WO2024091985A1

WO2024091985A1 - Methods of forming an electrode assembly for a battery

Info

Publication number: WO2024091985A1
Application number: PCT/US2023/077702
Authority: WO
Inventors: Xiaohong Gayden; Yunchao Li
Original assignee: Intecells, Inc.
Priority date: 2022-10-28
Filing date: 2023-10-25
Publication date: 2024-05-02

Abstract

The present invention provides solvent-free methods of forming an electrode assembly for a battery cell, and electrode assemblies formed by such methods.

Description

METHODS OF FORMING AN ELECTRODE ASSEMBLY FOR A BATTERY

CROSS REFERENCE TO RELATED APPLICATION

[0001] This PCT application claims the benefit of U.S. provisional application no. 63/381,398, filed October 28, 2022, the entire contents of which are hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The present invention relates to methods of forming an electrode assembly for a battery cell and electrode assemblies formed by such methods.

BACKGROUND

[0003] Battery cells are used in many applications, from rechargeable batteries for laptops and other personal devices to use in providing motive power in automotive vehicles. Each battery cell may provide an electrical potential of about three to four volts and a direct electrical current, depending on the composition and mass of the electrode active materials in the battery cell. Battery cells can be discharged and re-charged over many cycles. A battery may be assembled by combining a suitable number of individual battery cells in a combination of electrical parallel and series connections to satisfy voltage and current requirements for an electric device or motor. For example, the assembled battery for an automotive vehicle may have perhaps three hundred individually packaged battery cells that are electrically interconnected to provide forty to four hundred volts and sufficient electrical power to an electrical traction motor to drive a vehicle.

[0004] Each battery cell typically comprises a negative electrode layer (anode, during cell discharge), a positive electrode layer (cathode, during cell discharge), a thin, porous separator layer interposed in face-to-face contact between the positive and negative electrode layers, an electrolyte solution filling the pores of the separator and contacting the electrode layers for transport of ions during repeated cell discharging and re-charging cycles, and a thin layer of a metallic current collector. It is desirable to have a manufacturing process that does not waste the expensive materials used in making the various battery components (e.g., electrode assemblies). Because a battery requires such a great number of battery cells to provide sufficient electrical power to an electrical traction motor to drive a vehicle, an efficient, high quality production method is a key commercial consideration for this end use. [0005] Present production methods have several drawbacks. For example, electrode assemblies are made by spreading or spraying a liquid slurry composition containing electrode active material, conductive carbon material, and a polymeric binder in a solvent system onto one or both sides of a metal foil. The metal foil serves as the current collector for the electrode. The deposited slurry layer must then be dried (e.g., in an oven) to force off the solvent, then pressed between calendering rollers to fix the electrode coatings to their respective metal foils. The electrode coatings formed on metal foil sheets of a suitable area and shape may then be cut (if necessary), folded, rolled, or otherwise shaped for assembly into battery cell containers with suitable porous separators and a liquid electrolyte.

[0006] This current process requires a large manufacturing footprint for producing the liquid slurry mixture and for individual coating, drying, calendering, and assembly stations. This process also requires high capital investment for the equipment, as well as high energy costs, particularly in the drying step. Furthermore, use of solvents may introduce health and fire hazards and produce regulated emissions, and the production time is lengthy due to the required drying time.

[0007] Accordingly, there remains a need for improved methods of forming electrode assemblies for a battery cell. The methods described herein are directed towards this end.

SUMMARY OF THE INVENTION

[0008] The present invention provides a method of forming an electrode assembly for a battery comprising:

(a) providing a precursor mixture comprising a binder, an active material, and a conductive additive;

(b) treating the precursor mixture with atmospheric plasma to form a plasma-treated precursor mixture;

(c) forming an electrode coating from the plasma-treated precursor mixture, wherein the electrode coating is substantially free of any solvent; and

(d) applying the electrode coating to a metal foil to form the electrode assembly. [0009] In some implementations, the binder is a polymer binder. In other implementations, the polymer binder comprises polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), cellulose, carboxymethyl cellulose (CMC), polyisoprene, polyacrylic acid (PAA), styrenebutadiene rubber (SBR), polybutadiene rubber, ethylene-propylene rubber, syndiotactic 1,2- polybutadiene, poly(ethylene-vinyl acetate) (PEVA), copolymers of PTFE and ethylene, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride, sodium alginate (SA), polyurethane (PU), polyimide (PI), or any combination thereof. And, in some implementations, the polymer binder comprises PTFE, PVDF, or any combination thereof. In some implementations, the polymer binder is a powder (e.g., a powder having a particle size distribution giving a D90 of less than about 500 pm).

[0010] In some implementations, the active material comprises an anode active material. In other implementations, the anode active material comprises lithium titanate (LTO), titanium niobium oxide (TNO), graphite, silicon, hard carbon, silicon alloys, silicon oxides, LiSi alloys, metal oxides, Sn, Sn alloys, Mg, Mg alloys, Al, Al alloys, Ag, Ag alloys, Sb, Sb alloys, or any combination thereof. In some implementations, the anode active material is a powder (e.g., a powder having a particle size distribution giving a D90 of less than about 500 pm).

[0011] In some implementations, the active material comprises a cathode active material. In other implementations, the cathode active material comprises lithium manganese nickel cobalt oxides (NMC), lithium manganese oxides (LMO), lithium cobalt oxides (LCO), lithium nickel cobalt aluminum oxides (NCA), lithium iron phosphates (LFP), LiFeMnPCh, FeSz, S, Li S, sodium transition metal oxides, or any combination thereof. And, in some implementations, the cathode active material comprises LiCoCh, lithium manganese nickel cobalt oxides (NMC), LiFePO-i, LiMn CE, or any combination thereof. In some implementations, the cathode active material is a powder (e.g., a powder having a particle size distribution giving a D90 of less than about 500 pm).

[0012] In some implementations, the conductive additive comprises carbon black, acetylene black, carbon nanotube (CNT), graphene, graphite, or any combination thereof. In some implementations, the conductive additive is a powder (e.g., a powder having a particle size distribution giving a D90 of less than about 500 pm).

[0013] In some implementations, at least one (e.g., two or all) of the binder, the active material, or the conductive additive comprises a powder having a particle size distribution giving a D90 of less than about 500 pm. For example, the binder (e.g., polymer binder) is a powder having a particle size distribution giving a D90 of less than about 500 pm. In other examples, the active material (e.g., the anode active material and/or the cathode active material) is a powder having a particle size distribution giving a D$>o of less than about 500 pm. And, in some examples, the conductive additive is a powder having a particle size distribution giving a D90 of less than about 500 pm. In other examples, all of the binder, the active material, and the conductive additive comprise powders having particle sizes giving D90 values of less than about 500 pm.

