Pre- and post-treatment of electrode surfaces

Abstract

Methods and apparatus are provided for fabricating electrodes for use in energy storage devices. In some implementations, the surface of the electrode is activated due to (a) a pre-treatment process that removes loosely held particles from the electrode surface; (b) a pre-treatment process that activates the surface of the electrode material to improve bonding or wetting of subsequently deposited materials; (c) a post-treatment of a pre-lithiated layer to improve subsequent bonding with an additionally deposited layer, such as a passivation layer; and / or (d) a post-treatment of a pre-lithiated layer to improve / accelerate the absorption of lithium into the underlying electrode material.

Description

[Technical Field]

[0001] The present disclosure relates generally to energy storage devices and methods for manufacturing electrodes for use in energy storage devices. [Background technology]

[0002] In the energy storage device industry, energy storage devices are typically manufactured through multiple manufacturing processes. Some manufacturing processes may generate particles, which frequently contaminate the surface of the electrode being processed. For example, some processes include an atmospheric process performed in a non-cleanroom environment followed by a process performed in a vacuum environment. Non-cleanroom processes often generate contaminants such as dust, which adversely affect subsequent vacuum processes. In addition, electrostatic charges present on the substrate or web can attract additional dust and particulates. These contaminants can reduce the surface activation of the electrode, making subsequent material bonding difficult. However, removing contaminant particles, such as dust particles, carbon residue, organic contaminant particles, or other contaminants, can be quite difficult.

[0003] Therefore, there is a need for a system and method for removing contaminants from electrode surfaces. Summary of the Invention

[0004] The present disclosure relates generally to energy storage devices and methods for manufacturing electrodes for use in energy storage devices.

[0005] In one aspect, a method of forming an electrode structure is provided. The method includes exposing the electrode structure to a surface treatment process to activate a surface of the electrode structure. The method further includes forming a lithium metal film on the electrode structure. The surface treatment process is selected from a corona treatment process, an atmospheric plasma treatment process, a low-energy plasma treatment process, a plasma treatment process performed in a vacuum environment, or a combination thereof.

[0006] Embodiments may include one or more of the following: The surface treatment process is a corona treatment process. The corona treatment process includes generating an ionized corona discharge plasma. The generated corona discharge plasma includes positively or negatively charged plasma. The surface treatment process is an atmospheric plasma treatment process. The atmospheric plasma treatment process is performed at or near atmospheric pressure. The atmospheric plasma treatment process includes a plasma source gas including a chemically reactive species and a chemically unreactive species. The chemically reactive species is selected from oxygen, nitrogen, hydrogen, or a combination thereof. The chemically unreactive species is selected from argon, helium, or a combination thereof. The plasma source gas includes at least a 95% concentration of the chemically unreactive species and less than a 5% concentration of the chemically reactive species. The chemically reactive species is oxygen and the chemically unreactive species is argon. The chemically reactive species is hydrogen and the chemically unreactive species is argon. The atmospheric plasma treatment process includes generating an atmospheric pressure plasma using an RF frequency power source. The RF frequency power source is approximately 13.56 MHz to approximately 27 MHz. The surface treatment process is a plasma treatment process performed in a vacuum environment. The plasma treatment process includes exposing the electrode structure to a reducing plasma. The reducing plasma is formed from a reducing gas mixture including ammonia (NH), hydrazine (N2H4), hydrogen (H2), hydrogen halides, hydrogen chalcogenides, atomic hydrogen, their radicals, their derivatives, or combinations thereof. The reducing gas mixture further includes one or more inert gases. The reducing plasma can be a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma. The plasma treatment process includes exposing the electrode structure to an oxidizing plasma. The oxidizing plasma is formed from an oxidizing gas mixture including oxygen (O2), ozone (O3), nitrous oxide (N2O), fluorine (F2), chlorine (Cl2), carbon monoxide (CO), water (H2O), carbon dioxide (CO2), their radicals, their derivatives, or combinations thereof. The oxidizing gas mixture further includes one or more inert gases. The oxidizing plasma may be a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma.The electrode structure is a composite anode including at least one of carbon, graphite, silicon, silicon oxide, silicon-containing graphite, lithium, lithium metal foil or lithium alloy foil (e.g., lithium aluminum alloy), nickel, copper, silver, tin, indium, silicon, an oxide thereof, a composite thereof, or a combination thereof, and a binder material. The electrode structure further includes a continuous flexible substrate. The surface treatment process is performed in a roll-to-roll tool. The lithium metal film is exposed to CO gas to form a passivation layer.

[0007] In another aspect, a method of forming an electrode structure is provided. The method includes forming an anode structure in an atmospheric environment. The method further includes exposing the anode structure to a surface treatment process to activate the surface of the electrode structure. The method further includes forming a lithium metal film on the electrode structure in a vacuum environment. The surface treatment process is selected from a corona treatment process, an atmospheric plasma treatment process, a low-energy plasma treatment process, a plasma treatment process performed in a vacuum environment, or a combination thereof. The electrode structure further includes a continuous flexible substrate.

[0008] Embodiments may include one or more of the following: The surface treatment process is a corona treatment process. The corona treatment process includes generating an ionized corona discharge plasma. The generated corona discharge plasma includes positively or negatively charged plasma. The surface treatment process is an atmospheric plasma treatment process. The atmospheric plasma treatment process is performed at or near atmospheric pressure. The atmospheric plasma treatment process includes a plasma source gas including a chemically reactive species and a chemically unreactive species. The chemically reactive species is selected from oxygen, nitrogen, hydrogen, or a combination thereof. The chemically unreactive species is selected from argon, helium, or a combination thereof. The plasma source gas includes at least a 95% concentration of the chemically unreactive species and less than a 5% concentration of the chemically reactive species. The chemically reactive species is oxygen and the chemically unreactive species is argon. The chemically reactive species is hydrogen and the chemically unreactive species is argon. The atmospheric plasma treatment process includes generating an atmospheric pressure plasma using an RF frequency power source. The RF frequency power source is approximately 13.56 MHz to approximately 27 MHz. The surface treatment process is a plasma treatment process performed in a vacuum environment. The plasma treatment process includes exposing the electrode structure to a reducing plasma. The reducing plasma is formed from a reducing gas mixture including ammonia (NH), hydrazine (N2H4), hydrogen (H2), hydrogen halides, hydrogen chalcogenides, atomic hydrogen, their radicals, their derivatives, or combinations thereof. The reducing gas mixture further includes one or more inert gases. The reducing plasma can be a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma. The plasma treatment process includes exposing the electrode structure to an oxidizing plasma. The oxidizing plasma is formed from an oxidizing gas mixture including oxygen (O2), ozone (O3), nitrous oxide (N2O), fluorine (F2), chlorine (Cl2), carbon monoxide (CO), water (H2O), carbon dioxide (CO2), their radicals, their derivatives, or combinations thereof. The oxidizing gas mixture further includes one or more inert gases. The oxidizing plasma may be a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma.The electrode structure is a composite anode including at least one of carbon, graphite, silicon, silicon oxide, silicon-containing graphite, lithium, lithium metal foil or lithium alloy foil (e.g., lithium aluminum alloy), nickel, copper, silver, tin, indium, silicon, an oxide thereof, a composite thereof, or a combination thereof, and a binder material. The electrode structure further includes a continuous flexible substrate. The surface treatment process is performed in a roll-to-roll tool. The lithium metal film is exposed to CO gas to form a passivation layer.

[0009] In another aspect, a non-transitory computer-readable medium stores instructions that, when executed by a processor, cause a process to perform the operations of the apparatus and / or method described above.

