Composition of main positive electrode layer

Abstract

The present invention relates to a composition for preparing a main positive electrode layer, the composition comprising a polyacrylic binder having an extremely high molecular weight and carbon particles. The invention also relates to the use of the composition for producing a positive electrode, and to a positive electrode which can be used for producing a cell for a rechargeable battery.

Description

[0001] This invention relates to compositions for preparing a positive electrode undercoat, the compositions comprising a polyacrylic acid binder having an extremely high molecular weight and carbon particles. The invention also relates to the use of this composition in preparing a positive electrode, and its potential use in manufacturing a positive electrode for a secondary battery cell.

[0002] Known compositions for preparing cathodes typically contain carbon and metal in particulate form bonded to a binder composition. The binder composition is able to fix the particles onto a metal substrate. Therefore, when using these compositions to manufacture cathodes, the bonding properties are crucial.

[0003] The time and yield required to manufacture the cathode are also important factors. Therefore, improving the efficiency of the various reactions involved is crucial.

[0004] 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 impact on overall electrochemical performance is still considerable. These binder compounds should help form a stable network of active or conductive solid compounds present in the cathode.

[0005] The binding compound used in the preparation of the positive electrode should also be able to improve thermal stability, chemical stability, electrochemical stability, and tensile strength, especially through good adhesion and good cohesion, as well as a certain degree of flexibility.

[0006] Furthermore, the compatibility of the various components of the compositions used to prepare the positive electrode with the battery is also an important factor to consider when preparing these compositions and when using them to prepare the positive electrode. In particular, compatibility with the electrolyte in the battery, especially insolubility or low solubility, is a fundamental characteristic.

[0007] The composition used to prepare the positive electrode is expected to be easily and uniformly applied to obtain a uniform coating and limit or avoid defects on the electrode surface, thereby forming a uniform and particularly effective conductive coating. The surface leveling, remodeling, and flow behavior of the composition used to prepare the positive electrode must be well controlled.

[0008] The composition used to prepare the cathode must also be stable and homogeneous during its preparation, storage, or application. Therefore, sedimentation, cluster or aggregate formation, and component separation must be limited or avoided.

[0009] Generally, improving the adhesion of active elements is always a priority when preparing cathodes. Therefore, it is essential to improve the adhesion of coatings with different compositions deposited on metal substrates. In particular, improving the adhesion of carbon-containing undercoat layers is crucial when deposited on metal substrates. The performance of the undercoat composition is especially important because it is in direct contact with both the metal cathode substrate and the binder composition of the electroactive compounds.

[0010] Document CN 115881966 discloses a composition for preparing a positive electrode, which combines two polymers modified with conductive chemical groups, particularly polyaniline groups. Document EP 4095213 describes an electrode bonding composition comprising a copolymer of N-vinylpyrrolidone, methacrylonitrile, vinyl acetate, or propylene sulfonic acid. Document WO 2014024937 describes a composition for preparing a negative electrode comprising a fluorinated copolymer with a low molecular weight.

[0011] Document WO 2015008626 describes an electrode adhesive composition comprising a copolymer having extremely high molecular weight, essentially prepared from anionic monomers. Document US 20170018770 discloses a method for preparing a positive electrode using an adhesive composition combining at least two polyacrylic acids having very different molecular weights.

[0012] In addition to compositions for preparing positive electrodes containing PVDF binders in NMP, document KR20190143256 describes silicon negative electrode compositions containing two polyacrylic acid binders with different molecular weights. Document WO 24028544, published after this application, discloses compositions for preparing negative electrodes using acrylic-acrylate copolymers for carbon dispersion.

[0013] The compositions commonly used in the prior art for preparing positive electrode undercoatings are not always satisfactory. Therefore, there is a need for compositions used in preparing positive electrode undercoatings that provide solutions to all or part of the problems of the compositions in the prior art.

[0014] Therefore, the present invention provides an aqueous composition C for preparing a positive electrode undercoating, comprising:

[0015] • At least one material E, comprising carbon particles, and

[0016] • At least one adhesive Q comprising at least one water-soluble polymer P, wherein the water-soluble polymer P has a molecular weight Mw greater than 300,000 g / mol as measured by SEC, and wherein the water-soluble polymer P is selected from:

[0017] - Polymer P1, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound:

[0018] The amount relative to compounds (a), (b), and (c) by weight:

[0019] ▪ At least one compound (a) of 30% to 90% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof;

[0020] ▪ At least one compound (b) of 5% to 30% by weight, independently selected from styrene, C1 to C2. 12 Methacrylates, C1 to C 12 Acrylic esters, acrylamides, alkylacrylamides, N-hydroxymethylacrylamides, acrylonitrile, vinyl lactams, ureomethacrylates, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof; and

[0021] ▪ At least one compound (c) from 5% to 40% by weight, independently selected from 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonate, ethoxymethacrylic acid sulfonic acid, sodium methacrylate, styrene sulfonate / ester, and combinations thereof;

[0022] - Polymer P2, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound:

[0023] The amounts relative to compounds (a) and (b) by weight:

[0024] ▪ At least one compound (a) of 35% to 90% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; and

