Acrylate Binder

Abstract

The present invention relates to a polymer for a non-aqueous electrolyte secondary battery, an electrode slurry for the secondary battery, and a secondary battery including the same.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to European Patent Application Publication No. 21306620.2, filed November 22, 2021, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to a polymer for use in a non-aqueous electrolyte secondary battery, an electrode slurry for the secondary battery, and a secondary battery including the same. [Background technology]

[0003] Batteries for EV vehicles need to continue to improve in terms of energy density to eliminate range anxiety and enable wider and faster adoption. The adoption of silicon anodes is one of the most powerful techno-strategies to increase battery capacity and therefore energy density. Silicon (Si) has been widely studied as an anode active material due to its high theoretical specific capacity (3600mAh / g), much higher than the current anode active material, graphite (<400mAh / g).

[0004] However, in practical applications, Si is very challenging because the dramatic volume changes during lithium insertion and extraction (charging and discharging of the battery) promote the mechanical destruction of the electrode, causing the loss of electrical contact and resulting in continuous electrolyte decomposition at the active material surface. One strategy widely adopted in the battery market is to use a limited amount of silicon (<10%) mixed with graphite as the active material. This strategy mitigates the detrimental effect of silicon on the mechanical integrity of the electrode, but the improvement in energy density achieved in proportion to the amount of silicon is very limited. The binder, typically an organic polymer, acts as a binding matrix that maintains contact between the active material throughout the anode layer and the current collector on which the anode is deposited during fabrication.

[0005] The binder currently used in anodes, and therefore active material graphite with low Si content, is a combination of rubber (SBR) and cellulose derivatives (CMC). Said binder is not suitable for silicon-rich anodes (silicon content >10%) because it is not rigid enough. Further efforts to achieve Si-rich anodes (>10%) are still needed, especially in binder design, because the binder plays an important role in adapting to volume changes and can prevent electrical contact loss between Si particles. In fact, it is believed that a robust polymer binder that can reversibly interact with the silicon surface can suppress the mechanical fracture of the anode during cycling.

[0006] It is generally accepted that chemical functional groups that provide favorable surface interactions with both the active material and the current collector substrate are necessary. Furthermore, chemical compatibility with the liquid electrolyte and other additives is a prerequisite for any binder, regardless of the active material composition.

[0007] Many approaches are being pursued to develop next generation binders compatible with silicon anodes.

[0008] In this regard, polycarboxylate binders and derivatives containing polyacrylic acid, polyamic acid, polyacrylamide and other hydrogen bonding structures are being pursued.

[0009] 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.

[0010] WO 2022 / 013070 discloses that certain modified polycarboxylate polymers, in particular modified polyacrylic acids containing acrylamide monomers, make it possible to prevent the degradation of silicon-rich anodes. The distribution of acyl acid (AA) and acrylamide (AM) monomers in the polymers gives them better adhesion to metals compared to lithiated polyacrylic acid (PAA). Furthermore, anodes obtained by using the polymers as binders show good cycle stability, which is related to the higher cohesion of the polymers compared to SBR / CMC systems.

[0011] Although such binder types effectively form hydrogen bonds between the pendant acid groups and silanol groups on the silicon surface, which addresses the silicon volume change issue, they do not have favorable rheological and dispersant behavior, and therefore require additives such as carboxymethylcellulose (CMC), a well-known rheological modifier and dispersant, for effective electrode preparation.

[0012] Applicants have unexpectedly discovered that certain polycarboxylate polymers, when appropriately lithiated, exhibit surprisingly good dispersant properties and are therefore suitable for the preparation of anode slurries even in the absence of a dispersant. Summary of the Invention

[0013] The object of the present invention is to provide an acrylic polymeric dispersant [polymer (P)] for dispersing powder particles in an aqueous electrode-forming composition, comprising: (A) repeat units derived from at least one α,β-ethylenically unsaturated carboxylic acid monomer [monomer (AA)] in neutralized form; (B) a repeating unit derived from at least one (meth)acrylamide monomer [monomer (AM)]; and is an acrylic polymer dispersant [polymer (P)] having a weight average molecular weight of about 500 kDa to 10,000 kDa.

[0014] The applicant has surprisingly found that the polymer (P) dissolved in water can be suitably used as a binder for preparing the electrode-forming composition due to its excellent dispersing ability, which is much better than that of CMC or a blend of CMC and an acrylic polymer.

[0015] Indeed, polymer (P) gives stable slurries without settling for over 2 days without the use of rheology modifiers.

[0016] Thus, in another object, the present invention provides an aqueous electrode-forming composition [Composition (Comp)] for use in the preparation of an electrode for an electrochemical device, comprising: a) at least one polymer (P) as defined above, b) an electrode active material; c) an aqueous solvent; d) optionally, at least one conductivity-imparting additive; The present invention provides an aqueous electrode-forming composition [Composition (Comp)], characterized by comprising:

[0017] In another aspect, the present invention provides a process for producing an electrode [electrode (E)], comprising the steps of: (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 including:

[0018] In a further aspect, the present invention relates to an electrode [electrode (E)] obtainable by the process of the present invention.

[0019] In a still further object, the present invention relates to an electrochemical device comprising at least one electrode (E) of the present invention. [Brief description of the drawings]

[0020] [Figure 1] 1 shows optical microscope images of Preparations 1 to 3 of the examples. 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" is intended herein to mean an electrochemical cell comprising 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 in particular 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 and which can be deposited on a metal substrate and subsequently dried to form an 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) is characterized by comprising repeat units derived from at least one α,β-ethylenically unsaturated carboxylic acid monomer in neutralized form [monomer (AA)] and at least one (meth)acrylamide monomer [monomer (AM)].