[0014] In some implementations, step (a) further comprises mixing the precursor mixture to generate a substantially homogenous precursor mixture. In some implementations, step (a) further comprises drying the precursor mixture to generate a substantially solvent-free precursor mixture.

[0015] In some implementations, the atmospheric plasma is formed from a working gas. In other implementations, the working gas comprises dry air, nitrogen (N2), argon (Ar), helium (He), neon (Ne), oxygen (O2), hydrogen (H2), or any combination thereof.

[0016] In some implementations, step (b) further comprises treating the precursor mixture with atmospheric plasma from a plasma nozzle. In other implementations, the atmospheric plasma is generated with an input voltage of from about 50 W to about 4,000 W. In some implementations, the atmospheric plasma is generated with an input voltage of from about 100 W to about 2,000 W. And, in some implementations, the atmospheric plasma is generated with an input voltage of from about 150 W to about 1,500 W.

[0017] In some implementations, step (c) further comprises forming an electrode coating from the plasma-treated precursor mixture by calendering the plasma-treated precursor mixture.

[0018] In some implementations, the atmospheric plasma of step (b) is further defined as a first atmospheric plasma, and step (c) further comprises

(cl) forming an electrode coating from the plasma-treated precursor mixture, wherein the electrode coating is substantially free of any solvent; and

(c2) treating the electrode coating with a second atmospheric plasma.

[0019] In some implementations, the second atmospheric plasma is formed from a second working gas. In some implementations, the second working gas comprises dry air, N2, Ar, He, Ne, O2, H2, or any combination thereof. In other implementations, step (c2) further comprises treating the electrode coating with a second atmospheric plasma from a second plasma nozzle. [0020] In some implementations, step (c) is performed substantially free of any solvent. [0021] In some implementations, step (d) further comprises applying the electrode coating to a metal foil to form the electrode assembly by calendering or pressing the electrode coating to the metal foil. In other implementations, step (d) further comprises applying the electrode coating to a metal foil to form the electrode assembly by calendering the electrode coating to the metal foil. And, in some implementations, step (d) further comprises applying the electrode coating to a metal foil to form the electrode assembly by pressing the electrode coating to the metal foil.

[0022] In some implementations, step (d) further comprises

(dl) treating a metal foil with a third atmospheric plasma to form a plasma-treated metal foil; and

(d2) applying the electrode coating to the plasma-treated metal foil to form the electrode assembly.

[0023] In some implementations, the third atmospheric plasma is formed from a third working gas. In some implementations, the third working gas comprises dry air, N2, Ar, He, Ne, O2, H2, or any combination thereof. And, in some implementations, step (dl) further comprises treating the metal foil with a third atmospheric plasma from a third plasma nozzle.

[0024] In some implementations, the method further comprises

(e) treating the electrode assembly with a fourth atmospheric plasma.

[0025] In some implementations, the method further comprises

(f) calendering the electrode assembly.

[0026] In some implementations, step (f) is performed after step (e). In other implementations, step (f) is performed before step (e).

[0027] In some implementations, the fourth atmospheric plasma is formed from a fourth working gas, and wherein the fourth working gas comprises dry air, N2, Ar, He, Ne, O2, H2, or any combination thereof. And, in some implementations, step (e) further comprises treating the electrode assembly with a fourth atmospheric plasma from a fourth plasma nozzle.

[0028] In another aspect, the present invention provides an electrode assembly formed by any method described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The figures below are provided by way of example and are not intended to limit the scope of the claimed invention. [0030] FIG. l is a flow chart of a method of forming an electrode assembly according to one implementation of the invention.

[0031] FIG. 2 is an exemplary embodiment of a plasma nozzle apparatus for treating a precursor mixture with atmospheric plasma.

[0032] FIG. 3 is a flow chart of a method of forming an electrode assembly according to another implementation of the invention.

[0033] FIG. 4 is a flow chart of a method of forming an electrode assembly according to a further implementation of the invention.

[0034] FIG. 5 is a schematic of an exemplary embodiment of system for forming an electrode assembly.

[0035] FIGS. 6A and 6B are images depicting deionized (DI) water contact angles for PTFE surfaces prepared according to Example 1 .

DETAILED DESCRIPTION

[0036] The present invention provides methods of forming an electrode assembly for a battery cell and electrode assemblies formed by such methods.

[0037] As used herein, the following definitions shall apply unless otherwise indicated.

[0038] I. DEFINITIONS

[0039] “ A,” “an,” “the,” “at least one,” and “one or more” are used interchangeably to indicate that at least one of the item is present; a plurality of such items may be present unless the context clearly indicates otherwise. All numerical values of parameters (e.g., of quantities or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range.

[0040] As used herein, the term “electrode coating” refers to a layer comprising a binder, an active material, and a conductive additive. The electrode coating is formed via processing (e.g., chemical or mechanical processing) of a precursor mixture. The electrode coating herein is substantially free of any solvent (e.g., comprising less than 1% by volume, comprising less than 0.5% by volume, comprising less than 0.1% by volume, comprising less than 1 wt% of solvent by weight of the coating, comprising less than 0.5 wt% of solvent by weight of the coating, comprising less than 0.1 wt% of solvent by weight of the coating, comprising less than 0.05 wt% of solvent by weight of the coating, comprising less than 0.01 wt% of solvent by weight of the coating, or comprising less than 0.001 wt% of solvent by weight of the coating).

[0041] As used herein, the term “binder” refers to a component of the electrode coating suitable for holding other components in place when the electrode coating is formed. In some embodiments, the binder may also aid adherence of the electrode coating to a metal foil. In other embodiments, the binder is a polymer binder.

[0042] As used herein, the term “active material” refers to a component of the electrode coating capable of taking up and/or releasing ions and electrons during operation of a battery cell. In some embodiments, the active material is an anode active material. In other embodiments, the active material is a cathode active material.

[0043] As used herein, the term “conductive additive” refers to a component of the electrode coating that improves the conductivity of the electrode coating. In some embodiments, the conductive additive comprises carbon black, acetylene black, carbon nanotube (CNT), graphene, graphite, or any combination thereof.

[0044] As used herein, the term “metal foil” refers to a layer in a battery cell through which electrons conduct to or from the electrode coating. In an electrode assembly, the metal foil is in contact with the electrode coating. As used herein, the metal foil may be interchangeably referred to as a “current collector”. The metal foil may comprise any suitable metal. For example, the metal foil may comprise Al, Cu, Ni, steel, alloys thereof, or any combination thereof.

