Preparation of a cathode priming coat

Abstract

The invention relates to a process for preparing a cathode priming coat combining two polyacrylic binders having different molecular weights and carbon particles. The invention also relates to a composition suitable for said process and to a cathode that can be used for manufacturing cells for a rechargeable battery.

Description

[0001] PREPARATION OF A CATHODE PRIMER LAYER

[0002] The invention relates to a method for preparing a cathode primer layer combining two polyacrylic binders of different molecular weights and carbon particles. The invention also relates to a composition suitable for this method and to a cathode usable for the manufacture of secondary battery cells.

[0003] Cathode preparation compositions are known, which generally comprise carbon and a metal in the form of particles associated with a binder composition. Binder compositions allow the particles to be fixed on a metal substrate. The binding power is therefore decisive when manufacturing a cathode using these compositions.

[0004] Cathode manufacturing time and yield are also important factors. Improving the efficiency of the various reactions involved must therefore be sought.

[0005] As electrochemically inactive components during cathode operation, binder compounds do not directly contribute to the capacity of the battery cell including the cathode, but their influence on the overall electrochemical performance remains considerable. These binder compounds must contribute to the formation of stable networks of the active or conductive solid components present in the cathodes.

[0006] The binder compounds used during the preparation of a cathode should also improve thermal stability, chemical and electrochemical stability, tensile strength, in particular through good adhesion and cohesion, as well as a certain flexibility.

[0007] Furthermore, the compatibility of the various ingredients of the cathode and battery preparation compositions is also an important factor to consider when preparing these compositions as well as when preparing the cathodes using these compositions. In particular, compatibility, and especially the absence of solubility or low solubility, with the battery electrolyte is a crucial property.

[0008] Easy and homogeneous application of cathode preparation compositions is sought in order to obtain a homogeneous layer and to limit or avoid defects on the surface of the electrode, in order to achieve a homogeneous and particularly efficient conductive layer. Surface leveling, restructuring and flow behavior of cathode preparation compositions must be well controlled. Cathode preparation compositions must also be stable and homogeneous during their preparation, storage or application. Sedimentation, formation of agglomerates or aggregates, separation of ingredients must therefore be limited or avoided.

[0009] Generally, improving the adhesion of active elements should always be sought during cathode preparation. The adhesion of the different layers of ingredients deposited on the metal substrate must therefore be improved. In particular, when a primer layer comprising carbon is deposited on the metal substrate, improving its adhesion is essential. Because they are in direct contact with the metal substrate of the cathode and with the binder composition of the electroactive compound, the properties of the primer layer compositions are particularly important.

[0010] CN 115881966 describes a conductive adhesive formulation that is composed of 2 polymer compositions grafted with conductive monomers. US 20170018770 describes the preparation of a cathode from a composition comprising LiNiMn electroactive particles. KR 1020190143256 describes the preparation of an anode using electroactive and binder compositions comprising silicon particles.

[0011] The known compositions used in the preparation of cathode primer layers of the state of the art are not always satisfactory. There is therefore a need for compositions used in the preparation of cathode primer layers which make it possible to provide solutions to all or part of the problems of the compositions of the state of the art.

[0012] Thus, the invention provides a method of preparing a cathode primary layer comprising:

[0013] • the application: of at least one binding agent Q comprising at least one water-soluble polymer PI, of molecular mass Mw, measured by CES, ranging from more than 100,000 g / mol to 1,000,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (a1) chosen from acrylic acid, methacrylic acid, an acrylic acid oligomer, a methacrylic acid oligomer, an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt and combinations thereof, of at least one binding agent R comprising at least one water-soluble polymer P2, of molecular mass Mw, measured by CES, ranging from 2,000 g / mol to strictly less than 1 ... salt, a methacrylic acid oligomer salt and combinations thereof, of at least one binding agent R comprising at least one water-soluble polymer P2, of molecular mass Mw, measured by CES, ranging from 2,000 g / mol to strictly less than 100,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (a1) chosen from acrylic acid, at least one initiator compound, of at least one compound (a2) chosen from acrylic acid, methacrylic acid, an oligomer of acrylic acid, an oligomer of methacrylic acid,an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt and combinations thereof and at least one material E comprising carbon particles;,

[0014] • drying of the primer coat.

[0015] Thus, the invention provides a method for preparing a cathode primary layer. Preferably, the primary layer obtained according to the invention does not comprise silicon or a metallic electroactive compound.

[0016] Preferably for the method according to the invention, the compound (al) is chosen from acrylic acid, methacrylic acid, an acrylic acid salt, a methacrylic acid salt and combinations thereof, preferably the compound (al) is acrylic acid or methacrylic acid.

[0017] The PI polymer used according to the invention is a water-soluble polymer. Preferably according to the invention, the PI polymer is water-soluble at a pH greater than 4.

[0018] Preferably according to the invention, the polymer PI may be a homopolymer of the compound (a1). Also preferably according to the invention, the polymer PI may be a copolymer of compounds (a1) or be a copolymer of at least one compound (a1) and at least one other compound (b).

[0019] Preferably, compound (b) is selected from: a compound (b1) selected from C1-C12 esters of methacrylic acid, C1-C12 esters of acrylic acid and combinations thereof, preferably C1-Cs esters of methacrylic acid, C1-Cs esters of acrylic acid and combinations thereof, preferably methylmethacrylate, ethylmethacrylate, propylmethacrylate, butylmethacrylate, methylacrylate, ethylacrylate, propylacrylate, butylacrylate, more preferably, methylacrylate, ethylacrylate, butylacrylate; a compound (b2) selected from acrylonitrile, acrylamide, N-methylolacrylamide, vinyl-lactam, N-vinylpyrrolidone, ureidomethacrylate and combinations thereof, preferably acrylonitrile; a compound (b3) selected from maleic acid, maleic anhydride, itaconic acid, crotonic acid and combinations thereof;a compound (b4) chosen from hydroxyethylacrylate, hydroxyethylmethacrylate, hydroxypropylacrylate, hydroxypropylmethacrylate, hydroxybutylmethacrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, styrene, more preferably styrene; a compound (b5) selected from 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, ethoxymethacrylate sulfonic acid, sodium methallyl sulfonate, styrene sulfonate, phosphated hydroxyethylacrylate, phosphated hydroxyethylmethacrylate, phosphated hydroxypropylacrylate, phosphated hydroxypropylmethacrylate, phosphated hydroxybutylmethacrylate; a crosslinking compound (b6).;

[0020] According to the invention, the polymer PI can be prepared solely by a polymerization reaction of the monomer (a1) and optionally of at least one compound (b) chosen from compounds (b1) to (b6). Preferably according to the invention, the polymer PI is not crosslinked, in particular by means of calcium acetate, calcium hydroxide, calcium bicarbonate or calcium oxalate. Also preferably, the compound (b) is not acrylonitrile or acrylamide or it does not comprise fluorine; the polymer PI is then not a fluorinated polymer. Also preferably according to the invention, the polymer PI is a free polymer, it is not grafted, in particular it is not grafted to a fluorinated polymer or it is not grafted to a polyaniline, a polypyrrole, a polythiophene, a polyparaphenylene or to a polyphenylacetylene.