[0028] The at least one α,β-ethylenically unsaturated carboxylic acid monomer (AA) preferably has the formula (I): [ka] (In the formula, R a , R b and R c are equal to or different from each other and are independently selected from a hydrogen atom and a C1-C3 hydrocarbon group; S is a monovalent cation, preferably an alkali metal salt. It is a compound of the formula:

[0029] More preferably, monomer (AA) is a compound of formula (I) as defined above, selected from the group consisting of salts of acrylic acid, methacrylic acid, Sipomer® B-CEA (sold by Solvay), ethacrylic acid, crotonic acid, 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.

[0030] The (meth)acrylamide monomer [monomer (AM)] preferably has the formula (II): [ka] (In the formula, R 5represents a hydrogen atom or a methyl group, R 6 and R 7 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; R 8 and R 9 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. It is a compound of the formula:

[0031] The monomer (AM) is preferably selected from the group consisting of (meth)acrylamide or N-substituted (meth)acrylamides such as N-alkylacrylamides, N,N-dialkylacrylamides.

[0032] Polymer (P) may optionally comprise repeat units derived from at least one ethylenically unsaturated monomer (M) different from monomers (AA) and (AM), provided that the total amount of monomers (AA) and / or monomers (AM) is at least 60 mol % relative to the total moles of repeat units of polymer (P).

[0033] The monomer (M) is Monomer (M1), which is an ethylenically unsaturated monomer having an unsaturated heterocyclic group containing at least one nitrogen atom, and which has the following formula (III): [ka] (In the formula, R 1 is H or an alkyl group, the alkyl group being preferably a methyl group; R 2 is H or an alkyl group, R 3 and R 4 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 is, - a single covalent bond, and - Spacer is a bond selected from the group consisting of X, Y and Z are each independently selected from carbon atoms or nitrogen atoms; a, b and c are each independently selected from integers 1 to 2; Each dashed dotted line represents an optional double bond. A monomer (M1) having the formula a monomer (M2) different from the monomers (AA) and (AM) and having the following formula (IV): [ka] (In the formula, 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, B is a bond selected from the group consisting of a -C(O)-O- group and a -C(O)-NH- group; R x is a linear 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 salt of a sulfonic acid group (-SO3Cat), a phosphonic acid group (-PO3H2), a salt of a phosphonic acid group (-PO3Cat2), a phosphoric acid group (-OPO3H2), and a salt of a phosphoric acid group (-OPO3Cat2). 20 Cat is preferably a monovalent cation selected from alkali metal cations, more preferably Na + , K + and Li + (selected from A monomer (M2) having the formula - a monomer (M3), alkyl esters of maleic anhydride and (meth)acrylic acid, such as monomethyl maleic anhydride, dimethyl maleic anhydride, monoethyl maleic anhydride, diethyl maleic anhydride, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, hydroxyalkyl esters of maleic anhydride and (meth)acrylic acid, such as monohydroxyethyl maleic anhydride, dihydroxyethyl maleic anhydride, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, - ethoxylates and propoxylates derived from maleic anhydride, such as poly(propylene oxide)-b-poly(ethylene oxide) maleic acid half-esters or diesters, alkyl-poly(ethylene oxide) maleic acid half-esters or diesters, - ethoxylates and / or propoxylates derived from the ethoxylation and / or propoxylation of hydroxyalkyl (meth)acrylic acids, such as poly(propylene oxide)-b-poly(ethylene oxide)-ethyl (meth)acrylate; - ethoxylates and / or propoxylates derived from the esterification (transesterification) of (meth)acrylic acid and esters, such as poly(propylene oxide)-b-poly(ethylene oxide) (meth)acrylates and alkyl-poly(ethylene oxide) (meth)acrylates, vinyl esters, such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, 2-ethylhexyl vinyl ether, vinylcyclohexyl ether, dodecyl vinyl ether, 2-(diethylamino)ethyl vinyl ether, 2-(di-n-butylamino)ethyl vinyl ether, Allyl ethers, such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, 2-ethylhexyl vinyl ether; vinyl esters, such as vinyl acetate or vinyl propionate, Alkyl-substituted acrylamides, such as N-tert-butylacrylamide or N-methyl(meth)acrylamide Monomer (M3), which is a hydrophobic or amphiphilic monomer selected from the group consisting of may be suitably selected from the group consisting of:

[0034] The polymer (P) can be obtained by radical copolymerization of a mixture of at least one monomer (AA), at least one monomer (AM) and optionally at least one monomer (M), as described above, to provide a polymer (PH), followed by neutralization of the acid groups of the repeat units derived from the monomer (AA), the neutralization of the acid groups being carried out either with a salt [salt (S)], including a monovalent cation, preferably an alkali metal salt, in a suitable solvent or with ammonia.

[0035] 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.

[0036] The solvent used in the step of neutralizing the polymer (PH) can be any solvent capable of dissolving the salt (S) or ammonia and the resulting polymer (P). Preferably, the solvent is selected from at least one of water, NMP and aqueous solvents such as alcohols, for example methanol, isopropanol and ethanol. Most preferably, the solvent is an aqueous solvent. Even more preferably, the solvent is water.

[0037] 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).

[0038] 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.

[0039] According to said embodiment, the polymer (P) comprises repeat units derived from the lithiated form of at least one α,β-ethylenically unsaturated carboxylic acid monomer.

[0040] The content of polymer (P) in the solution after neutralization is in the range of 0.5 to 40% by weight, preferably 2 to 30% by weight, more preferably 4 to 20% by weight, based on the total weight of the solvent and polymer (P).

