIGS. 6A-6F illustrate only partial schematic views of the energy storage device 600, and the energy storage device 600 may contain any number of additional layers and/or additional materials common to energy storage devices, which are not shown for the sake of brevity. It should also be noted that although the method 500 illustrated in FIG. 5 is described sequentially, other process sequences that include one or more operations that have been omitted and/or added, and/or have been rearranged in another desirable order, fall within the scope of the implementations of the disclosure provided herein.

[0065] Referring to FIG. 6A, at operation 510 a flexible support layer stack 602 is provided. The flexible support layer stack 602 includes a flexible support layer 610. The flexible support layer 610 has a frontside 61 Of (also referred to as a front surface) and a backside 610b (also referred to as a back surface) opposite the frontside 61 Of. The flexible support layer 610 may include any suitable material that is compatible with the targeted processing conditions. In some implementations, the flexible support layer 610 includes a plurality of sub-layers. In one or more implementations, which can be combined with other implementations, the flexible support layer 610 can be or include, one or more layers selected from plastic, polymer materials, metallized plastic, metals, paper, multilayers thereof, or a combination thereof. Suitable polymer materials include polymer materials that are transparent to laser light and have low to no photon absorption to prevent overheating and fire incidents. Example of suitable polymer materials include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), poly(methyl methacrylate) (PMMA), cellulose tri-acetate (TAC), polypropylene (PP), polyethylene (PE), polycarbonates (PC), multilayers thereof, or a combination thereof. In one or more implementations, which can be combined with other implementations, the flexible support layer 610 is a web-based substrate.

[0066] In one or more implementations, which can be combined with other implementations, the flexible support layer 610 has a thickness in a range from about 1 micron to about 100 microns, or in a range from about 1 micron to about 100 microns, or in a range from about 10 microns to about 50 microns, or in a range from about 25 microns to about 50 microns.

[0067] The flexible support layer stack 602 may further include a release layer 620. As shown in FIG. 6A, the release layer 620 may be formed on the frontside 61 Of of the flexible support layer 610. The release layer 620 has a frontside 620f (also referred to as a front surface) and a backside 620b (also referred to as a back surface) opposite the frontside 620f. In one or more implementations, the release layer 620 is deposited on the frontside 61 Of of the flexible support layer 610 such that the backside 620b of the release layer 620 contacts the frontside 61 Of of the flexible support layer 610. Any suitable process may be used to form the release layer 620 on the frontside of the flexible support layer 610. The release layer 620 may be deposited using nonvacuum coating techniques, for example, coating techniques performed in atmosphere. In one or more implementations, which may be combined with other implementations, the release layer 620 and the flexible support layer 610 are prefabricated.

[0068] The release layer 620 may be or include any material suitable for releasing the subsequently formed materials from the flexible support layer 610 during the Substrate independent direct transfer (SIDT) process. The release layer 620 may be or include polymer release layers (for example, plastics, silicone, polymethylacrylate (PMA), polyethylene terephthalate (PET), fluorocarbons, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), etc.), poly(olefin sulfones), organic materials, inorganic materials, among other materials. In some implementations, which can be combined with other implementations, the release layer 620 includes one or more nanosheets, such as one or more two-dimensional (2D) materials. In one or more implementations, which can be combined with other implementations, the release layer has a thickness of about 1 nm to about 500 nm, such as about 10 nm to about 300 nm, such as about 50 to about 200 nm. In some implementations, the release layer includes a plurality of sub-layers, each layer having a thickness of about 5 nm or less. Organic or polymer based release layers can be deposited using wetchemistry coating processes, for example, slot die coating techniques, comma bar coating techniques, or gravure coating techniques, or vacuum deposition techniques as described. The release layer 620 may be or include inorganic materials, for example, BN, AIOx, AIOOH, Al, or a combination thereof. In particular implementations, the release layer 620 includes a multi-layer structure, for example, a multilayer structure of AI/AIOx/AIOOH. Inorganic based release layers can be deposited using vapor deposition techniques, for example, PVD techniques such as sputter deposition and electron beam deposition techniques.

