Anode composition containing an organosulfur 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 an organosulfur monomer. The invention also relates to a method for producing an anode using said aqueous composition.

Description

[0001] ANODE COMPOSITION WITH ORGANOSULFUR BINDER

[0002] The invention relates to an aqueous anode composition comprising graphite metal or carbon particles or fibers and a binding agent comprising at least one water-soluble polymer P which is prepared from an organosulfur monomer. The invention also relates to a method of 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. The compatibility of the different ingredients of the anode compositions is also an important factor in the preparation of anode compositions as well as when preparing anodes using these compositions.

[0008] EP 3214676 discloses a lithium-ion secondary battery anode preparation paste comprising a water-soluble polyacrylic copolymer. WO 2014024937 discloses an anode for a secondary battery prepared using a binder and a fluorinated and sulfonated polymer. WO 2015008626 discloses a poly(meth)acrylamide binder for battery preparation having a weight-average molecular weight of 300,000 to 6,000,000 g / mol. KR 20210064944 discloses a copolymer of PVDF and styrene sulfonic acid.

[0009] State-of-the-art anode compositions are not always satisfactory. There is therefore a need for anode compositions that can provide solutions to some or all of the problems of state-of-the-art anode compositions.

[0010] 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 of at least one organosulfur monomer M 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 monomer M which is an organosulfur compound. The monomer M comprises non-mineral sulfur combined with at least one organic residue, preferably combined with a hydrocarbon residue which may comprise one or more heteroatoms such as oxygen or nitrogen or phosphorus. Preferably according to the invention, the monomer M is chosen from a sulfonated monomer M1, a sulfated monomer M2, and combinations thereof. According to the invention, the sulfonated monomer M1 comprises at least one sulfonate ion or group of formula SO3' and the sulfated monomer M2 comprises at least one sulfate ion or group of formula SO4'. More preferably according to the invention, the monomer M is a sulfonated monomer M1.

[0014] According to the invention, the monomer M also comprises at least one polymerizable group, preferably at least one unsaturated ethylenic group, in particular a methacrylate group, an acrylate group, a methacrylamide group, an acrylamide group, a styrenic group, an allylic group, a methallyl group, an isoprenyl group, a vinyl group.

[0015] In a particularly preferred manner according to the invention, the organosulfur monomer M is chosen from 2-acrylamido-2-methylpropane sulfonic 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. Preferred monomers M are 2-acrylamido-2-methylpropanesulfonic acid sodium salt (AMPS), 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium salt and sodium styrene sulfonate, especially 2-acrylamido-2-methylpropanesulfonic acid sodium salt (AMPS).

[0016] Advantageously according to the invention, only the monomer M can be used during the preparation of the polymer P. Preferably according to the invention, the monomer M can be combined with at least one other monomer, preferably with at least one other monomer chosen from an anionic monomer, a non-ionic monomer and their combinations. Also more preferably, the monomer M can be combined with at least one other anionic monomer.

[0017] Preferably according to the invention, the monomer M may be combined with at least one other anionic monomer M3 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. More preferably according to the invention, the monomer M may be combined with at least one other anionic monomer M3 chosen from acrylic acid, methacrylic acid, an acrylic acid salt, a methacrylic acid salt and combinations thereof. Preferably according to the invention, the monomer M3 is used in an amount of 2% by weight to 98% by weight, preferably 5% by weight to 90% by weight or 15% by weight to 85% by weight relative to the total amount by weight of monomers.