[0010] This patent or patent application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0011] So that the above-mentioned features of the present disclosure can be understood in detail, a more particular description of the above briefly summarized embodiments may be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the present disclosure is also susceptible to other equally effective embodiments, and therefore, the accompanying drawings illustrate only typical embodiments of the present disclosure and should not be considered as limiting the scope of the invention. [Brief explanation of the drawings]

[0012] [Figure 1A] FIG. 1 is a cross-sectional view of an example battery structure incorporating an electrode structure formed in accordance with one or more embodiments described herein. [Figure 1B] 1 is a cross-sectional view of an example of a double-sided electrode structure formed in accordance with one or more embodiments described herein. [Figure 2] 1 is a process flow diagram of a method of forming an electrode structure according to one or more embodiments described herein. [Figure 3] 1 is an SEM image showing the morphology and EDX oxygen signal of the negative electrode material of a battery formed in accordance with one or more embodiments described herein. DETAILED DESCRIPTION OF THE INVENTION

[0013] For ease of understanding, wherever possible, like reference numerals are used to designate like elements common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0014] The following disclosure describes electrode structures, high performance electrochemical cells and batteries including the aforementioned electrode structures, and methods of fabricating the same. To provide a thorough understanding of various embodiments of the present disclosure, certain specific details are set forth in the following description and in Figures 1A-5B. In many cases, other details describing well-known structures and systems associated with electrochemical cells and batteries are not set forth in the following disclosure to avoid unnecessarily obscuring the description of the various embodiments.

[0015] Many of the details, dimensions, angles, and other features shown in the figures are merely illustrative of particular embodiments. Thus, other embodiments may have other details, components, dimensions, angles, and features without departing from the spirit or scope of the present disclosure. Additionally, further embodiments of the present disclosure may be practiced without some of the details described below.

[0016] The embodiments described herein are described below with reference to roll-to-roll coating systems such as TopMet™, SmartWeb™, and TopBeam™, all of which are available from Applied Materials, Inc., Santa Clara, California, USA. Other tools capable of performing rapid evaporation processes can also be adapted to benefit from the embodiments described herein. In addition, any system that enables the rapid evaporation processes described herein can be advantageously used. The apparatus descriptions described herein are exemplary and should not be understood or interpreted as limiting the scope of the embodiments described herein. Also, although described as a roll-to-roll process, it should be understood that the embodiments described herein may also be performed on individual substrates.

[0017] Some embodiments described herein are described below with reference to a roll-to-roll coating system. The apparatus descriptions described herein are exemplary and should not be understood or interpreted as limiting the scope of the embodiments described herein. Also, although described as a roll-to-roll process, it should be understood that the embodiments described herein may be practiced on other types of substrates, such as, for example, individual substrates.

[0018] Some embodiments described herein refer to a coating system adapted for prelithiation of flexible substrates, such as webs for lithium-ion battery devices. In particular, the coating system is suitable for continuous processing of flexible substrates, such as webs unwound from an unwind module. The coating system can be configured with a modular design, e.g., a suitable number of process modules can be positioned adjacent to each other in a processing line, with the flexible substrate being inserted into the first process module and removed from the last process module in the line. Furthermore, the entire coating system can be reconfigured if modifications to individual processing operations are desired.

[0019] While the particular substrate on which some embodiments described herein are practiced is not limited, it should be noted that it is particularly beneficial to practice embodiments on flexible substrates, including, for example, web-based substrates, panels, and individual sheets. The substrate may be in the form of a foil, film, or sheet.

[0020] It should also be noted that the flexible substrate or web used within the embodiments described herein can typically be characterized as being bendable. The term "web" may be used synonymously with the term "strip" or the term "flexible substrate." For example, the web described in the embodiments herein may be a foil.

[0021] Energy storage devices, such as batteries, typically include a positive electrode, a negative electrode separated by a porous separator, and an electrolyte used as an ion-conducting matrix. Graphite anodes and silicon-mixed anodes represent the current state-of-the-art, but these anode materials often suffer from irreversible capacity loss during the first cycle. Therefore, a method for replenishing this first-cycle capacity loss is needed.

[0022] Deposition of lithium metal, or prelithiation, is one method for replenishing this first-cycle capacity loss of anode materials. Direct prelithiation of anodes under vacuum can be scaled for mass production. However, particulates or contaminants physically attached to the electrode surface, for example, by van der Waals forces, or chemically bonded to the electrode surface, can interfere with subsequent deposition of the prelithiation layer. For example, these particulates can originate from humans, the environment in which the electrode is processed (e.g., particles generated by friction between moving objects in a processing chamber), or from films deposited or grown on the electrode structure. Some embodiments include (a) a pretreatment process to remove loosely held particles from the electrode surface; (b) a pretreatment process to activate the surface of the electrode material to improve bonding or wetting of subsequently deposited materials; (c) a post-treatment of the prelithiated layer to improve subsequent bonding with additionally deposited layers, such as a passivation layer; and / or (d) activating the surface of the electrode for post-treatment of the prelithiated layer to improve / accelerate lithium absorption into the underlying electrode material.

[0023] In some embodiments, direct prelithiation of lithium-ion battery anodes under vacuum atmosphere can be scaled for high volume manufacturing (HVM), and implementations described herein provide a roll in roll-to-roll process for vacuum deposition of lithium by removing loosely held particles held to the surface of the electrode by van der Waals forces, surface activation of the electrode material, e.g., carbon, graphite, Si / SiOx, and binder materials to strengthen bonding with subsequently deposited lithium for surface treatment for integration under HVM conditions.

[0024] In some embodiments, integration of current slurry coating processes with next-generation prelithiation applications is provided. Electrode materials can be enhanced through prelithiation and appropriate pre- and post-treatment processes. Additionally, lithium inventory can be optimized for long cycle life and increased throughput.

[0025] In some embodiments, the electrode surface pretreatment can be performed under atmospheric or vacuum conditions. The pretreatment process can include a corona treatment process, an atmospheric plasma treatment process, a low-energy plasma treatment process, a plasma treatment process performed in a vacuum environment, or a combination thereof. The pretreatment process can be performed under an oxidizing or reducing atmosphere.

[0026] In some embodiments, post-treatment is performed in a controlled atmosphere, including a vacuum, which provides for easier handling of the prelithiated electrodes in a mass production environment and improved device performance.

[0027] 1A shows an exemplary lithium-ion energy storage device 100 having a lithium metal film formed on the electrode surface in accordance with an embodiment of the present disclosure. The lithium-ion energy storage device 100 includes a positive current collector 110, a positive electrode 120 or cathode, a separator 130, a negative electrode 140 or anode, a lithium metal film 145 or pre-lithiated film (on which an optional surface protective film 170 is formed), and a negative current collector 150. The lithium-ion energy storage device may include a negative electrode structure 112 and a positive electrode structure 114 separated by the separator 130. The negative electrode structure 112 may include the negative electrode 140, the lithium metal film 145 on which the optional surface protective film 170 is formed, and the negative current collector 150. The positive electrode structure 114 may include the positive current collector 110, the positive electrode 120, and, optionally, a lithium metal film or pre-lithiated film formed on the positive electrode 120. It should be noted that although the current collector is shown in FIG. 1 as extending beyond the stack, it is not necessary for the current collector to extend beyond the stack, and the portion that extends beyond the stack can be used as a tab.

[0028] The current collectors 110, 150 on the positive electrode 120 and the negative electrode 140 may be the same electronic conductor or different electronic conductors. Examples of metals from which the current collectors 110, 150 can be made include aluminum (Al), copper (Cu), zinc (Zn), nickel (Ni), cobalt (Co), tin (Sn), silicon (Si), manganese (Mn), magnesium (Mg), alloys thereof, and combinations thereof. In one example, at least one of the current collectors 110, 150 is perforated. Furthermore, the current collectors can be of any form factor (e.g., metal foil, sheet, or plate), shape, and micro / macrostructure. Generally, in prismatic cells, the tabs are formed of the same material as the current collectors and may be formed during stack fabrication or added later. All components except the current collectors 110 and 150 may contain a lithium-ion electrolyte.

