Cathode formed from dry coating process using water-soluble binder

Abstract

The present disclosure relates to a cathode, cells formed from said cathode, battery systems formed from said cell and vehicles including said battery systems. The present disclosure also relates to methods of preparing said cathode. The cathode contains a cathode active material, a binder comprising a water-soluble binder and optionally a conductive additive. The cathodes show excellent electrochemical performance and mechanical properties, including long cycle life, high capacity retention, good flexibility and good adhesion. The cathodes have a greater compatibility with battery recycling processes due to the water solubility of the binders, resulting in improved environmental friendliness and sustainability throughout the product life of the cell.

Description

[0001] Cathode formed from dry coating process using water-soluble binder

[0002] Field

[0003] The present disclosure relates to a composition for use in the formation of a cathode, a cathode comprising (or consisting of) the composition, a method of preparation of said cathode, a cell including the cathode, a battery system including the cell and a vehicle including the battery system.

[0004] Background

[0005] Commercial lithium-ion battery electrodes are typically manufactured using wet processing techniques by coating a slurry onto a conductive foil. This process involves using significant amounts of solvent, such as N-methyl-2-pyrrolidone (NMP). After casting the slurry onto the conductive foil, the electrode must be dried by evaporating the solvent. The drying process may take from several hours to days and is normally carried out at elevated temperatures to completely dry the electrode. Evaporated NMP also is generally recovered due to its high cost and potential as an environmental pollutant.

[0006] The drying process may also impart microstructural defects on the electrode surface during solvent evaporation. As a result, the use of solvents and the required drying system contribute to significant production costs for lithium-ion battery electrodes, e.g. in terms of time, materials and / or factory floor space.

[0007] The elimination of solvents from the manufacturing of lithium-ion battery electrodes is therefore an attractive approach to reduce production costs and processing times and improve electrode properties. The development of electrode manufacturing methods using dry processing conditions to deposit material onto conductive foils represents a potentially superior fabrication process. Furthermore, this may result in electrodes and batteries with superior mechanical and electrochemical properties, such as improved electrode adhesion strength, battery stability, cycle life and capacity retention, and lower internal resistance.

[0008] Spray deposition, in particular electrostatic deposition (ESD), is a promising approach for the preparation of electrodes for lithium-ion batteries. This method may provide numerous advantages to the resulting electrodes, such as increased production efficiency, lower environmental footprint, improved flexibility and / or peel strength, higher energy density, capacity and / or charge / discharge rate, greater control over electrode properties (e.g. thickness and / or density), more uniform distribution of the components (i.e. binder, electrode active material and / or conductive additive) throughout the electrode and / or better distribution of the binder and / or conductive additive around the electrode active material.

[0009] A further important aspect of use of lithium-ion batteries is the recycling of said batteries, in particular the recycling of valuable cathode active materials. Strong binding forces of standard organic binders such as polyvinylidene fluoride (PVDF) prevent effective separation of cathodes, thus affecting recycling. Therefore, there is interest in the development of new binders to facilitate recycling processes.

[0010] Water-soluble binders have previously been processed in aqueous slurries to prepare cathodes (see e.g., A. Pillai et al., Energy Fuels 36, 2022, 5063-5087). However, cathode active materials may be incompatible with water. One of the most promising cathode active materials is lithium nickel manganese cobalt oxide. It is known that lithium nickel manganese cobalt oxide can react with moisture or water, accelerating an electrolyte decomposition and a cation mixing, and decreasing a reversible capacity (see e.g., Z. Ahaliabadeh et al., Journal of Power Sources, 540, 2022, 231633). Therefore, wet (aqueous) fabrication methods to prepare cathodes are preferably avoided.

[0011] This disclosure relates to a novel composition, wherein the composition is substantially free of solvent, a cathode prepared from said composition, a method of preparation of said cathode, and cells, battery systems and vehicles formed from the cathode. The method of preparation of said cathode may provide a substantially solvent-free fabrication method (e.g. a dry deposition process) using water-soluble binders. It has been found that the application of this cathode leads to lithium-ion batteries with unexpectedly improved mechanical and / or electrochemical performance and stability. It also provides greater recyclability, resulting in improvement of environmental friendliness and sustainability throughout the product life of the battery.

[0012] Brief Description

[0013] According to an aspect of the present disclosure, there is provided a composition for spray deposition comprising: a cathode active material; a binder comprising a water-soluble binder; and optionally a conductive additive, wherein the composition is substantially free of solvent. According to a further aspect of the present disclosure, there is provided a cathode comprising: a conductive foil having a cathode active layer thereon, said cathode active layer comprising a cathode active material; a binder comprising a water-soluble binder; and optionally a conductive additive.

[0014] According to a further aspect of the present disclosure, there is provided a method for preparing a cathode (e.g. for use in a lithium and / or sodium-ion battery), comprising the steps of:

[0015] (i) providing a composition comprising a cathode active material, a binder comprising a water-soluble binder and optionally a conductive additive, wherein the composition is substantially free of solvent; and

[0016] (ii) depositing the composition onto a conductive foil to form a cathode, said cathode comprising a conductive foil having a cathode active layer thereon, said cathode being formed from the composition.

[0017] Detailed Description

[0018] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0019] Cathode active material

[0020] The cathode active material may comprise a suitable material for use as an electrochemically active material in the cathode of a cell, particularly a lithium and / or sodium-ion cell.

[0021] The term "electrochemically active material" is to be understood as an electrochemical species which can be oxidised and reduced in a system which enables a cell to produce electric energy during discharge. The role of the cathode active material is to reversibly store (or otherwise bind and / or intercalate) ions (such as lithium ions) during cell charge and discharge cycles.

[0022] In some embodiments, the cathode active material is in the form of particles. The cathode active material particles may have a D[4,3]50 particle size (i.e. Dv50, for example the maximum D[4,3] particle diameter below which 50% of the sample volume exists) of from about 0.1-50 pm, for example from about 1-35 pm, such as from about 5-25 pm.

[0023] In another embodiment, the cathode active material has a bimodal particle distribution, in particular when the cathode active material is a cathode active material.

[0024] The cathode active material particles may have an aspect ratio of from about 1-3, such as from about 1-2, for example from about 1-1.5.

[0025] Particle sizes disclosed herein may be measured, for instance, using a Mastersizer 3000 from Malvern Panalytical Ltd.

[0026] As disclosed herein, the particle size may refer to the mean particle size. The mean particle size will be understood by the skilled person to be the volume-based mean particle size, that is a mean particle size characterised and defined from a particle size distribution by volume.

[0027] The cathode active material may be present in the cathode active layer in an amount of from about 79-99.7 wt%, for example from about 86-99.5 wt%, such as from about 92.5-98.5 wt%, based on the total weight of the dry cathode active layer (i.e. the cathode active layer excluding solvent).

[0028] The cathode active material may comprise a material that stores, converts and / or alloys (with) lithium and / or sodium. For example, via intercalation / deintercalation (for instance with graphite), alloying / dealloying (for instance with silicon) or by plating / stripping (for instance with metallic lithium).

[0029] While lithium is used in the examples below, sodium may be used in addition to and / or instead of lithium, for example for use in a sodium-ion battery.