[0018] Also preferably according to the invention, the monomer M may be combined with at least one other non-ionic monomer M4 chosen from vinyl acetate, a C1-C8 ester of a compound derived from an acid chosen from acrylic acid, methacrylic acid, maleic acid, itaconic acid and crotonic acid, (ethyl methacrylate, methyl methacrylate, butyl methacrylate, ethyl acrylate, methyl acrylate, butyl acrylate), hydroxyethylmethacrylate, hydroxyethylacrylate, hydroxypropylmethacrylate, hydroxypropylacrylate, an amine monomer (acrylonitrile, vinyl lactam), styrene and combinations thereof.More preferably according to the invention, the monomer M can be combined with at least one other non-ionic monomer M4 chosen from vinyl acetate, a C1-C8 ester of a compound derived from an acid chosen from acrylic acid, methacrylic acid, maleic acid, itaconic acid and crotonic acid, (ethyl methacrylate, methyl methacrylate, butyl methacrylate, ethyl acrylate, methyl acrylate, butyl acrylate), hydroxyethylmethacrylate, hydroxyethylacrylate, hydroxypropylmethacrylate, hydroxypropylacrylate, styrene and combinations thereof. Much more preferably according to the invention, the monomer M can be combined with at least one other non-ionic monomer M4 chosen from ethyl acrylate, methyl acrylate, butyl acrylate, styrene and combinations thereof.

[0019] Preferably according to the invention, the monomer M4 is used in an amount of 2% by weight to 30% by weight, preferably 5% by weight to 25% by weight or 10% by weight to 20% by weight relative to the total amount by weight of monomers.

[0020] Preferably according to the invention, the polymer P is prepared in the absence of acrylamide monomer or acrylamide derivative, in particular in the absence of acrylamide, methacrylamide, dimethacrylamide, diethylacrylamide and N-methylolacrylamide.

[0021] Also preferably according to the invention, the polymer P is prepared in the absence of crosslinking monomer and in the absence of halogenated monomer, in particular in the absence of fluorinated monomer. Also preferably according to the invention, the polymer P is prepared by means of a combination of monomers M and M3, a combination of monomers M and M4, a combination of monomers M, M3 and M4.

[0022] More preferably according to the invention, the polymer P is prepared by means of a combination of monomers M1 and M3, a combination of monomers M1 and M4, a combination of monomers M1, M3 and M4.

[0023] When using another monomer during the preparation of polymer P, the proportions of monomer M and the additional monomer can vary widely. Preferably, the amount of monomer different from monomer M that is used makes it possible to obtain a water-soluble copolymer P. According to the invention, copolymer P is water-soluble. Preferably according to the invention, the water-soluble copolymer P is prepared using a majority by weight amount of anionic monomers. Advantageously, polymer P is soluble in water in any amount at room temperature, preferably at different pH values, in particular at pH values ​​ranging from 2 to 12. Preferably according to the invention, polymer P can be prepared from:

[0024] - from 2% by weight to 100% by weight, preferably from 2% by weight to 95% by weight, of monomer M, preferably a monomer M chosen from monomer M1, monomer M2 and their combinations.

[0025] More preferably according to the invention, the polymer P can be prepared from

[0026] - from 2% by weight to 100% by weight, preferably from 2% by weight to 95% by weight, of monomer M, preferably a monomer M chosen from monomer M1, monomer M2 and their combinations, and

[0027] - from 0 to 98% by weight, preferably from 5% by weight to 98% by weight, of another monomer, different from the monomer M, preferably another monomer chosen from acrylic acid, methacrylic acid, ethyl acrylate, butyl acrylate and combinations thereof. Much more preferably according to the invention, the polymer P can be prepared from:

[0028] - from 2% by weight to 100% by weight, preferably from 2% by weight to 95% by weight, of 2-acrylamido-2-methylpropane sulfonic acid and

[0029] - from 0 to 98% by weight, preferably from 5% by weight to 98% by weight, of another monomer, different from the monomer M, preferably at least one other monomer chosen from acrylic acid, methacrylic acid, ethyl acrylate, butyl acrylate and combinations thereof, in particular a combination of acrylic acid or methacrylic acid with ethyl acrylate or with butyl acrylate. Also much more preferably according to the invention, the polymer P can be prepared from:

[0030] - from 2% by weight to 100% by weight, preferably from 2% by weight to 95% by weight, of styrene sulfonate and

[0031] - from 0 to 98% by weight, preferably from 5% by weight to 98% by weight, of another monomer, different from monomer M, preferably at least one other monomer chosen from acrylic acid, methacrylic acid, ethyl acrylate, butyl acrylate and combinations thereof, in particular a combination of acrylic acid or methacrylic acid with ethyl acrylate or with butyl acrylate.

