Silicon Anode Binder

Abstract

The present invention relates to a binder for a non-aqueous electrolyte secondary battery, a negative electrode slurry for a secondary battery, a negative electrode for a secondary battery, and a secondary battery including them.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to European Patent Application No. 21306622.8, filed November 22, 2021, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to a binder for a non-aqueous electrolyte secondary battery, a negative electrode slurry for the secondary battery, a negative electrode for the secondary battery, and a secondary battery including them. [Background technology]

[0003] Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries are widely used as power sources for electronic devices. Although high capacity and long cycle life characteristics are desirable, current lithium ion batteries are limited in charge storage by the capacity of the negative electrode.

[0004] As an example of a method for increasing the capacity of a lithium ion secondary battery, an active material containing silicon atoms can be used in the negative electrode.

[0005] Silicon is important in terms of capacity for high capacity battery applications, as it has a theoretical capacity of about 4,200 mAh / g. However, the volume of silicon expands by about four times upon charging, and during charging and discharging, the volume expansion causes irreversible reactions such as the destruction of the electrical connection between the active materials, the peeling of the active materials from the current collector, and the formation of a solid electrolyte interface (SEI) layer due to the erosion of the active materials by the electrodes, and the associated reduction in life. Furthermore, the current binder can only accommodate a limited silicon loading (up to 10 wt%) before the battery life is significantly reduced due to the reduced stability of the charging cycle.

[0006] Currently, there is a lot of activity dedicated to the development of new binders for silicon-containing anodes that will enable greater energy density storage.

[0007] The binder, typically an organic polymer, acts as a bonding matrix that maintains contact between the active material throughout the anode layer and the current collector onto which the anode is deposited during manufacture.

[0008] Many approaches are being pursued to develop next generation binders compatible with silicon anodes.

[0009] There are several polycarboxylate binders and derivatives being pursued, including polyacrylic acids, polyamic acids, polyacrylamides, and other hydrogen bonding structures.

[0010] Miranda, A. et al. ("A Comprehensive Study of Hydrolyzed Polyacrylamide as a Binder for Silicon Anodes" Appl. Mater. Interfaces, 2019, 11, 44090-44100) disclose the use of partially hydrolyzed polyacrylamide in the fabrication of composite silicon anodes with good adhesion, high strength, and high electrochemical storage capacity.

[0011] It is also well documented that for polycarboxylates, particularly polyacrylic acids, there is an advantage to first converting them to lithium salts by neutralization with a base such as lithium hydroxide. This is done primarily to avoid trapping of lithium ions by free acid groups in the cell, which could reduce the initial capacity.

[0012] WO 2015 / 163302 discloses that the capacity retention rate after 10 cycles of charging and discharging can be improved by using an aqueous solution of a crosslinked sodium polyacrylate copolymer. Sodium polyacrylate has been used as a water-soluble, high-strength, high-elasticity binder. It is expected that the use of sodium polyacrylate can suppress or reduce the volume change caused by charging and discharging a battery containing a silicon-containing active material, thereby improving the cycle characteristics. However, when an aqueous solution of a copolymer containing sodium polyacrylate as a main component is used, cracks occur in the electrode during the coating and drying process of the negative electrode slurry, so that it is considered difficult to apply an aqueous solution of a copolymer containing sodium polyacrylate in practice.

[0013] Despite current strategies to prevent the degradation of silicon-rich anodes, their effectiveness appears to be limited, and there is as yet no clear breakthrough to reach the higher levels of silicon required to achieve meaningful progress in this field. Numerous disclosures exist on mixed binder systems that exploit intermolecular cooperative effects to enhance binder performance.

[0014] US Patent Application Publication No. 2020 / 0343556 provides a binder for non-aqueous electrolyte secondary batteries, comprising a blend of a first copolymer including a unit derived from a (meth)acrylic acid monomer and a unit derived from a (meth)acrylonitrile monomer, and a second copolymer including a unit derived from an aromatic vinyl monomer and a unit derived from an ethylenically unsaturated monomer including a carboxylic acid moiety. The binder can suppress or reduce electrode expansion of the negative electrode and improve cycle characteristics.

[0015] The applicant has unexpectedly found that certain polymers obtained by copolymerization of certain monomers with at least one monomer selected from monomers having a carboxylic acid group and an acrylamide can be used for the preparation of binders for electrodes, in particular silicon-rich anodes, exhibiting high cycling and electrochemical stability. Summary of the Invention

[0016] The object of the present invention is to provide a terpolymer [polymer (P)], (A1) A repeating unit derived from an α,β-ethylenically unsaturated carboxylic acid monomer [monomer (AA)] of formula (III), [ka] In the formula, R a , R b and R c are the same or different and are independently selected from a hydrogen atom and a C1-C3 hydrocarbon group; A repeating unit derived from a monomer (AA); (A2) A repeating unit derived from a (meth)acrylamide monomer [monomer (AM)] of formula (I), [ka] During the ceremony, R 1 and R 2 are the same or different and may be selected from a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a carboxylic acid group or an amide group; R 3 represents a hydrogen atom or a methyl group, R 4 and R 5 are the same or different and may be selected from a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms; A repeat unit derived from a monomer (AM); (B) a repeating unit derived from a monomer (M) different from the monomers (AA) and (AM), the monomer (M) having the following formula (II): [ka] During the ceremony, R i is selected from the group consisting of H, -COOH, -CHCOOH or an alkyl group, the alkyl group being preferably a methyl group; R ii and R iii are the same or different and may be selected from a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, or may be a -COOH group, A is a linkage selected from the group consisting of a -C(O)-O- group or a -C(O)-NH- group; R x is a straight-chain or branched C3-C alkyl group containing at least one functional group selected from the group consisting of a hydrogen atom, an ether (-O-), a heterocyclic group, a sulfonic acid group (-SO3H), a phosphonic acid group (-PO3H2), and a phosphoric acid group (-OPO3H2). 20 selected from hydrocarbon chain moieties, A repeating unit derived from a monomer (M); The polymer (P) is a terpolymer consisting of the above.