[0030] The cathode active material may comprise any one or a mixture of two or more of a lithium metal oxide which may include lithium and a transition metal, such as lithium manganese oxide, lithium nickel oxide, lithium cobalt oxide, lithium nickel manganese oxide (LNMO), layered LNMO, spinel LNMO, lithium nickel cobalt oxide, lithium nickel manganese cobalt oxide (NMC), lithium-and-manganese-rich layered oxide (LMR), lithium iron phosphate (LFP), lithium iron manganese phosphate (LFMP) and lithium nickel cobalt aluminium oxide (NCA). Without wishing to be bound by theory, if the cathode active material, for example a NMC, is added to the dispersing medium such as water during aqueous cathode preparation routes, the lithium can leach out of the cathode active material and react with water, which results in the formation of hydroxide ions and an increase in the pH of the slurry. This subsequently results in the formation of LiOH and IJ2CO3, which leads to a reduction in the capacity of the cell. Furthermore, the high pH may result in corrosion of the conductive foil. Therefore, the use of a deposition method which is substantially free of solvent, in particular water, may mitigate such issues.

[0031] Preferably, the cathode active material is an LNMO or an NMC material, i.e. a lithium nickel manganese oxide or a lithium nickel manganese cobalt oxide.

[0032] Exemplary cathode active materials include NMC, which may be represented as LiNii- x-yCoxMnyO2, wherein 0<x+y<0.40, preferably 0<x+y<0.35, more preferably 0<x+y<0.30, further preferably 0<x+y<0.25, the most preferably 0<x+y<0.20.

[0033] In one or more embodiments, the cathode active material comprises LMR, which may be represented as Lii+xNiyMni-x-y-zCozO?, wherein 0<x<0.50, preferably 0<x<0.30, more preferably 0<x<0.20, further preferably 0<x<0.18, and 0<y+z<0.45, preferably 0<y+z<0.40, further preferably 0<y+z<0.38.

[0034] In some embodiments, the cathode active material comprises the NMC, which may be represented as LibNii x-y-zCoxMnyAzO? (wherein 0<x+y+z<0.40, preferably 0<x+y+z<0.35, more preferably 0<x+y+z<0.30, further preferably 0<x+y+z<0.25, the most preferably 0<x+y+z<0.2), where A is an element other than Li, Ni, Co, Mn or O and wherein 0<z<0.05, preferably 0<z<0.03, more preferably 0.001<z<0.01, and wherein 0.9<b< 1.2. A is one or more chosen from the group Al, B, Zr, Ba, Ca, Ti, Mg, Ta, Nb, V, Fe, Ru, Re, Pt and Mo. Preferably, A is chosen from the group Al and Zr.

[0035] In preferred embodiments, the NMC cathode materials is defined as LibNii x-y- zCoxMnyAzC>2, wherein 0<x+y+z<0.2, preferably 0<x+y+z<0.15, more preferably 0<x+y+z<0.12, and wherein 0<z<0.05, preferably 0.002<z<0.03, more preferably 0.001<z<0.01, and wherein 0.9<b< l.l. A is one or more chosen from the group Al, B, Zr, Ba, Ca, Ti, Mg, Ta, Nb, V, Fe, Ru, Re, Pt and Mo. Preferably, A is chosen from the group Al and Zr. The cathode active material may comprise a lithium metal oxide material that is coated with another material. For example, a lithium metal oxide may be coated with a different lithium metal oxide, carbon, graphene, or a combination thereof. Furthermore, the coating material may have been coated using atomic layer deposition (ALD) as a non-limiting example.

[0036] When formulating a sodium-ion cell, the cathode active material typically comprises sodium transition metal cyanides having six cyanide groups per formula unit. Each of these cyanide groups connect transition metals within the cathode active material to form a framework with large voids that allow intercalation and de-intercalation of sodium-ions.

[0037] Exemplary sodium transition metal cyanides include Prussian Blue (PB) and its derivatives, i.e. Prussian Blue Analogues (PBAs). Even more preferably, the cathode active material comprises Prussian Blue Analogues (PBAs).

[0038] Exemplary Prussian blue analogues include Prussian White, Turnbull's blue, potassium ferricyanide, and potassium ferrocyanide.

[0039] In some embodiments, the cathode active material comprises Prussian Blue Analogues (PBAs) having a formula of AxPy[Rz(CN)6]w, where A is a sodium ion, and P and R are transition metals. Prussian Blue Analogues (PBAs) offer many opportunities for structural variation and hence the properties are highly tunable. For example, the stoichiometry may vary: l<x<2, 0<y<2, l<z<2, and l<w<2.

[0040] The transition metals P and R may each be selected from manganese (Mn), Iron (Fe), Aluminium (Al), Titanium (Ti), Nickel (Ni), Vanadium (V) and Cobalt (Co). Preferably, R is iron (Fe).

[0041] Preferred are Prussian Blue Analogues (PBAs) selected from Fe-Fe-PBA, Mn-Fe-PBA, Fe-Ni-PBA, Ni-PBA, Co-PBA, or any combination thereof, especially Fe-Fe-PBA.

[0042] Prussian Blue Analogues (PBAs) may be complexed to water.

[0043] Optional conductive additive

[0044] The role of the optional conductive additive is to improve the electronic properties of the cathode active layer and to provide an electrical connection between the particles of the cathode active material in the cathode. As it is present merely to improve conductivity, it is optional as the inherent conductivity of the cathode active material may be sufficient.

[0045] For example, the optional conductive additive may comprise carbon black, acetylene black, graphene, graphite, mesocarbon microbead (MCMB), pitch-based carbon, coke powders, single-walled, thin-walled and / or multi-walled carbon nanotubes, metallic powders, or a combination thereof.

[0046] Preferred optional conductive additives are selected from carbon black, acetylene black, carbon nanotubes, or a combination thereof.

[0047] In an embodiment, the optional conductive additive may be present in the cathode active layer an amount of from about 0-6.0 wt%, for example from about 0.01-4.0 wt%, such as from about 0.1-3.0 wt%, for example from 0.25-2.5 wt%, such as from about 0.3-2.0 wt%, based on the total weight of the dry cathode active layer (i.e. the cathode active layer excluding solvent).

[0048] Preferably, the cathode active layer comprises a conductive additive (i.e. the conductive additive is present in the cathode active layer).

[0049] Water-soluble binder

[0050] The present disclosure relates to a composition having a binder comprising a water- soluble binder, as well as cathodes formed from the same.

[0051] The use of water-soluble binders in the cathode provides for more efficient recyclability, resulting in improvement of environmental friendliness and sustainability throughout a product life of said battery. However, utilising water-soluble binders typically involves an aqueous fabrication process, which is incompatible with moisture-sensitive cathode active materials in a mass production process. Furthermore, wet electrode manufacturing processes impose a number of drawbacks as aforementioned. Therefore, the use of a dry cathode fabrication process with a water-soluble binder may facilitate battery recycling, while also enabling the use of water-sensitive cathode active materials in the cathode.

[0052] The binder may comprise one or more types of water-soluble binder. For example, the binder may comprise several different water-soluble binders. The binder may comprise a water-soluble binder together with one or more other binder materials. Examples of water-soluble binders include, but are not limited to, water-soluble biopolymers, water-soluble homopolymers, water-soluble copolymers, water-soluble monomers and water-soluble oligomers.

[0053] In particular embodiments, the water-soluble binder may be selected from a water- soluble polymer, such as a synthetic water-soluble polymer, a water-soluble biopolymer, and mixtures thereof.