[0041] In a preferred embodiment, the lithium salt of the polymer (P), i.e., polymer (P-Li), was prepared by adding an amount of LiOH to at least partially neutralize an aqueous solution containing about 10% by weight of the polymer (PH). The resulting solution had a pH in the range of 6.5-9, preferably 7-8, and contained about 10% by weight of the polymer (P-Li).

[0042] Neutralized polymer solutions have advantages in slurry processing and dispersion capabilities since the neutralized polymers exhibit increased viscosity. Additionally, the polymer (P-Li) has a pH that is more compatible with the lithiated silicon forms, which typically perform better when processed in slurries having a pH greater than 7.

[0043] According to one embodiment of the present invention, the polymer (P) comprises at least one monomer (M1), which is an ethylenically unsaturated monomer having an unsaturated heterocyclic group having at least one nitrogen atom as defined above.

[0044] The "unsaturated heterocyclic group having at least one nitrogen atom" in the monomer (M1) of formula (III) is preferably a 5- to 6-membered aromatic cyclic group having at least one N in the ring, for example, [ka] (wherein * represents the attachment point of bond A) Includes.

[0045] Bond A and Residue R 2 may be attached to the heterocyclic group at any position, either at a carbon atom or at a nitrogen atom.

[0046] The monomer (M1) is, for example, - vinylimidazoles (VIm) of formula (IIIa): [ka] - 2-methyl-1-vinylimidazole of formula (IIIb) [ka] - 1-vinyl-1,2,4-triazole of formula (IIIc) [ka] - 2-vinylpyrazine of formula (IIId) [ka] - 4-vinylpyridine of formula (IIIe) [ka] - 2-vinylpyridine of formula (IIIf) [ka] - hydroxyl-(meth)acrylate imidazole derivatives of formula (IIIg) [ka] It could be.

[0047] The divalent spacer group A in formula (III) is typically a group -CO-NH-(CH2) n -, -CO-O-(CH2) n or -CO-O-(CH2) n -O-CO-, for example, formula (III-X): [ka] (In the formula, R 6 , R 8 and R 9 is as defined above) and a compound of formula (III-Y): [ka] (In the formula, R 2 is as defined above, and A 1 and A 2 are two groups that react together to form a covalent bond) Any other covalent linker group resulting from reaction with a compound of formula (I) may be considered.

[0048] For example, A 2 is -(CH2) m -NH2 group, where m is 1 to 4, preferably 2 or 3. In that case, A 1 can be, for example, a carboxylic acid, an acid chloride, an acid anhydride, or an epoxy.

[0049] According to another variant, A 2 is -(CH2) m In the formula, m is 1 to 4, preferably 2 or 3. In that case, A 1can be, for example, a carboxylic acid, an acid chloride, an anhydride or an ester.

[0050] According to this embodiment, the polymer (P) is obtained by copolymerizing the monomers (AA), (AM) and at least one monomer (M1) to obtain the polymer (PH), i.e. it is a polymer having a structure obtained by such a polymerization, followed by neutralization of the acid groups of the repeat units originating from the monomer (AA), although the polymer (P) is not necessarily obtained by this process. Alternatively, the polymer (PH) can be obtained, for example, by a first step (E1) of copolymerizing the monomers (AA), (AM) and a compound of formula (III-X), resulting in the polymer (P0), and then a second step (E2) of post-grafting the polymer (P0) by reaction with the compound (III-Y).

[0051] A in the compound (III-Y) used in step (E2) 2 Ga-(CH2) m When it is an -NH2 group, the compound (III-X) used in step (E1) may advantageously be chosen from additional acrylic or methacrylic acid or their esters, maleic anhydride, vinylbenzyl chloride, glycidyl methacrylate and (blocked) isocyanatoethyl methacrylate.

[0052] A in the compound (III-Y) used in step (E2) 2 Ga-(CH2) m When it is an --OH group, the compound (III-X) used in step (E1) may advantageously be chosen from additional acrylic acid, methacrylic acid, maleic anhydride or esters thereof.

[0053] In addition, quaternization of all or a portion of the imidazole functional groups of the polymer (PH) may occur and may result from the quaternization of all or a portion of the monomers and / or the subsequent quaternization of all or a portion of the imidazole functional groups of the polymer.

[0054] According to another embodiment of the invention, the polymer (P) comprises at least one monomer (M2) of formula (IV) as defined above.

[0055] Residue R of monomer (M2) x The "heterocyclic group" in the above formula (I) includes saturated heterocyclic groups having at least one nitrogen atom compound such as imidazolidinone.

[0056] According to a first variant in which B in formula (IV) is a -C(O)-O- group, the monomer (M2) is, for example, a compound of formula (IVa) [ka] Compound of formula (IVb) [ka] or a compound of formula (IVc) [ka] In formulae (IVa) to (IVc), R i , R ii and R iii is as defined above, and n is an integer from 1 to 40.

[0057] According to a second variant in which B in formula (IV) is a -C(O)-NH- group, the monomer (M2) is, for example, a compound of formula (IVd) [ka] or a compound of formula (IVe) [ka] In formula (IVd) and (IVe), R i , R ii and R iii is as defined above.

[0058] According to this embodiment, the polymer (P) is obtained by copolymerizing the monomers (AA), (AM) and at least one monomer (M2) to obtain a polymer (PH), i.e. a polymer having a structure obtained by such a polymerization, followed by neutralization of the acid groups of the repeat units originating from the monomer (AA), although the polymer (PH) is not necessarily obtained by this process.

[0059] According to another embodiment, the polymer (P) may comprise one or more further monomers (M3) as defined above.

[0060] Advantageously, the molar proportion of monomer (M3) in polymer (P) is less than 5% by mole.