[0045] As used herein, the term “atmospheric plasma” refers to a plasma operated and maintained at near atmospheric pressures. In some embodiments, the atmospheric plasma may be generated via DC excitation (e.g., arc discharge) or AC excitation (e g., corona discharge, dielectric barrier discharge, piezoelectric direct discharge, etc.).

[0046] As used herein, the term “calendering” refers to a process of smoothing and/or compressing a material by passing the material through one or more pairs of rolls. In some embodiments, the rolls are heated rolls. [0047] As used herein, the term “D90” refers to a percentile value of a particle size distribution curve wherein 90% of the particles have a diameter less than the stated value and 10% of the particles have a diameter greater than the stated value as determined using laser diffraction analysis methods known in the art.

[0048] I. METHODS OF FORMING AN ELECTRODE ASSEMBLY

[0049] In one aspect, the present invention provides a method of forming an electrode assembly for a battery cell.

[0050] With reference to FIG. 1, a flow chart depicting an exemplary implementation of forming an electrode assembly for a battery cell is provided. The method comprises

(a) providing a precursor mixture comprising a binder, an active material, and a conductive additive (102);

(b) treating the precursor mixture with atmospheric plasma to form a plasma-treated precursor mixture (104);

(c) forming an electrode coating from the plasma-treated precursor mixture, wherein the electrode coating is substantially free of any solvent (106); and

(d) applying the electrode coating to a metal foil to form the electrode assembly (108).

[0051] In some implementations, the binder is a polymer binder. When the binder is a polymer binder, the polymer binder may comprise a natural polymer or a synthetic polymer. For example, the polymer binder may comprise a fluoropolymer. Suitable fluoropolymers include, by way of example, polyvinylfluoride (PVF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxy alkanes (PF A), fluorinated ethyl ene-propylene (FEP), polyethylenetetrafluoroethylene (ETFE), polyethylenechlorotrifluoroethylene (ECTFE), perfluoroelastomer (FFPM/FFKM), tetrafluoroethylene propylene (FEPM), or any combination thereof. In some examples, when the polymer binder comprises a fluoropolymer, such as any of the suitable fluoropolymers recited herein, the fluoropolymer is a powder. For instance, the fluoropolymer powder has a particle size distribution giving a D90 of less than about 500 pm (e.g., less than about 475 pm, less than about 450 pm, less than about 400 pm, less than about 375 pm, less than about 350 pm, less than about 325 pm, less than about 300 pm, less than about 275 pm, less than about 250 pm, or less than about 200 pm).

[0052] In other implementations, the polymer binder may comprise a fluoropolymer, a cellulose polymer, polyisoprene, polyacrylic acid (PAA), styrene-butadiene rubber (SBR), polybutadiene rubber, ethylene-propylene rubber, syndiotactic 1,2-polybutadiene, poly(ethylene- vinyl acetate) (PEVA), copolymers of PTFE and ethylene, tetrafluoroethyl ene- hexafluoropropylene-vinylidene fluoride, sodium alginate (SA), polyurethane (PU), polyimide (PI), or any combination thereof. In some implementations, the polymer binder comprises PVDF, PTFE, cellulose, carboxymethyl cellulose (CMC), polyisoprene, polyacrylic acid (PAA), styrene-butadiene rubber (SBR), polybutadiene rubber, ethylene-propylene rubber, syndiotactic 1,2-polybutadiene, poly(ethylene-vinyl acetate) (PEVA), copolymers of PTFE and ethylene, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride, sodium alginate (SA), polyurethane (PU), polyimide (PI), or any combination thereof. And, in some implementations, the polymer binder comprises PTFE, PVDF, or any combination thereof. In some examples, when the polymer binder comprises a cellulose polymer, polyisoprene, polyacrylic acid (PAA), styrene-butadiene rubber (SBR), polybutadiene rubber, ethylene-propylene rubber, syndiotactic 1,2-polybutadiene, poly(ethylene-vinyl acetate) (PEVA), copolymers of PTFE and ethylene, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride, sodium alginate (SA), polyurethane (PU), polyimide (PI), or any combination thereof, such as any of those recited herein, the polymer binder is a powder. For instance, the polymer binder is powder having a particle size distribution giving a D$>o of less than about 500 pm (e.g., less than about 475 pm, less than about 450 pm, less than about 400 pm, less than about 375 pm, less than about 350 pm, less than about 325 pm, less than about 300 pm, less than about 275 pm, less than about 250 pm, or less than about 200 pm).

[0053] In some implementations, the active material comprises an anode active material. For example, the anode active material may comprise lithium titanate (LTO), titanium niobium oxide (TNO), graphite, silicon, hard carbon, silicon alloys, silicon oxides, Li Si alloys, metal oxides, Sn, Sn alloys, Mg, Mg alloys, Al, Al alloys, Ag, Ag alloys, Sb, Sb alloys, or any combination thereof. In some examples, when the active material comprises an anode active material, such as any of the anode active materials recited herein, the anode active material is in the form of a powder. For instance, the anode active material is a powder having particle size distribution giving a D90 of less than about 500 gm (e.g., less than about 475 gm, less than about 450 gm, less than about 400 gm, less than about 375 gm, less than about 350 gm, less than about 325 gm, less than about 300 gm, less than about 275 gm, less than about 250 gm, or less than about 200 gm).

[0054] In some implementations, the active material comprises a cathode active material. For example, the cathode active material may comprise lithium manganese nickel cobalt oxides (NMC), lithium manganese oxides (LMO), lithium cobalt oxides (LCO), lithium nickel cobalt aluminum oxides (NCA), lithium iron phosphates (LFP), LiFeMnPC , FeS , S, I 2S, sodium transition metal oxides, or any combination thereof. And, in some implementations, the cathode active material comprises LiCoCh, lithium manganese nickel cobalt oxides (NMC), LiFePCh, LiMnzCh, or any combination thereof. In some examples, when the active material comprises a cathode active material, such as any of the cathode active materials recited herein, the cathode active material is in the form of a powder. For instance, the cathode active material is a powder having particle size distribution giving a D90 of less than about 500 pm (e.g., less than about 475 gm, less than about 450 gm, less than about 400 gm, less than about 375 gm, less than about 350 gm, less than about 325 gm, less than about 300 gm, less than about 275 gm, less than about 250 gm, or less than about 200 gm).