[0054] In particular embodiments, the water-soluble binder may be selected from the group consisting of: carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (Na-CMC), carboxymethyl cellulose lithium (CMC-Li), hybrid humics / sodium carboxymethyl cellulose (HAC), poly(3, 4, -ethylenedioxythiophene) -polystyrenesulfonate

[0055] (PEDOT:PSS), polyacrylic acid (PAA), poly(vinyl alcohol) (PVA), a mixture of terpene resin and lithium polyacrylate (TA-Li-PAA), chitosan, carboxymethyl chitosan (C-CTS), cyanoethyl chitosan, cyanoethylated carboxymethyl chitosan (CN-C-CTS), copolymerizing 2-(perfluorohexyl) ethylmethacrylate (PFHEMA) and poly(ethylene glycol) methacrylate (PEGMA), n-cyanoethyl polyethylenimine (CN-PEI), xanthan gum (XG), polyvinyl acetate (PVAc), polytetrafluoroethylene (PTFE), locust bean gum (LBG, carob bean gum), alginate, metal alginate such as sodium alginate (SA), aluminium alginate, barium alginate, manganese alginate, zinc alginate; polyethylene oxide (PEO), amphiphilic cross-linked binder (acrylic-based latex), polyacrylate latex (PAL), polyacrylic latex (LA132), heat-curable polyurethane (PU), CMC-fluorinated acrylic hybrid latex (TRD 202A), lignin, acrylonitrile multi-copolymer (LA133), (temperature induced) citric acid (CA) cross linked Na-CMC, C-CTS / PEO composite, poly(methyl vinyl ether-alt-lithium maleic acid (P(MVE-LMA)), polyacrylonitrile (PAN), guar gum (GG), poly(diallyldimethylammonium) (PDADMA) with one or more anions consisting of FSI, TFSI, CFSO and BETI, sulfonated poly(phenylene oxide) (SPPO), sodium alginate (SA)- 3,4-propylenedioxythiophene-2,5-dicarboxylic acid (ProDOT) composite polymer, polyaniline (PANI), polypyrrole (PPy), gelatin, and mixtures thereof.

[0056] Preferably, the water-soluble binder is selected from carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (Na-CMC), carboxymethyl cellulose lithium (CMC-Li), polyacrylic acid (PAA), poly(vinyl alcohol) (PVA), polyvinyl acetate (PVAc), polytetrafluoroethylene (PTFE), alginate, metal alginate such as sodium alginate (SA), aluminium alginate, barium alginate, manganese alginate, zinc alginate, polyethylene oxide (PEO), polyacrylonitrile (PAN), polyaniline (PANI), polypyrrole (PPy), and mixtures thereof. The water-soluble binder can be used and are understood by those skilled in the art, being referred to, for example, D. Das et al., Batteries 9, 2023, 193, W. Dou et al., Adv. Func. Mater. 33, 2023, 2305161, N. Lingappan et al., Renewable and Sustainable Energy Reviews, 147, 2021, 111227 and A. Pillai et al., Energy Fuels 36, 2022, 5063- 5087.

[0057] A synthetic water-soluble polymer may be understood to include a water-soluble polymer of synthetic origin, such as an industrially produced polymer, for example a polymer produced by the polymerisation of monomers and / or the modification of a polymer. A water-soluble polymer may be understood to include a water-soluble polymer of biological origin, for example a natural water-soluble polymer.

[0058] The water-soluble binder may comprise an alkali metal and / or alkali earth metal salt of a water-soluble binder, such as a lithium and / or sodium salt of a water-soluble binder.

[0059] In one or more embodiments, the synthetic water-soluble polymer may be selected from polyethylene glycol (PEG), polypropylene glycol (PPG), PEG-block-PPB-block-PEG, polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyacrylamide (PAM), polyacrylic acid (PAA), poly methyl acrylamide, N-(2-hydroxypropyl) methacrylamide (HPMA), divinyl ether-maleic anhydride (DIVEMA), polyoxazoline, polyphosphate, polyphosphazene, and mixtures thereof.

[0060] Preferably, the water-soluble polymer is a water-soluble biopolymer.

[0061] The water-soluble biopolymer may be selected from a water-soluble polysaccharide, a water-soluble protein, and mixtures thereof. The water-soluble biopolymer may be neutral, cationic and / or anionic. The water-soluble biopolymer may be a derivative of a polysaccharide and / or a protein, for example a salt and / or a modified polysaccharide and / or protein. The water-soluble biopolymer may be a linear and / or branched polysaccharide and / or protein.

[0062] The water-soluble biopolymer may include one or more water-soluble gums.

[0063] In other embodiments, the water-soluble biopolymer is selected from starch, glucose, cellulose ether, cellulose acetate, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), pectin, dextran, hyaluronic acid, albumin, carrageenan, alginic acid, alginate (e.g. sodium and / or lithium alginate), gelatin, collagen, hydrolysed collagen, gum arable, gum Arabic, acacia gum, guar gum, xanthan gum, gellan gum, okra gum, fenugreek gum, tara gum, locust bean gum, cassia gum, karaya gum, carrageenan, agar, gum tragacanth, cashew gum, chitosan, scleroglucan, gum ghatti, pullulan, -glucan, glucomannan, psyllium gum, fructan, glucan, amylose, amylopectin, glycogen, mannan, xylan, lignin, araban, galactan, galacturonan, glucuronoxylan, arabinoxylan, xyloglucan, pectinic acid, arabinogalactan, glycosaminoglycan, galactomannan, inulin, and mixtures thereof.

[0064] In some embodiments, the water-soluble biopolymer is selected from starch, glucose, cellulose ether, cellulose acetate, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), pectin, dextran, hyaluronic acid, albumin, carrageenan, alginic acid, alginate (e.g. sodium and / or lithium alginate), gelatin, collagen, hydrolysed collagen, and mixtures thereof.

[0065] Preferably, the water-soluble biopolymer is selected from CMC, sodium alginate, gelatin, guar gum, xanthan gum, gum Arabic, and mixtures thereof.

[0066] More preferably, the water-soluble biopolymer is selected from CMC, sodium alginate, gelatin, and mixtures thereof.

[0067] The water-soluble gum may be selected from gum arable, gum Arabic, acacia gum, guar gum, xanthan gum, gellan gum, okra gum, fenugreek gum, tara gum, locust bean gum, cassia gum, karaya gum, carrageenan, agar, gum tragacanth, cashew gum, chitosan, scleroglucan, gum ghatti, pullulan, fructan, glucan, amylose, amylopectin, glycogen, mannan, xylan, lignin, araban, galactan, galacturonan, glucuronoxylan, arabinoxylan, xyloglucan, glucomannan, pectinic acid, arabinogalactan, glycosaminoglycan, galactomannan, inulin, and mixtures thereof.

[0068] Preferably, water-soluble gum is selected from guar gum, xanthan gum, gum Arabic, and mixtures thereof.

[0069] In one embodiment, the polysaccharide comprises units selected from glucose, glucopyranose, galacturonic acid, anhydroglucose, glucuronic acid, glucosamine, guluronic acid, mannuronic acid, mannose, galactose, galactomannan, mannopyranose, galactopyranose, arabinose, rhamnose, xylose, cellulose, maltotriose, agarobiose, anhydro-galactopyranose, galactopyranosyl uronic acid, fucopyranose, arabinogalactan, arabinofuranose, / V-acetylglucosamine, glucopyranosyl, glucopyranosyl uronic acid, and mixtures thereof, preferably guluronic acid, mannuronic acid, mannose, galactose, glucose, and mixtures thereof, more preferably guluronic acid, mannuronic acid, and mixtures thereof.

[0070] In some embodiments, the protein comprises amino acid units selected from glycine, hydroxyproline, proline, alanine, glutamic acid, aspartic acid, arginine, lysine, serine, leucine, valine, phenylalanine, threonine, isoleucine, hydroxylysine, tyrosine, and mixtures thereof.

[0071] A water-soluble binder, in particular a water-soluble biopolymer, may have numerous advantages, such as wide availability in nature, low toxicity risk (in particular a low level of fluorine), biodegradability, biocompatibility, more environmentally friendly (e.g. compared to PFAS materials such as PVDF), low cost and / or provide a way of using waste materials.

