CATHODE PREPARATION COMPOSITION

Abstract

The invention relates to the field of secondary batteries and the manufacture of cathodes for these batteries. It provides a cathode preparation composition comprising a combination of two aqueous polymeric binding agents for fixing carbon and the electroactive material to the metallic collector. The invention also relates to this mixed binding agent and the use of this composition for preparing a cathode, as well as the cathode itself, which can be used for manufacturing secondary battery cells.

Description

Title of the invention: CATHODE PREPARATION COMPOSITION

[0001] The invention relates to the field of secondary batteries and the manufacture of cathodes for these batteries. It provides a cathode preparation composition comprising a combination of two aqueous polymeric binding agents for fixing carbon and the electroactive material to the metallic collector. The invention also relates to this mixed binding agent and the use of this composition for preparing a cathode, as well as the cathode itself, which can be used for manufacturing secondary battery cells.

[0002] Cathode compositions are known that essentially comprise carbon and a metal in the form of particles combined with a binding agent. This binding agent must be able to effectively bind the carbon and the metal to the collector. Therefore, the binding strength is crucial in the manufacture of a cathode.

[0003] The manufacturing time and yield of cathodes are important factors in their production. The thixotropic and rheological behavior of the aqueous cathode preparation compositions must be controlled as closely as possible.

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

[0005] Easy and homogeneous application of the cathode compositions to the collector surface is necessary to obtain a homogeneous layer. Limiting or avoiding defects on the cathode surface is also particularly important to produce a homogeneous and efficient conductive layer.

[0006] It is therefore essential to have cathode compositions with very well-controlled rheology and in which the particles are well dispersed; the presence of aggregates is particularly detrimental to the final application. Indeed, in addition to application difficulties, excessive viscosity generally leads to numerous defects in the layer deposited on the cathode surface. Insufficient viscosity leads to the same types of problems and can also result in uncontrolled flow of the cathode composition during its application. Cathode preparation compositions must also be stable and homogeneous during their preparation, storage, and application. Sedimentation, formation of agglomerates or aggregates, and separation of ingredients must therefore be limited or avoided.

[0007] Surface leveling, restructuring and flow behavior of an aqueous cathode preparation composition must be well controlled.

[0008] When applying cathode preparation compositions to the collector, it is also important to carefully control the amount of material deposited in order to achieve a satisfactory compromise between the mass deposited and the desired final battery efficiency. Indeed, excessive deposition will increase the electrical resistance of the deposited layer as well as the final weight of the battery, while insufficient deposition will reduce the energy density of the layer and impair battery efficiency.

[0009] During the preparation of these binding agents and cathode preparation compositions, certain hazardous or polluting chemical compounds should be avoided, particularly certain organic solvents. Specifically, acrylamide derivatives, nitrile compounds, and N-methylpyrrolidone should be replaced with safer compounds or solvents. In particular, the substitution of organic solvents with aqueous supports, or simply with water, is highly desirable.

[0010] Also, the number of ingredients used in preparing cathode preparation compositions should be able to be reduced. The compatibility of the various ingredients in the cathode compositions is also an important factor both in preparing the cathode compositions and in preparing the cathodes using these compositions.

[0011] In particular, compatibility, and especially the absence of solubility or low solubility, with the battery electrolyte is a key property. Similarly, compatibility between the electroactive ingredients, particularly the essential metallic compounds, and an aqueous support has become essential.

[0012] The binding agents used in the preparation of a cathode should also improve the thermal, chemical, and electrochemical stability of both the cathode and the battery. When manufacturing a cathode using these binding agents, tensile strength is also sought, particularly through good adhesion, good cohesion, and a certain degree of flexibility, to allow the cathode to be bent or wound during battery manufacturing. Indeed, although these binding agents are electrochemically inactive during cathode operation because they do not directly contribute to the battery cell's capacity, they significantly influence the electrochemical performance of the resulting secondary battery. These binding agents must therefore contribute to the formation of stable networks of the active or conductive solid components present in the cathode.

[0013] Furthermore, during the charge-discharge cycles of secondary batteries containing these cathodes, deformation is commonly observed, which can lead to irreversible damage to the cathode, particularly due to the increase in volume of the deposited electroactive layer. Therefore, deformation tolerance is also a desirable property.

[0014] Prior art cathode preparation compositions are not always satisfactory. Therefore, there is a need for cathode preparation compositions that provide solutions to all or some of the problems with prior art compositions.

[0015] Thus, the invention provides an aqueous composition C for cathode preparation, comprising: - at least one material E comprising carbon particles, - at least one electroactive cathode material T, - at least one binding agent Q comprising at least one water-soluble, non-crosslinked polymer PI, of molecular mass Mw, measured by CES, ranging from more than 100,000 g / mol to 2,000,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiating compound, at least one compound (al) selected 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, non-crosslinked polymer P2, of molecular mass Mw, measured by CES, ranging from 2,000 g / mol to less than 50,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiating compound: * of at least one compound (a2) selected 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 and * of at least one compound (cl) selected from the following: C1-C12 esters of methacrylic acid, C1-C12 esters of acrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactame methacrylate, polycaprolactame acrylate, styrene, vinyl versatate, phosphated hydroxyethyl acrylate, phosphated hydroxyethyl methacrylate, phosphated hydroxypropyl acrylate, phosphated hydroxypropyl methacrylate, phosphated hydroxybutyl acrylate, phosphated hydroxybutyl methacrylate, methacrylate phosphated caprolactone, phosphated caprolactone acrylate, phosphated polycaprolactone methacrylate, phosphated polycaprolactone acrylate, phosphated poly(ethylene oxide) acrylate, phosphated poly(ethylene oxide) methacrylate, phosphated poly(propylene oxide) acrylate, phosphated poly(propylene oxide) methacrylate, phosphated poly(ethylene oxide and propylene oxide) acrylate, phosphated poly(ethylene oxide and propylene oxide) methacrylate and their combinations.