[0055] In some implementations, the conductive additive comprises carbon black, acetylene black, carbon nanotube (CNT), graphene, graphite, or any combination thereof. In some examples, the conductive additive, such as any of the conductive additives recited herein, the conductive additive is in the form of a powder. For instance, the conductive additive is a powder having particle size distribution giving a D90 of less than about 500 gm (e.g., less than about 475 gm, less than about 450 gm, less than about 400 gm, less than about 375 gm, less than about 350 gm, less than about 325 gm, less than about 300 gm, less than about 275 gm, less than about 250 gm, or less than about 200 gm).

[0056] In some implementations, the precursor mixture is substantially free (e.g., comprising less than 1% by volume, comprising less than 0.5% by volume, or comprising less than 0.1% by volume, comprising less than 1 wt% of solvent by weight of the mixture, comprising less than 0.5 wt% of solvent by weight of the mixture, comprising less than 0.1 wt% of solvent by weight of the mixture, comprising less than 0.05 wt% of solvent by weight of the mixture, comprising less than 0.01 wt% of solvent by weight of the mixture, comprising less than 0.001 wt% of solvent by weight of the mixture), or free, of any solvent.

[0057] In some implementations, step (a) further comprises mixing the precursor mixture to generate a substantially homogenous precursor mixture. For example, a polymer binder powder, an active material powder (e.g., an anode active material powder or a cathode active material powder), and a conductive additive powder are mixed or blended together to form a substantially homogenous precursor mixture powder that is advanced to step (b).

[0058] In some implementations, step (a) further comprises drying the precursor mixture (or any component(s) thereof, to generate a substantially solvent-free precursor mixture. For example, a polymer binder powder, an active material powder (e.g., an anode active material powder or a cathode active material powder), a conductive additive powder, or any combination thereof are dried in a vacuum oven or other suitable drier to generate a powder comprising less than 0.1 wt% (of solvent (e.g., water) that is advanced to step (b).

[0059] In some implementations, the atmospheric plasma is formed from a working gas. In other implementations, the working gas comprises dry air, nitrogen (N2), argon (Ar), helium (He), neon (Ne), oxygen (O2), hydrogen (H2), or any combination thereof.

[0060] In some implementations, step (b) further comprises treating the precursor mixture with atmospheric plasma from a plasma nozzle. A plasma nozzle typically has a metallic tubular housing which provides a flow path of suitable length for receiving a flow of a working gas and for enabling the formation of the plasma stream in an electromagnetic field established within the flow path of the tubular housing. The tubular housing typically terminates in a conically tapered nozzle outlet. A stream of a working gas is introduced at a gas inlet. As set forth above, suitable working gasses that can be used include, without limitation, N2, Ar, He, Ne, O2, H2, or any combination thereof. A linear (pin-like) electrode may be placed along the flow axis of the nozzle at the upstream end of the tubular housing. The metallic housing of the plasma nozzle is grounded, and an electrical discharge can be generated between the axial pin electrode and the housing. When an input voltage is applied an arc discharge from the electrode tip to the housing is formed. This arc discharge is carried by the turbulent flow of the working gas stream to the outlet of the nozzle. A reactive plasma of the working gas is formed at a relatively low temperature and at atmospheric pressure. [0061] In other implementations, the atmospheric plasma is generated with an input voltage of from about 50 W to about 4,000 W. In some implementations, the atmospheric plasma is generated with an input voltage of from about 100 W to about 2,000 W. And, in some implementations, 150 W to about 1,500 W.

[0062] In some implementations, step (b) is performed in a plasma nozzle apparatus. An exemplary plasma nozzle apparatus 10 is shown in FIG. 2. The plasma nozzle apparatus comprises the plasma nozzle 12, a precursor mixture feeder 14, and a collection vessel 16. A first passage 18 is in fluid communication with the plasma nozzle and the precursor mixture feeder. A second passage 20 is in fluid communication with the plasma nozzle and the collection vessel. A working gas allows the precursor mixture to flow from the precursor mixture feeder to the plasma nozzle through the first passage. The precursor mixture is plasma-treated at the plasma nozzle. After plasma-treatment, the plasma-treated precursor mixture flows from the plasma nozzle to the collection vessel through the second passage. The plasma-treated precursor mixture is collected in the collection vessel and the working gas is allowed to flow through an outlet 22 in fluid communication with the collection vessel. In some embodiments, the collection vessel may comprise a cyclone.

[0063] In some implementations, step (c) further comprises forming an electrode coating from the plasma-treated precursor mixture by calendering the plasma-treated precursor mixture. In some implementations, step (c) further comprises forming an electrode coating from the plasma- treated precursor mixture by extruding the plasma-treated precursor mixture. For example, the extruding may be performed with any suitable extruder (e.g., a single-screw or twin-screw extruder). And, in some implementations, step (c) further comprises forming an electrode coating from the plasma-treated precursor mixture by i) extruding the plasma-treated precursor mixture; and ii) calendering the extruded plasma-treated precursor mixture.

[0064] In some implementations, step (c) is performed substantially free of any solvent. In other words, the electrode coating is formed from the plasma-treated precursor mixture in a substantially solvent-free process.

[0065] In some implementations, the atmospheric plasma of step (b) is further defined as a first atmospheric plasma, and step (c) further comprises (cl) forming an electrode coating from the plasma-treated precursor mixture, wherein the electrode coating is substantially free of any solvent; and

(c2) treating the electrode coating with a second atmospheric plasma.

[0066] In some implementations, the first atmospheric plasma and the second atmospheric plasma are the same. In other implementations, the first atmospheric plasma and the second atmospheric plasma are different.

[0067] In some implementations, the second atmospheric plasma is formed from a second working gas. In some implementations, the first working gas and the second working gas are the same. In other implementations, the first working gas and the second working gas are different. In some implementations, the second working gas comprises dry air, N2, Ar, He, Ne, O2, H2, or any combination thereof.

[0068] In some implementations, step (c2) further comprises treating the electrode coating with a second atmospheric plasma from a second plasma nozzle. The second plasma nozzle may be any plasma nozzle as described herein.

[0069] In other implementations, the second atmospheric plasma is generated with an input voltage of from about 50 W to about 4,000 W. In some implementations, the second atmospheric plasma is generated with an input voltage of from about 100 W to about 2,000 W. And, in some implementations, the second atmospheric plasma is generated with an input voltage of from about 150 W to about 1,500 W.

[0070] In some implementations, the electrode coating is free-standing (i.e., the electrode coating is neither attached to, nor supported by, the metal foil or any other structure). When the electrode coating is free-standing, the electrode coating has a first surface and a second surface. The first surface of the electrode coating is a surface facing the metal foil and in direct contact with the metal foil when the electrode assembly is formed. The second surface of the electrode coating is a surface facing away from the metal foil when the electrode assembly is formed.