[0072] An advantage of employing water-soluble binder as binders in the cathode is the potential to facilitate the dismantling and recycling of the cathode. Part of the recycling process typically involves separating the cathode materials, including cathode active material, binder and conductive additive. This is typically challenging with standard binders such as PVDF. However, this recycling process may be helped due to the watersolubility of the binder. A cathode having a water-soluble binder may be separated from the other cathode materials by dissolving (partially and / or fully) the binder in solvent, such as water. Standard fluorine-based binder materials typically have poor solubility in many solvents, in particular water. Therefore, a cathode comprising a water-soluble binder allows for easy recycling of the cathode in a solvent, in particular a green solvent such as water.

[0073] Preferably, the water-soluble binder has a high solubility in water. The water-soluble binder may be soluble in solvents comprising water and one or more other solvent compounds. The solvent may be an organic, inorganic and / or aqueous solvent, including a supercritical fluid. For example, wherein water is combined with one or more other solvents, such as a non-polar and / or polar solvent. The one or more other solvent may be selected from an alcohol, ketone, aldehyde, acetate, aromatic, alkane, alkene, ether, glycol, chlorinated solvent, nitrile, amide, sulfoxide, nitro, carbonate, amine, hydroxide, ammonium, and mixtures thereof. The solubility of the water-soluble binder may vary at different pH levels. The water- soluble binder may be soluble in an aqueous solution at a pH of from about 1-14. Preferably, the water-soluble binder is soluble in an acidic, neutral and / or alkaline solution, preferably an alkaline solution. For example, at a pH of from about 7.5-14, such as from about 9-14, for example from about 11-14.

[0074] In some embodiments, the water-soluble binder may be soluble in water at a temperature of from about l-100°C.

[0075] In one embodiment, the water-soluble binder may be soluble in cold water, for example from about 1°C to room temperature, such as from 10°C to room temperature, for example from about 20°C to room temperature (i.e. 25°C).

[0076] In other embodiments, the water-soluble binder may be soluble in hot water (e.g. from about 30-100°C, such as from about 40-80°C, for example from about 50-70 °C.

[0077] In some embodiments, the water-soluble binder has a solubility in water of from about 10-3000 g / L, such as from about 100-1500 g / L, for example from about 500-1000 g / L.

[0078] Typically, the binder is mixed with the cathode active material and the optional conductive additive to form a composition before being applied (e.g. deposited and / or sprayed) onto a conductive foil to form a cathode.

[0079] Without wishing to be bound by theory, it is proposed that the water-soluble binder of the binder may have a high binding affinity to the other components of the cathode, in particular the cathode active material wherein it connects the active material via point contacts. Furthermore, the water-soluble binder may surround the cathode active material, while still maintaining its accessibility for lithium and / or sodium ions. The water-soluble binder may bind in this manner as it is in the form of particles during and / or after deposition.

[0080] These features may provide advantageous properties to the cathode active layer, in particular to the microstructure of the cathode active layer, for example high electrode density, low porosity, reduced incidence of defects (e.g. holes, cracks and / or surface pits), high tensile strength, resistance to shear stress, resistance to compressive stress, resistance to twisting stress, short diffusion paths and / or fast electronic and / or ionic transfer. As a result, the cells prepared with the cathode of the present disclosure may have excellent performance, such as high rate capacity, high specific capacity, long cycle life, lower internal resistance, high reliability, high energy density and / or faster charging.

[0081] Without wishing to be bound to theory, it is proposed that a water-soluble binder may be particularly favourable to binding to the cathode active material (and / or optional conductive additive). Water-soluble binders typically have a high number of functional groups, in particular polar groups, such as hydroxyls, acetals, carboxyls, carboxylic acids, ketones, esters, amines, sulfides, etc. Therefore, the water-soluble binder may comprise a high number of functional groups that can interact, connect and / or bond (chemically) with the other components of the cathode active layer.

[0082] For example, the functional groups of the water-soluble binder may form bonds, e.g. hydrogen bonds, with the cathode active material, thereby forming a chemical link and providing the cathode active layer with a high mechanical integrity, cohesiveness, adhesion strength and / or peel strength, reduced ionic tortuosity (e.g. trajectory for ion conduction) and / or improved heterointerface between the components. As a result, the cathode may have excellent cycle life, fast charge / discharge rate, high specific capacity, low impedance and / or resistance and / or high energy density. Such functional groups may provide an advantage over standard binder materials, such as PVDF (e.g. with fluorine functional groups), which only form weak interactions with the cathode active material. As a consequence of these weak interactions, cathodes prepared with PVDF as a binder typically result in binder occupying the void space in the cathode and creating adhesive connectivity in the layer by effectively embedding the active material in a continuous matrix formed from the binder, which results in a lower electrode density.

[0083] Water-soluble binders also typically have a high affinity for metal ions, and may form gel-like structures when interacting with multivalent metal ions. Water-soluble binders such as alginates may have a tendency to mitigate loss of activity through leaching of multivalent metal ions from the cathode active material.

[0084] Furthermore, the high binding affinity of the water-soluble binder to the cathode active material may result in the cathode active layer having a high electrode density and / or low porosity, due to the reduction of voids in the cathode active layer (thereby affecting the pore structure, microstructure and / or mesostructured), since the water-soluble binder may efficiently pack around and / or form point contacts with the cathode active material. Due to the dry processing conditions used to prepare the cathode comprising the water- soluble binder, the surface of the cathode active material remains accessible to charge transfer species (e.g. lithium ions). Furthermore, said conditions may facilitate the cathode active material, water-soluble binder and optional conductive additive forming a homogeneous mixture. In contrast, if wet processing conditions were used, this may result in blockage of the surface of the cathode active material owing to film formation and deposition of the binder across the surface of the active material.

[0085] As a result, the combination of these binding and / or packing features, and / or the dry processing conditions, the cathode may have a higher capacity, higher energy density, faster charge and discharge rate, higher rate capacity, higher integrity and / or higher adhesive strength compared to a cathode formed from a binder such as PVDF and / or using a wet manufacturing method.

[0086] Furthermore, other typical binder materials such as PTFE may be unsuitable for ESD due to its properties and / or behaviour under processing.

[0087] Preferably, the binder particles are smaller than the cathode active material particles. In this way, the binder may form a bridge-like connection between the cathode active particles and / or optional conductive additives of the cathode. Due to the dry deposition method and / or the properties of the water-soluble binder, the binder retains its form as a discrete particle, and has a reduced tendency to cover the surface of the active material and / or fill the void spaces of the cathode active layer, in comparison to a cathode active layer formed via wet deposition methods. This may reduce the impedance and / or resistance to lithium conduction into and out of active material particles (due to greater accessibility of the particles), and may affect the ionic and / or electronic conductivity of the cathode active layer, for example by resulting in a reduced ionic tortuosity and an improved heterointerface between the components, and / or the mechanical strength of the cathode active layer. Ionic tortuosity should be understood to mean the trajectory for ion conduction through the cathode active layer.

[0088] In some embodiments, the water-soluble binder is in the form of water-soluble binder particles. The water-soluble binder particles may have a D[4,3]50 particle size of from about 0.1-15 pm, such as from about 0.2-10 pm, for example from about 0.5-5 pm.

[0089] The water-soluble binder particles may have an aspect ratio of from about 1-3, such as from about 1-2, for example from about 1-1.5. It is preferable that the particle size of the water-soluble binder particles is significantly smaller than the particle size of the cathode active particles, so that the water-soluble binder particles may surround and / or interconnect the cathode active particles. The water-soluble binder particles may be distributed on the surface of the cathode active material particle, so as to form point contacts between the cathode active material particles, and thereby provide a linkage / connection between the cathode active particles.