[0069] In one or more implementations, each layer can have melting points that is equal and/or decreases with each added layer such that the flexible support layer 610 has the highest melting point, the release layer 620 has a melting point lower than the flexible support layer 610 and the subsequently deposited layers have the lower melting points. [0070] Referring to FIG. 6B, at operation 520 the third protective film 430 is formed over the flexible support layer stack 602. In one or more implementations, where the release layer 620 is present, the third protective film 430 may be formed directly on the release layer 620. In one or more implementations, as shown in FIG. 6B, the third protective film 430 is formed directly on the frontside 620f of the release layer 620. In one or more implementations where the release layer 620 is not present, the third protective film 430 may be formed directly the frontside 61 Of of the flexible support layer 610. The third protective film 430 may be a lithium salt film or a sodium salt film as described herein. In one or more implementations, operation 520 includes a thermal evaporation process for forming the third protective film 430.

[0071] Referring to FIG. 6C, at operation 530, the second protective film 420 is formed over the flexible support layer stack 602. In one or more implementations, where the third protective film 430 is present, the second protective film 420 may be formed directly on the third protective film 430. The second protective film 420 may be a metallic film as described herein. In one or more implementations, operation 530 includes a thermal evaporation process for forming the second protective film 420. The third protective film 430 and the second protective film 420 form a protective film stack 604.

[0072] Referring to FIG. 6D, at operation 540, an alkali metal-containing layer, for example the lithium metal film 404 is formed over the flexible support layer stack 602 and the protective film stack 604. The lithium metal film 404 includes a frontside 404f (also referred to as a front surface) and a backside 404b (also referred to as a back surface) opposite the frontside 404f. In one or more implementations, where the release layer 620 is present, the lithium metal film 404 may be formed directly on the release layer 620. In one or more implementations, as shown in FIG. 6D, the lithium metal film 404 is formed directly on the second protective film 420. The lithium metal film 404 may be or include lithium. In one or more implementations, operation 540 includes an evaporation process for forming the lithium metal film 404. The evaporation process may be an electron beam evaporation process or a thermal evaporation process.

[0073] In one or more implementations, the lithium metal film 404 may be part of a SIDT film stack 635. Referring to FIG. 6D, although the SIDT film stack 635 is shown as including only the lithium metal film 404 and the protective film stack 604, the SIDT film stack 635 typically contains additional layers, for example, additional protective layers, interface layers, and solid electrolyte interface (SEI) layers among other. If the SIDT film stack 635 is present, the lithium metal film 404 is typically deposited last when forming the SIDT film stack 635. Depositing the lithium metal film 404 last enables forming the SIDT film stack 635 without damaging the lithium metal film 404, which typically has a lower melting point relative to other materials that are formed in the energy storage device. Conventional methods of forming energy storage devices typically include direct deposition of molten lithium onto the current collector in lithium metal anode formation or onto the anode material in pre-lithiation implementations. These methods further include maintaining the underlying substrate as the lithium metal film 404 is formed to prevent damage to the lithium. In contrast, the SIDT film stack 635 and methods described herein, enable forming the lithium metal film 404 last prior to transferring the SIDT film stack 635 from the flexible support layer stack 602 to a flexible substrate stack 640.

[0074] In one or more implementations, which can be combined with other implementations, a solid electrolyte interface (SEI) layer can optionally be included in the SIDT film stack 635. In some implementations, the solid electrolyte interface layer can include or be a metal salt, such as lithium salt as described. The lithium salt can be one or more of LiPFe, LiAsFe, LiCFsSOs, LiN(CF3SO3)3, LiBFe, LiCICMBETTE electrolyte, or combinations thereof. The electrolyte can be in a gel or polymer matrix medium. In one or more implementations, the solid electrolyte interface layer can be or include materials selected from fluorocarbons (PTFE, PVDF), LiF, Li2CO3, MgO, AIOx, AIHO2, RENiO3 (RE=rare earth), BN, BaTiO3, Li4Ti5O12, ZrO2, TiO2, silicon doped lithium tantalum phosphates, for example, Li(1 +x)Ta2P(1-x)SixO8, Li1.5Ta2P0.5Si0.5O8, lithium tantalum phosphates, for example, LiTa2PO8 (LTPO), Li2Ta2SiO8 (LTSO), Li0.34La0.56TiO3, lithium aluminum titanium phosphates, for example, Li1 ,3AI0.3Ti1 ,7(PO4)3 (LATP), lithium aluminum germanium phosphates, for example, Li1.3AI0.3Ge1.7(PO4)3 (LAGP), garnet Li7La3Zr2O12 (LLZO), or a combination thereof.