[0021] According to the invention, the PI polymer is not a conductive polymer.

[0022] The amounts of monomers present in the PI polymer can vary relatively significantly. Preferably according to the invention, the PI polymer can be prepared by a polymerization reaction of 55% by weight to 100% by weight of compound (a1) and of 0% by weight to 45% by weight of compound (b). Also preferably, the PI polymer can be prepared by a polymerization reaction of 55% by weight to 90% by weight of compound (a1) and of 10% by weight to 45% by weight of compound (b) or of 55% by weight to 80% by weight of compound (a1) and of 20% by weight to 45% by weight of compound (b).

[0023] According to the invention, the polymer PI can also be prepared by a polymerization reaction of 55 wt% to 70 wt% of compound (a1) and 30 wt% to 45 wt% of compound (b).

[0024] Essentially according to the invention, the polymer PI has a molecular mass Mw, measured by CES, greater than 100,000 g / mol. Preferably according to the invention, the polymer PI has a molecular mass Mw, measured by CES, ranging from 120,000 g / mol to 800,000 g / mol or from 150,000 g / mol to 800,000 g / mol.

[0025] Also preferably according to the invention, the polymer PI has a molecular mass Mw, measured by CES, ranging from 200,000 g / mol to 800,000 g / mol or from 250,000 g / mol to 800,000 g / mol.

[0026] More preferably according to the invention, the polymer PI has a molecular mass Mw, measured by CES, ranging from 120,000 g / mol to 500,000 g / mol or from 150,000 g / mol to 500,000 g / mol or from 200,000 g / mol to 500,000 g / mol or from 250,000 g / mol to 500,000 g / mol.

[0027] According to the invention, the molecular weight or mass of the polymers PI and P2 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 chain is composed of a “Waters” 510 isocratic pump, whose flow rate is set at 0.8 mL / min, a “Waters” 717+ sample changer, an oven containing a “Waters” Guard Column Ultrahydrogel precolumn of 6 cm length and 40 mm inner diameter, followed by a “Waters” Ultrahydrogel linear column of 30 cm length and 7.8 mm inner diameter.Detection is carried out using a differential refractometer type RI “Waters” 410. The oven is heated to a temperature of 60°C and the refractometer is heated to a temperature of 45°C. The CES device is calibrated with a series of sodium polyacrylate standards supplied by “Polymer Standards Service” with a molecular weight at the peak 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.

[0028] Also preferably according to the invention, the polymer PI has a glass transition temperature Tg, calculated according to the Flory-Fox equation, ranging from -10°C to 230°C or from 20°C to 230°C. More preferably according to the invention, the polymer PI is a homopolymer whose Tg is greater than 0°C, preferably greater than 10°C.

[0029] Also more preferably according to the invention, the polymer PI is a copolymer whose Tg is greater than 50°C, preferably greater than 100°C.

[0030] The Flory-Fox equation allows the glass transition temperature of a copolymer to be calculated from the parameters of the monomers used for its preparation.

[0031] The PI polymer used according to the invention can be used in its acid form or in a form in which all or part of its carboxylic groups can be neutralized. Preferably according to the invention, the PI polymer is therefore totally or partially acidic or totally or partially non-neutralized. More preferably, the PI polymer is partially neutralized. According to the invention, the neutralization of the PI polymer is preferably carried out by means of at least one compound chosen from LiOH, NaOH, KOH, Zn(OH)2, Mg(OH)2, Ca(OH)2, ZnO, MgO, CaO, ammonium derivatives, ammonia, aqueous ammonia, amine bases, for example triethanolamine, aminomethylpropanol or 2-amino-2-methyl-propanol (AMP) and combinations thereof, more preferably LiOH or Zn(OH)2 or ZnO.

[0032] According to the invention, the polymer PI is prepared by a polymerization reaction at a temperature above 50°C, preferably at a temperature ranging from 60°C to 95°C or ranging from 65°C to 90°C, in particular at a temperature ranging from 70°C to 85°C.

[0033] Preferably, the initiator compound, for the preparation of polymer PI or polymer P2, is independently chosen from peroxides, hydroperoxides, persulfates and combinations thereof. More preferably according to the invention, the initiator compound is chosen from hydrogen peroxide, tert-butyl hydroperoxide, benzoyl peroxide, acetyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium persulfate, an alkali metal persulfate (in particular sodium persulfate, potassium persulfate), an azo compound and their respective combinations or associations with an ion chosen from Fe 11 , Fe 111 , Cu 1 , Cu 11and combinations thereof. According to the invention, the initiator compound may also be an organic compound, preferably an organic initiator compound chosen from compounds with an azo group, preferably chosen from 4,4'-azobis(4-cyanovaleric) acid (CAS No. 2638-94-0), 2,2'-azobis(2-methylpropionamidine) dihydrochloride (CAS No. 2997-92-4), azo-bis-isobutyronitrile (AZDN or AIBN) and combinations thereof.

[0034] Essentially, the method for preparing a cathode primer layer according to the invention comprises the application of binders Q and R and material E as well as drying the primer layer. Preferably for the method according to the invention, the binding agent Q comprises at least one polymer PI and at least one liquid support, preferably water, alone or combined with at least one polar solvent, for example a solvent chosen from ethanol, isopropanol and combinations thereof.

[0035] Also preferably according to the invention, the binding agent Q comprises: from 5% by weight to 60% by weight of polymer PI and from 40% by weight to 95% by weight of liquid support, more preferably: from 10% by weight to 40% by weight of polymer PI and from 60% by weight to 90% by weight of liquid support.

[0036] Preferably for the method according to the invention, the compound (a2) is chosen from acrylic acid, methacrylic acid, an acrylic acid salt, a methacrylic acid salt and combinations thereof, preferably the compound (a2) is acrylic acid or methacrylic acid.

[0037] The polymer P2 used according to the invention is a water-soluble polymer. Preferably according to the invention, the polymer P2 is water-soluble at a pH greater than 4.

[0038] The polymer P2 may be a homopolymer of the compound (a2). Preferably according to the invention, the polymer P2 may be a copolymer of compounds (a2) or else be a copolymer of at least one compound (a2) and at least one other compound (c). More preferably according to the invention, the polymer P2 is a copolymer of at least one compound (a2) and at least one other compound (c).