[0025] ▪ 10% to 65% by weight of at least one compound (b), independently selected from styrene, C1 to C24. 12 Methacrylates, C1 to C 12Acrylates, acrylamides, alkylacrylamides, N-hydroxymethylacrylamides, acrylonitrile, vinyl lactams, ureomethacrylates, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof;

[0026] - Polymer P3, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound:

[0027] The amount relative to compounds (a) and (c) by weight:

[0028] ▪ At least one compound (a) from 35% to 95% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; and

[0029] ▪ At least one compound (c) from 5% to 65% by weight, independently selected from 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonate, ethoxymethacrylic acid sulfonic acid, sodium methacrylate, styrene sulfonate / ester, and combinations thereof;

[0030] - A single polymer P4, which is prepared by polymerization of at least one compound (a) in the presence of at least one initiator compound, said compound (a) being independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof;

[0031] - Its combination.

[0032] According to the present invention, the molecular weight or molecular mass of polymers P1 and P2 is determined by size exclusion chromatography (SEC). A test portion of the polymer solution corresponding to 20 mg of dry solids is placed in a 10 mL flask. A mobile phase and 0.04% dimethylformamide (DMF) are added until a total mass of 10 g is reached. The composition of the mobile phase is as follows: NaHCO3: 0.05 mol / L, NaNO3: 0.1 mol / L, triethanolamine: 0.02 mol / L, NaN3: 0.03% by mass. The SEC column consists of a Waters 510 isocratic pump with a flow rate set to 1 mL / min, a Waters 717+ sample converter, and a column oven. The column oven includes a 5 cm long, 8 mm inner diameter PSS Suprema guard column, followed by a 30 cm long, 8 mm inner diameter 30000 Å PSS Suprema linear column. Detection is performed using a Waters 410 RI differential refractometer. The column oven temperature was raised to 60°C, and the detector temperature to 45°C. The SEC instrument was calibrated using a series of sodium polyacrylate standards supplied by Polymer Standards Service, with peak molecular weights ranging from 1200 g / mol to 1390000 g / mol and polydispersity indices (PI) from 1.09 to 2. The calibration curve was linear, and corrections obtained using the flow rate marker dimethylformamide (DMF) were considered. Chromatograms were acquired and processed using ConSenxus hs NTeqGPC software V5.1.5. The obtained chromatograms were merged into the region corresponding to molecular weights greater than 180 g / mol.

[0033] Preferably, according to the present invention, the polydispersity index (PI) of polymer P, as measured by SEC, is greater than 10, more preferably greater than 15 or greater than 20. More preferably, the polydispersity index (PI) of polymer P, as measured by SEC, is greater than 25, greater than 30, or greater than 40.

[0034] Preferably, according to the present invention, compound (a) is independently selected from acrylic acid, methacrylic acid, acrylates, methacrylates and combinations thereof; preferably, compound (a) is acrylic acid or methacrylic acid.

[0035] Also preferably, according to the invention, compound (b) is independently selected from styrene, tert-butylacrylamide, C1 to C2. 12 Methacrylates, C1 to C 12Acrylates and combinations thereof. More preferably, compound (b) is selected from C1 to C8 methacrylates, C1 to C8 acrylates and combinations thereof, preferably styrene, tert-butylacrylamide, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, more preferably methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate.

[0036] Also preferably, according to the invention, compound (c) is independently selected from 2-acrylamido-2-methylpropanesulfonic acid and 2-acrylamido-2-methylpropanesulfonate.

[0037] Essentially, polymers P1 to P4 according to the present invention are prepared using compound (a), compound (b), or compound (c). Polymers P1 to P4 according to the present invention are prepared using only compound (a), compound (b), or compound (c). Therefore, polymer P1 is prepared using only compound (a), compound (b), and compound (c). Polymer P2 is prepared using only compound (a) and compound (b). Polymer P3 is prepared using only compound (a) and compound (c). Polymer P4 is prepared using a single compound (a) or using two different compounds (a).

[0038] Preferably, polymer P is non-crosslinked. Also preferably, compound (b) is not acrylonitrile or acrylamide, or it does not contain fluorine; therefore, polymer P is not a fluorinated polymer. Also preferably, according to the invention, polymer P is a free polymer; it is not grafted, particularly not grafted onto a fluorinated polymer. Furthermore, polymer P according to the invention is not prepared in the presence of polyaniline; it does not contain conductive groups, particularly conductive groups generated from the reaction with polyaniline.

[0039] The amount of residual monomer present in polymer P can vary over a relatively wide range. Preferably, for composition C according to the invention, polymer P1 is prepared using the following substances:

[0040] The amount relative to compounds (a), (b), and (c) by weight:

[0041] - 50% to 90% by weight of compound (a),

[0042] - 5% to 30% by weight of compound (b), and

[0043] - 5% to 20% by weight of the compound (c).

[0044] Also preferably, for composition C according to the invention, polymer P2 is prepared using the following substances,

[0045] The amounts relative to compounds (a) and (b) by weight:

[0046] - 65% to 90% by weight of compound (a), and

[0047] - 10% to 35% by weight of the compound (b).