[0071] In some implementations, step (c2) further comprises treating the first surface of the electrode coating. In other implementations, step (c2) further comprises treating the second surface of the electrode coating. And, in some implementations, step (c2) further comprises treating the first and second surfaces of the electrode coating.

[0072] In some implementations, the electrode coating has a thickness of from about 5 micrometers (pm) to about 500 pm (e.g., from about 10 pm to about 400 pm). In other implementations, the electrode coating has a thickness of from about 30 pm to about 300 pm. And, in some implementations, the electrode coating has a thickness of from about 60 pm to about 200 pm.

[0073] The metal foil may comprise any suitable metal. For example, the metal foil may comprise aluminum (Al), copper (Cu), nickel (Ni), steel, alloys thereof, or any combination thereof. In some embodiments, when the electrode assembly is an anode assembly, the metal foil comprises Cu. In other embodiments, when the electrode assembly is a cathode assembly, the electrode assembly comprises Al.

[0074] In some implementations, the metal foil has a thickness of from about 1 pm to about 100 pm. In other implementations, the metal foil has a thickness of from about 1 pm to about 25 pm. And, in some implementations, the metal foil has a thickness of from about 10 pm to about 20 pm.

[0075] In some implementations, step (d) further comprises applying the electrode coating to a metal foil to form the electrode assembly by calendering or pressing the electrode coating to the metal foil. In other implementations, step (d) further comprises applying the electrode coating to a metal foil to form the electrode assembly by calendering the electrode coating to the metal foil. And, in some implementations, step (d) further comprises applying the electrode coating to a metal foil to form the electrode assembly by pressing the electrode coating to the metal foil.

[0076] In some implementations, step (d) further comprises

[0077] In some implementations, the metal foil has a first surface and a second surface. The first surface of the metal foil is a surface facing the electrode coating and in direct contact with the electrode coating when the electrode assembly is formed. The second surface of the metal foil is a surface facing away from the electrode coating when the electrode assembly is formed. [0078] In some implementations, step (dl) further comprises treating the first surface of the metal foil. In other implementations, step (dl) further comprises treating the second surface of the metal foil. And, in some implementations, step (dl) further comprises treating the first and second surfaces of the metal foil. [0079] In some implementations, the first atmospheric plasma and the third atmospheric plasma are the same. In other implementations, the first atmospheric plasma and the third atmospheric plasma are different. In some implementations, the second atmospheric plasma and the third atmospheric plasma are the same. In other implementations, the second atmospheric plasma and the third atmospheric plasma are different.

[0080] In some implementations, the third atmospheric plasma is formed from a third working gas. In some implementations, the first working gas and the third working gas are the same. In other implementations, the first working gas and the third working gas are different. In some implementations, the second working gas and the third working gas are the same. In other implementations, the second working gas and the third working gas are different. In some implementations, the third working gas comprises dry air, N2, Ar, He, Ne, O2, H2, or any combination thereof.

[0081] In some implementations, step (dl) further comprises treating the metal foil with a third atmospheric plasma from a third plasma nozzle. The third plasma nozzle may be any plasma nozzle as described herein.

[0082] In other implementations, the third atmospheric plasma is generated with an input voltage of from about 50 W to about 4,000 W. In some implementations, the third atmospheric plasma is generated with an input voltage of from about 100 W to about 2,000 W. And, in some implementations, the third atmospheric plasma is generated with an input voltage of from about 150 W to about 1,500 W.

[0083] In some implementations, the method further comprises

(e) treating the electrode assembly with a fourth atmospheric plasma.

[0084] In some implementations, the method further comprises

(f) calendering the electrode assembly.

[0085] In some implementations, step (f) is performed after step (e). In other implementations, step (f) is performed before step (e).

[0086] In some implementations, the first atmospheric plasma and the fourth atmospheric plasma are the same. In other implementations, the first atmospheric plasma and the fourth atmospheric plasma are different. In some implementations, the second atmospheric plasma and the fourth atmospheric plasma are the same. In other implementations, the second atmospheric plasma and the fourth atmospheric plasma are different. In some implementations, the third atmospheric plasma and the fourth atmospheric plasma are the same. In other implementations, the third atmospheric plasma and the fourth atmospheric plasma are different.

[0087] In some implementations, the fourth atmospheric plasma is formed from a fourth working gas. In some implementations, the first working gas and the fourth working gas are the same. In other implementations, the first working gas and the fourth working gas are different. In some implementations, the second working gas and the fourth working gas are the same. In other implementations, the second working gas and the fourth working gas are different. In some implementations, the third working gas and the fourth working gas are the same. In other implementations, the third working gas and the fourth working gas are different. In some implementations, the fourth working gas comprises dry air, N2, Ar, He, Ne, O2, H2, or any combination thereof.

[0088] In some implementations, step (e) further comprises treating the electrode assembly with a fourth atmospheric plasma from a fourth plasma nozzle. The fourth plasma nozzle may be any plasma nozzle as described herein.

[0089] In other implementations, the fourth atmospheric plasma is generated with an input voltage of from about 50 W to about 4,000 W. In some implementations, the fourth atmospheric plasma is generated with an input voltage of from about 100 W to about 2,000 W. And, in some implementations, the fourth atmospheric plasma is generated with an input voltage of from about 150 W to about 1,500 W.

[0090] In some implementations, the electrode assembly has a thickness of from about 5 pm to about 600 pm. In other implementations, the electrode assembly has a thickness of from about 30 pm to about 350 pm. And, in some implementations, electrode assembly has a thickness of from about 60 pm to about 225 pm.

[0091] In some implementations, the method comprises,

(a- 1 ) providing a precursor mixture comprising a binder, an active material, and a conductive additive;

(b-1) treating the precursor mixture with atmospheric plasma to form a plasma-treated precursor mixture; (c-1) forming an electrode coating from the plasma-treated precursor mixture, wherein the electrode coating is substantially free of any solvent, and wherein step (c-1) is performed substantially free of any solvent; and

(d-1) applying the electrode coating to a metal foil to form the electrode assembly.

[0092] A. Other Implementations

[0093] In another aspect, the present invention provides a method of forming an electrode assembly for a battery cell. With reference to FIG. 3, the method comprises

(a-2) providing a precursor mixture comprising a binder, an active material, and a conductive additive (302);

(b-2) forming an electrode coating from the precursor mixture, wherein the electrode coating is substantially free of any solvent (304);

(c-2) treating the electrode coating with atmospheric plasma to form a plasma-treated electrode coating (306); and

(d-2) applying the plasma-treated electrode coating to a metal foil to form the electrode assembly (308).