[0016] Preferably according to the invention, composition C does not comprise any fluorinated polymer. In particular, it does not comprise any fluorinated vinylidene polymer. Also preferably, composition C according to the invention does not comprise any organic solvent, in particular any aprotic polar solvent, including pyrrolidone, N-methylpyrrolidone (NMP), or alkyl carbonates.

[0017] According to the invention, composition C comprises agent Q comprising polymer PI and agent R comprising polymer P2. According to the invention, agents Q and R can be introduced separately into composition C. They can also be introduced simultaneously, in particular in the form of a mixed binding agent comprising these two polymers PI and P2. Preferably according to the invention, composition C according to the invention comprises a mixed binding agent QR combining polymer PI and polymer P2.

[0018] Essentially, according to the invention, composition C comprises at least one material E comprising carbon particles. Preferably for composition C, material E is selected from carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes, carbon nanofiber, hardened carbon, graphite, partially graphitized coke, and combinations thereof.

[0019] Also essentially according to the invention, composition C comprises at least one electroactive cathode material T. Preferably for composition C, the electroactive material T is selected from lithium, iron, nickel, manganese, cobalt, and combinations thereof. Preferably, material T is selected from lithium ferric phosphate, lithium manganese phosphate, lithium cobalt phosphate, lithium manganese ferric phosphate, lithium cobalt oxide, nickel lithium oxide, lithium manganese oxide, manganese nickel and lithium oxide, manganese nickel and cobalt oxide, aluminum nickel and cobalt oxide, lithium ferric phosphate, preferably LiFePO4 (LFP).

[0020] Preferably for composition C according to the invention, the PI polymer is not crosslinked or the P2 polymer is not crosslinked. More preferably, neither the PI nor the P2 polymers are crosslinked.

[0021] Also preferably for composition C according to the invention, the PI polymer or the P2 polymer or both PI and P2 polymers are prepared in the absence of (meth)acrylamide or in the absence of a (meth)acrylamide derivative. Also preferably, the PI polymer or the P2 polymer or both PI and P2 polymers are prepared in the absence of (meth)acrylonitrile or in the absence of a (meth)acrylonitrile derivative.

[0022] According to the invention, the PI polymer is preferably a water-soluble polymer at a pH greater than 4.

[0023] Essentially, the PI polymer is prepared by polymerizing at least one compound (al). Preferably for composition C according to the invention, the compound (al) is selected from acrylic acid, methacrylic acid, a salt of acrylic acid, a salt of methacrylic acid, and combinations thereof. More preferably, the compound (al) is acrylic acid or methacrylic acid.

[0024] Preferably according to the invention, the PI polymer is a homopolymer of the compound (al).

[0025] Also preferably according to the invention, the PI polymer may be a copolymer of compound (a1) and at least one other compound (b). Preferably, compound (b) is selected from: - a compound (bl) selected from vinyl-lactam, N-vinylpyrrolidone, ureidomethacrylate and their combinations; - a compound (b2) chosen from maleic acid, maleic anhydride, itaconic acid, crotonic acid and their combinations; - a compound (b3) selected from ethoxymethyl methacrylate sulfonic acid, sodium methyl sulfonate, styrene sulfonate, phosphated hydroxyethyl acrylate, phosphated hydroxyethyl methacrylate, phosphated hydroxypropyl acrylate, phosphated hydroxypropyl methacrylate, phosphated hydroxybutyl acrylate, phosphated hydroxybutyl methacrylate, phosphated caprolactone methacrylate, phosphated caprolactone acrylate and their combinations; - and their combinations.

[0026] More preferably, compound (b) is selected from phosphated hydroxyethylacrylate, phosphated hydroxyethylmethacrylate, phosphated hydroxypropylacrylate, phosphated hydroxypropylmethacrylate, phosphated hydroxybutylacrylate, phosphated hydroxybutylmethacrylate, phosphated caprolactone methacrylate, phosphated caprolactone acrylate and their combinations.

[0027] Preferably for composition C according to the invention, the PI polymer is prepared by a polymerization reaction of 55 wt% to 100 wt% of compound (a1) and 0 wt% to 45 wt% of compound (b) or of 55 wt% to 90 wt% of compound (a1) and 10 wt% to 45 wt% of compound (b). More preferably for composition C according to the invention, the PI polymer is prepared by a polymerization reaction of 55 wt% to 80 wt% of compound (al) and 20 wt% to 45 wt% of compound (b) or of 55 wt% to 70 wt% of compound (al) and 30 wt% to 45 wt% of compound (b).

[0028] Preferably according to the invention, the PI polymer has a molecular mass Mw, measured by CES, ranging from 120,000 g / mol to 1,500,000 g / mol or from 150,000 g / mol to 1,500,000 g / mol. Preferably, the molecular mass Mw of the PI polymer, measured by CES, ranges from 200,000 g / mol to 1,500,000 g / mol or from 250,000 g / mol to 1,500,000 g / mol, more preferably from 120,000 g / mol to 1,000,000 g / mol or from 150,000 g / mol to 1,000,000 g / mol. More preferably, the molecular mass Mw of the PI polymer, measured by CES, ranges from 200,000 g / mol to 1,000,000 g / mol or from 250,000 g / mol to 1,000,000 g / mol.