[0029] The negative electrode 140, or anode, can be any material compatible with the positive electrode 120. The negative electrode 140 can have an energy capacity of 372 mAh / g or greater, preferably 700 mAh / g or greater, and most preferably 1000 mAh / g or greater. The negative electrode 140 can be composed of carbon, graphite, silicon, silicon oxide, silicon-containing graphite, lithium, lithium metal foil, lithium alloy foil (e.g., lithium aluminum alloy, lithium silver alloy, etc.), nickel, copper, silver, tin, indium, gallium, tin, bismuth, niobium, molybdenum, tungsten, chromium, titanium, lithium titanate, silicon, oxides thereof, composites thereof, or combinations thereof. The negative electrode 140 can be a composite anode containing any of the aforementioned materials and a binder material. The composite anode can further include a conductive material, such as carbon black or acetylene black, and an optional solvent. In some implementations, the composite anode is made by mixing particles of the aforementioned materials in the form of a slurry with, for example, carbon black, a binder, and a solvent, and cast using a conventional slurry-based method, such as slot die coating. The conductive additive can be selected from graphite, graphene hard carbon, carbon black, carbon-coated silicon, or a combination thereof. The binder material can be a carbon-based binder material. The binder material can be an inorganic binder material.Binders include styrene butadiene rubber, acrylated styrene butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, and acrylic resin. , phenolic resins, epoxy resins, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl sucrose, polyesters, polyamides, polyethers, polyimides, polycarboxylates, polycarboxylic acids, polyacrylic acids, polyacrylates, polymethacrylic acids, polymethacrylates, polyacrylamides, polyurethanes, fluorinated polymers, chlorinated polymers, salts of alginic acid, polyvinylidene fluoride, poly(vinylidene fluoride)-hexafluoropropene, or combinations thereof. The solvent can be selected from N-methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, acetonitrile, butylene carbonate, propylene carbonate, ethyl bromide, tetrahydrofuran, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl propyl carbonate, ethylene carbonate, water, pure water, deionized water, distilled water, ethanol, isopropanol, methanol, acetone, n-propanol, t-butanol, or a combination thereof.

[0030] Composite anodes can be constructed using atmospheric processes, such as a slot die coating process, or they can be constructed in a vacuum environment.

[0031] The surface(s) of the negative electrode, e.g., negative electrode 140, can then be treated using any of the pretreatment processes described herein before depositing any additional films, e.g., lithium metal film 145.

[0032] In some embodiments, a lithium metal film 145 or a prelithiated film is formed on the anode 140. The lithium metal film 145 can be formed according to implementations described herein. In some embodiments, the anode 140 is a silicon graphite or graphite anode having a lithium metal film 145 formed thereon. The lithium metal film 145 replenishes lithium lost due to first cycle capacity loss of the anode 140. The lithium metal film 145 can be a thin lithium metal film (e.g., 20 microns or less, about 1 micron to about 20 microns, about 2 microns to about 10 microns). The lithium metal film 145 can be deposited using vapor deposition techniques. For example, the lithium metal film 145 can be deposited by thermal evaporation or electron beam evaporation. The lithium metal film 145 can be deposited in a vacuum environment. While the lithium metal film 145 is shown in FIGS. 1A and 1B, it should be understood that in some embodiments, the lithium metal film is partially or fully intercalated into the electrode structure.

[0033] The lithium metal film 145 and / or the surface(s) of the anode 140, such as, for example, the anode 140, can then be treated using any of the post-treatment processes described herein before depositing any additional films, such as, for example, the surface protection film 170.

[0034] In some embodiments, the surface overcoat 170 is formed on the lithium metal film 145. The surface overcoat 170 can be an ion-conducting polymer. The surface overcoat 170 can be porous. In some implementations, the surface overcoat 170 has nanopores. In one embodiment, the surface overcoat 170 has a plurality of nanopores sized to have an average pore size or diameter of less than about 10 nanometers (e.g., about 1 nanometer to about 10 nanometers; about 3 nanometers to about 5 nanometers). In another embodiment, the surface overcoat 170 has a plurality of nanopores sized to have an average pore size or diameter of less than about 5 nanometers. In one embodiment, the surface overcoat 170 has a plurality of nanopores having a diameter in the range of about 1 nanometer to about 20 nanometers (e.g., about 2 nanometers to about 15 nanometers; or about 5 nanometers to about 10 nanometers).

[0035] Overcoat 170 can be a coating or a discrete layer having a thickness in the range of 1 nanometer to 2,000 nanometers (e.g., 10 nanometers to 600 nanometers; 50 nanometers to 200 nanometers; 100 nanometers to 150 nanometers). Overcoat 170 can also be a discrete film having a thickness in the range of 5 microns to 50 microns (e.g., 6 microns to 25 microns). In some embodiments where overcoat 170 is an interleaf film, overcoat 170 functions as a separator and takes the place of separator 130.

[0036] Examples of surface protection films that can be formed using embodiments described herein include lithium carbonate films; lithium fluoride (LiF) films; dielectric or ceramic films (e.g., oxides of titanium (Ti), aluminum (Al), niobium (Nb), tantalum (Ta), zirconium (Zr), or combinations thereof); one or more metal films (e.g., tin (Sn), antimony (Sb), bismuth (Bi), gallium (Ga), germanium (Ge), copper films, silver films, gold films, or combinations thereof); copper chalcogenide films (e.g., CuS , Cu2Se, Cu2S); bismuth chalcogenide films (e.g., Bi2Te3, Bi2Se3); tin chalcogenide films (e.g., SnTe, SnSe, SnSe2, SnS), gallium chalcogenide films (e.g., GaS, Ga2S3, GaS, Ga2Se3, GaTe), germanium chalcogenide films (GeTe, GeSe, GeS), indium chalcogenide films (e.g., InS, In6S7, In2S3, InSe, InS4Se3, In6Se7, In2Se3, InTe, In4Te3, In3Te4, In7Te 10 , In2Te3, In2Te5), silver chalcogenide films (Ag2Se, Ag2S, Ag2Te), boron nitride, lithium nitrate, lithium borohydride, and combinations thereof; and carbon-containing films. In some examples, the one or more surface protective films are ion-conducting films. The ion-conducting film can be a lithium-ion-conducting ceramic or a lithium-ion-conducting glass. Li-ion-conducting materials include, for example, LiPON, Li7La3Zr2O ... 12 Doped variants of the crystalline or amorphous phase of the doped antiperovskite composition, Li2S-P2S5, Li 10 GeP2S 12, and Li3PS4, lithium phosphate glass, (1-x)LiI-(x)Li4SnS4, xLiI-(1-x)Li4SnS4, mixed sulfide and oxide electrolytes (crystalline LLZO, amorphous (1-x)LiI-(x)Li4SnS4 mixtures, and amorphous xLiI-(1-x)Li4SnS4), etc. In one embodiment, x is between 0 and 1 (e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9). In some examples, the one or more surface protection films 170 are permeable to at least one of lithium ions and lithium atoms. The one or more surface protection films 170 provide surface protection for the metal or metal alloy film, thereby enabling handling of the metal or metal alloy film in a dry chamber. The surface protection film 170 can be formed by any suitable technique, including but not limited to vapor deposition techniques, dip coating, slot die coating, spraying, doctor blading, gravure coating, printing, or any of a number of coating methods. In some embodiments, the lithium ion conductive material can be deposited directly onto the lithium metal film using either physical vapor deposition (PVD) or chemical vapor deposition (CVD) techniques.