[0048] Also preferably, for composition C according to the invention, polymer P3 is prepared using the following substances:

[0049] The amount relative to compounds (a) and (c) by weight:

[0050] - 65% to 95% by weight of compound (a), and

[0051] - 5% to 35% by weight of the compound (c).

[0052] Essentially, according to the present invention, the molecular weight Mw of polymer P, as measured by SEC, is greater than 300,000 g / mol. Preferably, according to the present invention, the molecular weight Mw of polymer P, as measured by SEC, is from 300,000 g / mol to 10,000,000 g / mol or from 350,000 g / mol to 10,000,000 g / mol. More preferably, the molecular weight Mw of polymer P is from 300,000 g / mol to 8,000,000 g / mol or from 350,000 g / mol to 8,000,000 g / mol, even more preferably from 300,000 g / mol to 5,000,000 g / mol or from 350,000 g / mol to 5,000,000 g / mol or from 300,000 g / mol to 2,000,000 g / mol or from 350,000 g / mol to 2,000,000 g / mol.

[0053] Also preferably, the molecular weight Mw of polymer P, as measured by SEC, can be greater than 1,000,000 g / mol, more preferably strictly greater than 1,000,000 g / mol. Also preferably, the molecular weight Mw of polymer P, as measured by SEC, can be less than 4,000,000 g / mol, more preferably less than 3,500,000 g / mol.

[0054] Also preferably, according to the present invention, the glass transition temperature Tg of polymer P calculated using the Flory-Fox equation is -10°C to 230°C or 20°C to 230°C. More preferably, according to the present invention, polymer P is a homopolymer with a Tg greater than 0°C, preferably greater than 10°C.

[0055] More preferably, according to the present invention, polymer P is a copolymer with a Tg greater than 50°C, preferably greater than 100°C. The Flory-Fox equation is used to calculate the glass transition temperature of the copolymer based on the parameters of the monomers used in the copolymer preparation.

[0056] The polymer P used according to the present invention can be used in its acidic form, or in a form where its carboxyl groups are completely or partially neutralized. Therefore, preferably, according to the present invention, polymer P is completely acidic or partially acidic or completely unneutralized or partially unneutralized. More preferably, polymer P is partially neutralized. According to the present invention, polymer P is preferably neutralized using at least one compound selected from LiOH, NaOH, KOH, Zn(OH)2, Mg(OH)2, Ca(OH)2, ZnO, MgO, CaO, ammonium derivatives, ammonia, ammonia water, amino bases, such as triethanolamine, aminomethylpropanol, or 2-amino-2-methylpropanol (AMP) and combinations thereof, and more preferably using NaOH, Ca(OH)2, or CaO for neutralization.

[0057] The polymer P according to the invention is prepared by polymerization, wherein the conditions under which it is used can vary. Preferably, according to the invention, polymer P is prepared by polymerization in a liquid medium, wherein the initial concentration of monomer is 5% to 20% by weight, preferably 5% to 15% by weight or 8% to 15% by weight, more preferably 10% to 12% by weight.

[0058] Preferably, according to the invention, the polymerization reaction is carried out in water alone or in a combination of water and at least one polar solvent, said polar solvent being, for example, a solvent selected from ethanol, isopropanol, and combinations thereof.

[0059] According to the present invention, an initiator or a radical-generating compound is present during the polymerization reaction. Preferably, according to the present invention, the radical-generating compound is selected from 4,4'-azobis(4-cyanopentanoic acid) (ACPA or 4,4'-azobis(4-cyanovaleric acid) or AZDN or 2,2'-azobisisobutyronitrile), hydrogen peroxide, benzoyl peroxide, acetyl peroxide, lauroyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ammonium persulfate, alkali metal persulfates (especially sodium persulfate, potassium persulfate), azo compounds, and combinations thereof, or with compounds selected from Fe II Fe III Cu I Cu II And its combinations of ionic aggregates. According to the present invention, Fe II FeIII Cu I or Cu II The ions can be used by at least one compound selected from ferric sulfate, hydrated ferric sulfate, hemihydrated ferric sulfate, heptahydrated ferric sulfate, ferric carbonate, hydrated ferric carbonate, hemihydrated ferric carbonate, ferric chloride, copper carbonate, hydrated copper carbonate, hemihydrated copper carbonate, copper acetate, copper sulfate, pentahydrated copper sulfate, copper hydroxide, and copper halide.

[0060] According to the present invention, the polymerization reaction can be carried out in the presence of a compound containing phosphorus with an oxidation state of I, particularly hypophosphorous acid (H3PO2) or a derivative thereof, for example containing at least one hypophosphorous acid ion (H2PO2). - Compounds of sodium hypophosphite (H2PO2Na), potassium hypophosphite (H2PO2K), and calcium hypophosphite ([H2PO2]2Ca).

[0061] According to the present invention, the polymerization reaction can also be carried out in the presence of compounds containing phosphorus in the III oxidation state, particularly phosphorous acid or its derivatives. According to the present invention, the polymerization reaction can also be carried out in the presence of compounds containing bisulfite ions, preferably sodium bisulfite or potassium bisulfite.