[0017] Another object of the present invention is to provide an aqueous electrode-forming composition [Composition (Comp)] for use in the preparation of electrodes for electrochemical devices, comprising a) at least one polymer (P), b) an electrode active material; c) an aqueous solvent; d) optionally at least one conductivity-imparting additive; and The aqueous electrode-forming composition [Composition (Comp)] is characterized by comprising:

[0018] In another object, the present invention relates to a process for producing an electrode [electrode (E)], the process comprising: (i) providing a metal substrate having at least one surface; (ii) providing a composition (Comp) as defined above; (iii) applying the composition (Comp) provided in step (ii) to at least one surface of the metal substrate provided in step (i), thereby providing an assembly comprising a metal substrate coated with said composition (Comp) on at least one surface; (iv) drying the assembly provided in step (iii); (v) subjecting the dried assembly obtained in step (iv) to a compression step to obtain the electrode (E) of the present invention; The present invention provides a process for producing an electrode [electrode (E)], comprising:

[0019] In a further aspect, the present invention relates to an electrode [electrode (E)] obtainable by the process of the present invention.

[0020] In a still further object, the present invention relates to an electrochemical device comprising at least one electrode (E) of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] In the context of the present invention, the term "weight percent" (wt%) indicates the content of a particular component in a mixture calculated as the ratio between the weight of the component and the total weight of the mixture. When referring to the total solids content (TSC) of a liquid composition, weight percent (wt%) indicates the ratio between the weights of all non-volatile components in the liquid.

[0022] The term "electrochemical cell", as used herein, is intended to mean an electrochemical cell that includes a positive electrode, a negative electrode, and a liquid electrolyte, with a single or multi-layer separator attached to at least one surface of one of the electrodes.

[0023] Non-limiting examples of electrochemical cells include, inter alia, batteries, preferably secondary batteries, and electric double layer capacitors.

[0024] For the purposes of the present invention, "secondary battery" is intended to denote a rechargeable battery. Non-limiting examples of secondary batteries include, inter alia, alkaline or alkaline earth secondary batteries.

[0025] As known in the art, an electrode-forming composition is a composition of matter, typically a liquid composition, in which solid components are dissolved or dispersed in a liquid, that can be deposited onto a metal substrate and subsequently dried to form the resulting electrode, with the metal substrate acting as a current collector. Electrode-forming compositions typically include at least an electroactive material and at least a binder.

[0026] The electrode-forming composition of the present invention [composition (Comp)] comprises at least one polymer (P) which functions as a binder.

[0027] Polymer (P) The polymer (P) may be obtained by radical copolymerization of a mixture of monomers (M) as defined above, α,β-ethylenically unsaturated carboxylic acid monomers [monomers (AA)] as defined above and (meth)acrylamide monomers [monomers (AM)].

[0028] The at least one α,β-ethylenically unsaturated carboxylic acid monomer (AA) of formula (III) defined above is preferably selected from the group consisting of acrylic acid, methacrylic acid, ethacrylic acid, crotonic, methyl(meth)acrylic acid, ethyl(meth)acrylic acid, propyl(meth)acrylic acid, isopropyl(meth)acrylic acid, n-butyl(meth)acrylic acid, 2-ethylhexyl(meth)acrylic acid, n-hexyl(meth)acrylic acid and n-octyl(meth)acrylic acid.

[0029] The (meth)acrylamide monomer [monomer (AM)] of formula (I) is preferably selected from the group consisting of (meth)acrylamide or N-substituted (meth)acrylamides such as N-alkylacrylamides, N,N-dialkylacrylamides.

[0030] Residue R of Monomer (M) x The "heterocyclic group" in the above formula (I) includes saturated heterocyclic groups having at least one nitrogen atom compound such as imidazolidinone.

[0031] According to a first variant in which A in formula (II) is a -C(O)-O- group, the monomer (M) is, for example, a compound of formula (IIa) [ka] A compound of formula (IIb), [ka] Or a compound of formula (IIc) [ka] In formulae (IIa) to (IIc), R i , R ii and R iii is as defined above, and n is an integer from 1 to 40.

[0032] According to a second variant in which A in formula (II) is a -C(O)-NH- group, the monomer (M) is, for example, a compound of formula (IId): [ka] Or a compound of formula (IIe) [ka] In formula (IId) and (IIe), R i , R ii and R iii is as defined above.

[0033] Typically, the polymer (P) is - monomer (M), Monomer (AA) and / or -Monomer (AM) A mixture of It is obtained by radical copolymerization in the presence of a source of free radicals.

[0034] Any free radical source can be used. It is particularly possible to generate free radicals spontaneously, for example by increasing the temperature, with a suitable monomer, such as styrene. It is possible to generate free radicals by irradiation, in particular by UV irradiation, preferably in the presence of a suitable UV-sensitive initiator. It is possible to use radical or redox type initiators or initiator systems. The free radical source may be water-soluble or not. It may be preferable to use water-soluble initiators or initiators that are at least partially water-soluble.

[0035] In general, the higher the amount of free radicals, the easier the polymerization is initiated (the more it is accelerated), but the lower the molar mass of the resulting copolymer. peroxides, such as, for example, hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, tert-butyl peroxyacetate, tert-butyl peroxybenzoate, tert-butyl peroxyoctoate, tert-butyl peroxyneodecanoate, tert-butyl peroxyisobutyrate, lauroyl peroxide, tert-amyl peroxypivalate, tert-butyl peroxypivalate, dicumyl peroxide, benzoyl peroxide, potassium persulfate or ammonium persulfate, - azo compounds, such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-butanenitrile), 4,4'-azobis(4-pentanoic acid), 1,1'-azobis(cyclohexanecarbonitrile), 2-(t-butylazo)-2-cyanopropane, 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis[2-methyl-N-(hydroxyethyl)propionamide], 2,2'-azobis(N,N'-dimethyleneisobutyronitrile), 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutyramide), 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)ethyl]propionamide}, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] or 2,2'-azobis(isobutyramide) dihydrate, redox systems including combinations such as hydrogen peroxide, alkyl peroxides, peresters, percarbonates, etc. with any mixture of iron salts, titanium salts, zinc or sodium formaldehyde sulfoxylates, and reducing sugars, - alkali metal bisulfites, such as sodium metabisulfite, and alkali metal or ammonium persulfates, perborates or perchlorates in combination with reducing sugars; - Aryl phosphinic acids and others of similar nature, such as benzenephosphonic acid, and alkali metal persulfates in combination with reducing sugars. may in particular be used.

[0036] The polymerization temperature may in particular be between 25° C. and 95° C. The temperature may depend on the source of free radicals. If it is not a source of UV initiator type, it will be preferable to operate at between 50° C. and 95° C., more preferably between 60° C. and 80° C. In general, the higher the temperature, the more easily the polymerization is initiated (it is accelerated), but the lower the molar mass of the copolymer obtained.