[0094] The binder may be any binder as described herein. The active material may be any active material as described herein. And, the conductive additive may be any conductive additive as described herein.

[0095] In some implementations, the precursor mixture is substantially free (e.g., comprising less than 1% by volume, comprising less than 0.5% by volume, or comprising less than 0.1% by volume, comprising less than 1 wt% of solvent by weight of the mixture, comprising less than 0.5 wt% of solvent by weight of the mixture, comprising less than 0.1 wt% of solvent by weight of the mixture, comprising less than 0.05 wt% of solvent by weight of the mixture, comprising less than 0.01 wt% of solvent by weight of the mixture, comprising less than 0.001 wt% of solvent by weight of the mixture), or free, of any solvent.

[0096] In some implementations, step (b-2) further comprises forming an electrode coating from the precursor mixture by calendering the precursor mixture. In some implementations, step (b-2) further comprises forming an electrode coating from the precursor mixture by extruding the precursor mixture. For example, the extruding may be performed with any suitable extruder (e.g., a single-screw or twin-screw extruder). And, in some implementations, step (b-2) further comprises forming an electrode coating from the precursor mixture by i) extruding the precursor mixture; and ii) calendering the extruded precursor mixture.

[0097] In some implementations, step (b-2) is performed substantially free of any solvent. In other words, the electrode coating is formed from the precursor mixture in a substantially solvent-free process.

[0098] In some implementations, the atmospheric plasma is formed from a working gas. In some implementations, the working gas comprises dry air, N2, Ar, He, Ne, Ch, H2, or any combination thereof.

[0099] In some implementations, step (c-2) further comprises treating the electrode coating with atmospheric plasma from a plasma nozzle. The plasma nozzle may be any plasma nozzle as described herein.

[0100] In other implementations, the atmospheric plasma is generated with an input voltage of from about 50 W to about 4,000 W. In some implementations, the atmospheric plasma is generated with an input voltage of from about 100 W to about 2,000 W. And, in some implementations, the atmospheric plasma is generated with an input voltage of from about 150 W to about 1,500 W.

[0101] In some implementations, the electrode coating is free-standing (i.e., the electrode coating is neither attached to, nor supported by, the metal foil or any other structure). When the electrode coating is free-standing, the electrode coating has a first surface and a second surface. The first surface of the electrode coating is a surface facing the metal foil and in direct contact with the metal foil when the electrode assembly is formed. The second surface of the electrode coating is a surface facing away from the metal foil when the electrode assembly is formed.

[0102] In some implementations, step (c-2) further comprises treating the first surface of the electrode coating. In other implementations, step (c-2) further comprises treating the second surface of the electrode coating. And, in some implementations, step (c-2) further comprises treating the first and second surfaces of the electrode coating.

[0103] The electrode coating may have any thickness as described herein.

[0104] The metal foil may be any metal foil described herein (e.g., may comprise any material and/or may comprise any thickness as described herein). [0105] In some implementations, step (d-2) further comprises applying the plasma-treated electrode coating to a metal foil to form the electrode assembly by calendering or pressing the plasma-treated electrode coating to the metal foil. In other implementations, step (d-2) further comprises applying the plasma-treated electrode coating to a metal foil to form the electrode assembly by calendering the plasma-treated electrode coating to the metal foil. And, in some implementations, step (d-2) further comprises applying the plasma-treated electrode coating to a metal foil to form the electrode assembly by pressing the plasma-treated electrode coating to the metal foil.

[0106] In some implementations, the atmospheric plasma of step (c-2) is further defined as an electrode coating atmospheric plasma, and step (d-2) further comprises

(dl-2) treating a metal foil with a metal foil atmospheric plasma to form a plasma-treated metal foil; and

(d2-2) applying the plasma-treated electrode coating to the plasma-treated metal foil to form the electrode assembly.

[0107] In some implementations, the metal foil has a first surface and a second surface. The first surface of the metal foil is a surface facing the plasma-treated electrode coating and in direct contact with the plasma-treated electrode coating when the electrode assembly is formed. The second surface of the metal foil is a surface facing away from the plasma-treated electrode coating when the electrode assembly is formed.

[0108] In some implementations, step (dl-2) further comprises treating the first surface of the metal foil. In other implementations, step (dl-2) further comprises treating the second surface of the metal foil. And, in some implementations, step (dl-2) further comprises treating the first and second surfaces of the metal foil.

[0109] In some implementations, the electrode coating atmospheric plasma and the metal foil atmospheric plasma are the same. In other implementations, the electrode coating atmospheric plasma and the metal foil atmospheric plasma are different.

[0110] In some implementations, the metal foil atmospheric plasma is formed from a metal foil working gas. In some implementations, the electrode coating working gas and the metal foil working gas are the same. In other implementations, the electrode coating working gas and the metal foil working gas are different. In some implementations, the metal foil working gas comprises dry air, N2, Ar, He, Ne, O2, H2, or any combination thereof. [0111] In some implementations, step (dl-2) further comprises treating the metal foil with a metal foil working atmospheric plasma from a metal foil plasma nozzle. The metal foil plasma nozzle may be any plasma nozzle as described herein.

[0112] In other implementations, the metal foil atmospheric plasma is generated with an input voltage of from about 50 W to about 4,000 W. In some implementations, the metal foil atmospheric plasma is generated with an input voltage of from about 100 W to about 2,000 W. And, in some implementations, the metal foil atmospheric plasma is generated with an input voltage of from about 150 W to about 1,500 W.

[0113] The electrode assembly may have any thickness as described herein. In some implementations, the method comprises

(a-3) providing a precursor mixture comprising a binder, an active material, and a conductive additive;

(b-3) forming an electrode coating from the precursor mixture, wherein the electrode coating is substantially free of any solvent, and wherein step (b-3) is performed substantially free of any solvent;

(c-3) treating the electrode coating with atmospheric plasma to form a plasma-treated electrode coating; and

(d-3) applying the plasma-treated electrode coating to a metal foil to form the electrode assembly.

[0114] In another aspect of the invention, the present invention provides a method of forming an electrode assembly for a battery cell. With reference to FIG. 4, the method comprises

(a-4) providing a precursor mixture comprising a binder, an active material, and a conductive additive (402);

(b-4) forming an electrode coating from the precursor mixture, wherein the electrode coating is substantially free of any solvent (404);

(c-4) applying the electrode coating to a metal foil to form the electrode assembly (406); and (d-4) treating the electrode assembly with atmospheric plasma to form a plasma-treated electrode assembly (408).

[0115] The binder may be any binder as described herein. The active material may be any active material as described herein. And, the conductive additive may be any conductive additive as described herein.