[0062] Preferably, according to the invention, the adhesive Q comprises a single polymer P. Advantageously, according to the invention, the adhesive Q comprises at least one polymer P and at least one liquid matrix, said liquid matrix preferably being water alone or a combination of water and at least one polar solvent, said polar solvent being, for example, a solvent selected from ethanol, isopropanol, and combinations thereof.

[0063] Also preferably, according to the present invention, adhesive Q comprises:

[0064] - 5% to 20% by weight of polymer P and 95% to 80% by weight of liquid matrix, also preferably:

[0065] - 10% to 40% by weight of polymer P and 60% to 90% by weight of liquid matrix.

[0066] In composition C according to the invention, the components can be present in amounts that vary over a relatively wide range. Preferably, according to the invention, composition C according to the invention comprises, on a dry weight basis, the total amount of adhesive Q and material E relative to the total dry weight of:

[0067] - 0.5% to 70% adhesive Q,

[0068] - 30% to 99.5% of material E; preferably:

[0069] - 0.5% to 60% adhesive Q,

[0070] - 40% to 99.5% of material E.

[0071] Essentially, according to the present invention, in addition to polymer P, composition C according to the present invention comprises material E, which comprises carbon particles. Preferably, according to the present invention, material E is selected from carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, carbon nanofibers, hard carbon, and combinations thereof.

[0072] This invention also provides a method for preparing a water-soluble polymer P, wherein the water-soluble polymer P has a molecular weight Mw greater than 300,000 g / mol as measured by SEC, and the water-soluble polymer P is selected from:

[0073] - Polymer P1, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound:

[0074] The amount relative to compounds (a), (b), and (c) by weight:

[0075] ▪ At least one compound (a) of 30% to 90% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof;

[0076] ▪ At least one compound (b) of 5% to 30% by weight, independently selected from styrene, C1 to C2. 12 Methacrylates, C1 to C 12 Acrylic esters, acrylamides, alkylacrylamides, N-hydroxymethylacrylamides, acrylonitrile, vinyl lactams, ureomethacrylates, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof; and

[0077] ▪ At least one compound (c) from 5% to 40% by weight, independently selected from 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonate, ethoxymethacrylic acid sulfonic acid, sodium methacrylate, styrene sulfonate / ester, and combinations thereof;

[0078] - Polymer P2, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound:

[0079] The amounts relative to compounds (a) and (b) by weight:

[0080] ▪ At least one compound (a) of 35% to 90% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; and

[0081] ▪ 10% to 65% by weight of at least one compound (b), independently selected from styrene, C1 to C24. 12 Methacrylates, C1 to C 12 Acrylates, acrylamides, alkylacrylamides, N-hydroxymethylacrylamides, acrylonitrile, vinyl lactams, ureomethacrylates, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof;

[0082] - Polymer P3, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound:

[0083] The amount relative to compounds (a) and (c) by weight:

[0084] ▪ At least one compound (a) from 35% to 95% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; and

[0085] ▪ At least one compound (c) from 5% to 65% by weight, independently selected from 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonate, ethoxymethacrylic acid sulfonic acid, sodium methacrylate, styrene sulfonate / ester, and combinations thereof;

[0086] - A single polymer P4, which is prepared by polymerization of at least one compound (a) in the presence of at least one initiator compound, said compound (a) being independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof;

[0087] - Its combination.

[0088] Preferably, according to the invention, the method for preparing polymer P according to the invention comprises a polymerization reaction carried out in a liquid medium, wherein the initial concentration of the monomer is 5% to 20% by weight. Preferably, the initial concentration of the monomer is 5% to 15% by weight or 8% to 15% by weight, more preferably 10% to 12% by weight. Also preferably, the polymerization reaction is carried out alone in water or in a combination of water and at least one polar solvent, said polar solvent being, for example, a solvent selected from ethanol, isopropanol, and combinations thereof.

[0089] The use of composition C according to the invention is particularly advantageous for manufacturing a positive electrode. Therefore, the invention also provides a method for preparing a positive electrode, comprising:

[0090] - Apply at least one base coating of composition C as defined in the present invention to a metal substrate containing at least one metal selected from aluminum, nickel and combinations thereof;

[0091] - The metal substrate bearing the base coating is dried, and then optionally rolled; subsequently

[0092] - Apply an electroactive composition comprising at least one electroactive compound, at least one binding compound of the electroactive compound, and at least one organic solvent.

[0093] - The metal substrate carrying the base coating and electroactive coating is dried and then calendered.

[0094] Preferably, according to the present invention, the substrate is a pure metal substrate or a composite substrate comprising at least one metal and at least one insulating substrate.

[0095] Also preferably, according to the invention, the electroactive compound comprises at least one metal selected 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 in the form of a polymetallic salt, and more preferably, the electroactive compound is selected from LiFePO4 (LFP), Li(Ni,Mn,Co)O2 (NMC), and combinations thereof.

