Anode composition containing anionic binder

Abstract

The invention relates to an aqueous anode composition comprising metal particles or fibres or carbon graphite particles or fibres, and a binding agent containing at least one water-soluble polymer P prepared on the basis of (meth)acrylic acid and (meth)acrylate. The invention also relates to a method for producing an anode using said aqueous composition.

Description

[0001] ANODE COMPOSITION WITH ANIONIC BINDER

[0002] The invention relates to an aqueous anode composition comprising metallic or carbon graphite particles or fibers and a binding agent comprising at least one water-soluble anionic copolymer P which is prepared from (meth)acrylic acid and (meth)acrylate. The invention also relates to a method for manufacturing an anode using this aqueous composition.

[0003] Anode compositions are known that generally comprise carbon or a metal in particulate form combined with a binder composition. This binder composition must be able to effectively bind the carbon or metal to a substrate to form an anode. The most common binder compositions include a styrene-butadiene polymer. The composition allows the particles to be fixed to a metal substrate. Binding power is therefore crucial when manufacturing an anode using these anode compositions. In addition, mechanical strength or electrochemical resistance is particularly sought after.

[0004] Easy and homogeneous application of the anode compositions is necessary in order to obtain a homogeneous layer and to limit or avoid defects on the anode surface, in order to achieve a homogeneous and particularly efficient conductive layer.

[0005] Typically, binder compositions also include various additives such as thickening agents, dispersing agents, for example, a cellulose derivative. The most common cellulose derivatives are carboxymethylcellulose, hydroxyethylcellulose, and hydroxymethylcellulose.

[0006] Often, these anode compositions include silicon to increase the capacity of the prepared anodes. During charge-discharge cycles of batteries containing these anodes, it is common to observe deformation that can lead to irreversible damage to the anode, particularly due to the increase in volume of silicon. Deformation tolerance is therefore also a sought-after property.

[0007] The number of ingredients used in the preparation of anode compositions should be reduced.

[0008] The compatibility of the different ingredients of the anode compositions is also an important factor when preparing the anode compositions as well as when preparing the anodes using these compositions.

[0009] EP 2680349 relates to the preparation of a secondary battery anode using a polyacrylic binder. EP 2592679 discloses a binder for a secondary battery electrode comprising water-insoluble copolymer particles having an average diameter ranging from 0.3 μm to 0.7 μm. EP 3001487 discloses a water-insoluble core-shell binder for a secondary battery electrode, the core of which comprises styrene-butadiene rubber and the shell of which comprises a poly(styrene-acrylate) copolymer.

[0010] The anode compositions of the state of the art are not always satisfactory. There is therefore a need to have anode compositions which make it possible to provide solutions to all or part of the problems of the anode compositions of the state of the art. Thus, the invention provides an aqueous anode composition T comprising:

[0011] * from 0.5% to 15% by dry weight of at least one binding agent L comprising at least one water-soluble polymer P, having a weight-average molecular mass Mw (measured by CES) ranging from 2,000 g / mol to 1,000,000 g / mol, prepared in the presence of at least one initiator compound, by a polymerization reaction: a. from 20 to 95% by weight of at least one anionic monomer (a) chosen from acrylic acid, an acrylic acid salt, methacrylic acid, a methacrylic acid salt and combinations thereof; b. from 5 to 80% by weight of at least one C1-C8 ester (b) of a compound derived from an acid chosen from acrylic acid, methacrylic acid, maleic acid, itaconic acid and crotonic acid, relative to the total amount by weight of monomers (a) and (b); and

[0012] * from 85% to 99.5% by dry weight of at least one material E chosen from metal fibers, metal particles, graphite carbon fibers, graphite carbon particles, silicon particles and combinations thereof, relative to the total quantity by dry weight of binding agent L and material E.

[0013] Essentially for the invention, the preparation of the polymer P is carried out using the monomers a and b.

[0014] Preferably according to the invention, the anionic monomer (a) may be chosen from acrylic acid, methacrylic acid and combinations thereof, preferably the anionic monomer (a) is acrylic acid. Also preferably according to the invention, the monomer (a) may be combined with at least one other anionic monomer, different from the monomer (a), and chosen from acrylic acid, methacrylic acid, an acrylic acid salt, a methacrylic acid salt, maleic acid, a maleic acid salt, itaconic acid, an itaconic acid salt, crotonic acid, a crotonic acid salt, an acrylic acid oligomer and combinations thereof. Preferably according to the invention, the ester (b) is a C1-C7 ester or a C1-C6 ester or a C1-C4 ester, preferably a C1-C3 ester. More preferably according to the invention, the ester (b) is an acrylic acid ester or a methacrylic acid ester, preferably an acrylic acid ester.

[0015] Also preferably according to the invention, the ester (b) is chosen from methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, ethylhexyl methacrylate and combinations thereof. More preferably, the ester (b) is chosen from ethyl acrylate, methyl acrylate, butyl acrylate, methyl methacrylate and combinations thereof.