[0037] The positive electrode 120, or cathode, can be any material compatible with the anode and can include an intercalation compound, an insertion compound, or an electrochemically active polymer. Suitable intercalation materials include, for example, sulfur, lithium-containing metal oxides, MoS2, FeS2, MnO2, TiS2, NbSe3, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, VO 13 and V2O5. Suitable polymers include, for example, polyacetylene, polypyrrole, polyaniline, and polythiophene. The positive electrode 120 or cathode can be fabricated from layered oxides such as lithium cobalt oxide, olivines such as lithium iron phosphate, or saltpeters such as lithium manganese oxide. Exemplary lithium-containing oxides are layered, such as lithium cobalt oxide (LiCoO2), or LiNi x Co 1-2xMnO2, LiNiMnCoO2 (“NMC”), LiNi 0.5 Mn 1.5 O4, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, LiMn2O4, and mixed metal oxides such as doped lithium-rich layered materials, where x is zero or a non-zero number. Exemplary phosphates include iron olivine (LiFePO4) and its variants (LiFe (1-x) Mg x PO4, etc.), LiMoPO4, LiCoPO4, LiNiPO4, Li3V2(PO4)3, LiVOPO4, LiMP2O7, or LiFe 1.5 PO7, where x is zero or a non-zero number. Exemplary fluorophosphates can be LiVPO4F, LiAlPO4F, Li5V(PO4)2F2, Li5Cr(PO4)2F2, Li2CoPO4F, or Li2NiPO4F. Exemplary silicates can be Li2FeSiO4, Li2MnSiO4, or Li2VOSiO4. An exemplary non-lithium compound is Na5V2(PO4)2F3.

[0038] In some embodiments of lithium-ion cells according to the present disclosure, lithium is contained in atomic layers in the crystalline structure of, for example, carbon graphite (LiC) in the anode and lithium manganese oxide (LiMnO) or lithium cobalt oxide (LiCoO) in the cathode, although in some embodiments the anode may also include a lithium absorbing material such as silicon, tin, etc. Although the cell is shown as a planar structure, it can also be formed into a cylindrical shape by rolling up the stack of layers; furthermore, other cell configurations (e.g., prismatic cells, button cells) can also be formed.

[0039] The surface(s) of a positive electrode, such as, for example, positive electrode 120, can then be treated using any of the pretreatment processes described herein before depositing any additional film, such as, for example, a lithium metal film, on the surface of the positive electrode.

[0040] The electrolytes injected into cell components 120, 130, 140, 145, and 170 may be composed of a liquid / gel or a solid polymer, and each may be different. In some embodiments, the electrolyte primarily comprises a salt and a medium (e.g., in a liquid electrolyte, the medium may be referred to as a solvent, while in a gel electrolyte, the medium may be a polymer matrix). The salt may be a lithium salt. Lithium salts may include, for example, LiPF, LiAsF, LiCF, SO, LiN(CF, SO), LiBF, and LiClO, BETTE electrolyte (commercially available from 3M Corp., Minneapolis, Minnesota, USA), and combinations thereof. Solvents can include, for example, ethylene carbonate (EC), propylene carbonate (PC), EC / PC, 2-MeTHF (2-methyltetrahydrofuran) / EC / PC, EC / DMC (dimethyl carbonate), EC / DME (dimethylethane), EC / DEC (diethyl carbonate), EC / EMC (ethyl methyl carbonate), EC / EMC / DMC / DEC, EC / EMC / DMC / DEC / PE, PC / DME, and DME / PC. Polymer matrices can include, for example, PVDF (polyvinylidene fluoride), PVDF:THF (PVDF:tetrahydrofuran), PVDF:CTFE (PVDF:chlorotrifluoroethylene), PAN (polyacrylonitrile), and PEO (polyethylene oxide).

[0041] FIG. 1B illustrates an example of an anode cell 160 that can be combined with a cathode cell to form a lithium-ion energy storage device. The anode cell 160 has lithium metal films 145a, 145b with surface protective films 170a, 170b formed thereon in accordance with implementations of the present disclosure. The lithium metal films 145a, 145b can be thin lithium metal films (e.g., 20 microns or less, about 1 micron to about 20 microns, about 2 microns to about 10 microns). The surface protective films 170a, 170b can be interleaf films or ion-conducting polymer films described herein. In some implementations where the surface protective films 170a, 170b are interleaf films, the interleaf films are typically removed before combining the anode cell 160 with a cathode cell to form a lithium-ion storage device. In some embodiments where the surface protective films 170a, 170b are ion-conducting polymer films, the ion-conducting polymer films are incorporated into the final battery structure.

[0042] The negative electrode cell 160 includes a negative current collector 150, negative electrodes 140a, 140b formed on either side of the negative current collector 150, lithium metal films 145a, 145b formed on the negative electrodes 140a, 140b, and surface protection films 170a, 170b formed on the lithium metal films 145a, 145b. Although the negative electrode cell 160 is shown as a double-sided cell, it should be understood that the embodiments described herein also apply to single-sided cells.

[0043] FIG. 2 shows a process flow diagram of a method 200 for forming an electrode structure according to one or more embodiments described herein. The electrode structure can be exposed to a pre-treatment process prior to deposition of additional layers on the electrode structure. The electrode structure can be exposed to a post-treatment process after deposition of additional layers on the electrode structure. Method 200 can be used to form anode structures and cathode structures. Method 200 can be used to form a portion of the lithium ion energy storage device 100 and / or a portion of the anode cell 160 shown in FIGS. 1A and 1B, respectively. Method 200 can be performed as part of a roll-to-roll process on a roll-to-roll tool.

[0044] In step 210, an electrode structure is provided. The electrode structure may include at least a portion of the negative electrode structure 112 or the positive electrode structure 114. The electrode structure may include a negative electrode (e.g., an anode film) or a positive electrode (e.g., a cathode film), such as the positive electrode 120 or the negative electrode 140. The electrode structure may have contaminants formed thereon. The contaminants may include, for example, particulates and organic matter. The contaminants may be electrically charged. In some implementations where the electrode structure is a negative electrode, the negative electrode is a composite anode composed of carbon, graphite, silicon, silicon oxide, silicon-containing graphite, lithium, nickel, copper, silver, tin, indium, silicon, oxides thereof, composites thereof, or combinations thereof. The negative electrode further includes a binder material. The negative electrode may further include a conductive material, such as carbon black or acetylene black, and an optional solvent. In some embodiments, the composite anode is formed under atmospheric conditions. In one example, a composite anode is formed by mixing particles of the aforementioned materials in the form of a slurry with, for example, carbon black or acetylene black, a binder, and a solvent, and cast using a conventional slurry-based method such as, for example, slot die coating.

[0045] Optionally, in step 220, the electrode structure is exposed to a surface treatment process. The surface treatment process can be performed to remove contaminants (if present) from the surface of the electrode structure and activate the surface of the electrode structure for better bonding or wetting by subsequently deposited materials. The surface treatment process can be selected from a corona treatment process, an atmospheric plasma treatment process, a low-energy plasma treatment process, a plasma treatment process performed in a vacuum environment, or a combination thereof.

[0046] The surface treatment process of step 220 can be carried out under atmospheric, near-atmospheric, or vacuum conditions. In one example, the surface treatment process -2 mbar to approximately 1 × 10 -6 mbar (e.g., 1 × 10 -3 Less than 1 x 10 -4 The process can be carried out in a vacuum environment with an environment such as that described below.

[0047] The surface treatment in step 220 can be a plasma treatment performed in an oxidizing gas environment, a reducing gas environment, or a combination of an oxidizing gas and a reducing gas. The plasma treatment process can be performed under atmospheric, near-atmospheric, or vacuum conditions. The oxidizing environment can include one or more oxidizing gases. The one or more oxidizing gases can be selected from oxygen (O), ozone (O), nitrous oxide (NO), fluorine (F), chlorine (Cl), carbon monoxide (CO), carbon dioxide (CO), radicals thereof, derivatives thereof, or combinations thereof. In one embodiment, the one or more oxidizing gases include oxygen (O). The one or more oxidizing gases can be introduced with one or more inert gases, such as nitrogen, helium, or argon. The reducing environment can include one or more reducing gases. The reducing gas can be selected from ammonia (NH), hydrazine (N), hydrogen (H), NF, atomic hydrogen, radicals thereof, derivatives thereof, or combinations thereof. In one example, the one or more reducing gases include hydrogen. The one or more reducing gases may be introduced along with one or more inert gases such as nitrogen, helium, or argon.