[0061] At least one polymer (P) may further comprise less than 1 mol % of one or more further crosslinking monomers (XL-M) containing at least two ethylenic unsaturations.

[0062] In this embodiment in which an additional monomer (XL-M) is present in the polymer (P), said crosslinking monomers are selected from the group consisting of N,N'-methylenebisacrylamide (MBA), N,N'-ethylenebisacrylamide, polyethylene glycol (PEG) diacrylates, triacrylates, divinyl ethers, typically trifunctional divinyl ethers, such as tri(ethylene glycol) divinyl ether (TEGDE), N-diallylamine, N,N-diallyl-N-alkylamines, their acid addition salts and their quaternization products (alkyl as used here is preferentially (C1-C3) alkyl), compounds of N,N-diallyl-N-methylamine and of N,N-diallyl-N,N-dimethylammonium, such as chlorine. or alternatively may be selected from ethoxylated trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate (DiTMPTTA), divinylbenzene (DVB), ethoxylated or propoxylated bisphenol A diacrylate, dipropylene glycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA), propoxylated di(meth)acrylates, butyloxylated di(meth)acrylates, dimethylacrylamide, 1,4-butanediol dimethacrylate (BDDMA), 1,6-hexanediol dimethacrylate (HDDMA), 1,3-butylene glycol dimethacrylate (BGDMA) and derivatives thereof.

[0063] The molar proportion of monomer (XL-M) cannot exceed 1 mol % of the total moles of monomers present in polymer (P), in order to avoid gel formation and viscosity increase. Advantageously, the molar ratio of monomer (XL-M) is less than 0.5 mol %.

[0064] According to said embodiment, the polymer (P) obtained by a process comprising a polymerization step further comprising monomer (XL-M) is at least partially crosslinked.

[0065] In one preferred embodiment of the present invention, the monomers (M3) or (XL-M) are absent in the polymer (P), which is because the polymer (PH) at least one [monomer (AA)] as defined above, - at least one [monomer (AM)] as defined above, and at least one monomer (M) selected from monomer (M1) and monomer (M2); by radical copolymerization of, in particular of a mixture consisting essentially of, to give a polymer (PH), followed by neutralization of the acid groups of the repeating units originating from monomer (AA).

[0066] Typically, the polymer (P) is at least one monomer (AA), - at least one monomer (AM), at least one monomer (M) selected from the monomers (M1), (M2) and (M3), and - optionally at least one monomer (XL-M) in the presence of a free radical source, followed by neutralization of the acid groups of the repeating units derived from monomer (AA).

[0067] Any free radical source can be used. It is particularly possible to generate free radicals spontaneously, for example by raising the temperature, with a suitable monomer such as styrene. It is possible to generate free radicals by irradiation, especially 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 or may not be water-soluble. It may be preferable to use water-soluble initiators or initiators that are at least partially water-soluble.

[0068] 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 hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxyoctoate, t-butyl peroxyneodecanoate, t-butyl peroxyisobutyrate, lauroyl peroxide, t-amyl peroxypivalate, t-butyl peroxypivalate, dicumyl peroxide, benzoyl peroxide, sodium persulfate, 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'-dimethyleneisobutyl amidine) dihydrochloride, 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, for example, combinations of hydrogen peroxide, alkyl peroxides, peresters, percarbonates, persulfates, etc., and mixtures of any of the iron salts, titanium salts, zinc formaldehyde sulfoxylate or sodium formaldehyde sulfoxylate with reducing sugars, - alkali metal or ammonium persulfates, perborates or perchlorates in combination with alkali metal bisulfites such as sodium metabisulfite and reducing sugars; - Alkali metal persulfates in combination with aryl phosphinic acids such as benzenephosphonic acid and others of similar nature and reducing sugars may in particular be used.

[0069] The polymerization temperature may in particular be between 25°C and 95°C. The temperature may depend on the free radical source. If it is not a UV initiator type source, 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 resulting copolymer.

[0070] According to a preferred embodiment of the present invention, the polymer (PH) 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).

[0071] The polymer (PH) can also be prepared by any controlled radical polymerization technique, among which reversible addition-fragmentation chain transfer (RAFT) and polymer design by interchange of xanthates (MADIX).

[0072] 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.

[0073] Preferably, the polymer (PH) is obtained by radical copolymerization of a mixture having the following molar ratios, based on the total amounts of monomers (AA), (AM) and (M): Monomers (AA): 5 to 95%, in particular 5 to 50%, preferably 20 to 40%, - Monomer (AM): 25 to 90%, preferably 25 to 90%, more preferably 60 to 80%, Monomer (M): 0.1-50%, for example 1-30%, in particular 1-20%, further preferably 2-15%.

[0074] As a result, the polymer (P) is preferably - 5 to 95%, in particular 5 to 50% and preferably 20 to 40% of repeat units deriving from the monomer (AA) in neutralized form, - 25 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) All of the foregoing mole percentages are based on the total moles of repeat units of polymer (P).

[0075] Furthermore, the polymer (P) according to the present invention has a weight average molecular weight of about 500 kDa to 10,000 kDa.

[0076] According to a preferred embodiment, the polymer (P) is a statistical (random) copolymer having a weight average molecular weight of about 500 kDa to 10,000 kDa, and is prepared by radical polymerization of a mixture of monomers (AA), (AM) and (M), preferably by - Approximately 20-40% monomer (AA), - about 50-80% monomer (AM), and - Approximately 2-15% monomer (M) The molar ratio is:

[0077] 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.

[0078] 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, random copolymer, random terpolymer or gradient polymer.

[0079] According to a more preferred embodiment, the polymer (P) is obtained by radical polymerization of acrylic acid, acrylamide and vinylimidazole of formula (IIIa), followed by neutralization of the acid groups of the repeat units originating from monomer (AA), preferably with LiOH.