[0096] Preferably, according to the invention, the binder compound of the electroactive compound is polyvinylidene fluoride (PVDF), preferably a homopolymer of PVDF or a copolymer of PVDF with monomers selected from: vinyl fluoride, trifluoroethylene, trifluorochloroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl) ethers, such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE), and perfluoro(propyl vinyl) ether (PPVE), perfluoro(1,3-dioxacyclopentene), perfluoro(2,2-dimethyl-1,3-dioxacyclopentene) (PDD), perfluorobutylethylene (PFBE), trifluoropropylene, tetrafluoropropylene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropylene, trifluorobromoethylene, chlorofluoroethylene, and chlorotrifluoropropylene. Preferably, according to the invention, the binder compound of the electroactive compound is not a (meth)acrylic acid polymer.

[0097] Preferably, according to the present invention, the organic solvent is an aprotic polar solvent, preferably selected from pyrrolidone, N-methylpyrrolidone (NMP), alkyl carbonates and combinations thereof.

[0098] Preferably, according to the present invention, the electroactive composition comprises carbon, preferably selected from carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotube, carbon nanofiber, hard carbon, and combinations thereof.

[0099] The present invention also provides a positive electrode comprising at least one metal substrate coated with at least one base coating, the base coating comprising an adhesive Q and at least one material E, the positive electrode being obtained according to the preparation method of the present invention.

[0100] The present invention also provides a positive electrode produced by the production method according to the present invention.

[0101] The polymer P of the binder Q in composition C according to the invention has particularly advantageous properties for preparing the positive electrode undercoat and thus obtaining the positive electrode. In particular, the polymer P used according to the invention improves adhesion to the metal substrate of the positive electrode. Specifically, the polymer P used according to the invention improves adhesion to the metal substrate when used in combination with the binder compound of the electroactive compound. The compatibility of the polymer P used according to the invention with the binder compound of the electroactive compound is particularly advantageous when preparing the positive electrode.

[0102] Therefore, the present invention provides a method for improving the adhesion of an electroactive composition to a metal cathode substrate, wherein the metal cathode substrate comprises at least one metal selected from aluminum and nickel, and the electroactive composition comprises at least one electroactive compound, at least one binder compound of the electroactive compound, and at least one organic solvent. Preferably, this method for improving adhesion to a metal cathode substrate includes:

[0103] - At least one aqueous composition C according to the invention for preparing a base coating is first applied directly to a metal substrate, followed by drying and optionally calendering, then...

[0104] - Apply the electroactive composition,

[0105] - The metal substrate carrying the base coating and electroactive coating is dried and then calendered.

[0106] The polymer P used according to the present invention improves the subsequent adhesion to the adhesive compound of the electroactive compound. It acts as an adhesion promoter between the metal substrate and the adhesive compound of the electroactive compound. It also contributes to the adhesion of the carbon particles of material E to the metal substrate.

[0107] The advantageous, specific, or preferred features of composition C according to the invention define equally advantageous, specific, or preferred methods according to the invention for preparing a positive electrode, methods for improving adhesion to a metal positive electrode substrate, and a positive electrode.

[0108] Various aspects of the present invention can be illustrated through embodiments. Example

[0109] Preparation and characterization of polymer P and reagent Q according to the present invention

[0110] Polymer P1A and reagent Q1

[0111] 805 g of deionized water, 15 g of ethyl acrylate, 60 g of acrylic acid, and 50 g of a 50% aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonic acid (AMPS) were introduced into a 1 L glass reactor equipped with mechanical stirring and an oil bath heater. The mixture was then heated to approximately 70 °C.

[0112] Then, add a solution of 0.35g ammonium persulfate and 10g deionized water all at once. Heat the mixture to 85±2℃ for 1 hour while stirring continuously. Finally, add a solution of 0.35g ammonium persulfate and 20g deionized water over 1 hour, maintaining the temperature at 85℃.

[0113] After cooling to room temperature, reagent Q1 containing polymer P1A was obtained, with a solid content of 10% by weight and a pH of 2.1. The molecular weight (Mw) of polymer P1A, measured by SEC, was 533,000 g / mol, and its PI was 44.

[0114] Polymer P1B and reagent Q2

[0115] 805 g of deionized water, 15 g of ethyl acrylate, 60 g of acrylic acid, and 50 g of a 50% aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonic acid (AMPS) were introduced into a 1 L glass reactor equipped with mechanical stirring and an oil bath heater. The mixture was then heated to approximately 70 °C.

[0116] Then, add a solution of 0.25g ammonium persulfate and 10g deionized water all at once. Heat the mixture to 85±2℃ for 1 hour while stirring continuously. Finally, add a solution of 0.35g ammonium persulfate and 20g deionized water over 1 hour, maintaining the temperature at 85℃.

[0117] After cooling to room temperature, reagent Q2 containing polymer P1B was obtained, with a solid content of 10% by weight and a pH of 2.2. The molecular weight (Mw) of polymer P1B, measured by SEC, was 1,020,000 g / mol, and its PI was 49.

[0118] Polymer P4A and reagent Q3

[0119] 805 g of deionized water and 100 g of acrylic acid were introduced into a 1 L glass reactor equipped with mechanical stirring and oil bath heating. The mixture was then heated to approximately 70 °C.

[0120] Then, add a solution of 0.45g ammonium persulfate and 10g deionized water all at once. Heat the mixture to 85±2℃ for 1 hour while stirring continuously. Finally, add a solution of 0.35g ammonium persulfate and 20g deionized water over 1 hour, maintaining the temperature at 85℃.