[0075] In one or more implementations, which can be combined with other implementations, an interface layer can optionally be included in the SIDT film stack 635. The interface layers can include at least one of an interface dielectric material, plating and stripping enhancement layers, and lithiophilic layers. The interface layers are deposited under vacuum. The interface layers may be deposited under vacuum in a roll-to-roll deposition system. The interface dielectric layer may be selected from AIOx, AIOOH, LiF, BaTiO3, ZrO2, TiO2, Li4Ti5O12, LiAIO2, AIF3, BiF3, AgFx, rare earth (RE) nickelates RENiO3, or a combination thereof. RE can be a trivalent rare- earth. RE can be lanthanide. RE can be selected from La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Y, Lu, or a combination thereof. The plating and stripping enhancement layers may be selected from metals, alloys of metals, or chalcogenides of the metals. The plating and stripping enhancement layers may be selected from Ag, Bi, Sn, Si, Ga, In, alloys of metals or chalcogenides of Ag, Bi, Sn, Si, Ga, In, or a combination thereof. Deposition of alkali metal or alloys thereof, for example, lithium metal or its alloys. The interface layers and the alkali metal layers or alloys thereof may be deposited without breaking vacuum.

[0076] In one or more implementations, which may be combined with other implementations, the flexible support layer stack 602 and the lithium metal film 404 are pre-fabricated. In other implementations, the flexible support layer stack 602 is pre-fabricated and the lithium metal film 404 is formed on the flexible support layer stack 602 via a deposition process, for example, a physical vapor deposition (PVD) process.

[0077] After operation 540 and prior to operation 550, the flexible support layer stack 602 having the SIDT film stack 635 formed thereon may be transferred from a vacuum coating system, for example, a roll-to-roll coating apparatus to a lamination transfer apparatus, for example, the lamination transfer system. The lamination transfer process of operation 540 may include applying a flexible substrate stack 640 to the frontside 404f of the lithium metal film 404 and removing the flexible support layer 610 and optionally the release layer 620 from the lithium metal film 404 to form an anode film stack 645 as shown in FIG. 6E.

[0078] Referring to FIG. 6E, at operation 550, the SIDT film stack 635 is laminated to the flexible substrate stack 640. The flexible substrate stack 640 can include one or more layers. In some implementations, for example, for a lithium metal anode device, the flexible substrate stack 640 can include a current collector, for example, the current collector 160. In some implementations, for example, for a pre-lithiation process, the flexible substrate stack 640 can include anode material, for example, the anode film 170. In other implementations, for a pre-lithiation process, the flexible substrate stack 640 can include both a current collector and an anode material. In yet other implementations, the flexible substrate stack 640 can be or include a separator, for example, the separator film 130 as shown in FIG. 1 . The flexible substrate stack 640 can be or include a current collector or a current collector having anode material formed thereover. In one or more implementations, which can be combined with other implementations, the flexible substrate stack 640 includes a web-based substrate, for example, the current collector can be a web-based substrate. During the lamination process of operation 550, the lithium metal film 404 of the SIDT film stack 635 is contacted to the flexible substrate stack 640. For example, the frontside 404f of the lithium metal film 404 is contacted to a surface of the flexible substrate stack 640 as shown in FIG. 6E. In one or more implementations, where the flexible substrate stack 640 only includes a current collector, the frontside 404f of the lithium metal film 404 is contacted to a surface of the current collector. In one or more implementations, where the flexible substrate stack 640 includes the anode material, the frontside 404f of the lithium metal film 404 is contacted to a surface of the anode material to pre-l ithiate the anode material.