[0048] In some embodiments, the surface treatment process is a plasma treatment process performed in a vacuum environment. The plasma treatment process may include exposing the electrode structure to a reducing plasma. The reducing plasma may be formed from a reducing gas mixture including ammonia (NH), hydrazine (N2H4), hydrogen (H2), hydrogen halides, hydrogen chalcogenides, atomic hydrogen, their radicals, their derivatives, or combinations thereof. The reducing gas mixture may further include one or more inert gases. The reducing plasma may be a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma. The plasma treatment process may include exposing the electrode structure to an oxidizing plasma. The oxidizing plasma may be formed from an oxidizing gas mixture including oxygen (O2), ozone (O3), nitrous oxide (N2O), fluorine (F2), chlorine (Cl2), carbon monoxide (CO), water (H2O), carbon dioxide (CO2), their radicals, their derivatives, or combinations thereof. The oxidizing gas mixture may further include one or more inert gases. The oxidizing plasma can be a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma.

[0049] The surface treatment in step 220 can be a corona treatment (e.g., air plasma treatment) used to modify the surface of the electrode structure. Corona treatment can be performed using a low-temperature corona discharge plasma to alter the surface energy of the electrode structure. The corona treatment discharge process involves generating an ionized corona discharge plasma. The generated corona discharge plasma can include positively or negatively charged plasma.

[0050] Corona discharge typically involves two asymmetric electrodes positioned in the treatment area: one highly curved (e.g., a needle tip or small diameter wire), and one with a low curvature (e.g., a plate or ground). The high curvature ensures a high potential around the electrodes, resulting in the creation of a plasma. If the geometry and gradient are such that the ionized region continues to grow rather than stopping at a certain radius, a complete conductive path can be formed, resulting in a momentary spark or a continuous arc.

[0051] In some embodiments, the corona is positive. In other embodiments, the corona is negative. This depends on the polarity of the voltage across the highly curved electrode. If the curved electrode is positive relative to the planar electrode, a positive corona exists; otherwise, the corona is negative. In some embodiments, the corona treatment is carried out under partial or partial atmospheric pressure, under vacuum, or a combination thereof.

[0052] In one example, the surface treatment of step 220 is performed by exposing the electrode structure to an atmospheric plasma.

[0053] In some embodiments, the surface treatment process performed in step 220 includes supplying a treatment gas mixture to a treatment region. A plasma is then formed from the treatment gas mixture to plasma treat the surface of the electrode structure, activating at least a portion of the electrode structure to an excited state and forming a treated electrode structure having a treated upper surface, which can improve nucleation / growth conditions for a subsequently deposited material, such as a prelithiated layer.

[0054] In one embodiment, the process gas mixture includes at least one of an oxygen-containing gas, an inert gas (e.g., argon, helium), or a combination thereof. The oxygen-containing gas supplied to the process region may be oxygen (O), ozone (O), oxygen radicals (O * ), ionized oxygen atoms, carbon dioxide (CO2), nitric oxide (NO x), water vapor, or a combination thereof. Other oxygen-containing gases may also be used.

[0055] In one example of a process 220 involving oxidation, a gas source supplies oxygen gas (O) via a mass flow controller to an ozone generator, which converts most of the oxygen into ozone gas (O). The resulting O and O, and possibly some oxygen radicals O * An oxygen-based mixture of ozone and ionized oxygen atoms or molecules is supplied to the processing region. The oxygen-based gas reacts with the surface of the electrode structure in the processing region, which may be heated to a predetermined temperature, preferably a low temperature. Ozone is a metastable molecule and reacts with the surface of the electrode structure by the reaction O → O + O. * (where O * Ozone spontaneously and rapidly dissociates into ozone radicals (O2) which react very rapidly with any available substance that can be oxidized. Ozone generators can be implemented in many forms, including capacitively or inductively coupled plasma or UV lamp sources.

[0056] At these high ozone concentrations, the electrode structure does not need to be heated as much to achieve a relatively high oxidation rate. High ozone concentrations also allow for a reduction in the ozone partial pressure. High ozone fractions allow ozone oxidation to be carried out at pressures below 20 Torr. It should be understood that the surface modification techniques described above are exemplary, and that other surface modification techniques that achieve the desired surface modification may also be used.

[0057] In some embodiments, the surface treatment process includes a plasma treatment performed at or near atmospheric pressure. Atmospheric plasma can be composed of chemically unreactive species (e.g., argon or helium) and / or chemically reactive species (e.g., oxygen, nitrogen, or hydrogen).

[0058] In one embodiment of the method disclosed herein, the atmospheric pressure plasma is formed from a plasma source gas that is primarily composed of chemically unreactive species, such as argon or helium, for example, at least 95%. One or more chemically reactive plasma source gases may be present at a concentration ranging from about 0.005% to 5% of the plasma source gas. Chemically reactive plasma source gases that can be used include oxygen-containing gases, such as oxygen (O) and / or CO, which may be present in a range from about 0.005% to 4.75%; and / or reactive plasma source gases selected from the group consisting of hydrogen (H), nitrogen trifluoride (NF), tetrafluoromethane (CF), ammonia (NH), silane (SiH), and combinations thereof, which may be present in a range from about 0.005% to about 0.015%.

[0059] The spacing between the upper electrode and the electrode surface of the substrate can be set to a range of about 2 mm to about 15 mm, for example, about 3 mm. This selected spacing allows for the generation of very high energy density plasma at atmospheric pressure without arcing of the plasma. In one embodiment of the present disclosure, the upper electrode is a gas diffuser, such as a conductive showerhead, used as both an electrode and a plasma source gas distribution manifold to uniformly distribute gas within the plasma processing region. Alternatively, the showerhead may have a shape other than rectangular, and / or multiple smaller showerheads may be used instead of one large showerhead.

[0060] Atmospheric pressure plasma can be generated using an RF frequency power supply. The frequency of the RF power supply is typically about 13.56 MHz, about 27 MHz, or about 54 MHz. The frequency of the RF power supply is another variable in generating a very high energy density plasma source at atmospheric pressure without arcing the plasma. Those skilled in the art, given the present disclosure, will be able to select different frequencies depending on the particular processing equipment and plasma source gas used.

[0061] In one example, the atmospheric plasma process includes a plasma source gas comprising a flow of 11 liters / min of argon and 55 sccm of clean, dry air (CDA), an RF frequency of 13.56 MHz, a power of 333 watts, and a spacing between the plasma head and the electrode surface of 3.0 millimeters.

[0062] In some embodiments, the surface treatment process includes a short plasma etch to activate the electrode surface. The atmospheric plasma can be composed of chemically unreactive species, such as argon or helium, and / or chemically reactive species, such as oxygen. A short plasma etch can be performed following deposition of the electrode material to increase the external surface area of ​​the electrode surface.

[0063] In some embodiments, the electrode surface can be etched using a low-energy plasma treatment, such as 1 kV, with a dose ranging from 1E16 to 3E16 atoms per square centimeter implanted. The etching gas can be H, Cl, BCl, HBr, CF, CHF, and other halogen-based compounds. In some embodiments, the etching gas can be a mixture of the above gases with argon and / or nitrogen to improve the etching rate and tailor the etching profile.

[0064] In one embodiment, a mixture of SiCl4 plasma and Cl2 plasma is used to create a hydrophilic surface with a large surface area. Chlorine is a commonly used etchant that helps quickly remove some of the top layer of the electrode structure. Adding SiCl4 to the etching chemistry allows for the deposition of SiCl on the electrode surface. x After the etching step is complete, the electrode structure is exposed to slightly basic (e.g., pH >8.0) heated water to remove the surface SiCl x This promotes the hydrolysis of silicon tetrachloride, making part of the electrode surface superhydrophilic. Silicon tetrachloride is actually a by-product of silicon etching by chlorine, but the amount is small enough that sufficient SiCl xTherefore, the addition of SiCl4 is necessary.

[0065] A bias can be applied to the electrode structure in the surface treatment process described herein, and the bias can be in the range of 1-2 kV. Compared to a typical Cl etching process, this bias can be slightly higher, such as between 2-4 kV, which is advantageous for SiCl etching. x and / or Cl ions penetrate into the electrode structure, which helps enhance ion implantation compared to etching. However, this bias must be low enough so that the chlorine functionalities are not buried deep below the substrate surface. In addition, a lower process pressure, such as about 5 mTorr, can be used to reduce collisions within the sheath and create a high concentration of SiCl at the surface. x The probability of generating functional groups can be increased.