[0121] After cooling to room temperature, reagent Q3 containing polymer P4A was obtained, with a solid content of 10.6% by weight and a pH of 2.2. The molecular weight (Mw) of polymer P4A, measured by SEC, was 1,438,000 g / mol, and its PI was 86.

[0122] Preparation of the aqueous composition C for preparing the positive electrode undercoat according to the present invention

[0123] Weigh 91 g of deionized water and 100 g of reagent Q1, and mix them with stirring using a dispersion instrument (VMI) equipped with a 6.5 cm diameter toothed blade. Then add 10 g of carbon black (Imerys' "C-Nergy Super" C65) while continuing to stir at 1500 rpm for 1.25 hours to obtain the composition. Check the homogeneity of the composition using a North gauge to confirm the absence of aggregates. Composition C1 is obtained from reagent Q1 containing polymer P1A.

[0124] Similarly, positive electrode undercoating composition C2 and composition C3 were prepared using reagents Q2 and Q3.

[0125] Preparation and characterization of the positive electrode according to the present invention

[0126] On an aluminum sheet degreased with acetone, a 6 µm layer of the composition C1 according to the invention for preparing a positive electrode undercoat is applied at an application speed of 10 mm / s using a coating machine (“RK Control Coater”) equipped with a threaded rod.

[0127] Then dry in an oven at 150°C for 5 minutes. The mass of the base coating obtained by applying and drying with composition C1 was measured using a precision balance. For an aluminum disc with a diameter of 12 mm and a thickness of 10 µm ± 1 µm, the mass of the base coating was 0.2 mg.

[0128] Similarly, the positive electrode undercoat was prepared using composition C2 and composition C3.

[0129] The adhesion of the undercoat obtained using compositions C1 to C3 according to the invention to the positive electrode aluminum substrate was evaluated using a peel test. A standardized adhesive tape (“Intertape” 51596 CIC8091013) was manually applied to the positive electrode undercoat. The tape was then peeled off, and the adhesion of the undercoat to the aluminum was visually evaluated.

[0130] The compatibility of the base coating prepared according to the present invention with the secondary coating of the adhesive was evaluated for polyvinylidene fluoride adhesive (Kynar HSV900 PVDF from Arkema) applied in an N-methylpyrrolidone (NMP) solvent medium.

[0131] A PVDF adhesive coating was applied to the positive electrode undercoat obtained according to the above method by using a 5% PVDF solution in NMP and then applying it as a 9µm coating and drying it in an oven at 150°C for 5 minutes.

[0132] The standardized tape (“Intertape” 51596 CIC8091013) was manually applied to the secondary coating of the positive electrode. The tape was then peeled off, and the adhesion was visually assessed.

[0133] The adhesion of the obtained base coat and its compatibility with the PVDF secondary coating are shown in Table 1 according to the following grades:

[0134] - 1: Aluminum sheets are visible on most of the tape's surface.

[0135] - 2: Aluminum sheets are visible on the surface of the tape.

[0136] - 3: No aluminum sheet is visible on the surface of the tape.

[0137] - 4: The base coating is basically intact.

[0138] - 5: The base coat is completely intact.

[0139] Evaluations 1 and 2 are unacceptable for the use of a positive electrode in a secondary battery. Evaluations 3 to 5 are acceptable for the use of a positive electrode in a secondary battery. The results are shown in Table 1.

[0140]

[0141] The binder Q, comprising the polymer P according to the invention, can produce a base coating with good adhesion, which holds the conductive carbon very well on the surface of the aluminum sheet. They also act as a binder compatible with the PVDF secondary binder, which is the polymer component of the LFP coating, thereby increasing the adhesion of the LFP coating to the positive electrode base coating.

Claims

1. An aqueous composition C for preparing a positive electrode undercoating, comprising: • At least one material E, comprising carbon particles, and • At least one adhesive Q comprising at least one water-soluble polymer P, wherein the water-soluble polymer P has a molecular weight Mw greater than 300,000 g / mol as measured by SEC, and wherein the water-soluble polymer P is selected from: - Polymer P1, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound: The amount relative to compounds (a), (b), and (c) by weight: ▪ At least one compound (a) of 30% to 90% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; ▪ At least one compound (b) of 5% to 30% by weight, independently selected from styrene, C1 to C2. 12 Methacrylates, C1 to C 12 Acrylic esters, acrylamides, alkylacrylamides, N-hydroxymethylacrylamides, acrylonitrile, vinyl lactams, ureomethacrylates, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof; and ▪ At least one compound (c) from 5% to 40% by weight, independently selected from 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonate, ethoxymethacrylic acid sulfonic acid, sodium methacrylate, styrene sulfonate / ester, and combinations thereof; - Polymer P2, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound: The amounts relative to compounds (a) and (b) by weight: ▪ At least one compound (a) of 35% to 90% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; and ▪ 10% to 65% by weight of at least one compound (b), independently selected from styrene, C1 to C24. 12 Methacrylates, C1 to C 12 Acrylates, acrylamides, alkylacrylamides, N-hydroxymethylacrylamides, acrylonitrile, vinyl lactams, ureomethacrylates, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof; - Polymer P3, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound: The amount relative to compounds (a) and (c) by weight: ▪ At least one compound (a) from 35% to 95% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; and ▪ At least one compound (c) from 5% to 65% by weight, independently selected from 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonate, ethoxymethacrylic acid sulfonic acid, sodium methacrylate, styrene sulfonate / ester, and combinations thereof; - A single polymer P4, which is prepared by polymerization of at least one compound (a) in the presence of at least one initiator compound, said compound (a) being independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; - Its combination.