[0039] Preferably, compound (c) is selected from: a compound (c1) selected from C1-C12 esters of methacrylic acid, C1-C12 esters of acrylic acid and combinations thereof, preferably C1-Cs esters of methacrylic acid, C1-Cs esters of acrylic acid and combinations thereof, preferably methylmethacrylate, ethylmethacrylate, propylmethacrylate, butylmethacrylate, methylacrylate, ethylacrylate, propylacrylate, butylacrylate, more preferably, methylacrylate, ethylacrylate, butylacrylate; a compound (c2) selected from acrylonitrile, acrylamide, N-methylolacrylamide, vinyl-lactam, N-vinylpyrrolidone, ureidomethacrylate and combinations thereof, preferably acrylonitrile; a compound (c3) selected from maleic acid, maleic anhydride, itaconic acid, crotonic acid and combinations thereof;a compound (c4) chosen from hydroxyethylacrylate, hydroxyethylmethacrylate, hydroxypropylacrylate, hydroxypropylmethacrylate, hydroxybutylmethacrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, styrene, more preferably styrene; a compound (c5) selected from 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, ethoxymethacrylate sulfonic acid, sodium methallyl sulfonate, styrene sulfonate, phosphated hydroxyethylacrylate, phosphated hydroxyethylmethacrylate, phosphated hydroxypropylacrylate, phosphated hydroxypropylmethacrylate, phosphated hydroxybutylmethacrylate; a crosslinking compound (c6).;

[0040] According to the invention, the polymer P2 can be prepared solely by a polymerization reaction of the monomer (a2) and optionally of at least one compound (c) chosen from compounds (c1) to (c6).

[0041] Preferably according to the invention, the polymer P2 is a free polymer, it is not grafted, in particular it is not grafted to a fluorinated polymer or it is not grafted to a polyaniline, a polypyrrole, a polythiophene, a polyparaphenylene or to a polyphenylacetylene. Also preferably according to the invention, the polymer P2 does not comprise a urethane group.

[0042] According to the invention, the polymer P2 is not a conductive polymer.

[0043] The amounts of monomers present in the polymer P2 can vary relatively significantly. Preferably according to the invention, the polymer P2 can be prepared by a polymerization reaction of 55% by weight to 100% by weight of compound (a2) and of 0% by weight to 45% by weight of compound (c). Also preferably, the polymer P2 can be prepared by a polymerization reaction of 55% by weight to 90% by weight of compound (a2) and of 10% by weight to 45% by weight of compound (c) or of 55% by weight to 80% by weight of compound (a2) and of 20% by weight to 45% by weight of compound (c).

[0044] According to the invention, polymer P2 can also be prepared by a polymerization reaction of 55% by weight to 70% by weight of compound (a2) and 30% by weight to 45% by weight of compound (c).

[0045] Essentially according to the invention, the polymer P2 has a molecular mass Mw, measured by CES, strictly less than 100,000 g / mol. Preferably according to the invention, the polymer P2 has a molecular mass Mw, measured by CES, ranging from 2,000 g / mol to 80,000 g / mol or from 2,000 g / mol to 50,000 g / mol.

[0046] Also preferably according to the invention, the polymer P2 has a molecular mass Mw, measured by CES, ranging from 2,000 g / mol to 40,000 g / mol or from 2,000 g / mol to 30,000 g / mol. More preferably according to the invention, the polymer P2 has a molecular mass Mw, measured by CES, ranging from 2,000 g / mol to 25,000 g / mol or from 2,000 g / mol to 20,000 g / mol or from 5,000 g / mol to 25,000 g / mol or from 5,000 g / mol to 20,000 g / mol.

[0047] Also preferably according to the invention, the polymer P2 has a glass transition temperature Tg, calculated according to the Flory-Fox equation, ranging from -10°C to 230°C or from 20°C to 230°C. More preferably according to the invention, the polymer P2 is a homopolymer whose Tg is greater than 0°C, preferably greater than 10°C.

[0048] Also more preferably according to the invention, the polymer P2 is a copolymer whose Tg is greater than 50°C, preferably greater than 100°C.

[0049] The polymer P2 used according to the invention can be used in its acid form or in a form in which all or part of its carboxylic groups can be neutralized. Preferably according to the invention, the polymer P2 is therefore totally or partially acidic or totally or partially non-neutralized. More preferably, the polymer P2 is partially neutralized. According to the invention, the neutralization of the polymer P2 is preferably carried out by means of at least one compound chosen from LiOH, NaOH, KOH, Zn(OH)2, Mg(OH)2, Ca(OH)2, ZnO, MgO, CaO, ammonium derivatives, ammonia, aqueous ammonia, amine bases, for example triethanolamine, aminomethylpropanol or 2-amino-2-methyl-propanol (AMP) and combinations thereof, more preferably LiOH or Zn(OH)2 or ZnO.According to the invention, the polymer P2 is prepared by a polymerization reaction at a temperature above 50°C, preferably at a temperature ranging from 60°C to 95°C or ranging from 65°C to 90°C, in particular at a temperature ranging from 70°C to 85°C.

[0050] Preferably for the method according to the invention, the binding agent R comprises at least one polymer P2 and at least one liquid support, preferably water, alone or combined with at least one polar solvent, for example a solvent chosen from ethanol, isopropanol and their combinations.

[0051] Also preferably according to the invention, the binding agent R comprises: from 5% by weight to 60% by weight of polymer P2 and from 40% by weight to 95% by weight of liquid support, more preferably: from 10% by weight to 40% by weight of polymer P2 and from 60% by weight to 90% by weight of liquid support.

[0052] Essentially according to the invention, the material E comprises carbon particles. Preferably according to the invention, the material E is chosen from carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes, carbon nanofiber, hardened carbon and combinations thereof.

[0053] The method according to the invention makes it possible to prepare a cathode primer layer. It comprises the application of the binding agents Q and R and of the material E as well as the drying of the primer layer. Preferably for the method according to the invention, the application of the binding agents Q and R and of the material E is carried out on a metal substrate comprising at least one metal chosen from aluminum, nickel and their combinations. Aluminum is particularly preferred.

[0054] According to the invention, the preparation method may comprise calendering the metal substrate carrying the primer layer.

[0055] Preferably for the method according to the invention, the binding agent Q and the material E are applied simultaneously and the agent R is applied separately. Also preferably, the binding agent Q and the material E are applied simultaneously and then the agent R is subsequently applied separately. More preferably according to the invention, the binding agent Q, the agent R and the material E are applied simultaneously.

[0056] More preferably, the method according to the invention comprises the application of a composition QE comprising the binding agent Q and the material E and of a composition RE comprising the binding agent R and the material E. More preferably, it comprises the application of a composition QE comprising the binding agent Q and the material E and then of a composition RE comprising the binding agent R and the material E. Also more preferably, the method according to the invention comprises the application of a composition QE comprising the binding agent Q and the material E and of the binding agent R. More preferably, it comprises the application of a composition QE comprising the binding agent Q and the material E and then of the binding agent R.

[0057] Also more preferably, the method according to the invention comprises the application of a QRE composition comprising the binding agent Q, the binding agent R and the material E.