[0037] According to a preferred embodiment of the present invention, the polymer (P) is obtained by radical polymerization of one monomer (AA), one monomer (AM) and one monomer (M) in the presence of a free radical source to obtain a polymer comprising repeat units derived from monomer (AA), repeat units derived from monomer (AM) and repeat units derived from monomer (M).

[0038] The polymer (P) can also be prepared by any controlled radical polymerization, among which reversible addition-fragmentation chain transfer (RAFT) and polymer design by interchange of xanthates (MADIX).

[0039] The use of RAFT or MADIX controlled radical polymerization agents (hereinafter referred to as "RAFT / MADIX agents") has been disclosed, for example, in WO 98 / 058974A (RHODIA CHIMIE), December 30, 1998, and WO 98 / 01478A (EIDUPONT DE NEMOURS AND COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANIZATION), January 15, 1998.

[0040] Preferably, the polymer (P) comprises monomers (AA), (AM) and (M): Monomer (AA): 1 to 95%, in particular 5 to 50%, preferably 20 to 40%, -monomer (AM): 1 to 90%, preferably 25 to 90%, more preferably 60 to 80%, Monomer (M): 0.1 to 50%, for example 1 to 30%, in particular 1 to 20%, further preferably 2 to 15% It is obtained by radical copolymerization of a mixture having the following molar ratios, based on the total amount of:

[0041] As a result, the polymer (P) is preferably - 1 to 95%, in particular 5 to 50%, preferably 20 to 40%, of repeat units derived from monomer (AA), -1 to 90%, preferably 25 to 90%, more preferably 50 to 80% of repeat units derived from monomer (AM), and - 0.1 to 50%, for example 1 to 30%, in particular 1 to 20%, further preferably 2 to 15%, of repeat units derived from monomer (M) Including, All of the foregoing mole percentages are based on the total number of moles of repeat units in the polymer (P).

[0042] In a preferred embodiment of the present invention, the polymer (P) is -5 to 50%, preferably 20 to 40%, of repeat units derived from monomer (AA), - 25 to 90%, more preferably 50 to 80%, of repeat units derived from monomer (AM); and - 0.1 to 50%, for example 1 to 30%, in particular 1 to 20%, further preferably 2 to 15%, of repeat units derived from monomer (M) Including, All of the foregoing mole percentages are based on the total number of moles of repeat units in the polymer (P).

[0043] Furthermore, the polymer (P) according to the invention preferably has a number average molecular weight (Mn) of at least 90 kDa, for example from 90 to 5000 kDa, preferably from 850 kDa to 2000 kDa.

[0044] According to a preferred embodiment, the polymer (P) is a statistical (random) copolymer having a weight average molecular weight of about 100 kDa to 10000 kDa, preferably 1000 kDa to 3000 kDa, and is obtained by radical polymerization of a mixture of monomers (AA), (AM) and (M), preferably in a ratio of about: -20~40% monomer (AA), - 50 to 80% monomer (AM), and -2 to 15% monomer (M) The molar ratio is:

[0045] According to one embodiment of the present invention, the polymer (P) is a block copolymer obtained by controlled radical polymerization using a RAFT / MADIX agent.

[0046] As used herein, "block copolymer" refers to any controlled architecture copolymer, including but not limited to true block polymers, which may be diblock, triblock, or multiblock, also known as linear star polymers; comb; and gradient polymers. Gradient polymers are linear polymers with a gradual change in composition along the polymer chain, which may range from random to block-like architecture. Each block of a block copolymer may itself be a homopolymer, a random copolymer, a random terpolymer, or a gradient polymer.

[0047] The polymer (P) can be provided in a solid or dry form or in a vectorized form, such as in the form of a solution or emulsion or suspension, in particular in the form of an aqueous solution. The vectorized form, such as an aqueous solution, can in particular contain 3 to 50% by weight, for example 5 to 30% by weight, of the polymer (P). The aqueous solution containing the polymer (P) can in particular be a solution obtained by the final aqueous phase preparation process of the radical polymerization process.

[0048] Since polymer (P) comprises repeat units derived from monomer (AA), it may suitably be converted into a polymer of its neutralized form [polymer (PN)] and thus comprises repeat units derived from at least an α,β-ethylenically unsaturated carboxylic acid in neutralized form.

[0049] Thus, in one embodiment, the present invention provides a polymer (PN), which comprises (A1) a repeating unit derived from a neutralized α,β-ethylenically unsaturated carboxylic acid monomer [monomer (AA)]; (A2) (Meth)acrylamide monomers [monomers (AM)] of formula (I), [ka] During the ceremony, R 1 and R 2 are the same or different and may be selected from a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a carboxylic acid group or an amide group; R 3 represents a hydrogen atom or a methyl group, R 4 and R 5 are the same or different and may be selected from a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms; a (meth)acrylamide monomer [monomer (AM)] of formula (I) (B) a repeat unit derived from at least one monomer (M) different from the monomers (AA) and (AM), the monomer (M) having the following formula (II): [ka] During the ceremony, R i is selected from the group consisting of H, -COOH, -CHCOOH or an alkyl group, the alkyl group being preferably a methyl group; R ii and R iiiare the same or different and may be selected from a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, or may be a -COOH group, A is a linkage selected from the group consisting of a -C(O)-O- group or a -C(O)-NH- group; R x is a straight-chain or branched C3-C alkyl group containing at least one functional group selected from the group consisting of a hydrogen atom, an ether (-O-), a heterocyclic group, a sulfonic acid group (-SO3H), a phosphonic acid group (-PO3H2), and a phosphoric acid group (-OPO3H2). 20 selected from hydrocarbon chain moieties, Repeat units derived from at least one monomer (M), It consists of:

[0050] The polymer (PN) can be prepared by neutralizing the acid groups of the repeating units derived from the monomers (AA) of the polymer (P) as defined above, the neutralization of the acid groups being carried out using either a salt containing a monovalent cation [salt (S)], preferably an alkali metal salt, a suitable solvent or ammonia.

[0051] The salt (S) can be any salt capable of neutralizing an acid group. In some embodiments, the salt (S) is a lithium salt selected from the group consisting of lithium carbonate, lithium hydroxide, lithium bicarbonate, and combinations thereof, preferably lithium carbonate. In some embodiments, the lithium salt does not contain lithium hydroxide.

[0052] The solvent for use in the step of neutralizing the polymer (P) can be any solvent capable of dissolving the salt (S) or ammonia and the resulting polymer (PN). Preferably, the solvent is selected from at least one of water, NMP, and aqueous solvents such as alcohols, for example, methanol, isopropanol, and ethanol. More preferably, the solvent is an aqueous solvent. Even more preferably, the solvent is water.