[0079] Optionally, during operation 550, pressure is applied to one or more of the flexible substrate stack 640 and the flexible support layer stack 602 having the SIDT film stack 635 formed thereon to laminate the flexible substrate stack 640 to the lithium metal film 404. In one or more implementations, where the method 500 is performed in a roll-to-roll tool, web tension is sufficient to laminate the lithium metal film 404 to the flexible substrate stack 640 and additional pressure is not needed. In one or more implementations, where additional pressure is used to laminate the lithium metal film 404 to the flexible substrate stack 640, the lamination process includes pressing the lithium metal film 404 to the flexible substrate stack 640 with a magnitude of pressure sufficient to attach the lithium metal film 404 to the flexible substrate stack 640 without damaging the lithium metal film 404. In other words, the pressure is such that the lithium metal film 404 is not mechanically destroyed or degraded, such as by cracking or crushing. Pressure may be applied using any suitable techniques. In one or more implementations, pressure is applied via a calendering process. For example, pressure may be applied to the backside 610b of the flexible support layer 610 and a backside 640b of the flexible substrate stack 640. In one or more other implementations, pressure is applied by a vacuum source. In one or more other implementations, the pressure is external pressure.

[0080] Referring to FIG. 6F, at operation 560, the lithium metal film 404 is separated from the flexible support layer stack 602 to form an anode film stack 645 including the SIDT film stack 635 formed on the flexible substrate stack 640. In one or more implementations, which can be combined with other implementations, portions of the release layer 620 can be transferred or partially transferred with the lithium metal film 404. Alternatively, in other implementations, the release layer 620 remains or partially remains on the flexible support layer 610 after operation 560.

[0081 ] At operation 570, the anode film stack 645 can be integrated with a cathode structure, for example, the cathode electrode structure 120, a separator, for example, the separator film 130, or both a cathode structure and a separator to form an energy storage device, for example, the energy storage device 100 shown in FIG. 1.

[0082] Examples:

[0083] The following non-limiting examples are provided to further illustrate implementations described herein. However, the examples are not intended to be all inclusive and are not intended to limit the scope of the implementations described herein.

[0084] Lithium metal is very reactive with ambient gases like O2, N2, and H2O in the normal atmospheric conditions. In the following examples, both the unmodified lithium metal and modified lithium samples were taken outside of a dry room where the materials are stable and then left exposed to ambient conditions for 15 minutes. Results demonstrated that the unmodified samples reacted very quickly to form shades of dark silvery color and finally turned to black in less than a few minutes when taken outside the dry room. As known from the literature, this is not surprising as lithium can quickly react to form LiOH, LisN, and Li2CO3. On the other hand, lithium surfaces modified with the protective layer stacks described herein was stable with minimal degradation/color change. The results indicate that the protective layer stacks described herein effectively protects lithium metal from ambient. Moreover, the protective layer stacks described herein enable shipping and transport of lithium metal films so that the underlying lithium metal is active and available for electrochemical performance.

[0085] Materials: Labelled as type A (LiF), type B (Bismuth), type C (Silver), type D (tin), and type E (LTO) along with a stack that includes combinations of the layers of coating materials that were tested. Results are summarized below in Table I. Table I denotes the thickness range tested for each of the materials along with the coating methodology.

Table I.

[0086] Process Start-up: Process start-up began with film thickness calibration, followed by initial sample deposition. Type A, B, C D, E and stack layer coatings of varying thicknesses were deposited onto Li-coated Cu foil (single sided, the thickness of both Li and Cu foil was 18 pm).

[0087] Protection Layer Characterization: SEM images were taken for initial samples and shown in FIG. 7. Note that all samples were exposed to an in-situ CO2 treatment forming a thin U2CO3 film, ~ <40 nm on the control samples. For passivated samples there was clear evidence of material coating with varying degrees of structural morphology changes depending on the protection layer. The contours of the lithium metal were masked in some cases. The surface roughness data is indicated in Table II. Table II includes surface roughness parameters for the modified samples and comparison with control samples. Initial data indicated there was no significant increase in the roughness of the samples after passivation with the protective stacks described. Coin cells were fabricated and tested to determine cell impedance and performance.

Table II

[0088] Coin Cell Formation and Testing

[0089] 1 cm² electrodes were manually punched using an 11.3 mm diameter punch. The coin cells were assembled using SUS3130L Ni-plated caps and cases. In symmetric cells, the anode was used for both electrodes but only as the positive electrode in the half-cell and the counter electrode is single-sided 11 pm Li on Cu. Electrolyte (1.0 M LiPFe in EC/DEC (1 :1 v/) + 2% FEC), also known as AM-4, was formulated for Applied Materials, and used as received. CELGARD® 2500 was used as the separator. The separator was wet with ~3 drops of electrolyte solution. All cells were pressed and sealed for 2.5 seconds using a standard battery crimper after assembly.