[0029] According to the invention, the molecular weight or mass of the PI and P2 polymers is determined by Size Exclusion Chromatography (SEC). A test portion of the polymer solution corresponding to 20 mg of dry matter is introduced into a 10 mL bottle. Mobile phase, supplemented with 0.04% dimethylformamide (DMF), is added up to a total mass of 10 g. The composition of this mobile phase is as follows: NaHCO3: 0.05 mol / L, NaNO3: 0.1 mol / L, triethanolamine: 0.02 mol / L, NaN3: 0.03 wt%. The CES chain consists of a Waters 510 type isocratic pump, with a flow rate set at 1 mL / min, a Waters 717+ sample changer, a furnace containing a PSS Suprema guard column 5 cm long and 8 mm in internal diameter, followed by a PSS Suprema 30,000 Â column 30 cm long and 8 mm in internal diameter.Detection is performed using a Waters RI 410 differential refractometer. The oven is heated to 60°C and the refractometer to 45°C. The CES device is calibrated with a series of sodium polyacrylate standards supplied by Polymer Standards Service, with peak molecular weights ranging from 1200 g / mol to 1390,000 g / mol and polymolecularity indices (Ip) ranging from 1.09 to 2. The calibration curve is linear and incorporates the correction obtained using the flow marker dimethylformamide (DMF). Acquisition and processing of the chromatogram are performed using ConSenxus hs NTeqGPC software version 5.1.5. The resulting chromatogram is integrated into the region corresponding to molecular weights greater than 180 g / mol.

[0030] Preferably according to the invention, the PI polymer 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.

[0031] Also preferably, the PI polymer is a homopolymer whose Tg is greater than 0°C, preferably greater than 10°C or for which the PI polymer is a copolymer whose Tg is greater than 50°C, preferably greater than 100°C.

[0032] Also, the PI polymer can be totally or partially acidic or totally or partially non-neutralized. Preferably, the PI polymer can be partially neutralized, preferably by means of 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, amino bases, for example triethanolamine, aminomethylpropanol or 2-amino-2-methylpropanol (AMP) and their combinations, more preferably LiOH or Zn(OH)2 or ZnO.

[0033] Essentially, the polymer P2 is prepared by polymerizing at least one compound (a2) and at least one compound (c1). Preferably for composition C according to the invention, compound (a2) is selected from acrylic acid, methacrylic acid, a salt of acrylic acid, a salt of methacrylic acid, and combinations thereof. More preferably, compound (a2) is acrylic acid or methacrylic acid.

[0034] Preferably according to the invention, compound (cl) is selected from phosphated hydroxyethylacrylate, phosphated hydroxyethyl methacrylate, phosphated hydroxypropyl acrylate, phosphated hydroxypropyl methacrylate, phosphated hydroxybutyl acrylate, phosphated hydroxybutyl methacrylate, phosphated caprolactone methacrylate, phosphated caprolactone acrylate, phosphated polycaprolactone methacrylate, phosphated polycaprolactone acrylate, phosphated poly(ethylene oxide) acrylate, phosphated poly(ethylene oxide) methacrylate, phosphated poly(propylene oxide) acrylate, phosphated poly(propylene oxide) methacrylate, phosphated poly(ethylene oxide and propylene oxide) acrylate, phosphated poly(ethylene oxide and oxide) methacrylate propylene phosphate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactam methacrylate, lactam acrylate, polycaprolactame methacrylatepolycaprolactam acrylate, styrene, vinyl versatate, CrC8 esters of methacrylic acid, Ci-C8 esters of acrylic acid and their combinations, preferably methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, more preferably methyl acrylate, ethyl acrylate, butyl acrylate.

[0035] According to the invention, the P2 polymer is preferably a water-soluble polymer at a pH greater than 4.

[0036] Also, the polymer P2 can be a copolymer of compounds (a2) and (cl) and at least one other compound selected from: - a compound (c2) selected from vinyl-lactam, N-vinylpyrrolidone, ureidomethacrylate and their combinations; - a compound (c3) selected from maleic acid, maleic anhydride, itaconic acid, crotonic acid and their combinations; - a compound (c4) selected from ethoxymethacrylate sulfonic acid, sodium methallyl sulfonate, styrene sulfonate and their combinations; - and their combinations.

[0037] Preferably for composition C according to the invention, polymer P2 is prepared by a polymerization reaction of 55% to 95% by weight of compound (a2) and 5% to 45% by weight of compound (cl) or of 55% to 90% by weight of compound (a2) and 10% to 45% by weight of compound (cl). More preferably for composition C according to the invention, polymer P2 is prepared by a polymerization reaction of 55% to 80% by weight of compound (a2) and 20% to 45% by weight of compound (cl) or of 55% to 70% by weight of compound (a2) and 30% to 45% by weight of compound (cl).

[0038] Preferably according to the invention, the P2 polymer has a molecular weight Mw, measured by CES, ranging from 3,000 g / mol to 40,000 g / mol or from 3,000 g / mol to 30,000 g / mol. Preferably, the molecular weight Mw of the P2 polymer, measured by CES, ranges from 3,000 g / mol to 20,000 g / mol or from 3,000 g / mol to 15,000 g / mol. More preferably, the molecular weight Mw of the P2 polymer, measured by CES, ranges from 3,000 g / mol to 12,000 g / mol or from 3,000 g / mol to 10,000 g / mol.