2. The composition C according to claim 1, wherein: - The polydispersity index (PI) of polymer P, as measured by SEC, is greater than 10, preferably greater than 15 or greater than 20, more preferably greater than 25 or greater than 30 or greater than 40; or wherein: - Compound (a) is independently selected from acrylic acid, methacrylic acid, acrylates, methacrylates, and combinations thereof, preferably, compound (a) is acrylic acid or methacrylic acid; or - Compound (b) is independently selected from styrene, tert-butylacrylamide, C1 to C2. 12 Methacrylates, C1 to C 12 Acrylates and combinations thereof, preferably C1 to C8 methacrylates and combinations thereof, preferably styrene, tert-butylacrylamide, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, more preferably methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate; or - Compound (c) is independently selected from 2-acrylamido-2-methylpropanesulfonic acid and 2-acrylamido-2-methylpropanesulfonate; or - Polymer P4 is prepared using a single compound (a) or using two different compounds (a).

3. Composition C according to any one of claims 1 or 2, wherein: Polymer P1 is prepared using the following substances, The amount relative to compounds (a), (b), and (c) by weight: • 50% to 90% by weight of compound (a), • 5% to 30% by weight of compound (b), and • 5% to 20% by weight of compound (c); or Polymer P2 is prepared using the following substances, The amounts relative to compounds (a) and (b) by weight: • 65% to 90% by weight of compound (a), and • 10% to 35% by weight of compound (b); or Polymer P3 is prepared using the following substances, The amount relative to compounds (a) and (c) by weight: • 65% to 95% by weight of compound (a), and • 5% to 35% by weight of compound (c); or wherein: - The molecular weight (Mw) of polymer P, as measured by SEC, is from 300,000 g / mol to 10,000,000 g / mol or 350,000 g / mol to 10,000,000 g / mol, preferably from 300,000 g / mol to 8,000,000 g / mol or 350,000 g / mol to 8,000,000 g / mol, more preferably from 300,000 g / mol to 5,000,000 g / mol or 350,000 g / mol to 5,000,000 g / mol or 300,000 g / mol to 2,000,000 g / mol or 350,000 g / mol to 2,000,000 g / mol; or - The polymer P has a glass transition temperature (Tg) of -10°C to 230°C or 20°C to 230°C calculated using the Flory-Fox equation; or wherein the polymer P is a homopolymer with a Tg greater than 0°C, preferably greater than 10°C; or wherein the polymer P is a copolymer with a Tg greater than 50°C, preferably greater than 100°C; or - The polymer P is completely acidic or partially acidic or completely unneutralized or partially unneutralized. Preferably, the polymer P is partially neutralized. Neutralization is preferably carried out using at least one compound selected from LiOH, NaOH, KOH, Zn(OH)2, Mg(OH)2, Ca(OH)2, ZnO, MgO, CaO, ammonium derivatives, ammonia, ammonia water, amino bases, such as triethanolamine, aminomethylpropanol or 2-amino-2-methylpropanol (AMP) and combinations thereof. Neutralization is more preferably carried out using NaOH, Ca(OH)2, or CaO.

4. Composition C according to any one of claims 1 to 3, wherein: - Polymer P is prepared by polymerization in a liquid medium, wherein the initial concentration of monomer is 5% to 20% by weight, preferably 5% to 15% by weight or 8% to 15% by weight, more preferably 10% to 12% by weight; or wherein: - The polymerization reaction is carried out in water alone or in a combination of water and at least one polar solvent, such as a solvent selected from ethanol, isopropanol and combinations thereof.

5. Composition C according to any one of claims 1 to 4, wherein: - Adhesive Q contains a single polymer P; or - Adhesive Q comprises at least one polymer P and at least one liquid matrix, wherein the liquid matrix is ​​preferably water alone or a combination of water and at least one polar solvent, wherein the polar solvent is, for example, a solvent selected from ethanol, isopropanol, and combinations thereof; or wherein: - Adhesive Q contains: • 5% to 20% by weight of polymer P and 95% to 80% by weight of liquid matrix, preferably: • 10% to 40% by weight of polymer P and 60% to 90% by weight of liquid matrix.

6. Composition C according to any one of claims 1 to 5, wherein material E is selected from carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, carbon nanofibers, hard carbon, and combinations thereof.

7. The composition C according to any one of claims 1 to 6, wherein, relative to the total amount of adhesive Q and material E on a dry weight basis, the composition C comprises: - 0.5% to 70% adhesive Q, - 30% to 99.5% of material E; preferably: - 0.5% to 60% adhesive Q, - 40% to 99.5% of material E.