[0066] A short plasma etch not only maintains a hydrophilic surface but also results in an electrode structure with high surface reaction rates. Increasing the surface area significantly improves the performance of thin-film electrodes by providing an increased active area for electrochemical reactions to occur. This may enable faster charging and discharging of the battery. Hydrophilic properties may be desirable to more thoroughly wet the electrolyte on the electrode. This may lead to more uniform lithium intercalation and increased rate capability.

[0067] After step 220, the electrode with the treated surface may be transferred from the atmospheric environment to a vacuum environment for further processing, if step 220 was performed in an atmospheric environment.

[0068] In step 230, a prelithiation layer can be formed on the treated surface of the electrode structure. The prelithiation layer can be a lithium metal film 145 formed on the surface of a negative electrode, such as the negative electrode 140. The prelithiation layer can be a lithium metal film formed on the surface of a positive electrode, such as the positive electrode 120. In some implementations, the surface treatment process of operation 220 activates the surface of the electrode structure and improves the wettability of the subsequently deposited prelithiation layer formed during step 230. The prelithiation process of step 230 can be performed in a vacuum environment. The lithium metal film replenishes lithium lost due to the first cycle capacity loss of the electrode structure. The lithium metal film can be a thin lithium metal film (e.g., 20 microns or less, about 1 micron to about 20 microns, about 2 microns to about 10 microns). The lithium metal film can be deposited using a vapor deposition method. For example, the lithium metal film 145 can be deposited by a PVD technique, such as thermal evaporation or electron beam evaporation.

[0069] Optionally, in step 240, the prelithiated layer or prelithiated electrode structure is exposed to a post-treatment process. The post-treatment process can be a surface treatment process to activate the prelithiated layer, to promote lithium absorption into the underlying electrode structure, or a combination of both. The post-treatment process of step 240 can be similar to any of the pre-treatment processes described in step 220.

[0070] The post-treatment process of step 240 can include a heat treatment or annealing process designed to promote the absorption of lithium from the prelithiated layer into the electrode structure. Examples of post-treatment processes include annealing in a vacuum environment, laser heating in a controlled atmosphere (e.g., argon or vacuum), exposure to thermal and / or radiation energy, adjusting pressure to promote absorption during the process, or a combination thereof. During step 240, heat or thermal energy can be applied to the electrode structure, the prelithiated layer formed on the electrode structure, or both the prelithiated layer and the electrode structure.

[0071] The post-treatment process conditions for step 240 can be selected so that the electrode structure and / or the pre-lithiated layer formed thereon is heated to a temperature below the melting point of the electrode structure but sufficient to promote diffusion of lithium from the pre-lithiated layer into the electrode structure. The post-treatment process temperature for step 240 can be within a range from about room temperature (e.g., 22-24°C) to about 200°C. The post-treatment process temperature for step 240 can be at or near room temperature. The post-treatment process temperature for step 240 can be 180°C or less, for example, within a range from room temperature or near room temperature to about 180°C. The post-treatment process temperature for step 240 can be 150°C or less, for example, within a range from room temperature or near room temperature to about 150°C. The post-treatment process temperature for step 240 can be 130°C or less, for example, within a range from room temperature or near room temperature to about 130°C. The post-treatment process temperature of step 240 can be 80 degrees Celsius or less, for example, in the range of at or near room temperature to about 80 degrees Celsius. The post-treatment process temperature of step 240 can be 60 degrees Celsius or less, for example, in the range of at or near room temperature to about 60 degrees Celsius. The electrode structure and / or prelithiated layer can be heated to a temperature in the range of about room temperature to about 200 degrees Celsius, more narrowly in the range of about room temperature to about 180 degrees Celsius, more narrowly in the range of about 50 degrees Celsius to about 130 degrees Celsius, and even more narrowly in the range of about 50 degrees Celsius to about 60 degrees Celsius.

[0072] For vacuum annealing, the electrode structure (and thus the prelithiated layer deposited thereon) can be heated to an annealing temperature for a predetermined time. Any suitable annealing temperature can be used. The annealing temperature can range from about room temperature (e.g., 22-24 degrees Celsius) to about 200 degrees Celsius, or any of the other ranges described with respect to step 240. Vacuum annealing can be performed for about 15 minutes to about 60 minutes. Vacuum annealing can be performed for 5 minutes or more at ambient pressure. Vacuum annealing can be performed in a variety of environments. Vacuum annealing can be performed in a vacuum environment. Vacuum annealing can be performed in an inert gas environment, such as argon, helium, neon, or a combination thereof. Vacuum annealing can be performed in an argon environment.

[0073] The post-treatment process of step 240 can be carried out under atmospheric, near-atmospheric, or vacuum conditions. -2 mbar to approximately 1 × 10 -6 mbar (e.g., 1 × 10 -3 Less than 1 x 10 -4 The post-treatment process may be performed in a vacuum environment with an environment of 10 mTorr or less. In some post-treatment vacuum processes, the pressure in the processing chamber during step 240 may be less than atmospheric pressure (e.g., 1013 mbar), for example, from about −2 mbar (e.g., −1500 mTorr) to about −25 mbar (e.g., −18751 mTorr). In some post-treatment processes performed at positive pressure, the pressure in the processing chamber during step 240 may be performed within a range of from about 10 mTorr to about 50 mTorr.

[0074] In one embodiment, for laser heating, the electrode structure (and thus the prelithiated layer deposited thereon) is exposed to radiant energy from a laser source to heat the electrode structure for a predetermined period of time. At least a portion of the electrode structure can be annealed using a laser in a controlled atmosphere. Laser heating can be performed in a variety of environments. In one embodiment, the laser heating is performed in a vacuum environment. In another embodiment, the laser heating is performed in an inert gas environment. In another embodiment, the laser heating is performed in an argon environment.

[0075] In one embodiment, for thermal heating, the electrode structure (and thus the prelithiated layer deposited thereon) is exposed to radiant energy. Any suitable thermal heating temperature can be used. The thermal heating temperature can range from about room temperature (e.g., 22-24 degrees Celsius) to about 200 degrees Celsius, or any of the other ranges described with respect to operation 240. Thermal heating can be performed by exposing the electrode structure to a heat source, such as an internally formed lamp or heating assembly connected to an optional microwave generator. The microwave power applied during the thermal / annealing process can gently heat / thermalize the electrode structure without adversely affecting the anode material or other film structures present in the electrode structure.

[0076] In step 250, the prelithiated electrode structure may be exposed to additional processing. The additional processing may include forming an additional film on the prelithiated electrode structure, e.g., a surface overcoat such as surface overcoat 170. In one example, the surface overcoat is a lithium carbonate film formed by exposing a lithium metal film to a plasma formed from CO gas. Pre-activating the lithium metal film using a post-processing technique can increase the rate of formation of the lithium carbonate film, if formed, and can also improve the quality of the deposited lithium carbonate film.

[0077] Embodiments of the present disclosure may include one or more of the following potential advantages. Some embodiments include: (a) a pretreatment process to remove loosely held particles from the electrode surface; (b) a pretreatment process to activate the surface of the electrode material to improve bonding or wetting of subsequently deposited materials; (c) a post-treatment of the prelithiation layer to improve subsequent bonding with additionally deposited layers, such as a passivation layer; and / or (d) activating the surface of the electrode for post-treatment of the prelithiation layer to improve / accelerate lithium absorption into the underlying electrode material. The pretreatment and post-treatment processes described herein can not only provide a clean surface but also activate the surface to improve bonding or wetting of subsequently deposited materials. This can improve the deposition rate of subsequent films as well as the quality of the deposited lithium carbonate film. In addition, current slurry coating processes can be integrated with next-generation prelithiation applications using the processes described herein. In addition, lithium inventories can be optimized for long cycle life and increased throughput.