[0090] Electrochemical Impedance Spectroscopy (EIS)

[0091 ] EIS (Bio-Logic) was conducted on symmetric cells in a two-cell configuration with a 5-mV perturbation, scanning between 10 MHz and 1 MHz. FIG. 8 indicates Impedance data collected for assembled cells and impedance Nyquist plot. Stack design with Type A+B, Type A+ D and Type E had the highest value of the total impedance and control and Type A+C the lowest. The rest of the data falls in between. The inset in FIG. 8 shows impedance values at 150 Hz frequency. The regions in Green in the inset of FIG. 8 had lower than 250 Ohm cm2 for samples (Control, Type A+C, Type B and Type C) whereas rest of the sample fell in the region marked red which is higher (>400-ohm cm²). Note that at all frequencies the values of the control and type A+ C are the lowest. A good balance of lower impedance and cycling behavior at higher current density (> 3 mAh/cm²) is chosen as a success criterion.

[0092] Electrochemical Cycling

[0093] The cells were rested for 24 hours before capacity and cycling tests using Maccor Series 4600 battery tester. FIG. 9 demonstrates Li plating/stripping behavior of the symmetric cells that were charged for 15 minutes and then discharged for 15 minutes at a current rate of 0.2, 2 and 3 mA/cm² with upper and lower voltage limit of ±1V, which is analogous to the formation cycle needed. Typical voltage vs. time profile for Li/Li symmetric- cell Li plating/stripping are shown for control samples and its comparison to Type A+C, Type A, Type B, Type C, Type D and Type D protective coatings. Trace in black corresponds to control samples and red type A+ C and others. This was followed by testing at the desired current density for long term cycling. FIG. 10 demonstrates the discharge and charge capacity against cycle numbers collected for the cells. After around 140 charging-discharging cycles or when the capacity degraded to zero as shown in FIG. 10. Type A+ B shown in green trace in FIG. 10 shows the best cycling of >100 cycles while the rest shorted earlier. The control samples in orange trace performed the least when compared with all samples. The current density for the charge-discharge cycles was 3.0 mA/cm².

[0094] The previously described implementations of the present disclosure have many advantages. However, the present disclosure does not require that all the advantageous features and all the advantages need to be incorporated into every implementation of the present disclosure.

[0095] In the Summary and in the Detailed Description, and the claims, and in the accompanying drawings, reference is made to particular features (including method steps) of the present disclosure. It is to be understood that the disclosure in this specification includes all possible combinations of such particular features. For example, where a particular feature is disclosed in the context of a particular aspect or implementation of the present disclosure, or a particular claim, that feature can also be used, to the extent possible in combination with and/or in the context of other particular aspects and implementations of the present disclosure, and in the present disclosure generally.

[0096] The term “at least” followed by a number is used herein to denote the start of a range beginning with that number (which may be a range having an upper limit or no upper limit, depending on the variable being defined). For example, “at least 1” means 1 or more than one. The term “at most” followed by a number is used herein to denote the end of a range ending with that number (which may be a range having 1 or 0 as its lower limit, or a range having no lower limit, depending upon the variable being defined). For example, “at most 4” means 4 or less than 4, and “at most 40%” means 40% or less than 40%. When, in this specification, a range is given as “(a first number) to (a second number)” or “(a first number)-(a second number),” this means a range whose lower limit is the first number and whose upper limit is the second number. For example, 25 to 100 mm means a range whose lower limit is 25 mm, and whose upper limit is 100 mm.

[0097] Embodiments and all of the functional operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structural means disclosed in this specification and structural equivalents thereof, or in combinations of them. Embodiments described herein can be implemented as one or more non-transitory computer program products, i.e. , one or more computer programs tangibly embodied in a machine readable storage device, for execution by, or to control the operation of, data processing apparatus, e.g., a programmable processor, a computer, or multiple processors or computers.

[0098] The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). [0099] The term "data processing apparatus" encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer.