[0090] In some embodiments, the D[4,3]50 particle size of the water-soluble binder particle and the D[4,3]50 particle size of the cathode active material particle may range from about 1: 1 to 1:25, for example from about 1:3 to 1 : 15, such as from about 1 :5 to 1: 10.

[0091] The water-soluble binder particles are preferably able to bind to and / or be distributed over the surface of the cathode active material particle while still maintaining the accessibility of the cathode active material particle to charge transfer species. Furthermore, using spray deposition, in particular ESD, to prepare the cathode may facilitate formation of a cathode active layer with said characteristics.

[0092] Wet processing using a binder emulsion may result in the binder covering the surface of the cathode active material and / or blocking space around the cathode active material particles, thereby reducing the accessibility of the particles and / or hindering the movement of the lithium and / or sodium ions throughout the cathode. Moreover, solvent processing of water-soluble binder may not be possible due to the tendency to form gel-like structures.

[0093] In some embodiments, the water-soluble binder, in particular gelatin, may have a gel strength, or bloom value, of 50 or more, such as 225 or more, for example from about 50-325, such as from about 175-325, for example from about 225-325. The bloom value is a measure of the strength and stiffness of the water-soluble binder (e.g. gelatin).

[0094] Preferably, the water-soluble binder is not a fibrillisable polymer and / or does not readily undergo fibrillation. For example, water-soluble binder may not undergo fibrillation (i.e. the polymer may not form microscopic elongate fibrils) when subjected to a shear force (i.e. the water-soluble binder does not form fibrils under shear stress). For the water-soluble binder to be used in an ESD process, it should be sprayable as an aerosol. Without wishing to be bound by theory, it is proposed that a fibrillisable polymer is not typically suitable for spraying as an aerosol.

[0095] The water-soluble binder may have an average molecular weights (Mw) of from about 10,000-600,000 g / mol, such as from about 50,000-400,000 g / mol, for example from about 100,000-300,000 g / mol.

[0096] In embodiments when the water-soluble biopolymer is a gelatin, the water-soluble biopolymer may have an average molecular mass of 50,000 g / mol or more, such as 50,000-100,000 g / mol.

[0097] The binder may be present in the cathode active layer in an amount of from about 0.3- 15 wt%, for example from about 0.4-10 wt%, such as from about 0.5-5 wt%, for example from about 0.8-2.5 wt%, based on the total weight of the dry cathode active layer (i.e. the cathode active layer excluding solvent).

[0098] Cathode

[0099] The combination of water-soluble binder, cathode active material and optional conductive additive of the present disclosure enables the preparation of a cathode to be carried out under solvent-free processing conditions. Cathodes prepared in said manner provide unique advantages compared with conventional wet processing methods as a result of the solvent-free process. This includes greater environmental friendliness, lower cost, enhanced compatibility, higher production efficiency and improved cathode performance.

[0100] Furthermore, the dry processing conditions may overcome multiple issues that arise with wet processing methods, either during wet mixing, such as instability of mixtures / compositions, rheological instabilities, binder degeneration, agglomeration, gas generation, and / or during wet coating, such as the formation of pin holes, curling, cracks and binder migration. Dry processing methods may also enable a wider and / or alternative range of materials, which would not be compatible with wet processing methods, and / or may also avoid any issues arising during solvent evaporation, for example microstructural defect formation on the cathode surface.

[0101] The composition and / or cathode may be substantially free of solvent and / or substantially solvent-free, and / or prepared in such a manner. In some embodiments, the composition and / or cathode is solvent-free and / or free of solvent, or prepared in such a manner. By "substantially free of solvent" or "substantially solvent-free" is meant about 10 wt% solvent or less, for example about 5 wt% solvent or less, such as about 4 wt% solvent or less, for example about 3 wt% solvent or less, for example about 2.5 wt% solvent or less, such as about 2 wt% solvent or less, for example about 1 wt% solvent or less, such as about 0.5 wt% solvent or less, preferably about 0.1 wt% solvent or less, based on the total weight of the composition and / or cathode active layer.

[0102] By "solvent-free" or "free of solvent" is meant less than about 0.05 wt% solvent, preferably less than about 0.01 wt% solvent, based on the total weight of the composition and / or cathode active layer.

[0103] Solvent may refer to volatile compounds, such as organic, inorganic, supercritical fluid and / or aqueous solvents. A volatile compound (e.g. a volatile organic compound) may be defined as a compound having a high vapour pressure at room temperature, such as a compound that has a boiling point from about 50-250 °C. The term 'solvent' may be understood to include dispersing medium.

[0104] Solvent is preferably avoided in the composition, cathode active layer and / or fabrication / mixing processes. However, a solvent may be included in order to aid the processing of the components and / or facilitate the processing and / or mixing (e.g. components may be provided as a solution / emulsion). The composition and / or cathode active layer may comprise solvent, for example as a result of the manufacturing process, operation process and / or due to absorption of solvent from the atmosphere.

[0105] Without being bound by theory, it is proposed that in some embodiments, the composition may comprise some solvent. For example, in order to facilitate electrostatic charging of the composition during deposition it may be preferable that the composition comprises solvent (e.g. so as to retain a charge in the material being deposited).

[0106] The water-soluble binder may be in a hydrated form. The water-soluble binder may be hygroscopic and absorb solvent, such as atmospheric moisture and / or water. For example, the water-soluble binder may have a moisture content of from about 0.1-40 wt%, for example from about 1-30 wt%, such as from about 5-20 wt%.

[0107] Without wishing to be bound by theory, it is believed that the water-soluble binder provides flexibility, stability and / or reduced brittleness to the cathode active layer. For example, the water-soluble binder may have flexible properties, which may allow the cathode active layer to be rolled for incorporation into a cell, such as a cylindrical cell, prismatic cell, pouch cell, or coin cell.

[0108] As such, in some embodiments the cathode of the disclosure consists of: a conductive foil having a cathode active layer thereon, said cathode active layer consisting of: a cathode active material; a binder consisting of a water-soluble binder; and optionally a conductive additive.

[0109] In some embodiments, the cathode active layer has a thickness of from about 10 pm to 3 mm, such as from about 20 pm to 1 mm, such as from about 40-600 pm, for example from about 50-300 pm.

[0110] In some embodiments, the cathode has a specific capacity on charge or discharge of from about 100-400 mAh / g, such as from about 150-350 mAh / g, for example from about 180-330 mAh / g, such as from about 190-300 mAh / g, for example from about 200-280 mAh / g, based on the weight of the cathode active material.

[0111] In some embodiments, the cathode may have an areal capacity of from about 1.0-10.0 mAh / cm2, such as from about 1.5-9.0 mAh / cm2, for example from about 2.0-8.0 mAh / cm2, such as from about 2.5-7.0 mAh / cm2.

[0112] In one embodiment, the cathode active layer has a porosity of from about 1-50%, for example from about 15-40%, such as from about 15-35%, such as from about 20- 30%.

[0113] In some embodiments, the cathode active layer has an electrode density of from about 0.8-5.0 g / cm3, such as from about 1.5-4.5 g / cm3, such as from about 2.0-4.0 g / cm3, for example from about 2.5-3.8 g / cm3.

[0114] A cathode active layer prepared using ESD may have a lower porosity and / or higher electrode density compared to one prepared using wet processing methods.

[0115] The electrode density and / or porosity of the cathode active layer may be determined using various techniques, for example 3D imaging techniques, X-ray tomography, focused ion-beam scanning electron microscopy (FIB-SEM), pycnometry (e.g. helium), gas sorption techniques (e.g. nitrogen) and / or porosimetry (e.g. mercury) techniques.