[0039] Preferably according to the invention, the P2 polymer 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. Preferably according to the invention, the P2 polymer has a Tg greater than 50°C, preferably greater than 100°C.

[0040] Also, the polymer P2 can be totally or partially acidic or totally or partially non-neutralized. Preferably, the polymer P2 can be partially neutralized, preferably by means of 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, amino bases, for example triethanolamine, aminomethylpropanol or 2-amino-2-methylpropanol (AMP) and their combinations, more preferably LiOH or Zn(OH)2 or ZnO.

[0041] Preferably according to the invention, the polymerization reaction for the preparation of the PI polymer or the P2 polymer is carried out in water, alone or combined with at least one polar solvent, for example a solvent chosen from ethanol, isopropanol and their combinations.

[0042] According to the invention, a radical initiator or generating compound is present during the polymerization reaction. Preferably according to the 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'-azobisisobutyroni trile), hydrogen peroxide, 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 selected from Fe11, Fe111, Cu1, Cu11 and their combinations.According to the invention, the Fe11, Fe111, Cu1, Cu11 ions can be implemented by means of at least one compound selected from iron sulfate, hydrated iron sulfate, hemihydrated iron sulfate, heptahydrated iron sulfate, iron carbonate, hydrated iron carbonate, hemihydrated iron carbonate, iron chloride, copper carbonate, hydrated copper carbonate, hemihydrated copper carbonate, copper acetate, copper sulfate, pentahydrated copper sulfate, copper hydroxide, copper halide.

[0043] According to the invention, the polymerization reaction can be carried out in the presence of a compound comprising phosphorus in oxidation state I, in particular hypophosphorous acid (H3PO2) or a derivative of hypophosphorous acid (H3PO2), such as compounds comprising at least one hypophosphite ion (H2PO2), in particular a compound selected from sodium hypophosphite (H2PO2Na), potassium hypophosphite (H2PO2K), calcium hypophosphite ([H2PO2]2Ca).

[0044] According to the invention, the polymerization reaction can also be carried out in the presence of a compound comprising phosphorus in oxidation state III, in particular phosphorous acid or a derivative of phosphorous acid. According to the invention, the polymerization reaction can also be carried out in the presence of a compound comprising a bisulfite ion, preferably sodium bisulfite or potassium bisulfite.

[0045] Preferably for composition C according to the invention, the binding agent Q comprises at least one PI polymer and at least one liquid support, preferably water alone or combined with at least one polar solvent, for example a solvent selected from ethanol, isopropanol, and combinations thereof. Preferably, this liquid support is solely water, in particular the water used during the preparation of the PI polymer.

[0046] Also preferably, the binding agent Q comprises from 5% by weight to 60% by weight of PI polymer and from 40% by weight to 95% by weight of liquid support. More Preferably, the binding agent Q comprises 10% by weight to 40% by weight of PI polymer and 60% by weight to 90% by weight of liquid carrier.

[0047] Preferably for composition C 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 selected from ethanol, isopropanol, and combinations thereof. Preferably, this liquid support is solely water, in particular the water used during the preparation of polymer P2.

[0048] Preferably, the binding agent R comprises from 5% to 60% by weight of polymer P2 and from 40% to 95% by weight of liquid support. More preferably, the binding agent R comprises from 10% to 40% by weight of polymer P2 and from 60% to 90% by weight of liquid support.

[0049] According to the invention, the QR binding agent comprises at least one PI polymer, at least one P2 polymer, and at least one liquid support, preferably water alone or combined with at least one polar solvent, for example, a solvent selected from ethanol, isopropanol, and combinations thereof. Preferably, this liquid support is solely water, in particular the water used during the preparation of the PI and P2 polymers.

[0050] Preferably, the QR binding agent comprises 5% to 30% by weight of PI polymer, 5% to 30% by weight of P2 polymer, and 40% to 90% by weight of liquid support. More preferably, it comprises 10% to 30% by weight of PI polymer, 10% to 30% by weight of P2 polymer, and 60% to 80% by weight of liquid support.

[0051] In composition C according to the invention, the quantities of its ingredients may vary. Preferably, composition C according to the invention comprises, by dry weight: -del%àl0%de matériel E, - from 40% to 98% T material, - from 0.5% to 30% of Q binding agent, - from 0.5% to 20% of binding agent R, relative to the total quantity by dry weight of binding agents Q and R, material T and material E. Preferably, composition C according to the invention comprises, by dry weight: - from 2% to 6% of material E, - from 54% to 97% T material, - from 0.5% to 25% of binding agent Q, - from 0.5% to 15% of binding agent R, relative to the total quantity by dry weight of binding agents Q and R, material T and material E.

[0052] In a particularly preferred manner, composition C according to the invention comprises, by dry weight: -del%àl0%de matériel E, - from 40% to 98% T material, - from 1% to 50% of QR binding agent, relative to the total quantity by dry weight of QR binding agent, material T and material E. Preferably, composition C according to the invention comprises, by dry weight: - from 2% to 6% of material E, - from 54% to 97% T material, - from 1% to 40% of QR binding agent, relative to the total quantity by dry weight of QR binding agent, material T and material E.