[0080] Electrode forming composition [Composition (Comp)] 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.

[0081] 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).

[0082] 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.

[0083] As an alternative, when forming a positive electrode for a lithium-ion secondary battery, furthermore, the electrode active material can be a lithiated or partially lithiated transition metal oxyanion-based electroactive material 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 any 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).

[0084] M1M2(JO4) as defined above f E 1-f The electrode active material preferably can be phosphate-based and have an ordered or modified olivine structure.

[0085] More preferably, the electrode active material when forming the positive electrode has 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.

[0086] 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.

[0087] 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.

[0088] The carbon-based material is preferably graphite.

[0089] 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.

[0090] More particularly, the silicon-based compound may be silicon oxide or silicon carbide.

[0091] 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.

[0092] 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.

[0093] Examples 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®.

[0094] When present, the conductive agent is different from the carbon-based materials described above.

[0095] 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.

[0096] For anode-forming compositions that do not include a silicon based electroactive compound, the optional conductive agent is typically between 0% and 5% by weight, more preferably between 0% and 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 between 0.5 and 30% by weight of the total amount of solids in the composition.

[0097] The surprisingly good dispersing ability exhibited by polymer (P), despite its very high molecular weight, makes it suitable for use as a binder in the preparation of electrode-forming compositions with excellent rheological profiles and thus stable slurries without settling over a period of two days without the use of rheological modifiers.

[0098] 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 and 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 polymer particles provide bridges between the conductive material particles, keeping them in contact.

[0099] The composition (Comp) does not contain a rheology modifier such as CMC, and the excellent dispersibility of the polymer (P) allows the amount of the polymer (P) in the electrode-forming composition to be increased.

[0100] The amount of polymer (P) in the composition (Comp) is suitably about 2-10%, preferably about 3-5%, of the total amount of solids in the composition.

[0101] Thus, the high dispersing ability of the polymer (P) makes it possible to obtain compositions with a higher binder content, which has the advantage that higher efficiency, higher productivity and higher battery energy are obtained.

[0102] The electrode-forming composition of the present invention [composition (Comp)] makes it possible to obtain a composition with a non-trivial increased total solids content (TSC) in the absence of a rheology modifier such as CMC, due to the excellent dispersing ability of the polymer (P).

[0103] The total solids content (TSC) of the composition (Comp) of the invention is typically greater than 40% by weight, preferably between 40 and 70% by weight, based on 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.

[0104] The composition (Comp) may be prepared according to any method known to those skilled in the art.

[0105] In one embodiment, the electrode-forming composition (Comp) of the present invention may be prepared by a process comprising the following steps: - Step 1: Powder wetting, the powders (electrode active material, conductivity imparting additives) are premixed with the polymer (P) in a centrifugal mixer for 10 seconds to achieve wetting of the powders. - Step 2: Homogenization, the wet powder obtained in step 1 is homogenized in a centrifugal mixer for 10 seconds to obtain a slurry with a final total solids content of at least 40% and to achieve the target viscosity (target range 2000-8000 cP at 10 s-1). Step 3: Slurry mixing, the slurry obtained in step 2 is stirred in a disperser.

[0106] When preparing an aqueous solution of the polymer (P) separately and then combining the electrode active material, 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 can 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.

[0107] Electrode (E) The electrode-forming composition (Comp) of the present invention can be used in a process for producing an electrode [electrode (E)], said 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 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. Includes.

[0108] 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.

[0109] 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.

[0110] 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).

[0111] 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).

[0112] The drying temperature will be selected to achieve evaporative removal of the aqueous medium from the electrode (E) of the present invention.

[0113] In step (v), the dried assembly obtained in step (iv) may 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.

[0114] 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.

[0115] 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.

[0116] In a further aspect, the present invention relates to an electrode [electrode (E)] obtainable by the process of the present invention.

[0117] Thus, the present invention provides - a metal substrate having at least one surface; - directly adhered onto at least one surface of said 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; At least one layer comprising, preferably consisting of, The present invention relates to an electrode (E) comprising:

[0118] The composition directly applied 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 of the preferred embodiments described with respect to the electrode-forming composition (Comp) of the invention can also be applied to the composition directly applied 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.

[0119] 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.

[0120] In a further preferred embodiment, the present invention provides a method for manufacturing a semiconductor device comprising the steps of: - 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 a carbon-based material, - 3 to 50% by weight, preferably 10 to 50% by weight, of silicon-based material; - 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:

[0121] The Applicant has surprisingly found that the electrodes according to the invention have good mechanical properties and excellent cycling stability.

[0122] In addition, the binders containing the polymer (P) of the present invention not only exhibit higher adhesion to the current collector compared to SBR / CMC binders, but also exhibit higher adhesion to binders containing the polymer (P) and a rheology modifier such as CMC and chlorinated PAA.

[0123] The electrode (E) of the present invention is therefore particularly suitable for use in electrochemical devices, in particular secondary batteries.

[0124] The secondary battery of the present invention is preferably an alkaline secondary battery or an alkaline earth secondary battery.

[0125] The secondary battery of the present invention is more preferably a lithium ion secondary battery.

[0126] Electrochemical devices according to the present invention can be prepared by standard methods known to those skilled in the art.

[0127] 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 it may render a term unclear, this statement shall control.