[0053] Preferably, the content of the salt (S) in the solvent is in the range of 0.5 to 10% by weight, preferably 1 to 5% by weight, based on the total weight of the solvent and the salt (S).

[0054] In some embodiments where the salt (S) is a lithium salt, the concentration of the lithium salt in the solvent provides at least 0.25, 0.5, 0.8, 1, 1.5, 2, 2.5, 3, 4 equivalents of lithium to the acid groups, in some embodiments, the concentration of the lithium salt in the solvent provides at most 5 equivalents, preferably at most 4 equivalents of lithium to the acid groups.

[0055] According to this embodiment, the polymer (PN) comprises repeat units derived from the lithiated form of at least one α,β-ethylenically unsaturated carboxylic acid monomer.

[0056] The content of the polymer (PN) in the solution after neutralization is in the range of 0.5 to 40% by weight, preferably 2 to 30% by weight, and more preferably 4 to 20% by weight, based on the total weight of the solvent and the polymer (PN).

[0057] The polymer (PN) can be isolated as a solid from the solution after neutralization and optionally stored for later use. The solid polymer (PN) can also be dissolved (or redissolved) in water to prepare the electrode-forming composition described below. However, preferably, the solution containing the polymer (PN) after neutralization is an aqueous solution that can be used directly, optionally with further dilution with water, in preparing the binder composition as described below.

[0058] In a preferred embodiment, the lithium salt of polymer (P), i.e., polymer (P-Li), was prepared by adding an amount of LiOH to completely neutralize an aqueous solution containing about 10 wt.% of polymer (P). The resulting solution had a pH in the range of 6.5-9 and contained about 10 wt.% of polymer (P-Li).

[0059] Neutralized polymer solutions have advantages in slurry processing and dispersion capabilities, since neutralized polymers exhibit increased viscosity. Furthermore, polymer (P-Li) has a pH more compatible with lithiated silicon forms, which usually perform better when processed in slurries with a pH higher than 7. An additional advantage is that the salified form of the repeating unit derived from monomer (AA) can avoid lithium ion capture by free acid groups in the cell, which can reduce the first cycle coulombic efficiency and therefore initial capacity.

[0060] Electrode forming composition [Composition (Comp)] The amount of polymer (P) that can be used in the electrode-forming composition (Comp) depends on various factors. One such factor is the surface area and amount of the active material, as well as the surface area and amount of the conductivity-imparting additive that is added to the electrode-forming composition. These factors are considered important because the binder particles provide a bridge between the conductive material particles, keeping them in contact.

[0061] The electrode-forming composition of the invention [Composition (Comp)] comprises one or more electrode active materials. For the purposes of the present invention, the term "electrode active material" is intended to mean a compound capable of incorporating or inserting into its structure and subsequently releasing therefrom alkali or alkaline earth metal ions during the charging and discharging phases of an electrochemical device. The electrode active material is preferably capable of incorporating or inserting and releasing lithium ions.

[0062] The nature of the electrode active material in the electrode-forming composition (Comp) of the present invention varies depending on whether the composition is used to manufacture a negative electrode (anode) or a positive electrode (cathode).

[0063] When forming a positive electrode for a lithium-ion secondary battery, the electrode active material can include a composite metal chalcogenide of the formula LiMQ2 (where M is at least one metal selected from transition metals such as Co, Ni, Fe, Mn, Cr, and V, and Q is a chalcogen such as O or S). Among these, it is preferable to use a lithium-based composite metal oxide of the formula LiMO2 (where M is the same as defined above). Preferred examples of these include LiCoO2, LiNiO2, LiNi x Co 1-x O2 (0 < x < 1) and spinel-structured LiMn2O4 can be mentioned.

[0064] As an alternative, when forming a positive electrode for a lithium-ion secondary battery, furthermore, the electrode active material is of the formula M1M2(JO4) f E 1-f (where M1 is lithium and can be partially substituted by another alkali metal corresponding to less than 20% of the M1 metal, M2 is a transition metal with a +2 oxidation level selected from Fe, Mn, Ni, or a mixture thereof, and can be partially substituted by one or more additional metals with an oxidation level of +1 to +5 corresponding to less than 35% of the M2 metal including 0, JO4 is an arbitrary oxyanion, J is any of P, S, V, Si, Nb, Mo, or a combination thereof, E is a fluoride, hydroxide, or chloride anion, and f is usually the molar fraction of the JO4 oxyanion included in the range of 0.75 to 1) of a lithiated or partially lithiated transition metal oxyanion-based electroactive material.

[0065] M1M2(JO4) as defined above f E 1-f The electrode active material is preferably phosphate-based and can have an ordered or modified olivine structure.

[0066] More preferably, the electrode active material when forming the positive electrode is of the formula Li 3-x M’ y M’’ 2-y(JO4)3, where 0≦x≦3 and 0≦y≦2, M′ and M″ are the same or different metals, at least one of which is a transition metal, JO4 is preferably PO4, which may be partially substituted with another oxyanion, and J is any of S, V, Si, Nb, Mo or a combination thereof. Even more preferably, the electrode active material has the formula Li(Fe x Mn 1-x LiFePO4 is a phosphate-based electroactive material (i.e., lithium iron phosphate of formula LiFePO4), where 0≦x≦1, and x is preferably 1.

[0067] When forming a negative electrode for a lithium ion secondary battery, the electrode active material may preferably include one or more carbon-based materials and / or one or more silicon-based materials.

[0068] In some embodiments, the carbon-based material may be selected from graphite, such as natural or artificial graphite, graphene, or carbon black. These materials may be used alone or as a mixture of two or more thereof.

[0069] The carbon-based material is preferably graphite.

[0070] The silicon-based compound may be one or more selected from the group consisting of chlorosilanes, alkoxysilanes, aminosilanes, fluoroalkylsilanes, silicon, silicon chloride, silicon carbide, silicon oxide, and lithium silicon oxide.

[0071] More particularly, the silicon-based compound may be silicon oxide or silicon carbide.

[0072] When present in the electrode active material, the silicon-based compound is included in an amount ranging from 1 to 70% by weight, preferably from 5 to 30% by weight, based on the total weight of the electroactive compound.

[0073] One or more optional conductivity-imparting additives may be added to improve the electrical conductivity of the resulting electrodes made from the compositions of the present invention. Conductive agents for batteries are known in the art.