[0016] Generally, ester (b) is not a C1-C8 alicyclic ester.

[0017] Advantageously according to the invention, a single polymerization reaction is involved.

[0018] Preferably according to the invention, the polymerization reaction can also use at least one crosslinking monomer (c) or at least one monomer (c) comprising at least two olefinic unsaturations. More preferably, the monomer (c) is chosen from polyvinyl aromatic monomers (for example divinylbenzene and diallyl phthalate); polyalkenyl ethers (for example triallyl pentaerythritol, diallyl pentaerythritol, diallyl sucrose, octaallyl sucrose, trimethylolpropane diallyl ether); polyunsaturated esters of polyalcohols or polyunsaturated esters of polyacids (for example trimethylolpropane tri(meth)acrylate, trimethylolpropane, polyethylene glycol di(meth)acrylates); diacrylic esters, dimethacrylic esters derived from polyols, in particular chosen from pentaerythritol, sorbitol, sucrose;Divinyl naphthalene, trivinylbenzene, 1,2,4-trivinylcyclohexane, triallyl pentaerythritol, diallyl pentaerythritol, diallyl sucrose, trimethylolpropane diallyl ether, 1,6-hexanediol di(meth)acrylate, allyl(meth)acrylate, diallyl itaconate, diallyl fumarate, diallyl maleate, butanediol dimethacrylate, ethylene di(meth)acrylate, poly(ethylene glycol) di(meth)acrylate, trimethylolpropane tri(meth)acrylate, methylenebis(meth)acrylamide, triallylcyanurates, diallyl phthalate, divinylbenzene; diallyl phthalate (DAP); ethylene glycol dimethacrylate (EGDMA); methylene bis acrylamide (MBA); divinylbenzene (DVB); bicyclopentenyloxyethyl-methacrylate (FRA); trimethylol propane triallyl ether (APE) and combinations thereof. More preferably according to the invention, the monomer (c) may be chosen from diallyl phthalate (DAP); ethylene glycol dimethacrylate (EGDMA), trimethylolpropane diacrylate, trimethylolpropane dimethacrylate and combinations thereof.;

[0019] Preferably, less than 5% by weight, preferably from 0.01 to 4% by weight, in particular from 0.02 to 4% by weight or from 0.02 to 2% by weight, in particular from 0.02 to 1% by weight, of monomer (c) can be used relative to the total amount by weight of monomers.

[0020] Also preferably according to the invention, the polymerization reaction can use at least one hydrophobic monomer (d) different from the compound (c). Preferably, the monomer (d) is a compound of formula (I):

[0021] R 1 -(OE) m -(OP) p -R 2 (I) in which:

[0022] - m and p, identical or different, independently represent 0 or an integer or decimal number less than 150, m or p is different from 0,

[0023] - OE independently represents a CH2CH2O group,

[0024] - OP independently represents a group chosen from CH(CH3)CH2O and CH2CH(CH3)O,

[0025] - R 1 independently represents a group comprising at least one polymerizable olefinic unsaturation, preferably an acrylate group or a methacrylate group and

[0026] - R 2 independently represents a linear or branched C6-C4o-alkyl group, a phenyl group, a polyphenyl group, preferably a linear or branched C10-Cso-alkyl group, more preferably a linear or branched C12-C22-alkyl group, or a group comprising 2 to 5 phenyls or a tristyrylphenyl group or a pentastyrylcumylphenyl group. Also preferably, less than 20% by weight, preferably from 0.05 to 20% by weight, in particular from 0.1 to 10% by weight, of monomer (d) may be used relative to the total amount by weight of monomers.

[0027] Also preferably according to the invention, the polymerization reaction may use at least one compound (e) chosen from phosphated hydroxyethyl acrylate, phosphated hydroxypropyl acrylate, phosphated hydroxyethylhexyl acrylate, phosphated hydroxyethyl methacrylate, phosphated hydroxypropyl methacrylate, phosphated hydroxy ethylhexyl methacrylate, their salts and their combinations. Also preferably, less than 20% by weight, preferably from 0.2 to 20% by weight, in particular from 0.5 to 10% by weight, of monomer (e) may be used relative to the total amount by weight of monomers.

[0028] Also preferably according to the invention, the polymerization reaction can use at least one compound (f) chosen from hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethylhexyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethylhexyl methacrylate.

[0029] Also preferably, less than 20% by weight, preferably 0.2 to 20% by weight, in particular 0.5 to 10% by weight, of monomer (f) can be used relative to the total amount by weight of monomers.

[0030] Also preferably according to the invention, the polymer P is prepared by means of a combination of monomers a and b, a combination of monomers a, b and c, a combination of monomers a, b and d, a combination of monomers a, b and e, a combination of monomers a, b and f, a combination of monomers a, b, c and d, a combination of monomers a, b, c and e, a combination of monomers a, b, c and f, a combination of monomers a, b, c, d and e, a combination of monomers a, b, c, d and f, a combination of monomers a, b, d and e, a combination of monomers a, b, d and f, a combination of monomers a, b, e and f, a combination of monomers a, b, c, d, e and f. More preferably according to the invention, the polymer P is prepared by means of a combination of only monomers a and b.