[0128] 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

[0129] raw materials AA: acrylic acid available from Aldrich; AM: Acrylamide monomer (50% in water) available from SNF; VIm: vinylimidazole monomer available from Aldrich; Transfer agent: a freshly prepared 1 wt% solution in ethanol of a MADIX type transfer agent available as Rhodixan A1 from Solvay; Sodium persulfate in powder form available from VWR (a 10 wt % solution in water was prepared immediately prior to the polymerization experiments); Sodium formaldehyde sulfoxylate in powder form available from Aldrich (a 10 wt % solution in water was prepared immediately prior to the polymerization experiments); V-50 initiator available in powder form from Aldrich: (2,2'-azobis(2-methyl-propionamidine) dihydrochloride) (a 10 wt % aqueous solution was prepared immediately prior to the polymerization experiment); Lithium hydroxide monohydrate (98% purity) available from Sigma-Aldrich; Chemically doped KSC-7144SiOx with a specific capacity of 2100 mAh / g available from Shin-Etsu Chemical Co., Ltd. Graphite from Imerys SA, ACTILION GHDR, Carbon black (CB), available as SC45 from Imerys SA; Carboxymethyl cellulose (CMC), available as MAC 500LC from Nippon Paper Industries Co., Ltd. Electrolyte mixture of 1M LiPF6 in EC / DMC 1 / 1 v / v with 2 wt% VC and 10 wt% F1EC from Solvionic. C1020R-H copper foil from Hohsen with a thickness of 10um SBR BM480B available from Zeon

[0130] Synthesis procedure of polymer (P-1H) The synthesis process was carried out in a thermally isolated reactor to minimize heat exchange with the surroundings (Thermos-like flask). The reactor was equipped with a lid containing a small reflux system, a mechanical stirring system, a nitrogen purge line and multiple inlets where the raw material feed lines were installed. In the first step, all the monomers, solvent (water) and transfer agent were charged to the reactor and kept under stirring and nitrogen purge at room temperature for about 1 hour. 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.

[0131] An exothermic effect was observed within about 30 minutes to an hour, increasing the temperature of the reaction mixture from room temperature to about 80-90°C. The reaction mixture was then maintained in the reaction flask for an additional 24 hours. In this way, an aqueous solution of polymer (P) was obtained.

[0132] Table 1 shows the amounts of the reagents inserted in the synthesis of the polymers (P-1H), (P-2H) and (P-3H).

[0133] [Table 1]

[0134] The Mw, solid content and residual monomer of the resulting polymer are shown in Table 2.

[0135] [Table 2]

[0136] Procedure for preparing aqueous solutions of lithiated polymers (P) The aqueous solutions of polymers (P-1H), (P-2H) and (P-3H) obtained as above were titrated with aqueous LiOH solution (4.25 wt.% of LiOH in water) using a Mettler Toledo titrator T5 until pH 7.5. Solutions of final lithiated P-1, P-2 and P-3 polymer concentrations in water of 7.5 or 5 wt.% were prepared.

[0137] Evaluation of the rheology and dispersion ability of lithiated polymers (P) The dispersing ability of polymer P-1 was evaluated using an aqueous formulation containing CB and polymer P-1, compared to aqueous formulations of the same viscosity containing CB alone, CB with CMC, and CB with CMC and polymer P-1.

[0138] The aqueous formulation was subjected to ambient mixing (Thinky ARE250) for 10 minutes at 2000 rpm sequence. The dispersion state of the carbon black was evaluated by optical microscopy. The results are listed in Table 3 below.

[0139] [Table 3]

[0140] Microscopic images of formulations 1-3 are reported in Figure 1.

[0141] The results show that the formulation containing only the polymeric dispersant of the present invention has better dispersion of carbon black than the formulation that also contains CMC, and has much better dispersion compared to the formulation containing only CMC.

[0142] The rheology of the aqueous formulation containing polymer P-1 (0.67 wt%) and CMC (2.6 wt%) used to prepare Formulation 2 was that of a shear-thinning fluid with a well-defined low-shear plateau viscosity.

[0143] Applicants have demonstrated that by using only 4.1 wt. % P-1, an aqueous formulation with similar viscosity can be obtained.

[0144] The low shear viscosities obtained at a shear rate of 0.1 s-1 are shown in Table 4.

[0145] [Table 4]

[0146] Thus, the use of polymeric dispersants according to the present invention allows the use of formulations containing higher amounts of binder without affecting the rheology of the binder itself.

[0147] Zeta potential characterization Zeta potential measurements were performed on very dilute suspensions of CB, CB / CMC and CB / polymer dispersants of the present invention.

[0148] The polymer dispersant solution was diluted to 0.01% by weight and left under stirring for 48 hours. Carbon black was then added (0.01% by weight) and dispersed by ultrasonic bath for 30 minutes. The results are shown in Table 5.

[0149] [Table 5]

[0150] The electrostatic repulsion of CB particles is insufficient to keep them stable at this pH, as suspension with CB exhibits only particle aggregation and rapid sedimentation.

[0151] When CMC or polymer dispersant was added to CB, the zeta potential value increased significantly, suggesting that the combination of CB and polymer resulted in greater electrostatic repulsion, resulting in better dispersion.

[0152] For the non-chlorinated polymer with CB, the ZP is close to that of the CB alone. Microscopic observation of the non-chlorinated polymer with CB shows large aggregates, i.e., the dispersing ability of the non-chlorinated polymer is low, consistent with the lower ZP value.

[0153] In contrast, the lithiated polymer dispersants of the present invention with CB provide high ZP in the range of 50-60 mV or greater.

[0154] Preparation of electrode-forming composition and negative electrode The electrode-forming compositions and negative electrodes were prepared as detailed below using the following equipment.

[0155] Mechanical mixers: Dispermat® series planetary mixers (Speedmixers) and high shear mechanical mixers with inclined impellers.

[0156] Film coater / doctor blade: Elcometer® 4340 with motor / Zehntner ZUA2000.