[00100] Computer readable media suitable for storing computer program instructions and data include all forms of nonvolatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[00101 ] The term “comprises,” “including,” and “having” and grammatical equivalents thereof are used herein to mean that other components, ingredients, operations, etc. are optionally present. For example, an article “comprising” (or “which comprises”) components A, B, and C can consist of (i.e. , contain only) components A, B, and C, or can contain not only components A, B, and C but also one or more other components. In addition, whenever a composition, an element or a group of elements is preceded with the transitional phrase “comprising” or grammatical equivalents thereof, it is understood that it is contemplated that the same composition or group of elements may be preceded with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa.

[00102] Where reference is made herein to a method comprising two or more defined operations, the defined operations can be carried out in any order or simultaneously (except where the context excludes that possibility), and the method can include one or more other operations which are carried out before any of the defined operations, between two of the defined operations, or after all of the defined operations (except where the context excludes that possibility).

[00103] When introducing elements of the present disclosure or exemplary aspects or embodiment(s) thereof, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements.

[00104] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

What is claimed is:

1 . An anode electrode structure, comprising: a current collector comprising copper and/or stainless steel; a lithium metal film formed over the current collector; and a protective film stack formed on the lithium metal film, comprising: a metallic film formed over the lithium metal film, the metallic film selected from a bismuth film, a tin film, a silver film, or a combination thereof; and a lithium salt film formed on the metallic film, the lithium salt film selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

2. The anode electrode structure of claim 1 , wherein the protective film stack further comprises a lithium carbonate film, the lithium carbonate film formed on the lithium metal film and the metallic film formed on the lithium carbonate film.

3. The anode electrode structure of claim 1 , further comprising an anode film, the anode film formed on the current collector and the lithium metal film formed on the anode film.

4. The anode electrode structure of claim 1 , wherein the metallic film is the silver film.

5. The anode electrode structure of claim 1 , wherein the metallic film has a thickness in a range from about 50 nanometers to about 500 nanometers.

6. The anode electrode structure of claim 5, wherein the lithium salt film is a lithium fluoride film having a thickness in a range from about 100 nanometers to about 500 nanometers.

7. The anode electrode structure of claim 1 , wherein the current collector comprises a polymer substrate and a copper film formed over the polymer substrate.

8. An energy storage device, comprising: the anode electrode structure of any of claims 1 to 7; a cathode electrode structure; and a separator film or solid electrolyte film formed between the anode electrode structure and the cathode electrode structure.

9. A method of forming an anode electrode structure, comprising: forming a protective film stack over a lithium metal film, the lithium metal film formed over a substrate, forming the protective film stack, comprising: forming a metallic film over the lithium metal film, the metallic film selected from a bismuth film, a tin film, a silver film, or a combination thereof; and forming a lithium salt film on the metallic film, the lithium salt film selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

10. The method of claim 9, further comprising: forming a lithium carbonate film on the lithium metal film prior to forming the protective film stack over the lithium salt film, the lithium carbonate film formed on the lithium salt film and the metallic film formed on the lithium carbonate film.

11 . The method of claim 10, wherein forming the lithium carbonate film comprises exposing the lithium metal film to CO2 gas in a first processing region defined by a first processing chamber.

12. The method of claim 11 , further comprising transferring the substrate from the first processing region to a second processing region in a second processing region defined by a second processing chamber, wherein the protective film stack is formed in the second processing chamber.

13. The method of claim 9, wherein the substrate is a current collector having an anode film formed thereon.

14. The method of claim 9, wherein forming the metallic film comprises a thermal evaporation process.

15. The method of claim 14, wherein forming the lithium salt film comprises a thermal evaporation process.

16. The method of claim 9, wherein the substrate is a web-based substrate.

17. The method of claim 9, wherein the metallic film is the silver film.

18. The method of claim 9, wherein the metallic film has a thickness in a range from about 50 nanometers to about 500 nanometers.

19. The method of claim 18, wherein the lithium salt film is a lithium fluoride film having a thickness in a range from about 100 nanometers to about 500 nanometers.

20. The method of claim 9, wherein the substrate comprises a polymer substrate and a copper film formed over the polymer substrate.