[0116] The porosity may be defined as the percentage of a pore volume of the material occupying material. For instance, the porosity of the cathode active layer may be defined as the fraction of the void volume of the cathode active layer over the total sample volume of the cathode active layer.

[0117] Preferably, the porosity and electrode density are determined by mercury intrusion porosimetry by measuring the diameter of mercury filled pores at a predetermined pressure according to ASTM UOP578-11, for example by using a mercury porosimeter such as Autopore produced by Micromeritics and PoreMaster produced by Quantachrome. The electrode density here may be understood to be the bulk density as measured by mercury intrusion porosimetry. In this technique, a non-wetting liquid (i.e. mercury) is intruded into the material at high pressure and a porosity / density calculation is made based on Washburn's equation and the critical pressure needed to force the liquid into the material. The diameter of the fine pores may be measured at each predetermined pressure while continuously applying a pressure of 0.5-60,000 psi. In this case, mercury intrusion porosimetry measurements are limited to the measurement of pores with a diameter greater than 50 nm (i.e. macropores).

[0118] In order to include the contribution of micropores (<2 nm) and mesopores (2 to 50 nm) towards the porosity and / or electrode density, N2 gas sorption may be used to calculate the Brunauer-Emmett-Teller (BET) specific surface area, pore volume and pore size distribution. The BET surface area may be measured by use of ASTM method D3663-03.

[0119] The electrode density of the cathode active layer may be calculated by a mass loading level of the cathode active layer divided by the thickness of the cathode active layer (e.g. the mass of the cathode active layer per plane area of the cathode (g / cm2) which is perpendicular to a thickness direction of the cathode active layer (cm)).

[0120] In some embodiments, the cathode active layer comprises about 79-99.7 wt% of a cathode active material, about 0.3-15 wt% of a binder and about 0-6 wt% of an optional conductive additive, based on the total weight of the dry cathode active layer (i.e. the cathode active layer excluding solvent). In another embodiment, the cathode active layer comprises about 86-99.5 wt% of a cathode active material, about 0.4-10 wt% of a binder and about 0.01-4 wt% of an optional conductive additive, based on the total weight of the dry cathode active layer (i.e. the cathode active layer excluding solvent).

[0121] In a preferred embodiment, the cathode active layer comprises about 92.5-98.5 wt% of a cathode active material, about 0.5-5.0 wt% of a binder and about 0.25-2.5 wt% of an optional conductive additive, based on the total weight of the dry cathode active layer (i.e. the cathode active layer excluding solvent).

[0122] The cathode may be prepared from the composition using standard fabrication processes, for example the process may include mixing, milling, dosing, spraying, depositing, curing (e.g. chemical, thermal and / or UV), charging, ionisation, atomising, pre-calendering, calendering, pre-heating, winding, slitting and / or assembly.

[0123] The best results to prepare the cathode are obtained when following the method of the disclosure which comprises the steps of:

[0124] (i) providing the composition of the disclosure; and

[0125] (ii) depositing the composition onto a conductive foil to form a cathode, said cathode comprising a conductive foil having a cathode active layer thereon, said cathode being formed from the composition.

[0126] Steps (i) and (ii) may be carried out using standard methodologies. The components of the composition may be combined in any order.

[0127] Typically, step (i) comprises: providing a composition comprising a cathode active material, a binder comprising a water-soluble binder and optionally a conductive additive, wherein the composition is substantially free of solvent.

[0128] Typically, step (i) comprises: forming a composition comprising a cathode active material, a binder comprising a water-soluble binder and optionally a conductive additive, wherein the composition is substantially free of solvent.

[0129] Step (i) of the method may involve mixing the cathode active material, binder comprising a water-soluble binder and optional conductive additive under a shear force, preferably resulting in a homogeneous distribution of components throughout the composition and / or avoiding excessive agglomeration.

[0130] Preferably, the shear force employed may result in the water-soluble binder particles arranging around, surrounding and / or attaching to the surface of the cathode active material particles.

[0131] The composition may be applied to the conductive foil, for example by using an ESD process.

[0132] Typically, step (ii) comprises: electrostatically depositing the composition onto a conductive foil to form a coated conductive foil and / or cathode.

[0133] ESD may involve depositing and / or spray coating the composition onto the conductive foil, for example using a spray gun system. Typical process parameters are used to control the deposition process in order to achieve a cathode with the desired properties, for example spray gun voltage, spray gun current, coating time, coating speed, deposition rate, nozzle size, air flow, coating passes (i.e. cycles), etc.

[0134] The composition may be mixed with fluidising air prior to and / or during deposition (e.g. using a powder feeding hopper). The composition may be charged prior to and / or during the deposition process (e.g. in the form of charged particles).

[0135] For example, the spray gun system may apply an electrostatic charge to the powder particles of the composition, which are then attracted to the grounded substrate. It is preferable that the composition being deposited is able to be electrostatically charged and retain a charge. For example, the composition may have a solvent content which allows the composition to be electrostatically deposited.

[0136] In some embodiments, the composition may have a solvent content which results in a conductivity that allows it to be electrostatically deposited. Preferably, the conductivity of the composition is low enough so that the powder particles of the composition retain an electrostatic charge until they reach the grounded substrate (e.g. wherein the charge on the particles is not fully dissipated via the deposition equipment itself, such as the spray gun, before the sprayed particles reach the substrate).

[0137] Typically, the conductive foil may be a primer-coated conductive foil. Pre-calendering and / or calendering may be carried out on the coated conductive foil (i.e. after deposition of the composition onto the conductive foil), for example by roll- to-roll calendering.

[0138] Typically, step (ii) comprises: pre-calendering and / or calendering the cathode and / or coated conductive foil to improve adhesion of the cathode active layer to the conductive foil and / or increase the density of the cathode active layer.

[0139] In other words, the calendering of the coated conductive foil compacts and bonds the coating on the conductive foil, forming a cathode active layer which is bonded to the underlying conductive foil.

[0140] The adhesion or peel strength of a cathode prepared by ESD may typically be very high. The adhesion strength of the cathode active layer onto the conductive foil may be measured using a peel test. The peel strength of the cathode comprising the components of the composition of the disclosure (i.e. a cathode active material, a binder comprising a water-soluble binder and optionally a conductive additive) may be about 5 N / m or greater, such as from about 10-150 N / m, for example from about 30- 140 N / m.

[0141] The peel strength may be measured in accordance with ASTM D3330. The peeling strength test may be carried out on a Universal Testing Machine (e.g. Instron 3345), for example, using a sample of a cathode having a width of 25 mm. Each of the cathode plates in which the coating layers were located on both surfaces of the conductive foils may be cut to a size of 25 mmx l50 mm. After an adhesive was coated on a glass substrate at room temperature, the cathode plate was adhered to the adhesive and roll-pressed. After one end of the cathode plate was folded 180°, a force applied to the sample was measured while pulling the sample in a direction opposite to the one end at a speed of 100 mm / min. The peel strength may be an average or a mean value of 20 samples.

[0142] The cathode active layer according to the present disclosure may also display good electrolyte penetration, which can facilitate processing of the cathode and preparation of the cell. The penetrability of the electrolyte into the cathode active layer may be measured using an electrolyte drop test. For example, electrolyte may be applied to the cathode active layer and the spreading of the electrolyte observed. The spreading rate of the electrolyte on the cathode active layer may be from about 1-100 mm / min, for example from about 5-50 mm / min, such as from about 10-30 mm / min.

[0143] The cathode of the present disclosure comprises a conductive foil. The conductive foil is typically aluminium.

[0144] Cell

[0145] The remaining features of the cell of the present disclosure will be briefly described.