[0078] In some embodiments, the electrode surface pretreatment can be performed under atmospheric or vacuum conditions. The pretreatment process can include a corona treatment process, an atmospheric plasma treatment process, a low-energy plasma treatment process, a plasma treatment process performed in a vacuum environment, or a combination thereof. The pretreatment process can be performed under an oxidizing or reducing atmosphere.

[0079] In some embodiments, the post-treatment is performed in a controlled atmosphere, including a vacuum, which provides for easier handling of the prelithiated electrodes in a mass production environment and improved device performance. The post-treatment process can include a corona treatment process, an atmospheric plasma treatment process, a low-energy plasma treatment process, a plasma treatment process performed in a vacuum environment, a heat treatment process, an annealing process, or a combination thereof.

[0080] While there are many methods for lithium metal deposition (e.g., thermal evaporation, lamination, printing, etc.), handling of the lithium metal deposited on spools prior to stacking of devices is required, especially in mass production environments. In one embodiment, a method and system for forming interleaves on a lithium metal film is provided. In another embodiment, a method and system for lithium polymer deposition is provided. In yet another embodiment, an integrated tool for both lithium metal deposition and ion-conducting polymer deposition is provided. [Example]

[0081] The following non-limiting examples are provided to further illustrate the embodiments described herein. However, these examples are not intended to be exhaustive or to limit the scope of the embodiments described herein. Table I provides an example of surface treatment conditions using atmospheric plasma according to one or more embodiments described herein. TIFF0007772821000001.tif48170

[0082] The effect on the process after the absorption of excess lithium into the active material of the battery's negative electrode. After vacuum deposition of a few microns of lithium metal onto a battery anode, a certain amount of the deposited lithium is absorbed into the electrode layer. In this case, the lithium is either intercalated into the active graphite material or forms a Li-Si alloy with silicon-containing compounds in the battery electrode. Areas of the anode with high absorption are observed to retain their black color. However, some of the deposited metallic lithium remains on the surface as a film called "excess lithium." This excess lithium can be visually identified as a gray / white layer on the typically black battery anode.

[0083] It was found that storing lithium-coated battery anodes under an inert gas atmosphere / vacuum (absence of nitrogen, oxygen, and water) resulted in further absorption of metallic lithium into the active material of the porous battery anode material, a process known as the post-absorption process. Optically, it was observed that the gray / white layer of excess lithium decreased over time, causing the area to turn black. This indicates that lithium atoms may diffuse from the metal surface film into the active material of the battery anode over time.

[0084] In comparison, it was found that the post-absorption process can be suppressed by exposing the lithium-coated battery anode to a carbon dioxide-containing atmosphere immediately after the lithium vacuum deposition process step. After treatment in a carbon dioxide-containing atmosphere, the excess lithium areas did not discolor over time. The optical appearance of the gray / white layer did not change during storage under an inert gas atmosphere / vacuum. This means that the additional treatment suppresses the diffusion of lithium atoms into the active material of the battery anode. Gas treatment in a carbon dioxide-containing atmosphere results in the conversion of a certain amount of lithium metal to lithium carbonate. Because the gas penetrates and can completely react with lithium at all active sites in the porous electrode matrix, the exact amount of converted lithium depends on the porosity of the electrode layer, the roughness, and the thickness of the excess lithium film. In particular, while the upper atomic layer of the excess lithium layer begins to react with carbon dioxide molecules, the gas reaction can sometimes form a uniform carbonate layer with a thickness of more than 100 nm. Notably, in a battery anode with higher porosity, the same amount of deposited lithium is distributed over a larger electrode surface area. In this case, the thickness of the excess lithium layer is reduced and the conversion rate to lithium carbonate during gas treatment is increased.

[0085] FIG. 3 shows SEM images 310-360 illustrating the morphology and EDX oxygen signal of a battery anode material formed according to one or more embodiments described herein. The SEM images show examples of the morphology and EDX oxygen signal of A) the battery anode material (images 310, 320); B) a lithium-coated electrode that was stored under vacuum / inert gas atmosphere and then treated in carbon dioxide gas atmosphere (images 330, 340); and C) a lithium-coated electrode that was stored under vacuum / inert gas atmosphere and then not treated in carbon dioxide gas atmosphere (images 350, 360). The oxygen signal intensity of both lithium-coated electrodes reflects the presence of lithium carbonate or other lithium.

[0086] In a comparative study, battery anodes 1 and 2 were coated with the same amount of lithium and stored in vacuum / inert gas for the same period of time. Electrode 1 was treated in a carbon dioxide gas atmosphere after the lithium deposition process, while electrode 2 was not. SEM and EDX analysis demonstrated that electrode 2 (without CO2 treatment) did not exhibit a significant excess lithium layer after storage (similar to the pristine electrodes shown in images 310 and 320). A large amount of oxygen, corresponding to the lithium carbonate layer, was found on the surface of electrode 2 (images 330 and 340). This observation provides further evidence that CO2 treatment of lithium-coated battery anodes inhibits further intercalation of lithium into the electrode's active material.

[0087] Storing lithium-deposited battery anode materials in vacuum / inert gas prior to treatment in an atmosphere containing carbon dioxide can increase the degree of excess lithium after absorption.

[0088] All of the embodiments and functional operations described herein can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structural means disclosed herein and their structural equivalents, or in combinations of these. The 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 a data processing apparatus (e.g., a programmable processor, a computer, or multiple processors or computers).

[0089] The processes and logic flows described herein may be implemented by one or more programmable processors that execute one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows may also be performed by, and apparatus may be implemented as, an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), for example.

[0090] 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. In addition to hardware, such apparatus may include code that creates the execution environment for a subject computer program, such as, for example, code comprising processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of these. Processors suitable for the execution of computer programs include, by way of example, both general-purpose and special-purpose microprocessors, and any one or more processors of any kind of digital computer.

[0091] Computer-readable media suitable for storing computer program instructions and data include, by way of example only, all forms of non-volatile memory, e.g., semiconductor memory devices such as 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.

[0092] Embodiments of the present disclosure may further relate to any one or more of the following:

[0093] 1. A method of forming an electrode structure, comprising: exposing the electrode structure to a surface treatment process to activate a surface of the electrode structure; and forming a lithium metal film on the electrode structure, wherein the surface treatment process is selected from a corona treatment process, an atmospheric plasma treatment process, a low-energy plasma treatment process, a plasma treatment process performed in a vacuum environment, or a combination thereof.

[0094] 2. The method according to claim 1, wherein the surface treatment process is a corona treatment process.

[0095] 3. The method of claim 2, wherein the corona treatment process includes generating an ionized corona discharge plasma.

[0096] 4. The method of claim 3, wherein the generated ionized corona discharge plasma comprises a positively or negatively charged plasma.

[0097] 5. The method according to claim 1, wherein the surface treatment process is an atmospheric plasma treatment process.

[0098] 6. The method of claim 5, wherein the atmospheric plasma treatment process is conducted at or near atmospheric pressure.

[0099] 7. The method of claim 5, wherein the atmospheric plasma treatment process includes a plasma source gas that includes chemically reactive species and chemically non-reactive species.

[0100] 8. The method of paragraph 7, wherein the chemically reactive species is selected from oxygen, nitrogen, hydrogen, or a combination thereof.

[0101] 9. The method of claim 8, wherein the chemically non-reactive species is selected from argon, helium, or a combination thereof.

[0102] 10. The method of claim 9, wherein the plasma source gas comprises at least a 95% concentration of chemically unreactive species and less than a 5% concentration of chemically reactive species.

[0103] 11. The method of claim 7, wherein the chemically reactive species is oxygen and the chemically unreactive species is argon.

[0104] 12. The method of claim 7, wherein the chemically reactive species is hydrogen and the chemically unreactive species is argon.

[0105] 13. The method of claim 7, wherein the atmospheric plasma treatment process includes generating atmospheric pressure plasma using an RF frequency power source.