[0031] When preparing the polymer P of the invention, the monomers a and b are therefore essential. The monomers c, d, e and f can therefore be used optionally. In the absence of these monomers c, d, e and f, the polymer P is prepared from the monomers a and b alone.

[0032] Furthermore, the preparation of polymer P may exclude certain monomers. Polymer P is in particular prepared in the absence of organosulfur monomer, such as sulfonated monomer or sulfated monomer. In this case, the particular organosulfur monomers which are not used are chosen from 2-acrylamido-2-methylpropanesulfonic acid (AMPS), allylsulfonic acid, alkylenesulfonates, alkylenearylsulfonates in particular styrenesulfonate, vinylsulfonate, methallylsulfonate, allylsulfonate, methallyl sulfate, allyl sulfate, 2-sulfoethyl methacrylate, 3-allyloxy-2-hydroxy-1-propanesulfonic acid, 3 sulfopropyl methacrylate, their salts and their combinations.

[0033] Other monomers may be excluded from the preparation of the polymer P, in particular a (meth)acrylamide monomer, an (acrylo)nitrile monomer, a fluorinated monomer, an acetate monomer, an imide monomer. Preferably according to the invention, the polymer P is prepared in the absence of halogenated monomer, in particular in the absence of fluorinated monomer.

[0034] When preparing polymer P, the proportions of monomers a and b can vary widely. Preferably according to the invention, the polymerization reaction involves:

[0035] - from 30 to 70% by weight, preferably from 35 to 70% by weight, of monomer (a) or

[0036] - from 30 to 70% by weight, preferably from 30 to 65% by weight, of monomer (b), relative to the total quantity by weight of monomers (a) and (b).

[0037] According to the invention, the copolymer P is water-soluble. Preferably, according to the invention, the water-soluble copolymer P is prepared using a majority weight quantity of anionic monomers. Advantageously, the polymer P is soluble in water in any quantity at room temperature, preferably at different pH values, in particular at pH values ​​ranging from 2 to 12.

[0038] Preferably according to the invention the pH of the polymer P is less than 12 or less than 11 or ranges from 2 to 12 or from 5 to 11. Also preferably according to the invention the pKa of the polymer P is less than 5 or ranges from 1.5 to 5.

[0039] Preferably according to the invention, the polymerization reaction is carried out at a temperature above 30°C and below 130°C, preferably below 100°C or below 90°C or below 80°C or 75°C. Preferably during the polymerization reaction to prepare the polymer P, the initiator compound is chosen from a peroxide (for example hydrogen peroxide), a hydroperoxide (for example tert-butyl hydroperoxide), a persulfate (for example sodium persulfate, ammonium persulfate, potassium persulfate), their combinations and their associations with a metal salt, preferably a metal salt chosen from an iron salt (for example Fe II or Fe III), a copper salt (for example Cu I or Cu II) and their combinations.

[0040] Preferably according to the invention, the polymer P is prepared in a polar solvent, in particular a solvent chosen from water, alcohol, toluene, a ketone, a chlorinated solvent, an ester and their combinations.

[0041] Also preferably according to the invention, the polymer P can be prepared in the presence of a chain transfer agent, preferably in the presence of a compound chosen from isopropyl alcohol, mercaptan, dodecyl mercaptan, phosphorous acid, phosphite, hypophosphorous acid, hypophosphite, bisulfite, an alkyl iodide, an alkyl bromide and combinations thereof. According to the invention, the polymer P can be non-neutralized or it can be partially neutralized or totally neutralized. Preferably, the polymer P is non-neutralized or partially neutralized. According to the invention, the carboxylic groups of the polymer P can be partially neutralized at a rate of 70 to 97 mol%, preferably at a rate of 90 to 95 mol%. The polymer P can be partially or totally neutralized by means of at least one monovalent ion or at least one divalent ion.According to the invention, the polymer P can be partially or completely neutralized by means of a combination of at least one monovalent ion and at least one divalent ion. According to the invention, the total or partial neutralization of the polymer P can then be carried out in variable relative molar proportions of the monovalent and divalent ions. Preferably, according to the invention, the monovalent ion / divalent ion molar proportions are between 90 / 10 and 10 / 90 or between 80 / 20 and 20 / 80, preferably between 80 / 20 and 60 / 40, for example 70 / 30 or 50 / 50.

[0042] According to the invention, the neutralization can be carried out using a primary amine, a secondary amine or a monovalent ion chosen from K + , N / A + , Li + , NH4 + or an amine and combinations thereof. The preferred monovalent ion is selected from Na + and Li + . The polymer P according to the invention can nevertheless be neutralized in the absence of Li ion+ . According to the invention, the neutralization can also be carried out by means of a divalent ion chosen from Ca 2+ , Zn 2+ , Mg 2+ and their combinations. The preferred divalent ion is Ca 2+ .