[0053] Advantageously according to the invention, the composition is particularly easy to prepare. Thus, the invention also provides a method for preparing a composition C according to the invention, comprising the preparation of a binding agent Q, the preparation of a binding agent R, and then their separate or successive mixing under stirring with at least one material E, at least one material T and a liquid support, preferably water, alone or combined with at least one polar solvent, for example a solvent selected from ethanol, isopropanol and their combinations.

[0054] More preferably, the invention provides a method for preparing a composition C according to the invention, comprising preparing a binding agent Q, preparing a binding agent R, then mixing them under agitation to obtain the binding agent QR and then mixing it under agitation with at least one material E, at least one material T and a liquid support, preferably water, alone or combined with at least one polar solvent, for example a solvent selected from ethanol, isopropanol and their combinations.

[0055] Composition C according to the invention comprises the binding agents Q and R. Thus, the properties of composition C according to the invention go well beyond the individual properties of agents Q and R in the preparation of a cathode composition. Its properties are specifically provided by the binding agent QR according to the invention, which combines agents Q and R. Thus, the invention provides an aqueous binding agent QR comprising at least one binding agent Q and at least one binding agent R as defined in the invention.

[0056] The properties of composition C according to the invention make it possible to efficiently and easily prepare a cathode, in particular a cathode for a secondary battery. Thus, the invention provides a method for manufacturing a cathode comprising: - the application on a metallic substrate comprising aluminium, nickel or their combinations of at least one aqueous composition C according to the invention, - the drying, preferably carried out hot and under an inert atmosphere for example under a nitrogen atmosphere, then the calendering of the metallic substrate bearing the layer of composition C according to the invention.

[0057] The cathode obtained is also part of the invention, which therefore provides such a cathode manufactured according to the manufacturing method according to the invention.

[0058] The advantageous, particular or preferred characteristics of composition C according to the invention define binding agents Q, R and QR, methods of preparation or manufacture according to the invention, as well as cathodes, which are also advantageous, particular or preferred.

[0059] The various aspects of the invention can be illustrated by examples.

[0060] EXAMPLES

[0061] Preparation of the PLI polymer and the Ql agent according to the invention

[0062] In a 1 L glass reactor equipped with mechanical stirring and oil bath heating, 498 g of deionized water are introduced. The assembly is then heated to approximately 95°C and, over 120 minutes, the following are added 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.

[0063] Then, heating is continued for 60 minutes. The mixture is then cooled and diluted to obtain the aqueous binding agent Ql according to the invention, which has a dry matter content of 25% by weight, a pH of 2.3 and comprises the PLI polymer, whose molecular mass Mw, measured by CES, is 305,000 g / mol.

[0064] Preparation of polymer P2.1 and agent RI according to the invention

[0065] In a 1 L reactor equipped with mechanical stirring, an oil bath heater, and peristaltic pumps, the following are weighed out: 121 g of water, 121 g of isopropanol, 0.06 g of iron(II) sulfate heptahydrate, and 11 g of hydrazine hydrate at a concentration of 35% in water. The mixture is then heated under reflux to approximately 81°C, and over 120 minutes, the following are added using the peristaltic pumps: - in a first test tube: 174 g of acrylic acid, 35 g of methyl methacrylate, 110 g of ethylene glycol methacrylate phosphate and 80 g of water, - in a second test tube: 20 g of 130V hydrogen peroxide and 100 g of water.

[0066] After the additions are complete, heating is continued under reflux for 60 minutes at 80°C, and then the isopropanol is distilled with the addition of water during the distillation. The mixture is then cooled and diluted to obtain the aqueous binding agent RI according to the invention, which has a dry matter content of 40% by weight, a pH of 2.0, and comprises the P2.1 polymer whose molecular mass Mw, measured by CES, is 15,000 g / mol.

[0067] Preparation of polymer P2.2 and agent R2 according to the invention

[0068] In a 1 L reactor equipped with mechanical stirring, an oil bath heater, and peristaltic pumps, 200 g of isopropanol and 2 g of AZDN are weighed out. The mixture is then heated under reflux at approximately 80°C, and over 120 minutes, using the peristaltic pumps, 200 g of acrylic acid and 80 g of caprolactone acrylate (Arkema product SR 495B) are added. Heating under reflux is then continued for 60 minutes. The isopropanol is then distilled, and it is gradually replaced by water during the distillation process. The mixture is then cooled and diluted to obtain the aqueous binding agent R2 according to the invention, the dry matter content of which is 40% by weight, the pH is 2.3 and which comprises the polymer P2.2, the molecular mass of which Mw, measured by CES, is 7,500 g / mol. Preparation of agent QRl# according to the invention

[0069] In a beaker and with mechanical stirring, 250 g of agent Q1 and 39.5 g of agent RL are mixed. The resulting aqueous binding agent QR1 comprises the polymers PLI and P2.2, with a dry matter content of 27.1% by weight and a pH of 2.1. Preparation of agent QR2 according to the invention

[0070] In a beaker and under mechanical stirring, 250 g of agent Q1 and 67 g of agent R2 are mixed. The aqueous binding agent QR2 is obtained, comprising the polymers PLI and P2.2, with a dry matter content of 28.4% by weight and a pH of 2.3.

[0071] Preparation of a cathode preparation composition Cl according to the invention

[0072] In the bowl of a planetary mixer, 94.5 parts by weight of material T (lithium ferric phosphate) and 4 parts by weight of material E (carbon black) are introduced and mixed at 20 revolutions per minute and 800 revolutions per minute for 30 to 60 minutes in order to obtain a homogeneous mixture.