[0074] Examples of these may include carbon-based materials such as carbon black, graphite fine powder, carbon nanotubes, graphene, or fibers, or metal fine powders or fibers such as nickel or aluminum. The optional conductive agent is preferably carbon black. Carbon black is available, for example, under the brand names Super P® or Ketjenblack®.

[0075] When present, the conductive agent is different from the carbon-based material described above.

[0076] The amount of the optional conductive agent is preferably 0 to 30% by weight of the total solids in the electrode-forming composition. In particular, for the cathode-forming composition, the optional conductive agent is typically 0 to 10% by weight, more preferably 0 to 5% by weight, of the total solids in the composition.

[0077] For anode-forming compositions that do not include a silicon based electroactive compound, the optional conductive agent is typically present in an amount of from 0% to 5% by weight, more preferably from 0% to 2% by weight, of the total amount of solids in the composition, while for anode-forming compositions that include a silicon based electroactive compound, it has been found beneficial to incorporate a larger amount of the optional conductive agent, typically from 0.5 to 30% by weight of the total amount of solids in the composition.

[0078] Furthermore, the electrode-forming composition of the present invention may contain at least one thickener, and when present, the amount of the thickener (also called rheology modifier) ​​is not particularly limited and generally ranges from 0.1 to 10% by weight, preferably 0.5 to 5% by weight, based on the total weight of the composition (Comp). The thickener is generally added to prevent or slow down settling of the powdered electrode material from the aqueous composition of the present invention while providing the appropriate viscosity of the composition for casting processes.

[0079] Non-limiting examples of suitable thickening agents include organic thickening agents such as carboxylated alkyl celluloses, such as carboxylated methyl cellulose, among others, and inorganic thickening agents such as natural clays, such as montmorillonite and bentonite, man-made clays, such as laponite, and others, such as silica and talc.

[0080] The total solids content (TSC) of the composition (Comp) of the invention is typically comprised between 15 and 70% by weight, preferably between 40 and 60% by weight, relative to the total weight of the composition (Comp). The total solids content of the composition (Comp) is understood to be the cumulative total of all its non-volatile components, including in particular the polymer (P), the electrode active material and any solid non-volatile additional additives, such as thickeners.

[0081] When preparing an aqueous binder solution separately and then combining the electrode active material with the optional conductive material and other additives to prepare the composition (Comp), a sufficient amount of water is used to form a stable solution. The amount of water used may range from the minimum amount required to form a stable solution to the amount required to achieve the desired total solids content in the electrode mixture after the electrode active material, optional conductive material, and other solid additives have been added.

[0082] Electrode (E) The electrode-forming composition (Comp) of the present invention can be used in a process for producing an electrode [electrode (E)], the process comprising: (i) providing a metal substrate having at least one surface; (ii) providing an electrode-forming composition [Composition (Comp)] as defined above; (iii) applying the composition (Comp) provided in step (ii) to at least one surface of the metal substrate provided in step (i), thereby providing an assembly comprising a metal substrate coated with said composition (Comp) on at least one surface; (iv) drying the assembly presented in step (iii); (v) subjecting the dried assembly obtained in step (iv) to a compression step to obtain the electrode (E) of the present invention; Includes.

[0083] The metal substrate is typically a foil, mesh or net made of a metal such as copper, aluminum, iron, stainless steel, nickel, titanium or silver.

[0084] Under step (iii) of the process of the present invention, the electrode-forming composition (Comp) is typically applied onto at least one surface of the metal substrate by any suitable procedure such as casting, printing and roll coating.

[0085] Optionally, step (iii) may be repeated, typically one or more times, by applying an electrode-forming composition (Comp) provided in step (ii) onto the assembly provided in step (iv).

[0086] Under step (iv) of the process of the invention, drying can be carried out either under atmospheric pressure or under vacuum. Alternatively, drying can be carried out under a modified atmosphere, such as, for example, under an inert gas, typically specifically devoid of moisture (water vapor content less than 0.001% v / v).

[0087] The drying temperature will be selected to achieve evaporative removal of the aqueous medium from the electrode (E) of the present invention.

[0088] In step (v), the dried assembly obtained in step (iv) can be subjected to a compression step, such as a calendaring process, to achieve the target porosity and density of the electrode (E) of the present invention.

[0089] Preferably, the dried assembly obtained in step (iv) is hot pressed, the temperature during the pressing step being comprised between 25°C and 130°C, preferably about 60°C.

[0090] The preferred target density of the electrode (E) is comprised between 1.4 and 2 g / cc, preferably at least 1.55 g / cc. The density of the electrode (E) is calculated as the sum of the products of the densities of the electrode's constituents multiplied by their mass ratio in the electrode formulation.

[0091] In a further aspect, the present invention relates to an electrode [electrode (E)] obtainable by the process of the present invention.

[0092] Thus, the present invention provides - a metal substrate having at least one surface; - directly adhered onto at least one surface of the metal substrate; a) at least one polymer (P), b) an electrode active material; c) an aqueous solvent; d) optionally at least one conductivity-imparting additive; and At least one layer of a composition comprising: The present invention relates to an electrode (E),

[0093] The composition directly adhered onto at least one surface of the metal substrate corresponds to the electrode-forming composition (Comp) of the invention from which the aqueous medium has been at least partially removed during the manufacturing process of the electrode, for example in step (iv) (drying) and / or in the pressing step (v). Thus, all preferred embodiments described with respect to the electrode-forming composition (Comp) of the invention are also applicable to the composition directly adhered onto at least one surface of the metal substrate in the electrode of the invention, except for the aqueous medium removed during the manufacturing process.

[0094] In a preferred embodiment of the present invention, the electrode (E) is a negative electrode. More preferably, the negative electrode comprises a silicon-based electrode active material.

[0095] In a further preferred embodiment, the present invention comprises, based on the total weight of the electrode: - 0.5 to 15% by weight, preferably 0.5 to 10% by weight, of a polymer (P), - 45 to 95% by weight, preferably 70 to 90% by weight, of carbon-based material, - 3 to 50% by weight, preferably 10 to 50% by weight, of silicon-based materials, and - 0 to 5% by weight, preferably 0.5 to 2.5% by weight, more preferably about 1% by weight of a conductivity imparting additive, The present invention relates to a negative electrode comprising:

[0096] The electrode (E) of the present invention is particularly suitable for use in electrochemical devices, in particular in secondary batteries.

[0097] The secondary battery of the present invention is preferably an alkaline secondary battery or an alkaline earth secondary battery.

[0098] The secondary battery of the present invention is more preferably a lithium ion secondary battery.

[0099] Electrochemical devices according to the present invention can be prepared by standard methods known to those skilled in the art.