[0058] The method for preparing a cathode primer layer according to the invention comprises the application of the binding agents Q and R and the material E. The application can be carried out by means of a particular composition. Thus, the invention also provides a QRE composition, preferably an aqueous QRE composition, for preparing a cathode primer layer, comprising: at least one binding agent Q comprising at least one water-soluble polymer PI, with a molecular mass Mw, measured by CES, ranging from more than 100,000 g / mol to 1,000,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (a1) chosen from acrylic acid, methacrylic acid, an acrylic acid oligomer, a methacrylic acid oligomer, an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt and combinations thereof,at least one binding agent R comprising at least one water-soluble polymer P2, of molecular mass Mw, measured by CES, ranging from 2,000 g / mol to strictly less than 100,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (a2) chosen from acrylic acid, methacrylic acid, an acrylic acid oligomer, a methacrylic acid oligomer, an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt, and combinations thereof, and at least one material E comprising carbon particles.,

[0059] Preferably according to the invention, the QRE composition comprises, by dry weight: from 0.5% to 40% of binding agent Q, from 0.5% to 30% of binding agent R, from 30% to 99% of material E, relative to the total quantity by dry weight of binding agents Q and R and of material E. Preferably according to the invention, it comprises, by dry weight: from 0.5% to 50% of binding agent Q, from 0.5% to 20% of binding agent R, from 30% to 99% of material E, relative to the total quantity by dry weight of binding agents Q and R and of material E. Preferably according to the invention, the QRE composition comprises water, alone or combined with at least one polar solvent, for example a solvent chosen from ethanol, isopropanol and their combinations. More preferably according to the invention, the QRE composition does not comprise a polar solvent or does not comprise a solvent chosen from ethanol, isopropanol and their combinations, in particular not isopropanol.Very advantageously, the method of preparing a cathode primer layer can be carried out during the preparation of a cathode. Thus, the invention also provides a method of preparing a cathode comprising:.

[0060] • the application to a metal substrate comprising at least one metal chosen from aluminum, nickel and their combinations, of a primer layer obtained by the application: of at least one binding agent Q comprising at least one water-soluble polymer PI, of molecular mass Mw, measured by CES, ranging from more than 100,000 g / mol to 1,000,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (a1) chosen from acrylic acid, methacrylic acid, an acrylic acid oligomer, a methacrylic acid oligomer, an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt and their combinations, of at least one binding agent R comprising at least one water-soluble polymer P2, of molecular mass Mw, measured by CES, ranging from 2,000 g / mol strictly less than 100,000 g / mol, prepared by a polymerization reaction,in the presence of at least one initiator compound, at least one compound (a2) chosen from acrylic acid, methacrylic acid, an acrylic acid oligomer, a methacrylic acid oligomer, an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt, and combinations thereof, and at least one material E comprising carbon particles; • drying the primer layer, then the optional calendering of the metal substrate carrying the primer layer, then,

[0061] • the application, on the primary layer, of an electroactive composition comprising at least one electroactive compound, at least one binding compound of the electroactive compound and at least one organic solvent,

[0062] • drying then calendering of the metal substrate bearing the primer layer and the electroactive coating.

[0063] The method of preparing a cathode according to the invention therefore comprises the preparation of a primary cathode layer defined according to the invention.

[0064] Preferably according to the invention, the metal substrate is a purely metal substrate or a composite substrate comprising at least one metal and at least one insulating support. Also preferably according to the invention, the electroactive compound comprises at least one metal chosen from lithium, iron, nickel, manganese, cobalt and combinations thereof. Also preferably according to the invention, the electroactive compound is in the form of a metal salt, preferably a polymetallic salt, more preferably the electroactive compound is chosen from LiFcPCL (LFP), Li(Ni,Mn,Co)O2 (NMC) and combinations thereof.

[0065] Preferably according to the invention, the binder compound of the electroactive compound is chosen from polyvinylidene fluoride (PVDF). Preferably according to the invention, the binder compound of the electroactive compound is not a (meth)acrylic polymer.

[0066] Preferably according to the invention, the organic solvent is an aprotic polar solvent, preferably chosen from pyrrolidone, N-methyl-pyrrolidone (NMP), alkyl carbonates and combinations thereof.

[0067] Also preferably according to the invention, the electroactive composition comprises carbon, preferably selected from carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes, carbon nanofiber, hardened carbon and combinations thereof.

[0068] This preparation method according to the invention makes it possible to obtain a cathode which has particularly advantageous properties. Thus, the invention also provides a cathode comprising at least one metal substrate covered with at least one primary layer comprising a binding agent Q, a binding agent R and at least one material E according to the invention. Preferably, the cathode according to the invention is obtained according to the method for preparing a primary layer according to the invention or a method for preparing a cathode according to the invention. Also preferably, the cathode according to the invention is prepared using a QRE composition according to the invention. In a particularly preferred manner according to the invention, the QRE composition according to the invention comprises a mass quantity of polymer PI greater than the mass quantity of polymer P2.

[0069] The combination of polymers PI and P2 present in binding agents Q and R which is implemented according to the invention has particularly advantageous properties for the preparation of a cathode primer layer and therefore for obtaining a cathode. This combination of polymers used according to the invention makes it possible in particular to improve the adhesion to the metal substrate of the cathode. In particular, it makes it possible to improve the adhesion to the metal substrate when it is implemented in combination with the binding compound of the electroactive compound. The compatibility of polymers PI and P2, in particular the compatibility of polymer P2, and the binding compound of the electroactive compound is particularly advantageous during the preparation of a cathode.

[0070] Thus, the invention also provides a method for improving the adhesion to a metal cathode substrate comprising at least one metal selected from aluminum, nickel and combinations thereof, of an electroactive composition comprising at least one electroactive compound, at least one binding compound of the electroactive compound and at least one organic solvent, comprising:

[0071] • the prior application directly onto the metal substrate, then the possible drying and the possible calendering, of at least one aqueous composition for preparing a primer layer comprising:

[0072] - at least one binding agent Q comprising at least one water-soluble polymer PI, of molecular mass Mw, measured by CES, ranging from more than 100,000 g / mol to 1,000,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (al) chosen from acrylic acid, methacrylic acid, an oligomer of acrylic acid, an oligomer of methacrylic acid, an acrylic acid salt, a methacrylic acid salt, an oligomer salt of acrylic acid, a methacrylic acid oligomer salt and combinations thereof,

[0073] - at least one binding agent R comprising at least one water-soluble polymer P2, of molecular mass Mw, measured by CES, ranging from 2,000 g / mol to strictly less than 100,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (a2) chosen from acrylic acid, methacrylic acid, an oligomer of acrylic acid, an oligomer of methacrylic acid, an acrylic acid salt, a methacrylic acid salt, an oligomer salt of acrylic acid, a methacrylic acid oligomer salt, and combinations thereof, and

[0074] - at least one material E comprising carbon particles, then

[0075] • the application of the electroactive composition,

[0076] • drying then calendering of the metal substrate bearing the primer layer and the electroactive coating.

[0077] The combination of polymers PI and P2, and in particular polymer P2, used according to the invention make it possible to improve subsequent adhesion with the binder compound of the electroactive compound. This combination, and in particular polymer P2, acts as adhesion promoters between the metal substrate and this binder compound of the electroactive compound. They also participate in adhering the carbon particles of material E to the metal substrate.

[0078] The advantageous, particular or preferred characteristics of the method for preparing a cathode primer layer according to the invention define methods for preparing a cathode according to the invention, compositions for preparing a primer layer, methods for improving adhesion to a cathode metal substrate, as well as cathodes, which are also advantageous, particular or preferred.