[0073] Next, 23 parts by weight of deionized water and 1.5 parts by weight of binding agent RI comprising polymer P2.1 are added. Stirring is continued for a few minutes to distribute the RI evenly. Then, 3.6 parts by weight of binding agent Q1 comprising polymer PLI and an amount of deionized water sufficient to obtain the composition Cl according to the invention at a concentration of 60% by dry weight are added. Stirring is continued at 15 to 30 rpm and at 800 to 1500 rpm for 180 to 300 minutes to obtain a visually homogeneous composition Cl.

[0074] Preparation of a C2 composition of cathode preparation according to the invention

[0075] In the bowl of a planetary mixer, 94.5 parts by weight of material T (lithium ferric phosphate) and 4 parts by weight of material E (carbon black) are introduced which is mixed at 20 revolution / min and at 800 revolution / min rotation for 30 to 60 minutes in order to obtain a homogeneous mixture.

[0076] Next, 23 parts by weight of deionized water and 1.5 parts by weight of binding agent R2 comprising polymer P2.2 are added. Stirring is continued for a few minutes to distribute the R2 agent uniformly. Then, 3.6 parts by weight of binding agent Q1 comprising polymer P1 and an amount of deionized water sufficient to obtain composition C2 according to the invention at a concentration of 60% by dry weight are added. Stirring is continued at 15 to 30 rpm and at 800 to 1500 rpm for 180 to 300 minutes to obtain a visually homogeneous composition C2.

[0077] Preparation of a C3 cathode preparation composition according to the invention

[0078] In the bowl of a planetary mixer, 94.5 parts by weight of material T (lithium ferric phosphate) and 4 parts by weight of material E (carbon black) are introduced and mixed at 20 revolutions per minute and 800 revolutions per minute for 30 to 60 minutes in order to obtain a homogeneous mixture.

[0079] Next, 23 parts by weight of deionized water and 2.21 parts by weight of QR1 binding agent, comprising polymers Pl.1 and P2.1, are added. Stirring is continued for a few minutes to distribute the QR1 agent uniformly. Then, 3.3 parts by weight of QR1 binding agent and an amount of deionized water sufficient to obtain composition C3 according to the invention at a concentration of 60% by dry weight are added. Stirring is continued at 15 to 30 rpm and at 800 to 1500 rpm for 180 to 300 minutes to obtain a visually homogeneous composition C3.

[0080] Preparation of a C4 composition of cathode preparation according to the invention

[0081] In the bowl of a planetary mixer, 94.5 parts by weight of material T (lithium ferric phosphate) and 4 parts by weight of material E (carbon black) are introduced and mixed at 20 revolutions per minute and 800 revolutions per minute for 30 to 60 minutes in order to obtain a homogeneous mixture.

[0082] Next, 23 parts by weight of deionized water and 2.11 parts by weight of QR2 binding agent, comprising polymers Pl.1 and P2.2, are added. Stirring is continued for a few minutes to distribute the QR2 agent uniformly. Then, 3.17 parts by weight of QR2 binding agent and an amount of deionized water sufficient to obtain composition C4 according to the invention at a concentration of 60% by dry weight are added. Stirring is continued at 15 to 30 rpm and at 800 to 1500 rpm for 180 to 300 minutes to obtain a visually homogeneous composition C4.

[0083] Preparation of cathodes using Cl to C4 compositions according to the invention

[0084] A layer of composition Cl according to the invention is deposited onto a cathode collector in the form of an aluminum foil and then dried for 30 minutes under a nitrogen atmosphere. After cooling, discs are cut to obtain a cathode according to the invention, the collector of which is coated with a homogeneous electroactive layer in a dry matter content of 0.23 mg / mm².

[0085] Similarly, cathodes are prepared by replacing composition Cl according to the invention respectively with compositions C2, C3 and C4.

Claims

1. Demands Aqueous composition C for cathode preparation, comprising: - at least one material E comprising carbon particles, - at least one electroactive cathode material T, - at least one binding agent Q comprising at least one water-soluble, non-crosslinked polymer PI, with a molecular mass Mw, measured by CES, ranging from more than 100,000 g / mol to 2,000,000 g / mol, prepared by a polymerization reaction, in the presence of at least one initiator compound, at least one compound (al) selected 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, non-crosslinked polymer P2, with a molecular mass Mw, measured by CES, ranging from 2,000 g / mol to less than 50,000 g / mol, prepared by a polymerization reaction, in the presence of at least an initiating compound: * of at least one compound (a2) selected 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 and * of at least one compound (cl) selected from the following CrCi2 esters of methacrylic acid, CrCi2 esters of acrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate, lactame methacrylate, lactame acrylate, polycaprolactame methacrylate, polycaprolactame acrylate, styrene, vinyl versatate, phosphated hydroxyethyl acrylate, phosphated hydroxyethyl methacrylate, phosphated hydroxypropyl acrylate, phosphated hydroxypropyl methacrylate, phosphated hydroxybutyl acrylate, phosphated hydroxybutyl methacrylate, caprolactone acrylate, caprolactone acrylate phosphate, polycaprolactone methacrylate phosphated, phosphated polycaprolactone acrylate, phosphated poly(ethylene oxide) acrylate, phosphated poly(ethylene oxide) methacrylate, phosphated poly(propylene oxide) acrylate, phosphated poly(propylene oxide) methacrylate, phosphated poly(ethylene oxide and propylene oxide) acrylate, phosphated poly(ethylene oxide and propylene oxide) methacrylate and their combinations.

