CATHODE COMPOSITION FOR LI-ION BATTERY

Abstract

The present invention relates generally to the field of electrical energy storage in rechargeable secondary batteries of the Li-ion type. More specifically, the invention relates to a cathode composition for a Li-ion battery. The invention also relates to a method for manufacturing such a cathode composition, as well as to Li-ion secondary batteries comprising such a cathode.

Description

Title of the invention: CATHODE COMPOSITION FOR LI-ION BATTERY FIELD OF THE INVENTION

[0001] The present invention relates generally to the field of electrical energy storage in rechargeable secondary batteries of the Li-ion type. More specifically, the invention relates to a cathode composition for a Li-ion battery. The invention also relates to a method for manufacturing such a cathode composition, as well as to Li-ion secondary batteries comprising such a cathode. TECHNICAL BACKGROUND

[0002] A lithium secondary battery can be used as a power source for a variety of electronic devices ranging from cell phones, laptops and small home electronics to vehicles and high capacity energy storage devices and the like, and the demand for lithium secondary batteries continues to grow.

[0003] For a massive development of electric vehicles, a reduction in the manufacturing cost of batteries is essential, and one of the options considered is the use of low-cost active materials without cobalt. In addition, increasing the mass energy density of electric vehicle batteries remains a major challenge for the mass adoption of this technology. Increasing the thickness of the electrodes and reducing the size of the active material particles would make it possible to achieve these objectives in terms of cost and energy density.

[0004] Increasing the thickness of the electrodes involves improving the electrode / collector adhesion. Reducing the particle size involves an increase in the viscosity of the ink, preventing it from being used in a conventional deposition process for producing an electrode.

[0005] The publication by M. Singh et al. in Journal of The Electrochemical Society, 162 (7) A1196-A1201 (2015) showed that thicker electrode layers (320 qm) for lithium-ion cells have a favorable electrode-to-current collector ratio per cell volume and can reduce cell manufacturing costs. However, while this thick electrode approach might be sufficient for some stationary energy storage applications, it would not be suitable for electric vehicle manufacturing.

[0006] Current industrial cathode coating equipment imposes a processability window on the viscosity of the ink to be deposited on the current collector. Indeed, an ink having a viscosity between 2000 and 8000 mPa.s @ 10s 1 is a ink easily applied to a current collector. Below 2000 mPa.s, relaxation of the ink is observed during coating application and drying, which causes a huge variation in thickness and deposited mass. Above 8000 mPa.s, the ink is no longer deposited uniformly.

[0007] Furthermore, in the battery industry, the rheological stability of the ink during its storage is a critical parameter for optimizing productivity. Indeed, the ink must retain its aforementioned rheological properties for up to 72 hours of storage.

[0008] Furthermore, industrial manufacturing processes for electrodes by rolling (in English "roll to roll") involve a minimum adhesion value of the dry material deposited on the current collector. For good mechanical strength of the electrode, this adhesion value obtained by a 180° peel test must be greater than 20N / m.

[0009] There continues to be a need to develop cathode binder compositions that can increase the mass energy density in a Li-ion battery for application in electric vehicles, while maintaining good mechanical and adhesion properties.

[0010] Surprisingly, the inventors discovered the importance of a physical parameter of the polymer binder used in the manufacture of cathodes on the rheological and mechanical performances of the cathodes obtained. Indeed, on active cathode materials coated with carbon, the present invention demonstrates that an initial turbidity of the fluorinated polymer binder of between 45 and 390 NTU makes it possible to be in an optimum processability and mechanical strength of the final electrodes. Summary of the invention

[0011] The technical solution proposed by the present invention is to provide a cathode composition for a battery, said composition comprising a fluorinated polymer binder, an electrode active material and a conductive material.

[0012] Typically, said fluorinated polymer binder has an initial turbidity of the polymer binder of between 45 and 390 NTU, preferably of between 100 and 300 NTU.

[0013] Typically, said electrode active material is coated with a carbon layer.

[0014] The invention also aims to provide a method for manufacturing cathode compositions using active materials coated with carbon, and a fluorinated polymer binder having an initial turbidity of between 45 and 390 NTU at a concentration of 7% in NMP.

[0015] Another object of the invention is a Li-ion secondary battery comprising a negative electrode, a positive electrode and an electrolyte (liquid or solid), in which the cathode is as described above.