[0079] The various aspects of the invention may be illustrated by examples.

[0080] EXAMPLES

[0081] Preparation and characterization of polymers PI and P2 and agents O and R according to the invention

[0082] PLI polymer and Q1 agent:

[0083] In a 1 L glass reactor equipped with mechanical stirring and heating by oil bath, 498 g of deionized water are introduced. The whole is then heated to approximately 95°C and the following are added over 120 minutes, using peristaltic pumps: in a first test tube 270 g of acrylic acid, in a second test tube 2.55 g of ammonium persulfate dissolved in 50 g of deionized water. Then, heating is continued for 60 minutes. The whole is then cooled and then diluted in order to obtain the agent Q1 according to the invention whose dry matter content is 25% by weight, the pH is 2.3 and which comprises the PLI polymer whose molecular mass Mw, measured by CES, is 220,000 g / mol.

[0084] Polymer P 1.2 and agent 02:

[0085] In a 1 L glass reactor equipped with mechanical stirring and heating by oil bath, 498 g of deionized water are introduced. The whole is then heated to approximately 95°C and the following are added over 120 minutes, using peristaltic pumps: in a first test tube 270 g of acrylic acid, in a second test tube 1.8 g of ammonium persulfate dissolved in 50 g of deionized water.

[0086] Then, heating is continued for 60 minutes. The whole is then cooled and diluted in order to obtain the agent Q2 according to the invention whose dry matter content is 25% by weight, the pH is 2.3 and which comprises the polymer P1.2 whose molecular mass Mw, measured by CES, is 125,000 g / mol.

[0087] Polymer PI .3 and agent 03:

[0088] In a 1 L glass reactor equipped with mechanical stirring and heating by oil bath, 498 g of deionized water are introduced. The whole is then heated to approximately 95°C and the following are added over 120 minutes, using peristaltic pumps: in a first test tube 270 g of acrylic acid, in a second test tube 5.2 g of ammonium persulfate dissolved in 50 g of deionized water.

[0089] Then, heating is continued for 60 minutes. The whole is then cooled and diluted in order to obtain the agent Q3 according to the invention whose dry matter content is 25% by weight, the pH is 2.3 and which comprises the polymer P1.3 whose molecular mass Mw, measured by CES, is 305,000 g / mol.

[0090] Polymer P 1.4 and agent 04:

[0091] 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 875 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. Then, heating is continued for 60 minutes at 85°C. Again, a solution comprising 0.35 g of ammonium persulfate in 20 g of deionized water is poured in one go. Then, heating is continued for 60 minutes. The whole is then cooled and then diluted in order to obtain the agent Q4 according to the invention, the dry matter content of which is 10.4% by weight, the pH is 2.5 and which comprises the polymer P1.4, the molecular mass Mw of which, measured by CES, is 256,000 g / mol.

[0092] Polymer PI .5 and agent 05:

[0093] 100 g of acrylic acid (monomer a) and 875 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 0.45 g of ammonium persulfate in 10 g of deionized water is poured in one go.

[0094] Then, heating is continued for 60 minutes at 85°C. The whole is then cooled and then diluted in order to obtain the agent Q5 according to the invention, the dry matter content of which is 10.4% by weight, the pH is 2.5 and which comprises the polymer P1.5, the molecular mass Mw of which, measured by CES, is 370,000 g / mol.

[0095] Polymer P2.1 and RI agent:

[0096] In a 1 L reactor equipped with mechanical stirring, oil bath heating and peristaltic pumps, 200 g of isopropanol and 1.7 g of AZDN are weighed. The mixture is then heated to reflux at approximately 80°C and 200 g of acrylic acid and 81 g of butyl acrylate are added over 120 minutes using peristaltic pumps. Refluxing is then continued for 60 minutes.

[0097] The isopropanol is then distilled and gradually replaced by water during the distillation. The whole is then cooled and then diluted in order to obtain the RI agent according to the invention, the dry matter content of which is 40% by weight, the pH is 2.3 and which comprises the polymer P2.1, the molecular mass of which Mw, measured by CES, is 9,000 g / mol.

[0098] Polymer P2.2 and agent R2:

[0099] In a 1 L reactor equipped with mechanical stirring, oil bath heating and peristaltic pumps, 200 g of isopropanol and 1.7 g of AZDN are weighed. The mixture is then heated to reflux at approximately 80°C and 200 g of acrylic acid and 80 g of ethyl acrylate are added over 120 minutes using peristaltic pumps. The reflux heating is then continued for 60 minutes. The isopropanol is then distilled and gradually replaced by water during the distillation.

[0100] The whole is then cooled and then diluted in order to obtain the agent R2 according to the invention whose dry matter content is 40% by weight, the pH is 2.2 and which comprises the polymer P2.2 whose molecular mass Mw, measured by CES, is 9,500 g / mol. Polymer P2.3 and agent R3:

[0101] In a 1 L reactor equipped with mechanical stirring, oil bath heating and peristaltic pumps, 200 g of isopropanol and 1.9 g of AZDN are weighed. The mixture is then heated to reflux at approximately 80°C and 200 g of acrylic acid and 83 g of methyl methacrylate are added over 120 minutes using peristaltic pumps. The reflux heating is then continued for 60 minutes. The isopropanol is then distilled and gradually replaced by water during the distillation.

[0102] The whole is then cooled and then diluted in order to obtain the agent R3 according to the invention, the dry matter content of which is 40% by weight, the pH is 2.5 and which comprises the polymer P2.3, the molecular mass of which Mw, measured by CES, is 8,000 g / mol.

[0103] Polymer P2.4 and agent R4:

[0104] In a 1 L reactor equipped with mechanical stirring, oil bath heating and peristaltic pumps, the following are weighed: 209.7 g of water, 0.08 g of iron sulfate heptahydrate and 0.011 g of copper sulfate pentahydrate. The mixture is then heated to 95°C and the following are added over 120 minutes, using peristaltic pumps: 302.5 g of acrylic acid and 13 g of water, 25.6 g of sodium hypophosphite monohydrate dissolved in 29 g of water, 20.46 g of 130V hydrogen peroxide diluted with 25 g of water. Heating is then continued for 60 minutes.

[0105] The whole is then cooled and then diluted in order to obtain the agent R4 according to the invention, the dry matter content of which is 40% by weight, the pH is 2.1 and which comprises the polymer P2.4, the molecular mass of which Mw, measured by CES, is 4,400 g / mol.

[0106] Polymer P2.5 and agent R5:

[0107] In a 1 L reactor equipped with mechanical stirring, oil bath heating and peristaltic pumps, the following are weighed: 121 g of water, 121 g of isopropanol, 0.06 g of iron sulfate heptahydrate and 11 g of hydrazine hydrate at 35% concentration in water. The whole is then heated to reflux at approximately 81°C and the following are added over 120 minutes, using peristaltic pumps: in a first test tube 174 g of acrylic acid, 35 g of methyl methacrylate, 110 g of ethylene glycol phosphate and 80 g of water, in a second test tube 20 g of hydrogen peroxide at 130V and 100 g of water.