[0106] 14. The method of claim 13, wherein the RF power source is from about 13.56 MHz to about 27 MHz.

[0107] 15. The method according to claim 1, wherein the surface treatment process is a plasma treatment process carried out in a vacuum environment.

[0108] 16. The method of claim 15, wherein the plasma treatment process comprises exposing the electrode structure to a reducing plasma.

[0109] 17. The method of claim 16, wherein the reducing plasma is formed from a reducing gas mixture including ammonia (NH3), hydrazine (N2H4), hydrogen (H2), hydrogen halide, hydrogen chalcogenide, atomic hydrogen, radicals thereof, derivatives thereof, or combinations thereof.

[0110] 18. The method of claim 17, wherein the reducing gas mixture further comprises one or more inert gases.

[0111] 19. The method of claim 17, wherein the reducing plasma is a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma.

[0112] 20. The method of claim 15, wherein the plasma treatment process includes exposing the electrode structure to an oxidizing plasma.

[0113] 21. The method of paragraph 20, wherein the oxidizing plasma is formed from an oxidizing gas mixture including oxygen (O2), ozone (O3), nitrous oxide (N2O), fluorine (F2), chlorine (Cl2), carbon monoxide (CO), water (H2O), carbon dioxide (CO2), radicals thereof, derivatives thereof, or combinations thereof.

[0114] 22. The method of claim 21, wherein the oxidizing gas mixture further comprises one or more inert gases.

[0115] 23. The method of claim 21, wherein the oxidizing plasma is a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma.

[0116] 24. The method of any of paragraphs 1 to 23, wherein the electrode structure comprises a composite anode comprising at least one of carbon, graphite, silicon, silicon oxide, silicon-containing graphite, lithium, lithium metal foil or lithium alloy foil (e.g., lithium aluminum alloy), nickel, copper, silver, tin, indium, silicon, oxides thereof, composites thereof, or combinations thereof, and a binder material.

[0117] 25. The method of any of paragraphs 1 to 24, wherein the electrode structure further comprises a continuous flexible substrate.

[0118] 26. The method of any of paragraphs 1 to 25, wherein the surface treatment process is carried out in a roll-to-roll tool.

[0119] 27. The method of any of paragraphs 1 to 26, further comprising exposing the lithium metal film to CO2 gas to form a passivation layer.

[0120] 28. The method of any of paragraphs 1 to 27, further comprising exposing the lithium metal film to a post-deposition surface treatment process, wherein the post-deposition surface treatment process comprises annealing the lithium metal film in a vacuum environment, heating the lithium metal film with a laser in a controlled atmosphere (e.g., argon or vacuum), exposing the lithium metal film to thermal energy and / or radiation energy, or a combination thereof.

[0121] 29. A method for forming an electrode structure, comprising: forming an anode structure in an atmospheric environment; exposing the anode structure to a surface treatment process to activate a surface of the electrode structure; and forming a lithium metal film on the electrode structure in a vacuum environment, wherein the surface treatment process is selected from a corona treatment process, an atmospheric plasma treatment process, a low-energy plasma treatment process, a plasma treatment process performed in a vacuum environment, or a combination thereof.

[0122] The articles "a," "an," "the," and "said" when introducing elements of the present disclosure or example aspects of implementations of the present disclosure are intended to mean that there are one or more of the elements.

[0123] The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0124] While the forgoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, the scope of which is determined by the claims that follow.

Claims

1. 1. A method of forming an electrode structure, comprising: exposing the electrode structure to a surface treatment process to activate the surface of the electrode structure; forming a lithium metal film on the electrode structure; and exposing the lithium metal film to a post-deposition surface treatment process to accelerate absorption of the lithium metal film into the electrode structure, thereby prelithiating the electrode structure; the surface treatment process is selected from a corona treatment process, an atmospheric plasma treatment process, a low-energy plasma treatment process, a plasma treatment process performed in a vacuum environment, or a combination thereof; method.

2. 10. The method of claim 1, wherein the surface treatment process is a corona treatment process that includes generating an ionized corona discharge plasma.

3. The method of claim 2 , wherein the generated ionized corona discharge plasma comprises a positively or negatively charged plasma.

4. 10. The method of claim 1, wherein the surface treatment process is an atmospheric plasma treatment process conducted at or near atmospheric pressure.

5. The atmospheric plasma treatment process includes a plasma source gas comprising chemically reactive and chemically non-reactive species, wherein: the chemically reactive species is selected from oxygen, hydrogen, or a combination thereof; and the chemically unreactive species is selected from argon, helium, or a combination thereof; The method of claim 4.

6. 6. The method of claim 5, wherein the plasma source gas comprises at least 95% concentration of the chemically unreactive species and less than 5% concentration of the chemically reactive species.

7. 6. The method of claim 5, wherein the chemically reactive species is oxygen, nitrogen, or hydrogen, and the chemically unreactive species is argon.

8. 6. The method of claim 5, wherein the atmospheric plasma treatment process comprises generating an atmospheric pressure plasma using an RF frequency power source, the RF frequency power source being between about 13.56 MHz and about 27 MHz.

9. The method of claim 1 , wherein the surface treatment process is the plasma treatment process performed in a vacuum environment.

10. The method of claim 9 , wherein the plasma treatment process comprises exposing the electrode structure to a reducing plasma.

11. The reducing plasma is ammonia (NH ３ ), hydrazine (N ２ H ４ ), hydrogen (H ２ 11. The method of claim 10, wherein the hydrogen is formed from a reducing gas mixture comprising atomic hydrogen, hydrogen halides, hydrogen chalcogenides, radicals thereof, derivatives thereof, or combinations thereof.

12. 12. The method of claim 11, wherein the reducing gas mixture further comprises one or more inert gases, and the reducing plasma is a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma.

13. The method of claim 9 , wherein the plasma treatment process comprises exposing the electrode structure to an oxidizing plasma.

14. The oxidizing plasma is oxygen (O ２ ), ozone (O ３ ), nitrous oxide (N ２ O), fluorine (F ２ ), chlorine (Cl ２ ), carbon monoxide (CO), carbon dioxide (CO ２ ), water (H ２ 14. The method of claim 13, wherein the oxidizing gas mixture comprises HCl, HCl, HCl(II), ...

15. The method of claim 13 , wherein the oxidizing plasma is a remotely formed plasma, a capacitively coupled plasma, or an inductively coupled plasma.

16. 1. A method of forming an electrode structure, comprising: forming an anode structure in an atmospheric environment; exposing the anode structure to a surface treatment process to activate the surface of the electrode structure; forming a lithium metal film on the electrode structure in a vacuum environment; and exposing the lithium metal film to a post-deposition surface treatment process to accelerate absorption of the lithium metal film into the electrode structure, thereby prelithiating the electrode structure; Including, The method, wherein the surface treatment process is selected from a corona treatment process, an atmospheric plasma treatment process, a low energy plasma treatment process, a plasma treatment process performed in a vacuum environment, or a combination thereof.

17. 17. The method of claim 16, wherein the surface treatment process is a corona treatment process that includes generating an ionized corona discharge plasma.

18. 17. The method of claim 16, wherein the surface treatment process is an atmospheric plasma treatment process conducted at or near atmospheric pressure.

19. 17. The method of claim 16, wherein the surface treatment process is the plasma treatment process performed in a vacuum environment.

20. A non-transitory computer-readable medium that, when executed by a processor, causes a computer system to: forming an anode structure in an atmospheric environment; exposing the anode structure to a surface treatment process to activate the surface of the electrode structure; forming a lithium metal film on the electrode structure in a vacuum environment; and exposing the lithium metal film to a post-deposition surface treatment process to accelerate absorption of the lithium metal film into the electrode structure, thereby prelithiating the electrode structure; Stores instructions to execute each step of 10. The non-transitory computer-readable medium, wherein the surface treatment process is selected from a corona treatment process, an atmospheric plasma treatment process, a low-energy plasma treatment process, a plasma treatment process performed in a vacuum environment, or a combination thereof.

Images