[0146] The present disclosure also relates to cells comprising the cathode of the disclosure, for example a secondary lithium and / or sodium-ion cell, preferably a lithium-ion cell. Such cells typically comprise a cathode, an anode, a separator disposed between the anode and the cathode, wherein the anode and / or cathode comprises the composition of the cathode disclosed herein. Said cathode, anode and separator may form an electrode assembly, the cell further comprising a housing for the electrode assembly. The cell will typically comprise an electrolyte to facilitate the transport of lithium ions between the cathode and the anode. The housing is typically sealed to ensure the electrolyte is retained within the housing. Said housing usually includes terminals in electrical contact with the anode and cathode.

[0147] These cells may be combined to form a battery system (i.e. an array of cells).

[0148] The disclosure also relates to a vehicle comprising the cell and / or battery system of the disclosure. The vehicle is preferably an electric vehicle, such as a car, truck, bus, scooter, motorbike, bicycle, boat, plane or the like, preferably a car, truck or bus.

[0149] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0150] All embodiments of the disclosure and particular features mentioned herein may be taken in isolation or in combination with any other embodiments and / or particular features mentioned herein (hence describing more particular embodiments and particular features as disclosed herein) without departing from the disclosure of the disclosure. As used herein, the term 'comprises' will take its usual meaning in the art, namely indicating that the component includes but is not limited to the relevant features (i.e. including, among other things). As such, the term 'comprises' will include references to the component consisting essentially of the relevant substance(s).

[0151] Wherever the word 'about' is employed herein in the context of amounts, for example absolute amounts, weights, volumes, sizes, diameters etc., or relative amounts (e.g. percentages) of individual constituents in a composition or a component of a composition (including concentrations and ratios), timeframes, and parameters such as temperatures etc., it will be appreciated that such variables are approximate and as such may vary by ±10%, for example ±5% and preferably ±2% (e.g. ±1%) from the actual numbers specified herein. This is the case even if such numbers are presented as percentages in the first place (for example 'about 10%' may mean ± 10% about the number 10, which is anything between 9% and 11%).'

[0152] The following numbered items summarise certain embodiments of the disclosure.

[0153] 1. A method of making a cathode comprising the steps of:

[0154] (i) providing a composition comprising a cathode active material, a binder comprising a water-soluble binder, and optionally a conductive additive, wherein the composition is substantially free of solvent; and

[0155] (ii) depositing the composition onto a conductive foil to form a cathode, said cathode comprising a conductive foil having a cathode active layer thereon, said cathode active layer being formed from the composition.

[0156] 2. The method of Item 1, wherein the method is solvent-free.

[0157] 3. The method of Item 1 or Item 2, wherein step (ii) comprises electrostatically depositing the composition onto the conductive foil to form the cathode.

[0158] 4. The method according to any one of the preceding Items, wherein the cathode active layer has a thickness of from about 10 pm to about 3 mm.

[0159] 5. The method according to any one of the preceding Items, wherein the binder is present in an amount of from about 0.3-15 wt%, based on the total weight of the dry cathode active layer (i.e. the cathode active layer excluding solvent). 6. The method according to any one of the preceding Items, wherein the water- soluble binder has a solubility in water of from about 10-3000 g / L.

[0160] 7. The method according to any of the preceding Items, wherein the water-soluble binder is soluble in water at a temperature of from about 1-100 °C.

[0161] 8. The method according to any of the preceding Items, wherein the water-soluble binder is soluble in an aqueous solution at a pH of from about 7.5-14.

[0162] 9. The method according to any one of the preceding Items, wherein the water- soluble binder is selected from a synthetic water-soluble polymer, a water-soluble biopolymer, and mixtures thereof, preferably a water-soluble biopolymer.

[0163] 10. The method according to any one of the preceding Items, wherein the water- soluble binder is selected from the group consisting of: carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (Na-CMC), carboxymethyl cellulose lithium (CMC-Li), hybrid humics / sodium carboxymethyl cellulose (HAC), poly(3, 4, -ethylenedioxythiophene) -polystyrenesulfonate (PEDOT:PSS), polyacrylic acid (PAA), poly(vinyl alcohol) (PVA), a mixture of terpene resin and lithium polyacrylate (TA-Li-PAA), chitosan, carboxymethyl chitosan (C-CTS), cyanoethyl chitosan, cyanoethylated carboxymethyl chitosan(CN-C-CTS), copolymerizing 2-(perfluorohexyl) ethylmethacrylate (PFHEMA) and poly(ethylene glycol) methacrylate (PEGMA), n-cyanoethyl polyethylenimine (CN-PEI), xanthan gum (XG), polyvinyl acetate (PVAc), polytetrafluoroethylene (PTFE), locust bean gum (LBG, carob bean gum), alginate, metal alginate such as sodium alginate (SA), aluminium alginate, barium alginate, manganese alginate, zinc alginate; polyethylene oxide (PEO), amphiphilic cross-linked binder (acrylic-based latex), polyacrylate latex (PAL), polyacrylic latex (LA132), heat-curable polyurethane (PU), CMC-fluorinated acrylic hybrid latex (TRD 202A), lignin, acrylonitrile multi-copolymer (LA133), (temperature induced) citric acid (CA) cross linked Na-CMC, C-CTS / PEO composite, poly(methyl vinyl ether-alt-lithium maleic acid (P(MVE-LMA)), polyacrylonitrile (PAN), guar gum (GG), poly(diallyldimethylammonium) (PDADMA) with one or more anions consisting of FSI, TFSI, CFSO and BETI, sulfonated poly(phenylene oxide) (SPPO), sodium alginate (SA)- 3,4-propylenedioxythiophene-2,5-dicarboxylic acid (ProDOT) composite polymer, polyaniline (PANI), polypyrrole (PPy), gelatin and mixtures thereof

[0164] 11. The method according to Item 9, wherein the synthetic water-soluble polymer is selected from polyethylene glycol (PEG), polypropylene glycol (PPG), PEG-block-PPB- block-PEG, polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyacrylamide (PAM), polyacrylic acid (PAA), poly methyl acrylamide, N-(2-hydroxypropyl) methacrylamide (HPMA), divinyl ether-maleic anhydride (DIVEMA), polyoxazoline, polyphosphate, polyphosphazene, and mixtures thereof.

[0165] 12. The method according to Item 9, wherein the water-soluble biopolymer is selected from a water-soluble polysaccharide, a water-soluble protein, and mixtures thereof.

[0166] 13. The method according to Item 9 or Item 12, wherein the water-soluble biopolymer is selected from starch, glucose, cellulose ether, cellulose acetate, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), pectin, dextran, hyaluronic acid, albumin, alginic acid, alginate (e.g. sodium and / or lithium alginate), gelatin, collagen, hydrolysed collagen, gum arable, gum Arabic, acacia gum, guar gum, xanthan gum, gellan gum, okra gum, fenugreek gum, tara gum, locust bean gum, cassia gum, karaya gum, carrageenan, agar, gum tragacanth, cashew gum, chitosan, scleroglucan, gum ghatti, pullulan, 0- glucan, glucomannan, psyllium gum, fructan, glucan, amylose, amylopectin, glycogen, mannan, xylan, lignin, araban, galactan, galacturonan, glucuronoxylan, arabinoxylan, xyloglucan, pectinic acid, arabinogalactan, glycosaminoglycan, galactomannan, inulin, and mixtures thereof, preferably CMC, sodium alginate, gelatin, guar gum, xanthan gum, gum Arabic, and mixtures thereof.