2. Composition C according to claim 1 not comprising a fluorinated polymer, in particular a fluorine vinylidene polymer or not comprising an organic solvent, in particular aprotic polar solvent, in particular pyrrolidone, N-methylpyrrolidone (NMP), alkyl carbonates, or comprising a mixed QR binding agent combining the PI polymer and the P2 polymer.

3. Composition C according to claim 1 or 2, wherein: - material E is selected from carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes, carbon nanofiber, hardened carbon, graphite, partially graphitized coke, and combinations thereof, or - electroactive material T is selected from lithium, iron, nickel, manganese, cobalt, and combinations thereof, preferably selected from lithium ferric phosphate, lithium manganese phosphate, lithium cobalt phosphate, lithium ferric manganese phosphate, lithium cobalt oxide, nickel lithium oxide, lithium manganese oxide, manganese nickel oxide, lithium manganese nickel oxide, manganese nickel oxide, cobalt manganese oxide, aluminum nickel cobalt oxide, lithium ferric phosphate, preferably LiFePO4(LFP).

4. Composition C according to any one of claims 1 to 3 wherein: - the PI polymer is not crosslinked, or - the P2 polymer is not crosslinked, or - the PI polymer is prepared in the absence of (meth)acrylamide or a (meth)acrylamide derivative, or - the PI polymer is prepared in the absence of (meth)acrylonitrile or a (meth)acrylonitrile derivative, or - the P2 polymer is prepared in the absence of (meth)acrylamide or a (meth)acrylamide derivative, or - the P2 polymer is prepared in the absence of (meth)acrylonitrile or (meth)acrylonitrile derivative.

5. Composition C according to any one of claims 1 to 4 wherein: * compound (al) is selected from acrylic acid, methacrylic acid, a salt of acrylic acid, a salt of methacrylic acid and combinations thereof, preferably compound (al) is acrylic acid or methacrylic acid; or * polymer PI is water-soluble at a pH greater than 4 or wherein: * polymer PI is a homopolymer of compound (al); or * polymer PI is a copolymer of compound (al) and at least one other compound (b), preferably compound (b) selected from: - compound (bl) selected from vinyl-lactam, N-vinylpyrrolidone, ureidomethacrylate and combinations thereof; - compound (b2) selected from maleic acid, maleic anhydride, itaconic acid, crotonic acid and combinations thereof;- a compound (b3) selected from ethoxymethacrylate sulfonic acid, sodium methallyl sulfonate, styrene sulfonate, phosphated hydroxyethyl acrylate, phosphated hydroxyethyl methacrylate, phosphated hydroxypropyl acrylate, phosphated hydroxypropyl methacrylate, phosphated hydroxybutyl acrylate, phosphated hydroxybutyl methacrylate, phosphated caprolactone methacrylate, phosphated caprolactone acrylate and their combinations; - and their combinations.;

6. Composition C according to any one of claims 1 to 5 wherein: * the PI polymer is 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); or - 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); or - of 55% by weight to 70% by weight of compound (a1) and of 30% by weight to 45% by weight of compound (b); or for which: * the PI polymer has a molecular weight Mw, measured by CES, ranging from 120,000 g / mol to 1,500,000 g / mol or from 150,000 g / mol to 1,500,000 g / mol, preferably from 200,000 g / mol to 1,500,000 g / mol or from 250,000 g / mol to 1,500,000 g / mol, more preferably from 120,000 g / mol to 1,000,000 g / mol or from 150,000 g / mol to 1,000,000 g / mol, preferably from 200,000 g / mol to 1,000,000 g / mol or from 250,000 g / mol to 1,000,000 g / mol; or * the PI polymer 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 PI polymer is a homopolymer whose Tg is greater than 0°C, preferably greater than 10°C, or for which the PI polymer is a copolymer whose Tg is greater than 50°C, preferably greater than 100°C;or * the PI polymer is totally or partially acidic or totally or partially non-neutralized, preferably the PI polymer is partially neutralized, preferably by means of 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, amino bases, for example triethanolamine, aminomethylpropanol or 2-amino-2-methylpropanol (AMP) and their combinations, more preferably LiOH or Zn(OH)2 or ZnO.;

7. Composition C according to any one of claims 1 to 6 wherein: * compound (a2) is selected from acrylic acid, methacrylic acid, a salt of acrylic acid, a salt of methacrylic acid and combinations thereof, preferably compound (a2) is acrylic acid or methacrylic acid;or * the compound (cl) is selected from phosphated hydroxyethylacrylate, phosphated hydroxyethyl methacrylate, phosphated hydroxypropyl acrylate, phosphated hydroxypropyl methacrylate, phosphated hydroxybutyl acrylate, phosphated hydroxybutyl methacrylate, phosphated caprolactone methacrylate, phosphated caprolactone acrylate, phosphated polycaprolactone methacrylate, phosphated polycaprolactone acrylate, phosphated poly(ethylene oxide) acrylate, phosphated poly(ethylene oxide) methacrylate, phosphated poly(propylene oxide) acrylate, phosphated poly(propylene oxide) methacrylate, phosphated poly(ethylene oxide and propylene oxide) acrylate, phosphated poly(ethylene oxide and propylene oxide) methacrylate, caprolactone methacrylate, caprolactone acrylate, polycaprolactone methacrylate, polycaprolactone acrylate; lactam methacrylate, lactame acrylate, polycaprolactam methacrylate, polycaprolactam acrylate, styrene, vinyl versatate, CrC8 esters of methacrylic acid, Ci-C8 esters of acrylic acid and their combinations, preferably methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, more preferably methyl acrylate, ethyl acrylate, butyl acrylate; or * the polymer P2 is water-soluble at a pH greater than 4 or for which: * the polymer P2 is a copolymer of compounds (a2) and (cl) and at least one other compound selected from: - a compound (c2) selected from vinyl-lactam, N-vinylpyrrolidone, ureidomethacrylate and their combinations; - a compound (c3) selected from maleic acid, maleic anhydride, itaconic acid, crotonic acid and their combinations;- a compound (c4) selected from ethoxymethacrylate sulfonic acid, sodium methyl sulfonate, styrene sulfonate and their combinations; - and their combinations.;