[0157] Vacuum oven: BINDER VD 23 with vacuum and Roll press: precision 4 inch hot rolling press / calendering up to 100°C.

[0158] Example 1 - Terpolymer Anode 5% Binder An aqueous composition was prepared by mixing 28.0 g of a 7.5 wt % lithiated P-1 aqueous solution, 0.42 g of carbon black, 7.89 g of silicon oxide, 31.58 g of graphite, and 32.1 g of deionized water. The mixture was homogenized by gentle stirring with a planetary mixer for 20 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 slow stirring.

[0159] The composition thus obtained was cast on a copper foil with a thickness of 10 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 72 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, 5% by weight of P-1, and 1% by weight of carbon black. Thus, electrode E1 was obtained.

[0160] Example 2 - Terpolymer Anode 4% Binder An aqueous composition was prepared by mixing 24.0 g of a 7.5 wt % lithiated P-1 aqueous solution, 0.45 g of carbon black, 8.55 g of silicon oxide, 34.2 g of graphite, and 32.8 g of deionized water. The mixture was homogenized by gentle stirring with a planetary mixer for 20 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 slow stirring.

[0161] The composition thus obtained was cast on a copper foil with a thickness of 10 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 70 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% by weight of silicon oxide, 76% by weight of graphite, 4% by weight of P-1, and 1% by weight of carbon black. Thus, electrode E2 was obtained.

[0162] Example 3 Terpolymer Anode 3% Binder An aqueous composition was prepared by mixing 30.0 g of a 5 wt % aqueous solution of lithiated P-1, 0.5 g of carbon black, 9.6 g of silicon oxide, 38.4 g of graphite, and 21.5 g of deionized water. The mixture was homogenized by gentle stirring with a planetary mixer for 20 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 slow stirring.

[0163] The composition thus obtained was cast on a copper foil with a thickness of 10 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 68 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 negative electrode obtained had the following composition: 19.2% by weight of silicon oxide, 76.8% by weight of graphite, 3% by weight of P-1, and 1% by weight of carbon black. Thus, electrode E3 was obtained.

[0164] Comparative Example CE1: Anode containing styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) An aqueous composition was prepared by mixing 29.0 g of a 2 wt% solution of CMC with 0.58 g of carbon black, and after 10 minutes of moderate stirring with a planetary mixer, 11.14 g of silicon oxide, 44.5 g of graphite, and 11.68 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. After mixing for about 1 hour, 3.06 g of SBR suspension was added to the composition and mixed again with low agitation for 1 hour.

[0165] The composition thus obtained was cast on a copper foil with a thickness of 10 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 69 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. Thus, the electrode CE1 was obtained.

[0166] Comparative Example 2 - Terpolymer Anode 5% Binder Containing Terpolymer and CMC An aqueous composition was prepared by mixing 19.0 g of a 2 wt % aqueous solution of CMC, 0.38 g of carbon black, 7.14 g of silicon oxide, 28.58 g of graphite, and 24.6 g of deionized water. After 10 minutes of gentle stirring in a planetary mixer, 20.27 g of a 7.5% 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 slow stirring.

[0167] The composition thus obtained was cast on a copper foil with a thickness of 10 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 74 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 P-1, 1% by weight of CMC, and 1% by weight of carbon black. Thus, the electrode CE2 was obtained.

[0168] Adhesion Test Peel tests were performed to evaluate the adhesion of the electrode composition coatings onto metal substrates. The tests were performed on the electrodes prepared as above according to the procedure of ASTM D903, operating at a speed of 300 mm / min at 25° C. The results are shown in Table 6.

[0169] [Table 6]

[0170] The data in Table 2 show that the electrodes obtained according to the invention have satisfactory adhesion to the current collector. In particular, by comparing the adhesion of E2 and CE2, it is clear that the presence of CMC does not positively affect the adhesion.

[0171] 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 and CE1, CE2 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.

[0172] Capacity retention test Cycling stability of full cells at a C-rate of 1C (open capacity was measured in triplicate and is shown in Table 7 below).

[0173] [Table 7]

[0174] The results in Table 3 show that the electrodes according to the invention have better cycling stability than electrodes containing the same amounts of polymer (P) and CMC.

[0175] Furthermore, although the use of higher amounts of the polymer (P) of the present invention further improves the performance of the battery, it is known in the art that increasing the amount of SBR / CMC binder significantly reduces performance and / or increases electrical resistivity.

[0176] The use of the polymer according to the invention therefore makes it possible to obtain electrodes containing higher amounts of binder, leading to improved performance of the battery containing said electrode.

Claims

1. An acrylic polymer dispersant [polymer (P)] for dispersing powder particles in an aqueous electrode-forming composition, (C) repeat units derived from at least one α,β-ethylenically unsaturated carboxylic acid monomer [monomer (AA)] in neutralized form; (D) a repeating unit derived from at least one (meth)acrylamide monomer [monomer (AM)]; and having a weight average molecular weight of about 500 kDa to 10,000 kDa [polymer (P)].

2. Monomer (AA) has the formula (I): 【Chemical 1】 (In the formula, R ａ , R ｂ and R ｃ are equal to or different from each other, and are a hydrogen atom and C １ ~C ３ are independently selected from hydrocarbon groups; S is a monovalent cation, preferably an alkali metal salt. The polymer (P) according to claim 1, which is a compound of the formula:

3. The monomer (AM) has the formula (II): 【Chemistry 2】 (In the formula, R ５ represents a hydrogen atom or a methyl group, R ６ and R ７ 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; R ８ and R ９ 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, and preferably, the monomer (AM) is selected from the group consisting of (meth)acrylamide or N-substituted (meth)acrylamides such as N-alkylacrylamides and N,N-dialkylacrylamides. The polymer (P) according to claim 1 or 2, which is a compound of the formula:

4. 3. Polymer (P) according to claim 1 or 2, further comprising repeating units derived from at least one ethylenically unsaturated monomer (M) different from monomers (AA) and (AM), provided that the total amount of monomers (AA) and / or monomers (AM) is at least 60 mol % relative to the total moles of repeating units of polymer (P).