[0116] In some implementations, the precursor mixture is substantially free (e.g., comprising less than 1% by volume, comprising less than 0.5% by volume, or comprising less than 0.1% by volume, comprising less than 1 wt% of solvent by weight of the mixture, comprising less than 0.5 wt% of solvent by weight of the mixture, comprising less than 0.1 wt% of solvent by weight of the mixture, comprising less than 0.05 wt% of solvent by weight of the mixture, comprising less than 0.01 wt% of solvent by weight of the mixture, comprising less than 0.001 wt% of solvent by weight of the mixture), or free, of any solvent.

[0117] In some implementations, step (b-4) further comprises forming an electrode coating from the precursor mixture by calendering the precursor mixture. In some implementations, step (b-4) further comprises forming an electrode coating from the precursor mixture by extruding the precursor mixture. For example, the extruding may be performed with any suitable extruder (e.g., a single-screw or twin-screw extruder). And, in some implementations, step (b-4) further comprises forming an electrode coating from the precursor mixture by i) extruding the precursor mixture; and ii) calendering the extruded precursor mixture.

[0118] In some implementations, step (b-4) is performed substantially free of any solvent. In other words, the electrode coating is formed from the precursor mixture in a substantially solvent-free process.

[0119] In some implementations, the electrode coating is free-standing (i.e., the electrode coating is neither attached to, nor supported by, the metal foil or any other structure). When the electrode coating is free-standing, the electrode coating has a first surface and a second surface. The first surface of the electrode coating is a surface facing the metal foil and in direct contact with the metal foil when the electrode assembly is formed. The second surface of the electrode coating is a surface facing away from the metal foil when the electrode assembly is formed.

[0120] In some implementations, step (c-4) further comprises applying the electrode coating to a metal foil to form the electrode assembly by calendering or pressing the electrode coating to the metal foil. In other implementations, step (c-4) further comprises applying the electrode coating to a metal foil to form the electrode assembly by calendering the electrode coating to the metal foil. And, in some implementations, step (c-4) further comprises applying the electrode coating to a metal foil to form the electrode assembly by pressing the electrode coating to the metal foil.

[0121] The electrode assembly may have any thickness as described herein.

[0122] In some implementations, the atmospheric plasma is formed from a working gas. In some implementations, the working gas comprises dry air, N2, Ar, He, Ne, O2, H2, or any combination thereof.

[0123] In some implementations, step (d-4) further comprises treating the electrode assembly with atmospheric plasma from a plasma nozzle. The plasma nozzle may be any plasma nozzle as described herein.

[0124] In other implementations, the atmospheric plasma is generated with an input voltage of from about 50 W to about 4,000 W. In some implementations, the atmospheric plasma is generated with an input voltage of from about 100 W to about 2,000 W. And, in some implementations, the atmospheric plasma is generated with an input voltage of from about 150 W to about 1,500 W.

[0125] In some implementations, step (d-4) further comprises treating an electrode coating surface of the electrode assembly with atmospheric plasma.

[0126] In some implementations, the method comprises

(a-5) providing a precursor mixture comprising a binder, an active material, and a conductive additive;

(b-5) forming an electrode coating from the precursor mixture, wherein the electrode coating is substantially free of any solvent;

(c-5) applying the electrode coating to a metal foil to form the electrode assembly; and (d-5) treating the electrode assembly with atmospheric plasma to form a plasma-treated electrode assembly.

[0127] Without wishing to be bound by theory, it is believed that the methods of forming an electrode assembly described herein result in electrode assemblies having improved characteristics (e.g., contact angle, surface energy, and/or distribution of the components of the precursor mixture) as compared to electrode assemblies formed by typical methods. Moreover, the methods described herein are substantially “solvent-free”. Because the methods are solvent- free, processing times and costs associated with solvent removal are advantageously reduced and/or eliminated.

[0128] II. SYSTEM FOR FORMING AN ELECTRODE ASSEMBLY

[0129] In another aspect, the present invention provides a system suitable for carrying out the methods described herein.

[0130] An exemplary schematic of a system 24 for forming an electrode assembly is shown in FIG. 5. The system comprises a coating apparatus 26. The coating apparatus forms the electrode coating from the precursor mixture. In some embodiments, the coating apparatus comprises calendering rollers. The calendering rollers may be any calendering rollers suitable for forming the electrode coating from the precursor mixture. In other embodiments, the coating apparatus comprises an extruder (e.g., a single-screw or twin-screw extruder). And, in some embodiments, the coating apparatus comprises the extruder and calendering rollers. When the coating apparatus comprises the extruder and calendering rollers, the precursor mixture can be extruded and subsequently calendered to form the electrode coating.

[0131] The coating apparatus may further comprise a plasma nozzle. The plasma nozzle may be any plasma nozzle as described herein. The plasma nozzle may be used to treat the electrode coating and/or the metal foil with atmospheric plasma.

[0132] The system further comprises an electrode forming apparatus 28. The electrode forming apparatus applies the electrode coating to the metal foil form the electrode assembly. In some embodiments, the electrode forming apparatus comprises calendering rollers. In some embodiments, the electrode forming apparatus comprises a first set of calendering rollers and a second set of calendering rollers after the first set of calendering rollers. In other embodiments, the electrode forming apparatus comprises a machine press.

[0133] The electrode forming apparatus may further comprise a plasma nozzle. The plasma nozzle may be any plasma nozzle as described herein. The plasma nozzle may be used to treat the electrode assembly after calendering and/or pressing. When the electrode forming apparatus comprises a first set of calendering rollers and a second set of calendering rollers, the plasma nozzle may be used to treat the electrode assembly between the first set of calendering rollers and the second set of calendering rollers, or after the second set of calendering rollers.

[0134] In some embodiments, the system comprises the plasma nozzle apparatus 10 as described herein. When present, the plasma nozzle apparatus treats the precursor mixture with atmospheric plasma.

[0135] III. ELECTRODE ASSEMBLY

[0136] In another aspect, the present invention provides an electrode assembly formed by any one of the methods described herein.

[0137] In some embodiments, an electrode coating surface of the electrode assembly has a reduced contact angle as compared to an electrode assembly that is not treated with atmospheric plasma. In other embodiments, an electrode coating surface of the electrode assembly has an increased surface energy as compared to an electrode assembly that is not treated with atmospheric plasma. In some embodiments, the electrode coating of the electrode assembly has a reduced electrolyte soaking time as compared to an electrode assembly that is not treated with atmospheric plasma. In some embodiments, the electrode coating of the electrode assembly has an improved electrolyte distribution as compared to an electrode assembly that is not treated with atmospheric plasma.