[0032] During the polymerization reaction, the use of a single monomer M, preferably a single monomer M1 or a single monomer M2, leads to a homopolymer PI according to the invention. The use of at least two different monomers M, preferably at least two different monomers M1 or M2, or at least one monomer M and at least one other different monomer, preferably at least one other monomer M3 or M4, leads to a copolymer P2 according to the invention. According to the invention, homopolymer PI and copolymer P2 can be used independently or can be combined. Thus, the composition T according to the invention can comprise at least one binding agent L chosen from homopolymers PI, copolymers P2 and combinations thereof.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] According to the invention, the polymer P may be non-neutralized or it may be partially neutralized or completely neutralized. Preferably, the polymer P is non-neutralized or partially neutralized. According to the invention, the carboxylic groups of the polymer P may be partially neutralized at a rate of 70 to 97 mol%, preferably at a rate of 90 to 95 mol%. The polymer P may be partially or completely neutralized by means of at least one monovalent ion or at least one divalent ion. According to the invention, the polymer P may 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 may then be carried out in variable relative molar proportions of the monovalent and divalent ions.Preferably according to the invention the molar proportions monovalent ion / divalent ion 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.

[0037] 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 + , Li + , NH4 + . 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+ .

[0038] 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.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 3.5 or ranges from 1.5 to 2.5.

[0039] Polymer P has a weight average molecular weight Mw (measured by CES) ranging from 2,000 g / mol to 1,000,000 g / mol. Preferably, polymer P has a weight average molecular weight Mw (measured by CES) of less than 800,000 g / mol, less than 500,000 g / mol, more preferably less than 300,000 g / mol. Polymer P generally has a weight average molecular weight Mw (measured by CES) of greater than 5,000 g / mol or greater than 15,000 g / mol, preferably greater than 50,000 g / mol or greater than 100,000 g / mol.

[0040] 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.

[0041] 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, NaNs 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.

[0042] Generally according to the invention, the binding agent L comprises the polymer P in the form of particles.

[0043] Preferably according to the invention, the binding agent L comprises from 5% by weight to 100%, preferably from 10% by weight to 70%, by weight of polymer P.

[0044] 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 (CMC), hydroxymethylcellulose, hydroxyethylcellulose, alginate, styrene-butadiene polymer, poly(allylamine, HCl), amilopectin, a copolymer of acrylic acid and acrylonitrile and combinations thereof.

[0045] 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 combinations thereof.

[0046] 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.

[0047] 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. According to the invention, the material E may include conductive materials or materials capable of intercalating or accepting lithium ions.

[0048] 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.

[0049] Within the composition T, the proportions of the different ingredients may vary. Preferably, the composition T according to the invention comprises: * from 1% to 15% by dry weight of binding agent L, and

[0050] * from 85% to 99% by dry weight of material E, relative to the total quantity by dry weight of binding agent L and material E.

[0051] The invention also provides a method of preparing a composition T. The method of preparation comprises:

[0052] - the preparation of a binding agent L according to the invention,

[0053] - 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.

[0054] 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:

[0055] - the application to a substrate of at least one composition T according to the invention,

[0056] - drying then calendering of the coated substrate.

[0057] Preferably according to the invention, the calendering is carried out by means of a press, for example at a pressure ranging from 0.1 t / cm 2 at 2 t / cm 2 , preferably 0.2 t / cm 2 at 1 t / cm 2 . 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 ).

[0058] 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 the 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.

[0059] 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 per se. It can be applied by spraying, by rolling, by coating, by gravure printing or by any other means allowing an aqueous formulation to be applied to a surface. 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.

[0060] 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.

[0061] The following examples illustrate the various aspects of the invention.