5. The monomer (M) is Monomer (M1), which is an ethylenically unsaturated monomer having an unsaturated heterocyclic group containing at least one nitrogen atom, and which has the following formula (III): 【Chemistry 3】 (In the formula, R １ is H or an alkyl group, the alkyl group being preferably a methyl group; R ２ is H or an alkyl group, R ３ and R ４ 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 is, a single covalent bond, and - Spacer is a bond selected from the group consisting of X, Y and Z are independently selected from carbon atoms or nitrogen atoms; a, b and c are independently selected from the integers 1 to 2; Each dashed dotted line represents an optional double bond. a monomer (M1) having the formula a monomer (M2) different from the monomers (AA) and (AM) and having the following formula (IV): 【Chemistry 4】 (In the formula, R ｉ is H, -COOH, -CH ２ COOH 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; B is a bond selected from the group consisting of a —C(O)—O— group and a —C(O)—NH— group; R ｘ is a hydrogen atom, an ether (—O—), a heterocyclic group, a sulfonic acid group (—SO ３ H), salts of sulfonic acid groups (-SO ３ Cat), phosphonic acid group (-PO ３ H ２ ), a salt of a phosphonic acid group (—PO ３ Cat ２ ), phosphate group (-OPO ３ H ２ ) and salts of phosphate groups (-OPO ３ Cat ２ ) a linear or branched C containing at least one functional group selected from the group consisting of ３ ~C ２０ Cat is preferably a monovalent cation selected from alkali metal cations, more preferably Na ＋ , K. ＋ and Li ＋ (selected from a monomer (M2) having the formula - monomers (M3), alkyl esters of maleic anhydride and (meth)acrylic acid, such as monomethyl maleic anhydride, dimethyl maleic anhydride, monoethyl maleic anhydride, diethyl maleic anhydride, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, hydroxyalkyl esters of maleic anhydride and (meth)acrylic acid, such as monohydroxyethyl maleic anhydride, dihydroxyethyl maleic anhydride, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, Ethoxylates and propoxylates derived from maleic anhydride, such as poly(propylene oxide)-b-poly(ethylene oxide) maleic acid half-esters or diesters, alkyl-poly(ethylene oxide) maleic acid half-esters or diesters, ethoxylates and / or propoxylates derived from the ethoxylation and / or propoxylation of hydroxyalkyl(meth)acrylic acids, such as poly(propylene oxide)-b-poly(ethylene oxide)-ethyl(meth)acrylate, ethoxylates and / or propoxylates resulting from the esterification (transesterification) of (meth)acrylic acid and esters, such as poly(propylene oxide)-b-poly(ethylene oxide)(meth)acrylates and alkyl-poly(ethylene oxide)(meth)acrylates, vinyl esters, such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, 2-ethylhexyl vinyl ether, vinylcyclohexyl ether, dodecyl vinyl ether, 2-(diethylamino)ethyl vinyl ether, 2-(di-n-butylamino)ethyl vinyl ether, allyl ethers, such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, 2-ethylhexyl vinyl ether; vinyl esters, such as vinyl acetate or vinyl propionate, Alkyl-substituted acrylamides, such as N-tert-butylacrylamide or N-methyl(meth)acrylamide Monomer (M3), which is a hydrophobic or amphiphilic monomer selected from the group consisting of The polymer (P) according to claim 1 or 2, selected from the group consisting of:

6. The monomer (M) has the formula (IIIa): 【Chemistry 5】 3. Polymer (P) according to claim 1 or 2, wherein the vinylimidazole (VIm) is

7. - 5 to 95%, in particular 5 to 50%, preferably 20 to 40%, of repeat units derived from the monomer (AA) in neutralized form, - 25 to 90%, preferably 25 to 90%, more preferably 50 to 80% of repeat units derived from monomer (AM), - 0.1 to 50%, for example 1 to 30%, in particular 1 to 20%, further in particular 2 to 15%, of repeat units derived from monomer (M); 3. The polymer (P) according to claim 1 or 2, comprising:

8. 3. A process for producing a polymer (P) according to claim 1 or 2, comprising radical copolymerisation of a mixture of at least one monomer (AA), at least one monomer (AM) and optionally at least one monomer (M) to provide a polymer (P-H), followed by neutralisation of the acid groups of the repeat units derived from the monomers (AA), wherein the neutralisation of the acid groups is carried out either with a salt [salt (S)] comprising a monovalent cation, preferably an alkali metal salt, in a suitable solvent or with ammonia.

9. 1. An aqueous electrode-forming composition [Composition (Comp)] for use in fabricating an electrode for an electrochemical device, comprising: a) at least one polymer (P) according to claim 1 or 2; b) an electrode active material; and c) an aqueous solvent; d) optionally at least one conductivity-imparting additive; An aqueous electrode-forming composition [Composition (Comp)] characterized by comprising:

10. 10. The aqueous electrode-forming composition [Composition (Comp)] according to claim 9, wherein the amount of polymer (P) is about 2 to 10%, preferably about 3 to 5%, of the total amount of solids in the composition.

11. 10. The aqueous electrode-forming composition [Composition (Comp)] according to claim 9, wherein the total solids content is greater than 40% by weight, preferably 40-70% by weight, based on the total weight of the composition (Comp).

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 9, (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 an electrode (E). A process involving:

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

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

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