[0167] 14. The method according to Item 12, wherein the polysaccharide comprises units selected from glucose, glucopyranose, galacturonic acid, anhydroglucose, glucuronic acid, glucosamine, guluronic acid, mannuronic acid, mannose, galactose, galactomannan, mannopyranose, galactopyranose, arabinose, rhamnose, xylose, cellulose, maltotriose, agarobiose, anhydro-galactopyranose, galactopyranosyl uronic acid, fucopyranose, arabinogalactan, arabinofuranose, / V-acetylglucosamine, glucopyranosyl, glucopyranosyl uronic acid, and mixtures thereof.

[0168] 15. The method according to Item 12, wherein the protein comprises units selected from glycine, hydroxyproline, proline, alanine, glutamic acid, aspartic acid, arginine, lysine, serine, leucine, valine, phenylalanine, threonine, isoleucine, hydroxylysine, tyrosine, and mixtures thereof. 16. The method according to any one of the preceding Items, wherein the water- soluble binder is in the form of water-soluble binder particles, optionally with a D[4,3]50 particle size of from about 0.1-15 pm.

[0169] 17. The method according to Item 16, wherein the water-soluble binder particles have an aspect ratio of from about 1-3.

[0170] 18. The method according to any one of the preceding Items, wherein the cathode active material is in the form of cathode active material particles, optionally with a D[4,3]50 particle size of from about 0.5-20 pm.

[0171] 19. The method according to Item 18, wherein the D[4,3]50 particle size of the water-soluble binder particles and the D[4,3]50 particle size of the cathode active material particles ranges from about 1: 1 to 1:25.

[0172] 20. The method according to any one of the preceding Items, wherein the cathode active material is selected from one or more of lithium nickel manganese oxide, lithium nickel manganese cobalt oxide, lithium-and-manganese-rich layered oxide, and mixtures thereof.

[0173] 21. The method according to any one of the preceding Items, wherein the composition comprises a conductive additive.

[0174] 22. The method according to any one of the preceding Items, wherein the cathode active layer comprises from about 86-99.5 wt% of the cathode active material, from about 0.4-10 wt% of the binder and from about 0.01-4 wt% of the conductive additive, based on the total weight of the dry cathode active layer (i.e. the cathode active layer excluding solvent).

[0175] 23. A cathode formed by the method of any preceding Item.

[0176] 24. A cathode comprising: a conductive foil having a cathode active layer thereon, said cathode active layer comprising: a cathode active material; a binder comprising a water-soluble binder; and optionally a conductive additive. 25. The cathode according to Item 24, wherein the binder is according to Item 5, wherein the water-soluble binder is according to any one of Items 6 to 17 and / or 19, wherein the cathode active material is according to any one of Items 18 to 20, wherein the optional conductive additive is according to Item 21 and / or wherein the cathode active layer is according to Item 4 and / or 22.

[0177] 26. The cathode according to any one of Items 23 to 25, wherein the cathode active layer has a porosity of from about 1-50%. 27. The cathode according to any one of Items 23 to 26, wherein the cathode active layer has an electrode density of from about 0.8-5.0 g / cm3.

[0178] 28. A cell comprising the cathode according to any one of Items 23 to 27. 29. A battery system comprising the cell according to Item 28.

[0179] 30. A vehicle comprising the battery system according to Item 29.

Claims

Claims1. A method of making a cathode comprising the steps of:(i) providing a composition comprising a cathode active material, a binder comprising a water-soluble binder, and optionally a conductive additive, wherein the composition is substantially free of solvent; and(ii) depositing the composition onto a conductive foil to form a cathode, said cathode comprising a conductive foil having a cathode active layer thereon, said cathode active layer being formed from the composition.

2. The method of Claim 1, wherein the method is solvent-free.

3. The method of Claim 1 or Claim 2, wherein step (ii) comprises electrostatically depositing the composition onto the conductive foil to form the cathode.

4. The method according to any one of the preceding claims, wherein the water- soluble binder is selected from a synthetic water-soluble polymer, a water-soluble biopolymer, and mixtures thereof, optionally wherein the water-soluble biopolymer is selected from starch, glucose, cellulose ether, cellulose acetate, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), pectin, dextran, hyaluronic acid, albumin, alginic acid, alginate (e.g. sodium and / or lithium alginate), gelatin, collagen, hydrolysed collagen, gum arable, gum arable, gum Arabic, acacia gum, guar gum, xanthan gum, gellan gum, okra gum, fenugreek gum, tara gum, locust bean gum, cassia gum, karaya gum, carrageenan, agar, gum tragacanth, cashew gum, chitosan, scleroglucan, gum ghatti, pullulan, -glucan, glucomannan, psyllium gum, fructan, glucan, amylose, amylopectin, glycogen, mannan, xylan, lignin, araban, galactan, galacturonan, glucuronoxylan, arabinoxylan, xyloglucan, pectinic acid, arabinogalactan, glycosaminoglycan, galactomannan, inulin, and mixtures thereof, preferably CMC, sodium alginate, gelatin, guar gum, xanthan gum, gum Arabic, and mixtures thereof.

5. The method according to any one of the preceding claims, wherein the water- soluble binder is selected from the group consisting of: carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (Na-CMC), carboxymethyl cellulose lithium (CMC-Li), hybrid humics / sodium carboxymethyl cellulose (HAC), poly(3, 4, -ethylenedioxythiophene) -polystyrenesulfonate (PEDOT:PSS), polyacrylic acid (PAA), poly(vinyl alcohol) (PVA), a mixture of terpeneresin and lithium polyacrylate (TA-Li-PAA), chitosan, carboxymethyl chitosan (C-CTS), cyanoethyl chitosan, cyanoethylated carboxymethyl chitosan(CN-C-CTS), copolymerizing 2-(perfluorohexyl) ethylmethacrylate (PFHEMA) and poly(ethylene glycol) methacrylate (PEGMA), n-cyanoethyl polyethylenimine (CN-PEI), xanthan gum (XG), polyvinyl acetate (PVAc), polytetrafluoroethylene (PTFE), locust bean gum (LBG, carob bean gum), alginate, metal alginate such as sodium alginate (SA), aluminium alginate, barium alginate, manganese alginate, zinc alginate; polyethylene oxide (PEO), amphiphilic cross-linked binder (acrylic-based latex), polyacrylate latex (PAL), polyacrylic latex (LA132), heat-curable polyurethane (PU), CMC-fluorinated acrylic hybrid latex (TRD 202A), lignin, acrylonitrile multi-copolymer (LA133), (temperature induced) citric acid (CA) cross linked Na-CMC, C-CTS / PEO composite, poly(methyl vinyl ether-alt-lithium maleic acid (P(MVE-LMA)), polyacrylonitrile (PAN), guar gum (GG), poly(diallyldimethylammonium) (PDADMA) with one or more anions consisting of FSI, TFSI, CFSO and BETI, sulfonated poly(phenylene oxide) (SPPO), sodium alginate (SA)- 3,4-propylenedioxythiophene-2,5-dicarboxylic acid (ProDOT) composite polymer, polyaniline (PANI), polypyrrole (PPy), gelatin, and mixtures thereof.

6. The method according to any one of the preceding claims, wherein the cathode active layer comprises from about 86-99.5 wt% of the cathode active material, from about 0.4-10 wt% of the binder and from about 0.01-4 wt% of the conductive additive, based on the total weight of the dry cathode active layer (i.e. the cathode active layer excluding solvent).

7. A cathode formed by the method of any preceding claim.

8. A cathode comprising: a conductive foil having a cathode active layer thereon, said cathode active layer comprising: a cathode active material; a binder comprising a water-soluble binder; and optionally a conductive additive.

9. The cathode according to Claim 8, wherein the water-soluble binder is according to Claims 4 or 5, and / or wherein the cathode active layer is according to Claim 6.

10. A cell comprising the cathode according to any one of Claims 7 to 9.