[0043] According to the invention, the polymer P can be neutralized by means of at least one compound chosen from NaOH, KOH, LiOH, ammonium derivatives, ammonia, aqueous ammonia, primary amine, secondary amine, CaO, Ca(OH)2, ZnO, Zn(OH)2, MgO, Mg(OH)2 and combinations thereof. Neutralization of the polymer P using ammonia proves to be particularly advantageous when implementing the composition T at a pH below 7, preferably at a pH below 5. According to the invention, the polymer P can be neutralized totally or partially using an amine base, for example a base chosen from ethylene diamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, α,α'-diaminoxylene, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, triethanolamine, aminomethylpropanol or 2-amino-2-methyl-propanol (AMP) and combinations thereof.

[0044] Preferably, the polymer P has a weight average molecular mass Mw (measured by CES) of less than 900,000 g / mol, less than 800,000 g / mol, less than 500,000 g / mol, more preferably less than 350,000 g / mol. The polymer P generally has a weight average molecular mass Mw (measured by CES) of greater than 5,000 g / mol, preferably greater than 20,000 g / mol.

[0045] Generally, the polymer P has a polymolecularity index Ip (measured by CES) less than 4 or ranging from 1.2 to 4 or from 1.5 to 4; from 1.2 to 3 or from 1.5 to 3; from 1.2 to 2.5 or even from 1.5 to 2.5.

[0046] According to the invention, the molecular weight or mass of the polymer P is determined by Size Exclusion Chromatography (SEC). A sample of the polymer solution corresponding to 90 mg of dry matter is introduced into a 10 mL flask. Mobile phase, containing 0.04% dimethylformamide (DMF), is added to a total mass of 10 g. The composition of this mobile phase is as follows: NaHCOs: 0.05 mol / L, NaNOs: 0.1 mol / L, triethanolamine: 0.02 mol / L, NaNi 0.03% by mass. The CES line consists of a Waters 510 isocratic pump with a flow rate set at 0.8 mL / min, a Waters 717+ autosampler, an oven containing a 6 cm long, 40 mm inner diameter Waters Guard Column Ultrahydrogel precolumn, followed by a 30 cm long, 7.8 mm inner diameter Waters Ultrahydrogel linear column.Detection is performed using a Waters RI 410 differential refractometer. The oven is heated to 60°C and the refractometer is heated to 45°C. The CES device is calibrated with a series of sodium polyacrylate standards supplied by Polymer Standards Service with a peak molecular weight between 1000 g / mol and 1.10. 6 g / mol and a polydispersity index between 1.4 and 1.7. The calibration curve is linear and takes into account the correction obtained using the flow marker: dimethylformamide (DMF). The acquisition and processing of the chromatogram are carried out using the software “PSS WinGPC Scientific” v 4.02. The chromatogram obtained is integrated into the area corresponding to molecular weights greater than 250 g / mol.

[0047] Generally according to the invention, the binding agent L comprises the polymer P in the form of particles.

[0048] Preferably according to the invention, the binding agent L comprises from 5% by weight to 100% by weight, preferably from 10% by weight to 70% by weight of polymer P.

[0049] Essentially according to the invention, the aqueous composition T comprises at least one binding agent L. Advantageously, the composition T according to the invention may not comprise any other binding agent.Also advantageously, the composition T according to the invention may also comprise at least one other binding agent, different from the agent L, preferably another binding agent chosen from a (meth)acrylic polymer, a comb polymer, carboxymethylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, alginate, styrene-butadiene polymer, poly(allylamine, HCl), amilopectin and combinations thereof, or also comprising polyethylene, a fluorinated binder, for example a compound chosen from polyvinylidene fluoride (PVDF), poly(vinyl-pyrrolidone), polytetrafluoroethylene (PTFE), chlorotrifluoroethylene (ECTFE), polyethylene tetrafluoroethylene (ETFE), fluorinated ethylene-propylene (FEP), perfluoro-alkoxy (PFA), polychlorotrifluoroethylene (PCTFE), fluoracrylates, fluorosilicones and combinations thereof.

[0050] Also advantageously, the composition T according to the invention may also comprise at least one organic acid or one mineral acid, preferably an acid chosen from sulfuric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, acetic acid and their combinations.

[0051] Essentially according to the invention, the aqueous composition T comprises at least one material E. Preferably according to the invention, the composition T comprises a material E chosen from silicon, lithium, graphite or graphitic carbon, hexagonal carbon, rhombohedral carbon and their combinations, optionally doped with at least one element, preferably chosen from lithium, germanium, silicon and their combinations. The preferred material E is chosen from graphite carbon, silicon and their combinations.

[0052] In particular, the material E may be selected from a conductive carbon compound, furnace black, acetylene black, Ketjen carbon black, carbon nanotubes (CNTs), synthetic graphite, natural graphite, hard carbon, activated carbon, carbon black, graphene, mesoporous carbon, amorphous silicon, semi-crystalline silicon, silicon oxides, silicon nanowires, tin, tin oxides, germanium, lithium titanate, materials usable as an anode in a lithium-ion battery and combinations thereof.