[0100] To the extent that the disclosures of any patents, patent applications, and publications incorporated herein by reference conflict with the statements in this application to the extent that any term may be unclear, the statements herein shall control.

[0101] The invention will now be described with reference to the following examples, the purposes of which are merely illustrative and are not intended to limit the scope of the invention. EXAMPLES

[0102] raw materials AA: acrylic acid available from Aldrich; AM: Acrylamide monomer (50% in water) available from SNF; Itaconic acid available from Aldrich; SIPOMER WAMII: available from Solvay, 50% in water; SIPOMER PAM100: Available from Solvay; AMPS (2-acrylamido-2-methyl-1-propanesulfonic acid), available from Aldrich; MPEGMA750 (methoxypolyoxyethylene methacrylate), available from Evonik, 50% in water, trade name VISIOMER® MPEG 750 MA W; Transfer agent: a freshly prepared 1 wt% solution of a RAFT-type transfer agent available as Rhodixan A1 from Solvay in ethanol; Sodium persulfate in powder form available from WVR; (a 10 wt % solution in water was prepared immediately prior to polymerization experiments); Sodium formaldehyde sulfoxylate in powder form available from Aldrich; (a 10 wt % solution in water was prepared immediately prior to polymerization experiments); V-50 initiator: (2,2'-azobis(2-methyl-propionamidine) dihydrochloride) available in powder form from Aldrich; (10 wt % aqueous solution prepared immediately prior to polymerization experiments); Lithium hydroxide monohydrate (98% purity) available from Sigma-Aldrich; (8% by weight solution in water was prepared just before the polymerization experiment in the case of Example P-1) Silicon oxide, KSC-1064, commercially available from Shin-Etsu Chemical Co., Ltd., with a theoretical capacity of about 2100 mAh / g; Graphite, ACTILION2 from Imerys SA; Carbon black available as SC45 from Imerys SA; carboxymethyl cellulose (CMC), available as MAC 500LC from Nippon Paper; Styrene butadiene rubber (SBR) suspension (40 wt. % in water) available from Zeon Corporation as Zeon® BM-480B; Electrolyte mixture of 1M LiPF6 in EC / DMC 1 / 1 v / v containing 2 wt% VC and 10 wt% F1EC from Solvionic.

[0103] Synthesis procedures for polymers P-1, P-2, P-3, P-4, P-5 and P-6 The synthesis process was carried out in a thermally isolated reactor (Thermos-like flask) to minimize heat exchange with the surroundings.

[0104] The reactor was equipped with a small reflux system, a mechanical stirring system, a nitrogen purge line, and a lid containing multiple inlets into which the raw material feed lines were installed.

[0105] In the first step, all the monomers, solvent (water) and optional transfer agent were charged into the reactor and kept under stirring and nitrogen purge at room temperature for about 1 hour. In the case of Example P-1 before the nitrogen purge step, the pH of the reaction mixture was adjusted to pH=2.5 with 8% aqueous LiOH solution. Then, the redox type initiator was added to the reaction mixture. The thermal initiator was also added to the reaction mixture at the same time. The initiator was homogenized in the reaction mixture with mechanical stirring for a few minutes, and then the stirring and nitrogen purge were stopped.

[0106] An exothermic effect was observed within about 30 minutes to an hour increasing the reaction mixture temperature from room temperature to about 80-90° C. The reaction mixture was then maintained in the reaction flask for an additional 24 hours.

[0107] The reagent charges used in the synthesis of polymers P-1, P-2, P-3, P-4, P-5 and P-6 are shown in Table 1 below.

[0108] Synthesis procedure of polymer P-6 All syntheses were carried out in a reactor equipped with a temperature controlled heating system, a lid containing multiple inlets equipped with a reflux system, a mechanical stirring system, a nitrogen purge line, and raw material feed lines.

[0109] In the first step of the polymerization, 10% of the total monomers and 50% of the solvent (water) were charged into the reactor and kept under stirring and nitrogen purge at room temperature for about 1 hour. Then, a portion of thermal initiator V-50 (20% of the total amount) was added to the reaction mixture. The initiator was homogenized in the reaction mixture with mechanical stirring and the temperature was raised to 65°C using an external heating bath. After 15 minutes of temperature stabilization at 65°C, the remaining monomers solubilized in the remaining solvent (water) were added to the reaction mixture in a continuous feed over 4 hours. During and at the end of the monomer feed step, two portions of initiator (each portion being 20% ​​of the total initiator amount) were added in a shot mode. The polymerization reaction heat (exothermic effect) was controlled at 65°C by an external heating / cooling system. The temperature of the reaction mixture was then raised to 80°C over 1 hour, the last pending portion of initiator was added in a shot mode, and the reaction was continued for 2 hours. The reaction mixture was then cooled to room temperature. The flowable viscous product was further discharged from the reactor and analyzed in terms of solids content (1 gram sample heated at 130° C. to stable mass), residual monomers (HPLC analysis) and molecular weight distribution (SEC MALS analysis).

[0110] The molar ratios of monomers used in specific polymer examples are shown in Table 1.

[0111] [Table 1]

[0112] The reagent charges used in the synthesis of polymer P-6 are shown in Table 2 below.

[0113] [Table 2]

[0114] The flowable, highly viscous, gel-like products were then discharged from the flask and analyzed for their solids content (1 gram sample heated to stable mass at 130° C.), residual monomers (HPLC analysis) and molecular weight distribution (SEC MALS analysis).

[0115] The properties of polymers P-1 to P-6 are summarized in Table 3.

[0116] [Table 3]

[0117] Molecular weight determination The mass distribution of the polymers was determined by SEC MALS analysis (SEC: size exclusion chromatography - MALS: multi-angle laser scattering) to give real values ​​expressed in g / mol.

[0118] SEC MALS analysis was performed using two detectors: -Differential Refractometer RI-Concentration detector -MALS detector (multi-angle laser scattering) - mass detector The analysis was carried out using an HPLC chain equipped with

[0119] General procedure for preparation of aqueous Li-polymer solutions Approximately 40 g of a 5 wt % aqueous polymer solution was titrated with an aqueous LiOH solution (4.25 wt % LiOH in water) using a Mettler Toledo titrator T5 until the desired pH value was reached.

[0120] Preparation of electrode-forming composition and negative electrode The electrode-forming compositions and negative electrodes were prepared as detailed below using the following equipment: Mechanical mixers: Dispermat® series planetary mixers (Speedmixers) and high shear mechanical mixers with inclined impellers; Film coater / doctor blade: Elcometer® 4340 with motor / Zehntner ZUA2000; Vacuum oven: BINDER VD 23 with vacuum; and Roll press: precision 4 inch hot rolling press / calendering up to 100℃.