[0108] After the additions are complete, reflux heating is continued for 60 minutes at 80°C and then the isopropanol is distilled with the addition of water during the distillation. The whole is then cooled and then diluted in order to obtain the agent R5 according to the invention, the dry matter content of which is 40% by weight, the pH is 2.0 and which comprises the polymer P2.5, the molecular mass Mw of which, measured by CES, is 15,000 g / mol.

[0109] Polymer P2.6 and agent R6:

[0110] In a 1 L reactor equipped with mechanical stirring, oil bath heating and peristaltic pumps, 200 g of isopropanol and 2 g of AZDN are weighed. The mixture is then heated to reflux at approximately 80°C and 200 g of acrylic acid and 80 g of a caprolactone acrylate marketed by the "Arkema" group under the reference SR 495B are added over 120 minutes using peristaltic pumps. Then, reflux heating is continued for 60 minutes. The isopropanol is then distilled and gradually replaced by water during the distillation. The whole is then cooled and then diluted in order to obtain the agent R6 according to the invention, the dry matter content of which is 40% by weight, the pH is 2.3 and which comprises the polymer P2.6, the molecular mass of which Mw, measured by CES, is 7,500 g / mol.

[0111] Preparation of aqueous QRE compositions for preparing a cathode primary layer according to the invention

[0112] 150 g of deionized water are weighed with 28 g of agent Q1 and 7.5 g of agent RI according to the invention and then mixed with stirring using a dispersion apparatus (VMI) equipped with a toothed blade 6.5 cm in diameter. Then, 10 g of carbon black (C-Nergy Super C65 “Imerys”) are added while maintaining stirring for 1.25 h at 1,500 rpm to obtain a composition whose homogeneity and absence of aggregate are controlled using a North gauge. Composition QRE1 is obtained from agents Q1 and RL

[0113] Similarly, cathode primer layer compositions QRE2 to QRE14 are prepared from agents Q1 to Q5 and RI to R6 according to the respective dry matter quantities of polymers PI and P2 and a total quantity of 10 g dry matter of polymers PI and P2 present in agents Q and R and described in Table 1.

[0114] Preparation and characterization of cathodes according to the invention

[0115] On an aluminum foil degreased with acetone, 12 μm of cathode primer preparation composition QRE1 according to the invention are applied using a coater equipped with a threaded rod (RK Control Coater), at an application speed of 10 mm / s. Then, it is dried at 150°C in an oven for 5 minutes. The primer obtained using the applied and then dried composition QRE1 has a mass, measured using a precision balance, of 0.2 mg for an aluminum disc with a diameter of 12 mm and a thickness of 10 μm + / - 1 μm. In a similar manner, cathode primer layers are prepared using compositions QRE2 to QRE14.

[0116] The adhesion of the primer layer obtained using the compositions QRE1 to QRE14 according to the invention to the cathode aluminum substrate is evaluated using a peel-off test. A standardized adhesive tape ("Intertape" 51596 CIC8091013) is manually applied to the cathode primer layer. The adhesive tape is then peeled off and the adhesion of the primer layer to the aluminum is visually evaluated.

[0117] The compatibility of the primer layer prepared according to the invention with a secondary layer of binding agent is evaluated for a polyvinylidene fluoride (PVDF, “Kynar” HSV900 “Arkema”) binding agent applied in an N-methylpyrrolidone (NMP) solvent medium.

[0118] On a cathode primer layer obtained according to the method described above, a layer of PVDF binding agent is applied using a 5% concentration solution of PVDF in NMP and then applied in a 9 μm layer and then dried at 150°C in an oven for 5 minutes.

[0119] A standardized adhesive tape (“Intertape” 51596 CIC8091013) is manually applied to the secondary cathode layer. The adhesive tape is then peeled off and the adhesion is visually assessed.

[0120] The results obtained for the adhesion of the primary layer and for its compatibility with the secondary layer of PVDF are presented in Table 1 according to the scale:

[0121] 1: aluminum foil visible on the majority of the surface of the adhesive strip,

[0122] 2: aluminum foil visible on part of the surface of the adhesive strip,

[0123] 3: non-visible aluminum foil on the surface of the adhesive tape,

[0124] 4: primary layer mostly intact,

[0125] 5: primary layer completely intact.

[0126] Ratings 1 and 2 are not acceptable for use of the cathode in a secondary battery. Ratings 3 to 5 are acceptable for use of the cathode in a secondary battery. The results are shown in Table 1.

[0127] Table 1

[0128] The Q and R binding agents comprising the polymers according to the invention make it possible, on the one hand, to produce good quality primary adhesion layers which hold the conductive carbon very well on the surface of the aluminum foil. They also act as binding agents compatible with the PVDF secondary binding agent which is the polymeric constituent of the LFP layer, which makes it possible to increase the adhesion of the LFP layer to the primary adhesion layer of the cathode.

Claims

CLAIMS 1. Method of preparing a cathode primer layer comprising: • the application: of at least one binding agent Q comprising at least one water-soluble polymer PI, of molecular mass Mw, measured by CES, ranging from more than 100,000 g / mol to 1,000,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (a1) chosen from acrylic acid, methacrylic acid, an acrylic acid oligomer, a methacrylic acid oligomer, an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt and combinations thereof, of at least one binding agent R comprising at least one water-soluble polymer P2, of molecular mass Mw, measured by CES, ranging from 2,000 g / mol to strictly less than 100,000 g / mol, prepared by a polymerization reaction, in the presence of at least an initiator compound, of at least one compound (a2) chosen from acrylic acid, methacrylic acid, an oligomer of acrylic acid, an oligomer of methacrylic acid,an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt and combinations thereof and at least one material E comprising carbon particles;, • drying of the primer coat.