[0016] The present invention makes it possible to overcome the drawbacks of the state of the art. It provides a cathode composition for a battery making it possible to meet all the specifications required for the manufacture and production of high-performance cathodes, in terms of mechanical properties and adhesion to the current collector, regardless of the nature of the fluorinated polymer binder used, provided that its turbidity is between 45 and 390 NTU at a concentration of 7% in the NMP.

[0017] DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0018] The invention is now described in more detail and in a non-limiting manner in the following description.

[0019] According to a first aspect, the invention relates to a cathode composition for a battery, said composition comprising:

[0020] - a fluorinated polymer binder (component A),

[0021] - an active electrode material (component B), and

[0022] - a conductive material (component C),

[0023] wherein said polymer binder has an initial turbidity of the polymer binder of between 45 and 390 NTU, preferably of between 100 and 300 NTU, and said electrode active material is coated with a carbon layer.

[0024] According to various embodiments, said electrode composition comprises the following characteristics, where appropriate combined. The contents indicated are expressed by weight, unless otherwise indicated. Component A

[0025] The polymer binder used in the invention is a polymer based on vinylidene difluoride and is generically designated by the abbreviation PVDF.

[0026] According to one embodiment, the PVDF is a poly(vinylidene fluoride) homopolymer or a mixture of vinylidene fluoride homopolymers.

[0027] According to one embodiment, the PVDF is a poly(vinylidene fluoride) homopolymer or a copolymer of vinylidene difluoride with at least one comonomer compatible with vinylidene difluoride.

[0028] According to one embodiment, the PVDF is semi-crystalline.

[0029] Comonomers compatible with vinylidene difluoride may be halogenated (fluorinated, chlorinated or brominated) or non-halogenated.

[0030] Examples of suitable fluorinated comonomers are: vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, trifluoropropenes and in particular 3,3,3-trifluoropropene, tetrafluoropropenes and in particular 2,3,3,3-tetrafluoropropene or 1,3,3,3-tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropenes and in particular 1,1,3,3,3-pentafluoropropene or 1,2,3,3,3-pentafluoropropene, perfluoroalkylvi- nylethers and in particular those of general formula Rf-O-CF-CF2, Rf being an alkyl group, preferably C1 to C4 (preferred examples being perfluoropropylvinylether and perfluoromethylvinylether).

[0031] The fluorinated comonomer may comprise a chlorine or bromine atom. It may in particular be chosen from bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene and chlorotrifluoropropene. Chlorofluoroethylene may denote either 1-chloro-1-fluoroethylene or 1-chloro-2-fluoroethylene. The 1-chloro-1-fluoroethylene isomer is preferred. Chlorotrifluoropropene is preferably 1-chloro-3,3,3-trifluoropropene or 2-chloro-3,3,3-trifluoropropene.

[0032] The VDF copolymer may also comprise non-halogenated monomers such as ethylene, and / or acrylic or methacrylic comonomers.

[0033] Thus, said component A may be chosen from copolymers of vinylidene difluoride with at least one comonomer chosen from the list: vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropene, 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, 1,1,3,3,3-pentafluoropropene, 1,2,3,3,3-pentafluoropropene, perfluoropropylvinylether, perfluoromethylvinylether, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene, chlorotrifluoropropene, ethylene, and mixtures thereof.

[0034] The fluoropolymer preferably contains at least 50 mol% of vinylidene difluoride.

[0035] According to one embodiment, the PVDF is a copolymer of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) (P(VDF-HFP)), having a weight percentage of hexafluoropropylene monomer units of 2 to 23%, preferably of 4 to 15% by weight relative to the weight of the copolymer.

[0036] According to one embodiment, the PVDF is a mixture of a poly(vinylidene fluoride) homopolymer and a VDF-HFP copolymer.

[0037] According to one embodiment, the PVDF is a copolymer of vinylidene fluoride and tetrafluoroethylene (TFE).

[0038] According to one embodiment, the PVDF is a copolymer of vinylidene fluoride and

[0039] chlorotrifluoroethylene (CTFE).

[0040] According to one embodiment, the PVDF is a VDF-TFE-HFP terpolymer. According to one embodiment, the PVDF is a VDF-TrFE-TFE terpolymer (TrFE being trifluoroethylene). In these terpolymers, the mass content of VDF is at least 10%, the comonomers being present in variable proportions.

[0041] According to one embodiment, the PVDF comprises monomer units carrying at least one of the following functions: carboxylic acid, carbo- carboxylic acid esters, epoxy groups (such as glycidyl), amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenolic, ester, ether, siloxane, sulfonic, sulfuric, phosphoric, or phosphonic. The function is introduced by a chemical reaction which may be grafting, or a copolymerization of the fluorinated monomer with a monomer carrying at least one of said functional groups and a vinyl function capable of copolymerizing with the fluorinated monomer, according to techniques well known to those skilled in the art.