[0053] According to the invention, the material E may include conductive materials or materials capable of intercalating or accepting lithium ions.

[0054] Advantageously according to the invention, the composition T may also comprise other ingredients. In particular, the composition T according to the invention may also comprise polyethylene, a fluorinated binder compound, for example a compound chosen from polyvinylidene fluoride (PVDF), poly(vinyl-pyrrolidone), polytetrafluoroethylene (PTFE), chlorotrifluoroethylene (ECTFE), polyethylene tetrafluoroethylene (ETFE), fluorinated ethylene-propylene (FEP), perfluoro-alkoxy (PFA), polychlorotrifluoroethylene (PCTFE), fluoracrylates, fluorosilicones and combinations thereof.

[0055] Within the composition T, the proportions of the different ingredients may vary. Preferably, the composition T according to the invention comprises:

[0056] * from 0.5% to 15% by dry weight of binding agent, in particular binding agent L, and

[0057] * from 85% to 99.5% by dry weight of material E, relative to the total quantity by dry weight of binding agent and material E.

[0058] The invention also provides a method of preparing an aqueous composition T. The method of preparation comprises:

[0059] - the preparation of a binding agent L according to the invention,

[0060] - the addition of at least one material E chosen from metallic fibers, metallic particles, graphite carbon fibers, graphite carbon particles and combinations thereof, preferably the material E is chosen from silicon, lithium, graphite or graphitic carbon, hexagonal carbon, rhombohedral carbon and combinations thereof, optionally doped with at least one element, preferably chosen from lithium, germanium and combinations thereof.

[0061] Also, the invention provides a method of manufacturing an anode using a composition T according to the invention. The method of manufacturing an anode comprises:

[0062] - the application to a substrate of at least one composition T according to the invention,

[0063] - drying then calendering of the coated substrate.

[0064] Advantageously according to the invention, the substrate or current collector may be in the structural form of a plate, a film, a mesh, a foam, a sheet, a rod or another form which does not significantly impair its ability to collect electric current. Generally, the substrate is in the form of a sheet, preferably a metallic copper (Cu°) sheet or a metallic nickel (Ni 0). Preferably, the invention provides a manufacturing method according to the invention for which the application is carried out at a pH of less than 7 or at a pH ranging from 4 to 6.5. Also preferably, the invention provides a manufacturing method according to the invention for which the application of composition T to the substrate is carried out on a metal surface at a thickness after drying and calendering which is less than 500 μm, preferably less than 100 μm or less than 50 μm. Generally according to the invention, the thickness of composition T after application to the substrate, drying and calendering is greater than 5 μm. According to the invention, the thickness of composition T after application to the substrate, drying and calendering is measured by means of a coating thickness gauge of 1 μm to 1000 μm, in particular of 20 μm to 30 μm.Particularly preferably, the invention provides a manufacturing method for which the application of the composition T to the substrate is homogeneous. According to the invention, the application of the composition is homogeneous when the particles of material E are regularly distributed in the layer. According to the invention, the homogeneity is measured by visual control by direct observation with the naked eye. According to the invention, the application is homogeneous when no aggregate is visible on the surface of the layer observed from the front in daylight.

[0065] Preferably, when manufacturing an anode according to the invention, at least one of the application steps is carried out at a pH below 7, preferably at a pH below 5. The composition T according to the invention is applied by a method known as such. It can be applied by spraying, rolling, coating, gravure printing or by any other means allowing an aqueous formulation to be applied to a surface.

[0066] The invention makes it possible to manufacture an anode using the composition T according to the invention. Thus, the invention provides an anode prepared according to the manufacturing method according to the invention.

[0067] According to the invention, the particular, advantageous or preferred characteristics of the composition T according to the invention define methods of preparation, methods of manufacture and anodes according to the invention which are also particular, advantageous or preferred.

[0068] The following examples illustrate the various aspects of the invention.

[0069] EXAMPLES

[0070] Preparation and characterization of a binding agent L comprising the polymer PI according to the invention

[0071] In a 1 L glass reactor equipped with mechanical stirring and heating by oil bath, 90 g of acrylic acid (monomer a), 10 g of ethyl acrylate (monomer b) and 830 g of deionized water are introduced. The mixture is heated to 70°C. Then, a solution comprising 0.50 g of ammonium persulfate in 10 g of deionized water is poured in one go. The temperature is maintained at 85°C for 60 minutes. Again, a solution comprising 0.20 g of ammonium persulfate in 10 g of deionized water is poured in one go. The temperature is maintained at 85°C for 60 minutes. After cooling to room temperature, the pH is adjusted to 2.5 by adding a 50% by weight aqueous sodium hydroxide solution. A water-soluble binding agent L is obtained according to the invention comprising the copolymer PI with a weight-average molecular mass Mw, measured by CES, of 165,000 g / mol in aqueous solution having a concentration of 11.2% by weight.