2. Method according to claim 1 for which: • compound (al) is selected from acrylic acid, methacrylic acid, an acrylic acid salt, a methacrylic acid salt and combinations thereof, preferably compound (al) is acrylic acid or methacrylic acid; or • the PI polymer is water-soluble at a pH greater than 4 or in which: • the polymer PI is a homopolymer of the compound (al); or • the polymer PI is a copolymer of compounds (al); or • the polymer PI is a copolymer of at least one compound (al) and at least one other compound (b), preferably a compound (b) chosen from: a compound (bl) selected from C1-C12 esters of methacrylic acid, C1-C12 esters of acrylic acid and combinations thereof, preferably C1-Cs esters of methacrylic acid, C1-Cs esters of acrylic acid and combinations thereof, preferably methylmethacrylate, ethylmethacrylate, propylmethacrylate, butylmethacrylate, methylacrylate, ethylacrylate, propylacrylate, butylacrylate, more preferably, methylacrylate, ethylacrylate, butylacrylate; a compound (b2) selected from acrylonitrile, acrylamide, N-methylolacrylamide, vinyl-lactam, N-vinylpyrrolidone, ureidomethacrylate and combinations thereof, preferably acrylonitrile; a compound (b3) selected from maleic acid, maleic anhydride, itaconic acid, crotonic acid and combinations thereof;a compound (b4) chosen from hydroxyethylacrylate, hydroxyethylmethacrylate, hydroxypropylacrylate, hydroxypropylmethacrylate, hydroxybutylmethacrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, styrene, more preferably styrene; a compound (b5) selected from 2-acrylamido-2-methylpropane sulfonic acid, a salt of 2-acrylamido-2-methylpropane sulfonic acid, ethoxymethacrylate sulfonic acid, sodium methallyl sulfonate, styrene sulfonate, phosphated hydroxyethylacrylate, phosphated hydroxyethylmethacrylate, phosphated hydroxypropylacrylate, phosphated hydroxypropylmethacrylate, phosphated hydroxybutylmethacrylate; a crosslinking compound (b6).; 3. Method according to one of claims 1 or 2 for which: • the polymer PI is prepared by a polymerization reaction: from 55% by weight to 100% by weight of compound (al) and from 0% by weight to 45% by weight of compound (b); or from 55% by weight to 90% by weight of compound (al) and from 10% by weight to 45% by weight of compound (b); or from 55% by weight to 80% by weight of compound (al) and from 20% by weight to 45% by weight of compound (b); or from 55% by weight to 70% by weight of compound (al) and from 30% by weight to 45% by weight of compound (b); or for which: • the polymer PI has a molecular mass Mw, measured by CES, ranging from 120,000 g / mol to 800,000 g / mol or from 150,000 g / mol to 800,000 g / mol, preferably from 200,000 g / mol to 800,000 g / mol or from 250,000 g / mol to 800,000 g / mol, more preferably from 120,000 g / mol to 500,000 g / mol or from 150,000 g / mol to 500,000 g / mol or from 200,000 g / mol to 500,000 g / mol or from 250,000 g / mol to 500,000 g / mol; or • the polymer PI has a glass transition temperature Tg, calculated according to the Flory-Fox equation, ranging from -10°C to 230°C or from 20°C to 230°C; or for which the polymer PI is a homopolymer whose Tg is greater than 0°C, preferably greater than 10°C or for which the polymer PI is a copolymer whose Tg is greater than 50°C, preferably greater than 100°C; or • the polymer PI is totally or partially acidic or totally or partially non-neutralized, preferably the polymer PI is partially neutralized, preferably by means of at least one compound chosen from EiOH, NaOH, KOH, Zn(OH)2, Mg(OH)2, Ca(OH)2, ZnO, MgO, CaO, ammonium derivatives, ammonia, aqueous ammonia, amine bases, for example triethanolamine, aminomethylpropanol or 2-amino-2-methyl-propanol (AMP) and their combinations, more preferably EiOH or Zn(OH)2 or ZnO.

4. Method according to one of claims 1 to 3 for which: • the binding agent Q comprises at least one polymer PI and at least one liquid support, preferably water, alone or combined with at least one polar solvent, for example a solvent chosen from ethanol, isopropanol and their combinations; or for which: • the binding agent Q comprises: from 5% by weight to 60% by weight of polymer PI and from 40% by weight to 95% by weight of liquid support, more preferably: from 10% by weight to 40% by weight of PI polymer and from 60% by weight to 90% by weight of liquid carrier.

5. Method according to one of claims 1 to 4 for which: • compound (a2) is chosen from acrylic acid, methacrylic acid, an acrylic acid salt, a methacrylic acid salt and combinations thereof, preferably compound (a2) is acrylic acid or methacrylic acid; or • the polymer P2 is water-soluble at a pH greater than 4 or in which: • polymer P2 is a homopolymer of compound (a2); or • polymer P2 is a copolymer of compounds (a2); or • the polymer P2 is a copolymer of at least one compound (a2) and at least one other compound (c), preferably a compound (c) chosen from: a compound (cl) chosen from C1-C12 esters of methacrylic acid, C1-C12 esters of acrylic acid and combinations thereof, preferably C1-Cs esters of methacrylic acid, C1-Cs esters of acrylic acid and combinations thereof, preferably methylmethacrylate, ethylmethacrylate, propylmethacrylate, butylmethacrylate, methylacrylate, ethylacrylate, propylacrylate, butylacrylate, more preferably, methylacrylate, ethylacrylate, butylacrylate; a compound (c2) chosen from acrylonitrile, acrylamide, N-methylolacrylamide, vinyl-lactam, N-vinylpyrrolidone, ureidomethacrylate and combinations thereof, preferably acrylonitrile; a compound (c3) selected from maleic acid, maleic anhydride, itaconic acid, crotonic acid and combinations thereof;a compound (c4) chosen from hydroxyethylacrylate, hydroxyethylmethacrylate, hydroxypropylacrylate, hydroxypropylmethacrylate, hydroxybutylmethacrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, styrene, more preferably styrene; a compound (c5) chosen from 2-acrylamido-2-methylpropanesulfonic acid, a salt of 2-acrylamido-2-methylpropanesulfonic acid,; ethoxymethacrylate sulfonic acid, sodium methallyl sulfonate, styrene sulfonate, phosphated hydroxyethylacrylate, phosphated hydroxyethylmethacrylate, phosphated hydroxypropylacrylate, phosphated hydroxypropylmethacrylate, phosphated hydroxybutylmethacrylate; a crosslinking compound (c6).

6. Method according to one of claims 1 to 5 for which: • the polymer P2 is prepared by a polymerization reaction: from 55% by weight to 100% by weight of compound (a2) and from 0% by weight to 45% by weight of compound (c); or from 55% by weight to 90% by weight of compound (a2) and from 10% by weight to 45% by weight of compound (c); or from 55% by weight to 80% by weight of compound (a2) and from 20% by weight to 45% by weight of compound (c); or from 55% by weight to 70% by weight of compound (a2) and from 30% by weight to 45% by weight of compound (c); or for which: • the polymer P2 has a molecular mass Mw, measured by CES, ranging from 2,000 g / mol to 80,000 g / mol or from 2,000 g / mol to 50,000 g / mol, preferably from 2,000 g / mol to 40,000 g / mol or from 2,000 g / mol to 30,000 g / mol, more preferably from 2,000 g / mol to 25,000 g / mol or from 2,000 g / mol to 20,000 g / mol or from 5,000 g / mol to 25,000 g / mol or from 5,000 g / mol to 20,000 g / mol; or • the polymer P2 has a glass transition temperature Tg, calculated according to the Flory-Fox equation, ranging from -10°C to 230°C or from 20°C to 230°C; or for which the polymer P2 is a homopolymer whose Tg is greater than 0°C, preferably greater than 10°C or for which the polymer P2 is a copolymer whose Tg is greater than 50°C, preferably greater than 100°C; or • the polymer P2 is totally or partially acidic or totally or partially non-neutralized, preferably the polymer P2 is partially neutralized, preferably by means of at least one compound chosen from EiOH, NaOH, KOH, Zn(OH)2, Mg(OH)2, Ca(OH)2, ZnO, MgO, CaO, ammonium derivatives, ammonia, aqueous ammonia, amino bases, for example triethanolamine, aminomethylpropanol or 2-amino-2-methyl-propanol (AMP) and their combinations, more preferably LiOH or Zn(0H)2 or ZnO.