[0121] Example 1 - Terpolymer Anode 3% Binder An aqueous composition was prepared by mixing 22.0 g of an aqueous solution of 2% by weight of CMC, 0.44 g of carbon black, 8.448 g of silicon oxide, 33.792 g of graphite, and 17.790 g of deionized water. After gentle stirring in a planetary mixer for 10 minutes, 17.53 g of a 5% solids solution of polymer P-3 in water was added. The mixture was homogenized by gentle stirring in a planetary mixer for 10 minutes, and then mixed again by gentle stirring for 1 hour. After 1 hour, the shear force was reduced and the slurry was mixed again by low agitation.

[0122] The binder composition thus obtained was cast on a copper foil with a thickness of 18.5 μm using a doctor blade and the coating layer was dried in an oven at a temperature of 90 ° C for about 70 minutes to obtain a negative electrode. The thickness of the dried coating layer was about 60 μm. The electrode was then hot pressed at 60 ° C in a roll press to obtain a target density of 1.6 g / cc. The obtained negative electrode had the following composition: 19.2 wt. % silicon oxide, 76.8 wt. % graphite, 2 wt. % itaconic acid (content 21.4% ~ id48), 1 wt. % CMC and 1 wt. % carbon black. Thus, electrode E1 was obtained. The quality of the electrode is good enough for cell testing.

[0123] Example 2 - Terpolymer Anode 3% Binder An aqueous composition was prepared by mixing 22.0 g of an aqueous solution of 2% by weight of CMC, 0.44 g of carbon black, 8.448 g of silicon oxide, 33.792 g of graphite, and 26.153 g of deionized water. After 10 minutes of gentle stirring in a planetary mixer, 9.167 g of a 9.6% solids solution of polymer P-6 in water was added. The mixture was homogenized by gentle stirring in a planetary mixer for 10 minutes, and then mixed again by gentle stirring for 1 hour. After 1 hour, the shear force was reduced and the slurry was mixed again by low agitation.

[0124] The binder composition thus obtained was cast on a copper foil with a thickness of 18.5 μm using a doctor blade and the coating layer was dried in an oven at a temperature of 90 ° C for about 70 minutes to obtain a negative electrode. The thickness of the dried coating layer was about 60 μm. The electrode was then hot pressed in a roll press at 60 ° C to obtain a target density of 1.6 g / cc. The obtained negative electrode had the following composition: 19.2 wt. % silicon oxide, 76.8 wt. % graphite, 2 wt. % Sipomer WAMII (content 2.5% ~ id56), 1 wt. % CMC and 1 wt. % carbon black. Thus, electrode E2 was obtained. The quality of the electrode is good enough for cell testing.

[0125] Example 3 - Terpolymer Anode 3% Binder An aqueous composition was prepared by mixing 20.0 g of an aqueous solution of 2% by weight of CMC, 0.40 g of carbon black, 7.52 g of silicon oxide, 30.080 g of graphite, and 10.127 g of deionized water. After 10 minutes of gentle stirring in a planetary mixer, 31.873 g of a 5% solids solution of polymer P-1 in water was added. The mixture was homogenized by gentle stirring in a planetary mixer for 10 minutes, and then mixed again by gentle stirring for 1 hour. After 1 hour, the shear force was reduced and the slurry was mixed again by low agitation.

[0126] The binder composition thus obtained was cast on a copper foil with a thickness of 18.5 μm using a doctor blade, and the coating layer was dried in an oven at a temperature of 90° C. for about 70 minutes to obtain a negative electrode. The thickness of the dried coating layer was about 60 μm. The electrode was then hot pressed in a roll press at 60° C. to obtain a target density of 1.6 g / cc. The resulting negative electrode had the following composition: 18.8% by weight of silicon oxide, 75.2% by weight of graphite, 4% by weight of AMPS (content 20%-id27), 1% by weight of CMC and 1% by weight of carbon black. Thus, electrode E3 was obtained. The quality of the electrode is good enough for cell testing.

[0127] Example 4 - Terpolymer Anode 3% Binder An aqueous composition was prepared by mixing 20.0 g of an aqueous solution of 2% by weight of CMC, 0.40 g of carbon black, 7.52 g of silicon oxide, 30.080 g of graphite, and 10.127 g of deionized water. After gentle stirring in a planetary mixer for 10 minutes, 31.873 g of a 5% solids solution of polymer P-2 in water was added. The mixture was homogenized by gentle stirring in a planetary mixer for 10 minutes, and then mixed again by gentle stirring for 1 hour. After 1 hour, the shear force was reduced and the slurry was mixed again by low agitation.

[0128] The binder composition thus obtained was cast on a copper foil with a thickness of 18.5 μm using a doctor blade, and the coating layer was dried in an oven at a temperature of 90° C. for about 70 minutes to obtain a negative electrode. The thickness of the dried coating layer was about 60 μm. The electrode was then hot pressed in a roll press at 60° C. to obtain a target density of 1.6 g / cc. The resulting negative electrode had the following composition: 18.8% by weight of silicon oxide, 75.2% by weight of graphite, 4% by weight of MPEGMa (content 10%-id30), 1% by weight of CMC and 1% by weight of carbon black. Thus, electrode E4 was obtained. The quality of the electrode is good enough for cell testing.

[0129] Comparative Example CE1: Anode containing styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) An aqueous composition was prepared by mixing 25.0 g of an aqueous solution of 2% by weight of CMC and 0.50 g of carbon black, and after gentle stirring with a planetary mixer for 10 minutes, 9.60 g of silicon oxide, 38.4 g of graphite and 23.861 g of deionized water were added. The mixture was homogenized by gentle stirring with a planetary mixer for 10 minutes, and then mixed again by gentle stirring for 1 hour.

[0130] After mixing for about 1 hour, 2.639 g of SBR suspension was added to the composition and mixed again for 1 hour on low agitation.

[0131] The binder composition thus obtained was cast on a copper foil with a thickness of 18.5 μm using a doctor blade, and the coating layer was dried in an oven at a temperature of 90° C. for about 70 minutes to obtain a negative electrode. The thickness of the dried coating layer was about 60 μm. The electrode was then hot pressed in a roll press at 60° C. to obtain a target density of 1.6 g / cc. The resulting negative electrode had the following composition: 19.2% by weight of silicon oxide, 76.8% by weight of graphite, 2% by weight of SBR, 1% by weight of CMC and 1% by weight of carbon black. Electrode CE1 was thus obtained. The quality of the electrode is good enough for cell testing.