[0072] Preparation and characterization of a binding agent L comprising the polymer P2 according to the invention

[0073] 90 g of acrylic acid (monomer a), 10 g of ethyl acrylate (monomer b) and 820 g of deionized water are introduced into a 1 L glass reactor equipped with mechanical stirring and heating by oil bath. The mixture is heated to 70°C. Then, a solution comprising 0.35 g of ammonium persulfate in 10 g of deionized water is poured in one go. The temperature is maintained at 85°C for 60 minutes. Again, a solution comprising 0.35 g of ammonium persulfate in 20 g of deionized water is poured in one go. The temperature is maintained at 85°C for 60 minutes. After cooling to room temperature, the pH is adjusted to 5.7 by adding 39.4 g of LiOH.EEO in 40 g of deionized water.

[0074] A water-soluble binding agent L is obtained according to the invention comprising the copolymer P2 with a weight-average molecular mass Mw, measured by CES, of 256,000,000 g / mol in aqueous solution having a concentration of 10.4% by weight.

[0075] Preparation of aqueous anode compositions T according to the invention

[0076] With the binding agent L comprising the polymer Pl (11.2% by weight), with stirring for 2 hours at 3,000 rpm using a stirrer equipped with a 40 mm wheel, an aqueous composition is prepared comprising 5% by dry weight of polymer PI and 5% by dry weight of carbon black (Black C65 “Imerys”).

[0077] Then, in a glass beaker, with stirring for 1 hour at 4,500 rpm using a stirrer equipped with a 25 mm wheel, 0.32 g of this aqueous composition of carbon black and PI polymer, 1.2 g of silicon particles (SI-100 30-50 nm, "Get Nano Materials") and deionized water are introduced. 6.32 g of a mixture of graphites (GHDR 92.5% by weight, SFG15L 5% by weight, KS6L 2.5% by weight, "Imerys") and deionized water are added. Stirring is continued for 1 hour. 0.4 g of styrene-butadiene binder latex (latex SNRBM-451B "Zeon", 40% by weight) is then added and stirring is carried out for 30 minutes at 500 rpm. The quantities of water added are defined to obtain an aqueous anode composition Tl according to the invention whose final concentration by dry weight is 44.6%.

[0078] In a similar manner, the aqueous anode composition T2 according to the invention is prepared, the final concentration of which is also 44.6% by dry weight. It comprises the binding agent L according to the invention comprising the copolymer P2 (10.4% by weight). Manufacture and characterization of anodes according to the invention

[0079] A 100 μm thick copper foil is coated with a 20 μm thickness of composition Tl according to the invention using a hand-held application bar. 15 mm diameter discs are cut using a precision cutter. The coated discs are calendered at 0.6 t / cm2 using a press. The discs are then dried in an oven by gradually increasing the temperature to 110°C under vacuum for 18 hours.

[0080] After cooling to room temperature, the homogeneity of the layer is assessed by visual inspection: no aggregates or surface heterogeneities are visible on the surface of the layer observed from the front in daylight.

[0081] Then, the density of the anode obtained by weighing using a balance is measured and its porosity is calculated.

[0082] Similarly, an anode was prepared and characterized using the aqueous anode composition T2. ​​The results are shown in Table 1.

[0083] Table 1

[0084] The aqueous anode compositions comprising the binding agents according to the invention therefore make it possible to prepare anodes which are stable and which have good adhesion of the active materials to the copper layer. The anode compositions according to the invention make it possible to prepare anodes whose layer is homogeneous. These anodes can therefore be easily used for the manufacture of rechargeable batteries or secondary batteries.

[0085] Manufacture and characterization of half-cells comprising anodes according to the invention In a glove box (“MBraun LabStar”) maintained under an inert atmosphere (Ar, O2 and H2O < 0.5 ppm), the electrolyte (“Solvionic” IM, LiPFe in an ethylene carbonate-ethyl methyl carbonate mixture with 2% vinyl carbonate and 10% fluoro ethylene carbonate), an anode according to the invention, a pre-cut lithium disc (15.6 mm in diameter and 0.25 mm in thickness) then a separator disc (“Whatman” GF / C 1822-849, 17 mm in diameter, 0.26 mm in thickness and 1.2 pm in pore size) as well as a separator disc (“Celgard” 2325 tri-layer PE / PP / PE) are assembled on the working electrode. In a thermostatically controlled room at 25°C, the half-cell including the anode according to the invention prepared with the aqueous anode composition T2a is subjected to charge-discharge cycles:

[0086] - 2 cycles: C / 7 discharge to 0.005 V with C / 100 cut-off then C / 7 charge with 1.0 V cut-off, - 3 cycles: C / 5 discharge to 0.005 V with C / 50 cut-off then C / 5 charge with 1.0 V cut-off,

[0087] - 102 cycles: IC discharge to 0.005 V with C / 40 cut-off then IC charge with 1.0 V cut-off.