[0138] IV. EXAMPLES

[0139] In order that the invention described herein may be more fully understood, the following examples are set forth. The examples described in this application are offered to illustrate the methods and electrode assemblies provided herein and are not to be construed in any way as limiting their scope.

[0140] Example 1: Contact angle for polytetrafluoroethylene (PTFE) surfaces.

[0141] FIGS. 6A and 6B depict the results of an electrolyte wettability test on an untreated PTFE surface and a plasma-treated PTFE surface. One droplet of electrolyte solvent, i.e., deionized (DI) water, having a fixed volume, was dispensed on each of the untreated PTFE surface and the plasma-treated PTFE surface. A commercial contact angle analyzer was then used to determine the contact angle of each sample. As shown in FIG. 6A, the contact angle for the untreated PTFE surface was 62°. With reference to FIG. 6B, the contact angle for the plasma-treated PTFE surface was 18°. These results show that plasma-treatment can increase the wettability of a PTFE surface for aqueous electrolytes. OTHER EMBODIMENTS

[0142] It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method of forming an electrode assembly for a battery cell comprising:

(d) applying the electrode coating to a metal foil to form the electrode assembly.

2. The method of claim 1, wherein the binder is a polymer binder.

3. The method of claim 2, wherein the polymer binder comprises polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), cellulose, carboxymethyl cellulose (CMC), polyisoprene, polyacrylic acid (PAA), styrene-butadiene rubber (SBR), polybutadiene rubber, ethylene-propylene rubber, syndiotactic 1,2-polybutadiene, poly(ethylene-vinyl acetate) (PEVA), copolymers of PTFE and ethylene, tetrafluoroethyl ene-hexafluoropropylene-vinylidene fluoride, sodium alginate (SA), polyurethane (PU), polyimide (PI), or any combination thereof.

4. The method of any one of claims 1-3, wherein the active material comprises an anode active material.

5. The method of claim 4, wherein the anode active material comprises lithium titanate (LTO), titanium niobium oxide (TNO), graphite, silicon, hard carbon, silicon alloys, silicon oxides, LiSi alloys, metal oxides, Sn, Sn alloys, Mg, Mg alloys, Al, Al alloys, Ag, Ag alloys, Sb, Sb alloys, or any combination thereof.

6. The method of any one of claims 1-3, wherein the active material comprises a cathode active material.

7. The method of claim 6, wherein the cathode active material comprises lithium manganese nickel cobalt oxides (NMC), lithium manganese oxides (LMO), lithium cobalt oxides (LCO), lithium nickel cobalt aluminum oxides (NCA), lithium iron phosphates (LFP), LiFeMnPC , FeS2, S, Li2S, sodium transition metal oxides, or any combination thereof.

8. The method of claim 6 or claim 7, wherein the cathode active material comprises LiCoCh, lithium manganese nickel cobalt oxides (NMC), LiFePO4, LiM^C , or any combination thereof.

9. The method of any one of claims 1-8, wherein the conductive additive comprises carbon black, acetylene black, carbon nanotube (CNT), graphene, graphite, or any combination thereof.

10. The method of claim 1, wherein at least one of the binder, the active material, or the conductive additive comprises a powder having a particle size distribution giving a D90 of less than about 500 pm.

11. The method of claim 10, wherein the binder comprises a powder having a particle size distribution giving a D90 of less than about 500 pm.

12. The method of claim 10 or claim 11, wherein the active material comprises a powder having a particle size distribution giving a D90 of less than about 500 pm.

13. The method of any one of claims 10-12, wherein the conductive additive comprises a powder having a particle size distribution giving a D90 of less than about 500 pm.

14. The method of any one of claims 1-13, wherein the atmospheric plasma is formed from a working gas, and wherein the working gas comprises dry air, nitrogen (N2), argon (Ar), helium (He), neon (Ne), oxygen (O2), hydrogen (H2), or any combination thereof.

15. The method of any one of claims 1-14, wherein step (a) further comprises mixing the precursor mixture to generate a substantially homogenous precursor mixture.

16. The method of any one of claims 1-14, wherein step (a) further comprises drying the precursor mixture to generate a substantially solvent-free precursor mixture.

17. The method of any one of claims 1-16, wherein step (b) further comprises treating the precursor mixture with atmospheric plasma from a plasma nozzle.

18. The method of any one of claims 1-17, wherein the atmospheric plasma is generated with an input voltage of from about 50 W to about 4,000 W.

19. The method of any one of claims 1-18, wherein step (c) further comprises forming an electrode coating from the plasma-treated precursor mixture by calendering the plasma-treated precursor mixture.

20. The method of any one of claims 1-19, wherein the atmospheric plasma of step (b) is further defined as a first atmospheric plasma, and wherein step (c) further comprises

(c2) treating the electrode coating with a second atmospheric plasma.

21. The method of claim 20, wherein the second atmospheric plasma is formed from a second working gas, and wherein the second working gas comprises dry air, nitrogen (N2), argon (Ar), helium (He), neon (Ne), oxygen (O2), hydrogen (H2), or any combination thereof.

22. The method of claim 20 or claim 21, wherein step (c2) further comprises treating the electrode coating with a second atmospheric plasma from a second plasma nozzle.

23. The method of any one of claims 1-22, wherein step (d) further comprises applying the electrode coating to a metal foil to form the electrode assembly by calendering or pressing.

24. The method of any one of claims 1-23, wherein step (d) further comprises

25. The method of claim 24, wherein the third atmospheric plasma is formed from a third working gas, and wherein the third working gas comprises dry air, nitrogen (N2), argon (Ar), helium (He), neon (Ne), oxygen (O2), hydrogen (H2), or any combination thereof.

26. The method of claim 24 or claim 25, wherein step (dl) further comprises treating the metal foil with a third atmospheric plasma from a third plasma nozzle.

27. The method of any one of claims 1-26, further comprising

(e) treating the electrode assembly with a fourth atmospheric plasma.

28. The method of any one of claims 1-27, further comprising

(f) calendering the electrode assembly.

29. The method of claim 28, wherein step (f) is performed after step (e).

30. The method of claim 29, wherein step (f) is performed before step (e).

31. The method of any one of claims 27-30, wherein the fourth atmospheric plasma is formed from a fourth working gas, and wherein the fourth working gas comprises dry air, nitrogen (N2), argon (Ar), helium (He), neon (Ne), oxygen (O2), hydrogen (H2), or any combination thereof.

32. The method of any one of claims 27-31, wherein step (e) further comprises treating the electrode assembly with a fourth atmospheric plasma from a fourth plasma nozzle.

33. An electrode assembly formed according to the method of any one of claims 1-32.