[0132] Battery manufacturing Coin cells (CR2032 type, 20 mm diameter) were prepared in a glove box under Ar gas atmosphere by punching small disks of negative electrodes prepared according to E1, E2, E3, E4 and CE1 together with equilibrated NMC positive disks purchased from CUSTOMCELLS. The electrolyte used to prepare the coin cells was a mixture of 1M LiPF6 in EC / DMC 1 / 1 v / v containing 2 wt% VC and 10 wt% F1EC from Solvionic. Polyethylene separators (commercially available from Tonen Chemical Co., Ltd.) were used as received.

[0133] Capacity retention test Cycling stability of full cells at a C-rate of 1C (open capacity was measured three times and is shown in Table 4 below):

[0134] [Table 4]

[0135] The results show that the discharge capacity retention in the battery including the electrode of the present invention is surprisingly much higher than that of the battery fabricated using the electrode of Comparative Example 1.

Claims

1. A terpolymer [polymer (P)], (A1) A repeating unit derived from an α,β-ethylenically unsaturated carboxylic acid monomer [monomer (AA)] of formula (III), 【Chemistry 1】 In the formula, R ａ , R ｂ and R ｃ are the same or different from each other, and are a hydrogen atom and C １ ~C ３ independently selected from hydrocarbon groups, a repeating unit derived from monomer (AA); (A2) A repeating unit derived from a (meth)acrylamide monomer [monomer (AM)] of formula (I), 【Chemistry 2】 During the ceremony, R １ and R ２ are the same as or different from each other and may be selected from a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a carboxylic acid group or an amide group; R ３ represents a hydrogen atom or a methyl group, R ４ and R ５ are the same or different and may be selected from a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, a repeating unit derived from a monomer (AM); (B) a repeating unit derived from a monomer (M) different from the monomers (AA) and (AM), wherein the monomer (M) has the following formula (II): 【Transformation 3】 During the ceremony, R ｉ is H, -COOH, -CH ２ COOH or an alkyl group, said alkyl group being preferably a methyl group; R ｉｉ and R ｉｉｉ are the same as or different from each other and may be selected from a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, or may be a —COOH group; A is a linkage selected from the group consisting of a —C(O)—O— group or a —C(O)—NH— group; R ｘ represents a hydrogen atom, an ether (—O—), a heterocyclic group, a sulfonic acid group (—SO ３ H), phosphonic acid group (-PO ３ H ２ ) and a phosphate group (-OPO ３ H ２ ) a linear or branched chain C containing at least one functional group selected from the group consisting of ３ ~C ２０ selected from hydrocarbon chain moieties, a repeating unit derived from a monomer (M); A terpolymer [polymer (P)] consisting of:

2. The monomer (M) a compound of formula (IIa), 【Chemistry 4】 a compound of formula (IIb), 【Transformation 5】 or Compound of formula (IIc) 【Transformation 6】 is selected from the group consisting of The polymer (P) according to claim 1, wherein in the formulas (IIa) to (IIc), n is an integer of 1 to 15.

3. The monomer (M) Compound of formula (IId) 【Transformation 7】 or Compound of formula (IIe) 【Transformation 8】 The polymer (P) according to claim 1, selected from the group consisting of:

4. 4. The polymer (P) according to claim 1, wherein the monomer (AA) of formula (III) is selected from the group consisting of acrylic acid, methacrylic acid, ethacrylic acid, croton, methyl(meth)acrylic acid, ethyl(meth)acrylic acid, propyl(meth)acrylic acid, isopropyl(meth)acrylic acid, n-butyl(meth)acrylic acid, 2-ethylhexyl(meth)acrylic acid, n-hexyl(meth)acrylic acid and n-octyl(meth)acrylic acid.

5. The polymer (P) according to any one of claims 1 to 3, wherein the (meth)acrylamide monomer [monomer (AM)] of formula (I) is selected from the group consisting of (meth)acrylamide or N-substituted (meth)acrylamides such as N-alkylacrylamides and N,N-dialkylacrylamides.

6. - 1 to 95%, in particular 5 to 50%, preferably 20 to 40%, of repeat units derived from monomer (AA), - 1 to 90%, preferably 25 to 90%, more preferably 50 to 80% of repeat units derived from monomer (AM), and - 0.1 to 50%, for example 1 to 30%, in particular 1 to 20%, and even more particularly 2 to 15% of repeat units derived from monomer (M) Including, Polymer (P) according to any one of claims 1 to 3, wherein all of the foregoing mole percentages are based on the total number of moles of repeat units of said polymer (P).

7. - 5 to 50%, preferably 20 to 40%, of repeat units derived from monomer (AA), - 25 to 90%, more preferably 50 to 80%, of repeat units derived from monomer (AM), and - 0.1 to 50%, for example 1 to 30%, in particular 1 to 20%, and even more particularly 2 to 15% of repeat units derived from monomer (M) Including, 7. The polymer (P) of claim 6, wherein all of the foregoing mole percentages are based on the total number of moles of repeat units of said polymer (P).

8. Polymer (P) according to any one of claims 1 to 3, wherein the monomer (AA) is in its neutralized form.

9. 9. Polymer (P) according to claim 8, wherein the neutralized form of said monomer (AA) is the lithiated form.

10. An aqueous electrode-forming composition [Composition (Comp)], b) at least one polymer (P) according to any one of claims 1 to 3; and b) an electrode active material; and c) an aqueous solvent; d) optionally at least one conductivity-imparting additive; and An aqueous electrode-forming composition [composition (Comp)] comprising:

11. 11. The composition (Comp) of claim 10, further comprising at least one thickener.

12. A process for producing an electrode [electrode (E)], comprising: (i) providing a metal substrate having at least one surface; (ii) providing a composition (Comp) according to claim 10; (iii) applying the composition (Comp) provided in step (ii) to the at least one surface of the metal substrate provided in step (i), thereby providing an assembly comprising a metal substrate coated with the composition (Comp) on the at least one surface; (iv) drying the assembly provided in step (iii); (v) subjecting the dried assembly obtained in step (iv) to a compression step to obtain the electrode (E) of the present invention; A process for producing an electrode [electrode (E)], comprising:

13. 13. An electrode [electrode (E)] obtained by the process according to claim 12.

14. Electrochemical device comprising at least one electrode (E) according to claim 13.

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