[0088] Similarly, a half-cell including the anode according to the invention prepared with the aqueous anode composition T2 is prepared and characterized. For each half-cell, the loading, capacity, initial Coulomb efficiency (ICE), Coulomb efficiency after 10 cycles and then after 20 cycles (CE10, CE20), cycling Coulombic efficiency (CCE1), capacity retention compared to the first cycle after 10 cycles and then after 20 cycles (CR10, CR20) are determined. The results are presented in Table 2.

[0089] Table 2

[0090] The binding agents according to the invention make it possible to prepare very effective aqueous anode compositions for obtaining anodes and batteries with a high silicon concentration and whose electrochemical properties are particularly interesting.

Claims

CLAIMS 1. Aqueous anode composition T comprising: * from 0.5% to 15% by dry weight of at least one binding agent L comprising at least one water-soluble polymer P, having a weight-average molecular mass Mw, measured by CES, ranging from 2,000 g / mol to 1,000,000 g / mol, prepared in the presence of at least one initiator compound, by a polymerization reaction: a. from 20 to 95% by weight of at least one anionic monomer (a) chosen from acrylic acid, an acrylic acid salt, methacrylic acid, a methacrylic acid salt and combinations thereof; b. from 5 to 80% by weight of at least one C1-C8 ester (b) of a compound derived from an acid chosen from acrylic acid, methacrylic acid, maleic acid, itaconic acid and crotonic acid, relative to the total amount by weight of monomers (a) and (b); and * from 85% to 99.5% by dry weight of at least one material E chosen from metal fibers, metal particles, graphite carbon fibers, graphite carbon particles, silicon particles and combinations thereof, relative to the total quantity by dry weight of binding agent L and material E.

2. Composition T according to claim 1 for which: * the anionic monomer (a) is chosen from acrylic acid, methacrylic acid and combinations thereof, preferably the anionic monomer (a) is acrylic acid, or * the monomer (a) is combined with at least one other anionic monomer, different from the monomer (a), and chosen from acrylic acid, methacrylic acid, an acrylic acid salt, a methacrylic acid salt, maleic acid, a maleic acid salt, itaconic acid, an itaconic acid salt, crotonic acid, a crotonic acid salt, an acrylic acid oligomer and combinations thereof.

3. Composition T according to one of claims 1 or 2 for which: * ester (b) is not a C1-C8 alicyclic ester or ester (b) is a C1-C7 ester or a C1-C6 ester OR a C1-C4 ester, preferably a C1-C3 ester, or * ester (b) is an acrylic acid ester or a methacrylic acid ester, preferably an acrylic acid ester, or * the ester (b) is chosen from methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, ethylhexyl methacrylate and combinations thereof, more preferably the ester (b) is chosen from ethyl acrylate, methyl acrylate, butyl acrylate, methyl methacrylate and combinations thereof.

4. Composition T according to one of claims 1 to 3 for which a single polymerization reaction is involved or for which the polymerization reaction also involves: * at least one crosslinking monomer (c) or at least one monomer (c) comprising at least two olefinic unsaturations, preferably less than 5% by weight, preferably from 0.01 to 4% by weight, in particular from 0.02 to 4% by weight or from 0.02 to 2% by weight, in particular from 0.02 to 1% by weight, of monomer (c) relative to the total quantity by weight of monomers, or * at least one hydrophobic monomer (d) different from compound (c), preferably chosen from a compound of formula (I): R'-(OE) m -(OP) p -R 2 (I) in which: - m and p, identical or different, independently represent 0 or an integer or decimal number less than 150, m or p is different from 0, - OE independently represents a CH2CH2O group, - OP independently represents a group chosen from CE^CEhjCEbO and CH2CH(CH3)O, - R 1 independently represents a group comprising at least one polymerizable olefinic unsaturation, preferably an acrylate group or a methacrylate group and - R 2 independently represents a linear or branched C6-C4o-alkyl group, a phenyl group, a polyphenyl group, preferably a linear or branched C10-C12-alkyl group, more preferably a linear or branched C12-C22-alkyl group, or a group comprising 2 to 5 phenyls or a tristyrylphenyl group or a pentastyrylcumylphenyl group, of preferably less than 20% by weight, preferably from 0.05 to 20% by weight, in particular from 0.1 to 10% by weight, of monomer (d) relative to the total amount by weight of monomers, or * at least one compound (e) chosen from phosphated hydroxyethyl acrylate, phosphated hydroxypropyl acrylate, phosphated hydroxyethylhexyl acrylate, phosphated hydroxyethyl methacrylate, phosphated hydroxypropyl methacrylate, phosphated hydroxyethylhexyl methacrylate, their salts and their combinations, preferably less than 20% by weight, preferably from 0.2 to 20% by weight, in particular from 0.5 to 10% by weight, of monomer (e) relative to the total quantity by weight of monomers, or * at least one compound (f) chosen from hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethylhexyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethylhexyl methacrylate, preferably less than 20% by weight, preferably from 0.2 to 20% by weight, in particular from 0.5 to 10% by weight, of monomer (f) relative to the total quantity by weight of monomers. Composition T according to one of claims 1 to 4 for which: * the polymer P is prepared in the presence of at least one initiator compound chosen from a peroxide (for example hydrogen peroxide), a hydroperoxide (for example / c / V-butyl hydroperoxide), a persulfate (for example sodium persulfate, ammonium persulfate, potassium persulfate), their combinations and their associations with a metal salt, preferably a metal salt chosen from an iron salt (for example Fe II or Fe III), a copper salt (for example Cu I or Cu II) and their combinations, or * the polymer P is prepared in the presence of a chain transfer agent, preferably in the presence of a compound chosen from isopropyl alcohol, mercaptan, dodecyl mercaptan, phosphorous acid, phosphite, hypophosphorous acid, hypophosphite, bisulfite, an alkyl iodide, an alkyl bromide and combinations thereof, or * the pH of polymer P is less than 12 or less than 11 or ranges from 2 to 12 or from 5 to 11, or * the pKa of polymer P is less than 5 or ranges from 1.5 to 5, or * the polymer P is non-neutralized or the polymer P is totally or partially neutralized, preferably by means of at least one compound chosen from LiOH, NaOH, KOH, ammonium derivatives, ammonia, aqueous ammonia, amine bases, e.g. triethanolamine, aminomethylpropanol or 2-amino-2-methyl-propanol (AMP), CaO, Ca(OH)2, ZnO, Zn(OH)2, MgO, Mg(OH)2 and combinations thereof.