[0062] Preparation and characterization of a binding agent L comprising the polymer PI a according to the invention:

[0063] In a 1 L glass reactor equipped with mechanical stirring and heating by oil bath, 50 g of a 50% by weight aqueous solution of sodium 2-acrylamido-2-methylpropane sulfonate (monomer Mlb) and 850 g of deionized water are introduced. 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 120 min. After cooling to room temperature, the pH is adjusted to 6.0 by adding a 50% by weight aqueous sodium hydroxide solution. A binding agent L according to the invention is obtained comprising the homopolymer Pla with a weight-average molecular weight, Mw measured by CES, of 177,000 g / mol in aqueous solution having a concentration of 12% by weight.

[0064] Preparation and characterization of a binding agent L comprising the polymer Pib according to the invention:

[0065] In a 1 L glass reactor equipped with mechanical stirring and heating by oil bath, 165 g of sodium styrene sulfonate (monomer Mla) dissolved in 310 g of deionized water are introduced. The mixture is heated to 85 ° C. Then, a solution comprising 0.7 g of ammonium persulfate in 10 g of deionized water is poured in one go. The temperature is maintained at 90 ° C for 90 min. After cooling to room temperature, the pH is adjusted to 8.5 by adding a 50% by weight aqueous sodium hydroxide solution. A binding agent L according to the invention is obtained comprising the homopolymer Pib with a weight-average molecular mass, Mw measured by CES, of 183,500 g / mol in aqueous solution having a concentration of 25% by weight.

[0066] Preparation and characterization of a binding agent L comprising the Pic polymer according to the invention:

[0067] In a 1 L glass reactor equipped with mechanical stirring and heating by oil bath, 247 g of sodium styrene sulfonate (monomer Mla) dissolved in 464 g of deionized water are introduced. The mixture is heated to 85 ° C. Then, a solution comprising 2.2 g of ammonium persulfate in 16 g of deionized water is poured in one go. The temperature is maintained at 90 ° C for 90 min. After cooling to room temperature, the pH is adjusted to 8.5 by adding a 50% by weight aqueous sodium hydroxide solution. A binding agent L according to the invention is obtained comprising the homopolymer Pic with a weight-average molecular mass, Mw measured by CES, of 108,000 g / mol in aqueous solution having a concentration of 33% by weight.

[0068] Preparation and characterization of a binding agent L comprising the polymer Pld according to the invention:

[0069] In a 1 L glass reactor equipped with mechanical stirring and heating by oil bath, 50 g of isopropanol and 150 g of deionized water are introduced. The mixture is heated to reflux at 81 °C. Then, the following are poured in parallel, using 2 pumps for 120 min:

[0070] - a solution comprising 20g of ammonium persulfate in 30g of deionized water,

[0071] - a solution comprising 243g of sodium styrene sulfonate (monomer Mla) and 566g of deionized water.

[0072] The isopropanol is then separated by distillation. After cooling to room temperature, deionized water is added and the pH is adjusted to 8.3 by adding a 50% by weight aqueous sodium hydroxide solution. A binding agent L according to the invention is obtained comprising the homopolymer Pld with a weight-average molecular mass, Mw measured by CES, of 10,000 g / mol in aqueous solution having a concentration of 27% by weight.

[0073] Preparation and characterization of a binding agent L comprising the polymer P2a according to the invention:

[0074] In a 1 L glass reactor equipped with mechanical stirring and heating by oil bath, 50 g of a 50% by weight aqueous solution of sodium 2-acrylamido-2-methylpropane sulfonate (monomer Mlb), 60 g of acrylic acid (monomer M3a), 15 g of ethyl acrylate (monomer M4a) and 805 g of deionized water are introduced. 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 min. Again, 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 min. After cooling to room temperature, the pH is adjusted to 6.0 by adding a 50% by weight aqueous sodium hydroxide solution.A binding agent L according to the invention is obtained comprising the copolymer P2a with a weight-average molecular mass, Mw measured by CES, of 158,000 g / mol in aqueous solution having a concentration of 11.1% by weight.