8. A method for preparing a water-soluble polymer P, wherein the water-soluble polymer P has a molecular weight Mw greater than 300,000 g / mol as measured by SEC, and the water-soluble polymer P is selected from: - Polymer P1, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound: The amount relative to compounds (a), (b), and (c) by weight: ▪ At least one compound (a) of 30% to 90% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; ▪ At least one compound (b) of 5% to 30% by weight, independently selected from styrene, C1 to C2. 12 Methacrylates, C1 to C 12 Acrylic esters, acrylamides, alkylacrylamides, N-hydroxymethylacrylamides, acrylonitrile, vinyl lactams, ureomethacrylates, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof; and ▪ At least one compound (c) from 5% to 40% by weight, independently selected from 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonate, ethoxymethacrylic acid sulfonic acid, sodium methacrylate, styrene sulfonate / ester, and combinations thereof; - Polymer P2, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound: The amounts relative to compounds (a) and (b) by weight: ▪ At least one compound (a) of 35% to 90% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; and ▪ 10% to 65% by weight of at least one compound (b), independently selected from styrene, C1 to C24. 12 Methacrylates, C1 to C 12 Acrylates, acrylamides, alkylacrylamides, N-hydroxymethylacrylamides, acrylonitrile, vinyl lactams, ureomethacrylates, maleic acid, maleic anhydride, itaconic acid, crotonic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, and combinations thereof; - Polymer P3, which is prepared by polymerization of only the following substances in the presence of at least one initiator compound: The amount relative to compounds (a) and (c) by weight: ▪ At least one compound (a) from 35% to 95% by weight, independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; and ▪ At least one compound (c) from 5% to 65% by weight, independently selected from 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonate, ethoxymethacrylic acid sulfonic acid, sodium methacrylate, styrene sulfonate / ester, and combinations thereof; - A single polymer P4, which is prepared by polymerization of at least one compound (a) in the presence of at least one initiator compound, said compound (a) being independently selected from acrylic acid, methacrylic acid, acrylic acid oligomers, methacrylic acid oligomers, acrylates, methacrylic acid salts, acrylic acid oligomer salts, methacrylic acid oligomer salts, and combinations thereof; - Its combination.

9. The preparation method according to claim 8, wherein: - The polymerization reaction is carried out in a liquid medium, wherein the initial concentration of the monomer is 5% to 20% by weight, preferably 5% to 15% by weight or 8% to 15% by weight, more preferably 10% to 12% by weight; or wherein: - The polymerization reaction is carried out in water alone or in a combination of water and at least one polar solvent, such as a solvent selected from ethanol, isopropanol and combinations thereof.

10. A method for preparing a positive electrode, comprising: - Apply at least one base coating of composition C as defined in any one of claims 1 to 7 to a metal substrate comprising at least one metal selected from aluminum, nickel and combinations thereof; - The metal substrate bearing the base coating is dried, and then optionally rolled; subsequently - An electroactive composition comprising at least one electroactive compound, at least one binding compound of the electroactive compound, and at least one organic solvent. - The metal substrate carrying the base coating and electroactive coating is dried and then calendered.

11. The method of claim 10, wherein: - The substrate is a pure metal substrate or a composite substrate comprising at least one metal and at least one insulating substrate, or - The electroactive compound comprises at least one metal selected from lithium, iron, nickel, manganese, cobalt, and combinations thereof, or - The electroactive compound is in the form of a metal salt, preferably a multi-metal salt; preferably, the electroactive compound is selected from LiFePO4 (LFP), Li(Ni,Mn,Co)O2 (NMC) and combinations thereof, or - The binding compound of the electroactive compound is polyvinylidene fluoride (PVDF), preferably a homopolymer of PVDF or a copolymer of PVDF with monomers selected from: vinyl fluoride, trifluoroethylene, trifluorochloroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) and perfluoro(propyl vinyl) ether (PPVE), perfluoro(1,3-dioxacyclopentene), perfluoro(2,2-dimethyl-1,3-dioxacyclopentene) (PDD), perfluorobutylethylene (PFBE), trifluoropropylene, tetrafluoropropylene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropylene, trifluorobromoethylene, chlorofluoroethylene, trifluorochloropropylene, or - The organic solvent is an aprotic polar solvent, preferably selected from pyrrolidone, N-methylpyrrolidone (NMP), alkyl carbonates, and combinations thereof, or - The electroactive composition contains carbon, preferably selected from carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, carbon nanofibers, hard carbon, and combinations thereof.

12. A positive electrode comprising at least one metal substrate coated with at least one base coating, the base coating comprising an adhesive Q and at least one material E, the positive electrode being obtained according to the method of claim 10 or 11.

13. A method for improving the adhesion of an electroactive composition to a metal cathode substrate, said metal cathode substrate comprising at least one metal selected from aluminum and nickel, said electroactive composition comprising at least one electroactive compound, at least one binder compound of the electroactive compound, and at least one organic solvent, said method comprising: - First, at least one aqueous composition C for preparing a base coating according to any one of claims 1 to 7 is directly applied to a metal substrate, followed by drying and optionally calendering, then... - Apply the electroactive composition, - The metal substrate carrying the base coating and electroactive coating is dried and then calendered.

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