21 . A method of forming a film stack for an energy storage device, comprising: forming a protective film stack over a flexible support layer stack, forming the protective film stack comprising: forming a lithium salt film over the release layer; forming a metallic film on the lithium salt film, the metallic film selected from a bismuth film, a tin film, a silver film, or a combination thereof; and forming a lithium metal film on the metallic film; laminating the lithium metal film to a flexible substrate stack; and separating the protective film stack from the flexible support layer stack to form an anode film stack, the lithium salt film selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

22. The method of claim 21 , wherein the flexible support layer stack comprises a polymer substrate having a release layer formed thereon and the protective film stack is formed on the release layer.

23. The method of claim 21 , wherein the flexible support layer stack comprises a polymer substrate and the protective film stack is formed on the polymer substrate.

24. The method of claim 21 , wherein the flexible substrate stack comprises a current collector comprising copper.

25. The method of claim 24, wherein the flexible substrate stack further comprises an anode film formed over the current collector and the lithium metal film contacts the anode film.

26. The method of claim 21 , wherein forming the metallic film comprises a thermal evaporation process.

27. The method of claim 26, wherein forming the lithium salt film comprises a thermal evaporation process.

28. The method of claim 26, wherein the metallic film is the silver film.

29. An anode stack, comprising: a copper substrate configured to act as a current collector; a lithium layer disposed on the copper substrate and configured to act as an anode; a silver layer disposed on the lithium layer; and a lithium salt layer disposed on the silver layer, the lithium salt layer selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

30. The anode stack of claim 29, wherein a passivation layer is disposed between the lithium layer and the silver layer.

31 . The anode stack of claim 30, wherein the passivation layer includes lithium carbonate and is formed by passivating the lithium layer with carbon dioxide.

32. The anode stack of claim 29, wherein the lithium salt layer includes lithium fluoride.

33. The anode stack of claim 29, wherein the lithium salt layer has a thickness of 50 nm to 600 nm.

34. The anode stack of claim 29, wherein the silver layer has a thickness of 40 nm to 600 nm.

35. A method of forming an anode stack, comprising: depositing a lithium layer on a copper substrate using a roll to roll physical vapor deposition (PVD) tool; depositing a silver layer on the lithium layer using thermal evaporation; and depositing a lithium salt on the silver layer using thermal evaporation, the lithium salt layer selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

36. The method of forming the anode stack of claim 35, further comprising: passivating the lithium layer prior to depositing the silver layer with an in-situ carbon dioxide passivation process.

37. The method of forming the anode stack of claim 36, wherein the depositing of the lithium layer and passivating the lithium layer are done in the roll to roll PVD tool and the depositing of the silver layer and lithium salt layer are done in a different chamber.

38. The method of forming the anode stack of claim 35, wherein the method is done in the roll to roll PVD tool.

39. The method of forming anode stack of claim 35, wherein the lithium salt layer includes lithium fluoride.

40. The method of forming anode stack of claim 35, wherein the lithium salt layer has a thickness of 50 nm to 600 nm.

41 . The method of forming anode stack of claim 35, wherein the silver layer has a thickness of 40 nm to 600 nm.

42. The method of forming an anode stack of claim 35, further comprising: integrating the anode stack with a separator and cathode structure to form an energy storage device.

43. A method of forming an anode structure, comprising: forming a release layer on a polymer substrate; depositing a lithium salt layer on the release layer disposed on the polymer substrate; depositing a silver layer on the lithium salt layer; depositing a lithium layer on the silver layer forming an anode; and transferring the anode from the polymer substrate to a copper substrate forming an anode structure, the lithium salt layer selected from lithium sulfides, lithium oxides, lithium halides, lithium chalcogenides, lithium borohydride, or a combination thereof.

44. The method of forming anode stack of claim 43, wherein the lithium salt layer includes lithium fluoride.

45. The method of forming anode stack of claim 43, wherein the lithium salt layer has a thickness of 50 nm to 600 nm.

46. The method of forming anode stack of claim 43, wherein the silver layer has a thickness of 40 nm to 600 nm.

47. The method of forming anode stack of claim 43, wherein the lithium layer has a thickness of 2 microns to 25 microns.

48. The method of forming an anode stack of claim 43, further comprising: integrating the anode stack with a separator and cathode structure to form an energy storage device.