6. Composition T according to one of claims 1 to 5 for which the polymerization reaction involves: - from 30 to 70% by weight, preferably from 35 to 70% by weight, of monomer (a) or - from 30 to 70% by weight, preferably from 30 to 65% by weight, of monomer (b), relative to the total quantity by weight of monomers (a) and (b).

7. Composition T according to one of claims 1 to 6 for which: * the polymer P has a weight-average molecular mass Mw, measured by CES, of less than 900,000 g / mol, less than 800,000 g / mol, more preferably less than 500,000 g / mol or less than 350,000 g / mol, or * the polymer P has a weight-average molecular mass Mw, measured by CES, greater than 5,000 g / mol, preferably greater than 20,000 g / mol.

8. Composition T according to one of claims 1 to 7 comprising at least one binding agent L and no other binding agent or also comprising: * at least one other binding agent, different from agent L, preferably another binding agent chosen from a (meth)acrylic polymer, a comb polymer, carboxymethylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, alginate, styrene-butadiene polymer, poly(allylamine, HCl), amilopectin and combinations thereof, or also comprising polyethylene, a fluorinated binding compound, for example a compound chosen from polyvinylidene fluoride (PVDF), poly(vinyl-pyrrolidone), polytetrafluoroethylene (PTFE), chlorotrifluoroethylene (ECTFE), polyethylene tetrafluoroethylene (ETFE), fluorinated ethylene-propylene (FEP), perfluoro-alkoxy (PFA), polychlorotrifluoroethylene (PCTFE), fluoracrylates, fluorosilicones and combinations thereof, or also comprising * at least one organic acid or one mineral acid, preferably an acid chosen from sulfuric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, acetic acid and combinations thereof. Composition T according to one of claims 1 to 8 for which the material E is chosen from silicon, lithium, graphite or graphitic carbon, hexagonal carbon, rhombohedral carbon and their combinations, optionally doped with at least one element, preferably chosen from lithium, germanium, silicon and their combinations. Composition T according to claim 9 comprising: * from 0.5% to 15% by dry weight of binding agent, in particular binding agent L, and * from 85% to 99.5% by dry weight of material E, relative to the total quantity by dry weight of binding agent and material E. . Method for preparing an aqueous composition T according to claims 1 to 10, comprising: - the preparation of a binding agent L according to one of claims 1 to 8, - the addition of at least one material E chosen from metal fibers, metal particles, graphite carbon fibers, graphite carbon particles and combinations thereof, preferably the material E is chosen from silicon, lithium, graphite or graphitic carbon, hexagonal carbon, rhombohedral carbon and combinations thereof, optionally doped with at least one element, preferably chosen from lithium, germanium and combinations thereof. . Method of manufacturing an anode comprising: - the application to a substrate of at least one composition T according to one of claims 1 to 10, - drying then calendering the coated substrate. . Manufacturing method according to claim 12 for which: - the application is carried out at a pH lower than 7 or at a pH ranging from 4 to 6.5, or - the application of composition T to the substrate is carried out on a metal surface at a thickness after drying and calendering, measured by means of a coating thickness gauge of 1 pm to 1000 pm, which is less than 500 pm, preferably less than 100 pm or less than 50 pm, or - the application of composition T to the substrate is carried out at a thickness after drying and calendering, measured by means of a coating thickness gauge of 1 pm to 1000 pm, which is greater than 5 pm, or - the application of composition T on the substrate is homogeneous. node prepared according to the manufacturing method according to one of claims 12 or 3.

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