[0075] Preparation and characterization of a binding agent L comprising the polymer P2b according to the invention:

[0076] In a 1 L glass reactor equipped with mechanical stirring and heating by oil bath, 75 g of acrylic acid (monomer M3a), 25 g of sodium styrene sulfonate (monomer Mla) and 805 g of deionized water are introduced. 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 min. Again, 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 min. After cooling to room temperature, the pH is adjusted to 6.3 by adding a 50% by weight aqueous sodium hydroxide solution. A binding agent L according to the invention is obtained comprising the copolymer P2b with a weight-average molecular mass, Mw measured by CES, of 181,000 g / mol in aqueous solution having a concentration of 11.3% by weight.

[0077] Preparation and characterization of a binding agent L comprising the polymer P2c according to the invention:

[0078] In a 1 L glass reactor equipped with mechanical stirring and heating by oil bath, 25 g of sodium styrene sulfonate (monomer Mla), 60 g of acrylic acid (monomer M3a), 15 g of ethyl acrylate (monomer M4a) and 830 g of deionized water are introduced. 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 min. Again, 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 min. After cooling to room temperature, the pH is adjusted to 5.8 by adding a 50% by weight aqueous sodium hydroxide solution. A binding agent L according to the invention is obtained comprising the copolymer P2c 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.Preparation and characterization of a binding agent L comprising the polymer P2d according to the invention:.

[0079] 300g of deionized water are introduced into a 1 L glass reactor equipped with mechanical stirring and heating by oil bath. It is heated to 94°C. Then, the following are poured in parallel, using 2 pumps for 120 min:

[0080] - a solution comprising 8g of ammonium persulfate in 50g of deionized water,

[0081] - a solution comprising 206g of acrylic acid (monomer M3a), 36.4g of sodium styrene sulfonate (monomer Mla) and 50g of deionized water.

[0082] The temperature is maintained at 94°C for 60 min. After cooling to room temperature, the pH is adjusted to 8.7 by adding a 50% by weight aqueous sodium hydroxide solution. A binding agent L according to the invention is obtained comprising the copolymer P2d with a weight-average molecular mass, Mw measured by CES, of 26,800 g / mol in aqueous solution having a concentration of 38.5% by weight.

[0083] Preparation of aqueous anode compositions T according to the invention

[0084] With the binding agent L comprising the polymer P2a (11.1% 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 P2a and 5% by dry weight of carbon black (Black C65 “Imerys”).

[0085] 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 P2a 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 SNR BM-45 IB “Zeon”, 40% by weight) is then added and the mixture is stirred for 30 min at 500 rpm. The quantities of water added are defined to obtain an aqueous anode composition T2a according to the invention whose final concentration by dry weight is 44.6%.

[0086] In a similar manner, the aqueous anode compositions T2b to T2d according to the invention are prepared, the final concentration of which is also 44.6% by dry weight. They respectively comprise the binding agents L according to the invention comprising the copolymers P2b to P2d. Manufacture and characterization of anodes according to the invention

[0087] A 100 μm thick copper foil is coated with a 20 μm thickness of composition Tla according to the invention using a hand-operated 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.

[0088] 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.

[0089] Then, the density of the anode obtained by weighing using a balance is measured and its porosity is calculated.

[0090] Similarly, anodes were prepared and characterized using aqueous anode compositions T2b to T2d. The results are shown in Table 1.

[0091] Table 1

[0092] 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.

[0093] Manufacture and characterization of half-cells comprising anodes according to the invention In a glove box (“MBraun LabSta”r) maintained under an inert atmosphere (Ar, O2 and H2O < 0.5 ppm), the electrolyte (“Solvionic” IM, LiPF6 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 μm in pore size) as well as a separator disc (“Celgard” 2325 tri-layer PE / PP / PE) are assembled on the working electrode.

[0094] 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:

[0095] - 2 cycles: C / 7 discharge down to 0.005 V with C / 100 cut-off then C / 7 charge with 1.0 V cut-off,

[0096] - 3 cycles: C / 5 discharge down to 0.005 V with C / 50 cut-off then C / 5 charge with 1.0 V cut-off,

[0097] - 102 cycles: IC discharge to 0.005 V with C / 40 cut-off then IC charge with 1.0 V cut-off.