8. Composition C according to any one of claims 1 to 7 wherein: * the polymer P2 is prepared by a polymerization reaction: - of 55% by weight to 95% by weight of compound (a2) and of 5% by weight to 45% by weight of compound (cl); or - of 55% by weight to 90% by weight of compound (a2) and of 10% by weight to 45% by weight of compound (cl); or - of 55% by weight to 80% by weight of compound (a2) and of 20% by weight to 45% by weight of compound (cl); or - of 55% by weight to 70% by weight of compound (a2) and of 30% by weight to 45% by weight of compound (cl); or for which: * the polymer P2 has a molecular mass Mw, measured by CES, ranging from 3,000 g / mol to 40,000 g / mol or from 3,000 g / mol to 30,000 g / mol, preferably from 3,000 g / mol to 20,000 g / mol or from 3,000 g / mol to 15,000 g / mol, more preferably from 3,000 g / mol to 12,000 g / mol or from 3,000 g / mol to 10,000 g / mol;or * the P2 polymer has a glass transition temperature Tg, calculated according to the Flory-Fox equation, ranging from -10°C to 230°C or;

9. well from 20°C to 230°C; or for which the polymer P2 has a Tg 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 selected from LiOH, NaOH, KOH, Zn(OH)2, Mg(OH)2, Ca(OH)2, ZnO, MgO, CaO, ammonium derivatives, ammonia, ammonia, amino bases, for example triethanolamine, aminomethylpropanol or 2-amino-2-methylpropanol (AMP) and combinations thereof, more preferably LiOH or Zn(OH)2 or ZnO. Composition C according to any one of claims 1 to 8, wherein: * 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 selected from ethanol, isopropanol and combinations thereof; or wherein: * The binding agent Q comprises: - from 5% by weight to 60% by weight of PI polymer 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 support; or 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 selected from ethanol, isopropanol and their combinations; or for which: * The binding agent R comprises: - from 5% by weight to 60% by weight of P2 polymer and from 40% by weight to 95% by weight of liquid support, more preferably: - from 10% by weight to 40% by weight of P2 polymer and from 60% by weight to 90% by weight of liquid support; or for which: * The QR binding agent comprises at least one PI polymer, at least one P2 polymer, and at least one liquid carrier, preferably water alone or combined with at least one polar solvent, for example, a solvent selected from ethanol, isopropanol, and combinations thereof; or for which: * The QR binding agent includes: - from 5% by weight to 30% by weight of PI polymer, from 5% by weight to 30% by weight of P2 polymer and from 40% by weight to 90% by weight of liquid support, more preferably: - 10% by weight to 30% by weight of PI polymer, 10% by weight to 30% by weight of P2 polymer and 60% by weight to 80% by weight of liquid support.

10. Composition C according to any one of claims 1 to 9 comprising, by dry weight: - 10% to 10% of material E, - 40% to 98% of material T, - 0.5% to 30% of binder Q, - 0.5% to 20% of binder R, preferably: - 2% to 6% of material E, - 54% to 97% of material T, - 0.5% to 25% of binder Q, - 0.5% to 15% of binder R, relative to the total quantity by dry weight of binders Q and R, of material T and of material E; or comprising, by dry weight: - 10% to 1% of material E, - 40% to 98% of material T, - 1% to 50% of QR binding agent, preferably: - 2% to 6% of material E, - 54% to 97% of material T, - 1% to 40% of QR binding agent, relative to the total quantity by dry weight of QR binding agent, material T and material E.

11. Method of preparing a composition C according to any one of claims 1 to 10, comprising: - the preparation of a binding agent Q, the preparation of a binding agent R, and then their separate or successive mixing under stirring with at least one material E, at least one material T and a liquid support, preferably water, alone or combined with at least one polar solvent, for example a solvent selected from ethanol, isopropanol and their combinations; or - the preparation of a binding agent Q, the preparation of a binding agent R, and then their mixing under stirring to obtain the binding agent QR and then its mixing under stirring with at least one material E, at least one material T and a liquid support, preferably water, alone or combined with at least one polar solvent, for example a solvent selected from ethanol, isopropanol and their combinations.

12. Aqueous binding agent QR comprising at least one binding agent Q and at least one binding agent R as defined according to any one of claims 1 to 10.

13. Method of manufacturing a cathode comprising: - applying to a metallic substrate comprising aluminium, nickel or combinations thereof at least one aqueous composition C according to any one of claims 1 to 10, - drying, preferably carried out hot and under an inert atmosphere for example under a nitrogen atmosphere, then calendering the metallic substrate bearing the layer of composition C according to any one of claims 1 to 10.

14. Cathode manufactured according to the manufacturing method according to claim 13.