7. Method according to one of claims 1 to 6 for which: • the binding agent R comprises at least one polymer P2 and at least one liquid support, preferably water, alone or combined with at least one polar solvent, for example a solvent chosen from ethanol, isopropanol and their combinations; or for which: • the binding agent R comprises: from 5% by weight to 60% by weight of polymer P2 and from 40% by weight to 95% by weight of liquid support, more preferably: from 10% by weight to 40% by weight of polymer P2 and from 60% by weight to 90% by weight of liquid support.

8. Method according to one of claims 1 to 7 for which the material E is chosen from carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes, carbon nano fiber, hardened carbon and combinations thereof.

9. Method according to one of claims 1 to 8 for which: • the application of the binding agents Q and R and of the material E is carried out on a metal substrate comprising at least one metal chosen from aluminum, nickel and their combinations; or also comprising: • the calendering of the metal substrate carrying the primary layer; or for which: • the binding agent Q and the material E are applied simultaneously and the agent R is applied separately, preferably the binding agent Q and the material E are applied simultaneously and then the agent R is subsequently applied separately; or • the binding agent Q, the agent R and the material E are applied simultaneously; or • comprising the application: of a composition QE comprising the binding agent Q and the material E and of a composition RE comprising the binding agent R and the material E, preferably: of a composition QE comprising the binding agent Q and the material E then of a composition RE comprising the binding agent R and the material E; or of a QE composition comprising F binding agent Q and material E and F binding agent R, preferably: of a QE composition comprising binding agent Q and material E then binding agent R; or of a QRE composition comprising binding agent Q, binding agent R and material E.

10. QRE composition, preferably an aqueous QRE composition, for preparing a cathode primer layer, comprising: • at least one binding agent Q comprising at least one water-soluble polymer PI, of molecular mass Mw, measured by CES, ranging from more than 100,000 g / mol to 1,000,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (al) chosen from acrylic acid, methacrylic acid, an oligomer of acrylic acid, an oligomer of methacrylic acid, an acrylic acid salt, a methacrylic acid salt, an oligomer salt of acrylic acid, a methacrylic acid salt and combinations thereof, • at least one binding agent R comprising at least one water-soluble polymer P2, of molecular mass Mw, measured by CES, ranging from 2,000 g / mol to strictly less than 100,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (a2) chosen from acrylic acid, methacrylic acid, an oligomer of acrylic acid, an oligomer of methacrylic acid, an acrylic acid salt, a methacrylic acid salt, an oligomer salt of acrylic acid, a methacrylic acid salt, and combinations thereof, and • at least one material E comprising carbon particles.

11. QRE composition according to claim 10 comprising, by dry weight: from 0.5% to 40% of binding agent Q, from 0.5% to 30% of binding agent R, from 30% to 99% of material E; preferably: from 0.5% to 50% of binding agent Q, from 0.5% to 20% of binding agent R, from 30% to 99% of material E; relative to the total quantity by dry weight of binding agents Q and R and material E.

12. Method of preparing a cathode comprising: • the application to a metal substrate comprising at least one metal chosen from aluminum, nickel and their combinations, of a primer layer obtained by the application: of at least one binding agent Q comprising at least one water-soluble polymer PI, of molecular mass Mw, measured by CES, ranging from more than 100,000 g / mol to 1,000,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (a1) chosen from acrylic acid, methacrylic acid, an acrylic acid oligomer, a methacrylic acid oligomer, an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt and their combinations, of at least one binding agent R comprising at least one water-soluble polymer P2, of molecular mass Mw, measured by CES, ranging from 2,000 g / mol strictly less than 100,000 g / mol, prepared by a polymerization reaction,in the presence of at least one initiator compound, at least one compound (a2) chosen from acrylic acid, methacrylic acid, an acrylic acid oligomer, a methacrylic acid oligomer, an acrylic acid salt, a methacrylic acid salt, an acrylic acid oligomer salt, a methacrylic acid oligomer salt, and combinations thereof, and at least one material E comprising carbon particles;, • drying of the primer layer, then possible calendering of the metal substrate bearing the primer layer, then • F application, on the primary layer, of an electroactive composition comprising at least one electroactive compound, at least one binding compound of the electroactive compound and at least one organic solvent, • drying then calendering of the metal substrate bearing the primer layer and the electroactive coating.

13. Method of preparing a cathode according to claim 12 comprising the preparation of a cathode primary layer defined according to one of the claims 1 to 9.

14. Method of preparing a cathode according to claim 13 for which: - the metal substrate is a purely metal substrate or a composite substrate comprising at least one metal and at least one insulating support; or - the electroactive compound comprises at least one metal chosen from lithium, iron, nickel, manganese, cobalt and their combinations; or - the electroactive compound is in the form of a metal salt, preferably a polymetallic salt, preferably the electroactive compound is chosen from LiFePO4 (LFP), Li(Ni,Mn,Co)O2 (NMC) and their combinations; or - the binding compound of the electroactive compound is chosen from polyvinylidene fluoride (PVDF); or - the organic solvent is an aprotic polar solvent, preferably chosen from pyrrolidone, N-methyl-pyrrolidone (NMP), alkyl carbonates and combinations thereof; or - the electroactive composition comprises carbon, preferably selected from carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes, carbon nanofiber, hardened carbon and combinations thereof.

15. Cathode comprising at least one metal substrate covered with at least one primary layer comprising a binding agent Q, a binding agent R and at least one material E, preferably obtained according to the method of preparing a primary layer according to one of claims 1 to 9, or prepared using a QRE composition according to one of claims 10 or 11 or even prepared according to the preparation method according to one of claims 12 or 13.

16. Method for improving the adhesion on a metal cathode substrate comprising at least one metal chosen from aluminum, nickel and their combinations, of an electroactive composition comprising at least one electroactive compound, at least one binding compound of the electroactive compound and at least one organic solvent, comprising: the prior application directly onto the metal substrate, then the possible drying and the possible calendering, of at least one aqueous composition for preparing a primer layer comprising: - at least one binding agent Q comprising at least one water-soluble polymer PI, of molecular mass Mw, measured by CES, ranging from more than 100,000 g / mol to 1,000,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (al) chosen from acrylic acid, methacrylic acid, an oligomer of acrylic acid, an oligomer of methacrylic acid, an acrylic acid salt, a methacrylic acid salt, an oligomer salt of acrylic acid, a methacrylic acid oligomer salt and combinations thereof, - at least one binding agent R comprising at least one water-soluble polymer P2, of molecular mass Mw, measured by CES, ranging from 2,000 g / mol to strictly less than 100,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, of at least one compound (a2) chosen from acrylic acid, methacrylic acid, an oligomer of acrylic acid, an oligomer of methacrylic acid, an acrylic acid salt, a methacrylic acid salt, an oligomer salt of acrylic acid, a methacrylic acid oligomer salt, and combinations thereof, and - at least one material E comprising carbon particles, then • the application of the electroactive composition, • drying then calendering of the metal substrate bearing the primer layer and the electroactive coating.

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