[0098] In a similar manner, half-cells including anodes according to the invention prepared with the aqueous anode compositions T2b to T2d are prepared and characterized. For each half-cell, the charge (loading), capacity, initial Coulomb efficiency (ICE), Coulomb efficiency after 10 cycles and then after 20 cycles (CE 10, CE20), cycling Coulombic efficiency (CCE1), capacity retention compared to the first cycle after 10 cycles and then after 20 cycles (CR 10, CR20) are determined. The results are presented in Table 2.

[0099] Table 2

[0100] 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 of at least one organosulfur monomer M 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 weight of binding agent L and material E.

2. Composition T according to claim 1 for which the monomer M is chosen from a sulfonated monomer M1, a sulfated monomer M2, and combinations thereof, or for which only the monomer M is used during the preparation of the polymer P; preferably, the organosulfur monomer M is chosen from 2-acrylamido-2-methylpropanesulfonic acid (AMPS), allylsulfonic acid, alkylenesulfonates, alkylenearylsulfonates in particular styrenesulfonate, vinylsulfonate, methallylsulfonate, allylsulfonate, methallylsulfate, allylsulfate, 2-sulfoethyl methacrylate, 3-allyloxy-2-hydroxy-1-propanesulfonic acid, 3 sulfopropyl methacrylate, their salts and combinations thereof.

3. Composition T according to one of claims 1 or 2 for which: - the monomer M is combined with at least one other anionic monomer M3 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, or - the monomer M is combined with at least one other non-ionic monomer M4 chosen from vinyl acetate, a C1-C8 ester of a compound derived from an acid chosen from acrylic acid, methacrylic acid, maleic acid, itaconic acid and crotonic acid, (for example ethyl methacrylate, methyl methacrylate, butyl methacrylate, ethyl acrylate, methyl acrylate, butyl acrylate), hydroxyethylmethacrylate, hydroxyethylacrylate, hydroxypropylmethacrylate, hydroxypropylacrylate, an amine monomer (e.g. acrylonitrile, vinyl lactam), styrene and combinations thereof, or - polymer P is prepared from: - from 2% by weight to 100% by weight, preferably from 2% by weight to 95% by weight, of monomer M, preferably a monomer M chosen from monomer M1, monomer M2 and their combinations, and - from 0 to 98% by weight, preferably from 5% by weight to 98% by weight, of another monomer, different from monomer M, preferably another monomer chosen from monomer M3, monomer M4 and their combinations, or - 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 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, 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 polymer P is non-neutralized or the polymer P is partially or totally neutralized, preferably neutralized by means of at least one compound chosen from NaOH, KOH, LiOH, ammonium derivatives, ammonia, ammonia, primary amine, secondary amine, CaO, Ca(OH)2, ZnO, Zn(OH)2, MgO, Mg(OH)2 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 3.5 or ranges from 1.5 to 2.

5.

4. Composition T according to one of claims 1 to 3 for which: - the polymer P has a weight-average molecular mass Mw (measured by CES) of less than 800,000 g / mol, less than 500,000 g / mol, more preferably less than 300,000 g / mol, or - the polymer P has a weight-average molecular mass Mw (measured by CES) greater than 5,000 g / mol or greater than 15,000 g / mol, preferably greater than 50,000 g / mol or greater than 100,000 g / mol.

5. Composition T according to one of claims 1 to 4 comprising at least one binding agent L chosen from homopolymers PI, copolymers P2 and their combinations.

6. Composition T according to one of claims 1 to 5 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 their combinations.

7. Composition T according to one of claims 1 to 6 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 and their combinations.

8. Composition T according to one of claims 1 to 7 not comprising any 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.

9. Composition T according to one of claims 1 to 8 also comprising 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.

10. Composition T according to one of claims 1 to 8 comprising: * from 1% to 15% by dry weight of binding agent L, and * from 85% to 99% by dry weight of material E, relative to the total quantity by weight of binding agent L and material E.

11. Method for preparing an aqueous composition T according to claims 1 to 10, comprising: - the preparation of a binding agent L one of claims 1 to 6, - 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.

12. 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 of the coated substrate.

13. 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 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 20 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.

14. Anode prepared according to the manufacturing method according to one of claims 12

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