[0042] According to one embodiment, the functional group carries a carboxylic acid function which is a (meth)acrylic acid type group chosen from acrylic acid, methacrylic acid, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate and hydroxyethylhexyl(meth)acrylate.

[0043] According to one embodiment, the units carrying the carboxylic acid function further comprise a heteroatom chosen from oxygen, sulfur, nitrogen and phosphorus.

[0044] According to one embodiment, the functionality is introduced via the transfer agent used during the synthesis process. The transfer agent is a polymer with a molar mass less than or equal to 20,000 g / mol and carrying functional groups chosen from the groups: carboxylic acid, carboxylic acid anhydride, carboxylic acid esters, epoxy groups (such as glycidyl), amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenolic, ester, ether, siloxane, sulfonic, sulfuric, phosphoric, or phosphonic. An example of a transfer agent of this type is acrylic acid oligomers.

[0045] The content of functional groups in the PVDF is at least 0.01 mol%, preferably at least 0.1 mol%, and at most 15 mol%, preferably at most 10 mol%.

[0046] The PVDF preferably has a high molecular weight. By high molecular weight, as used herein, is meant a PVDF having a melt viscosity greater than 100 Pa.s, preferably greater than 500 Pa.s, more preferably greater than 1000 Pa.s, advantageously greater than 2000 Pa.s. The viscosity is measured at 232°C, at a shear rate of 100 s-1 using a capillary rheometer or a parallel plate rheometer, according to ASTM D3825. Both methods give similar results.

[0047] The PVDF homopolymers and VDF copolymers used in the invention can be obtained by known polymerization methods such as emulsion polymerization.

[0048] According to one embodiment, they are prepared by an emulsion polymerization process in the absence of fluorinated surfactant.

[0049] The polymerization of PVDF results in a latex generally having a content of solids of 10 to 60% by weight, preferably 10 to 50%, and having a weight average particle size of less than 1 micrometer, preferably less than 1000 nm, preferably less than 800 nm, and more preferably less than 600 nm. The weight average particle size is generally at least 10 nm, preferably at least 50 nm, and advantageously the average size is in the range of 100 to 400 nm. The polymer particles may form agglomerates, called secondary particles, whose weight average size is less than 5000 pm, preferably less than 1000 pm, advantageously between 1 and 80 micrometers, and preferably 2 to 50 micrometers. The agglomerates may break into discrete particles during formulation and application to a substrate.

[0050] According to certain embodiments, the PVDF homopolymer and the VDF copolymers are composed of bio-sourced VDF. The term "bio-sourced" means "derived from biomass". This makes it possible to improve the ecological footprint of the membrane. The bio-sourced VDF can be characterized by a renewable carbon content, i.e. carbon of natural origin and originating from a biomaterial or biomass, of at least 1 atomic % as determined by the 14C content according to standard NF EN 16640. The term "renewable carbon" indicates that the carbon is of natural origin and originates from a biomaterial (or biomass), as indicated below.According to certain embodiments, the bio-carbon content of the VDF may be greater than 5%, preferably greater than 10%, preferably greater than 25%, preferably greater than or equal to 33%, preferably greater than 50%, preferably greater than or equal to 66%, preferably greater than 75%, preferably greater than 90%, preferably greater than 95%, preferably greater than 98%, preferably greater than 99%, advantageously equal to 100%.

[0051] Typically, said fluoropolymer binder has an initial turbidity of between 45 and 390 NTU at a concentration of 7% in NMP, preferably between 100 and 300 NTU at a concentration of 7% in NMP. The acronym "NTU" means nephelometric turbidity units, and is equivalent to the acronym "NTU".

[0052] The turbidity value is measured using a turbidimeter previously calibrated with several Stablcal® formazin standard solutions ranging from 10 to 800 NTU. This measurement is carried out on a solution of polymer binder dissolved in N-methylpyrrolidone (NMP) at a mass concentration of 77.5 g / L and at a temperature of 25°C, which is equivalent to a concentration of 7% in NMP (dry extract).

[0053] The polymer binder is dissolved in the NMP by any methods known to those skilled in the art such as pseudo-planetary mixer, planetary mixer, roller type mixer, disperser and conventional stirring. The term "initial" refers to the state fluoropolymer dissolved in NMP. Component B

[0054] The expression "carbon-coated active material" means all inorganic lithium insertion compounds covered with a graphitic layer ranging from 5 nm to 1 pm, as measured by transmission electron microscopy.

[0055] The size of the elementary particles of active material is between 100 nm and 5 pm, as measured by laser granulometry.

[0056] According to one embodiment, the active material at the positive electrode is chosen from manganese dioxide (MnO2), iron oxide, copper oxide, nickel oxide, lithium-manganese composite oxides (for example LixMn2O4 or LixMnO2), lithium-nickel composition oxides (for example LixNiO2), lithium-cobalt composition oxides (for example LixCoO2), lithium-nickel-cobalt composite oxides (for example LiNiiyCoyO2), lithium-nickel-cobalt-manganese composite oxides (for example LiNixMnyCozO2 with x+y+z = 1), lithium-enriched lithium-nickel-cobalt-manganese composite oxides (for example Lii+x(Nix MnyCoz)i_xO2), lithium and transition metal composite oxides, lithium-manganese-nickel composite oxides of spinel structure (e.g. LixMn2.yNi yO4), high voltage nickel-manganese composite oxides (e.g. LiMn^Ni 0.5-XxO4(X being chosen from: Al, Fe, Cr, Co, Rh and Nd with 0 <x<0,l), les oxydes de vanadium, les oxydes du souffre de type S8 et leurs mélanges. .

[0057] According to one embodiment, said active material does not contain cobalt, it is chosen from LiFePO4, LiMnPO4, LiFexMnyPO4, LiFePO4F, LiMnPO4F and LiFex MnyPO4F where x+y =1. Component C

[0058] The electronically conductive material is chosen from carbon blacks, graphites, natural or synthetic, carbon fibers, carbon nanotubes, metal fibers and powders, and conductive metal oxides. Preferably, they are chosen from carbon blacks, graphites, natural or synthetic, carbon fibers and carbon nanotubes.

[0059] The mass composition of the cathode coating according to the invention is:

[0060] - Component A with a mass ratio between 80 and 99%;

[0061] - Component B with a mass ratio between 1 and 10%;

[0062] - Component C with a mass ratio between 1 and 10%;

[0063] the sum of these ratios being 100%.

[0064] The invention also relates to a method for manufacturing cathode compositions using active materials coated with carbon, a conductive material and a fluorinated polymer binder, said method comprising the following steps:

[0065] - preparation of a polymer binder solution by dissolving component A in N-methylpyrrolidone (NMP) with a dry extract content of 2 to 20%, preferably 2 to 15%, advantageously 4 to 14%;

[0066] - adding component B and component C to said polymer binder solution, and mixture to obtain an electrode formulation (also called ink) applicable to a metal support.

[0067] The invention also relates to a method for manufacturing a positive electrode of a Li-ion battery comprising the following steps:

[0068] - providing an electrode formulation applicable on a metal support;

[0069] - deposition of said electrode formulation on the metal substrate,

[0070] - the consolidation of said electrode by a heat treatment (application of a temperature up to 50°C above the melting temperature of the polymer, without mechanical pressure), and / or thermo-mechanical treatment such as calendering.

[0071] According to one embodiment, the manufacture of a cathode was carried out by following the following steps: a solution of polymer binder at 7% by mass in N-methyl-2-pyrrolidone is prepared until the polymer binder is completely dissolved. Then, Super P C65 carbon black (supplier Timcal) is added to this solution. The solution is mixed using a mechanical stirrer. Then the carbon-coated active material is added. An ink is obtained which contains by weight 94 parts of carbon-coated active materials, 3 parts of carbon black and 3 parts of binder per 100 parts of the carbon-coated active materials / carbon black / binder mixture. The ink obtained is deposited on an aluminum sheet so as to have a wet thickness of 200 μm. Then the NMP is evaporated by heating the coated sheet for 15 minutes at 90°C and then for 30 minutes at 150°C. This gives a coating with a thickness of 70 ± 10 m.

[0072] The metal supports of the electrodes are generally made of aluminum for the cathode. The metal supports may be surface treated and have a conductive primer with a thickness of 5 μm or more. The supports may also be carbon fiber woven or non-woven.

[0073] Another object of the invention is a Li-ion secondary battery comprising a negative electrode, a positive electrode and an electrolyte, wherein the cathode is as described above.

[0074] EXAMPLES

[0075] The following examples illustrate in a non-limiting manner the scope of the invention.

[0076] Homopolymer 1: Homopolymer of vinylidene fluoride characterized by a solution viscosity of 4000 mPa.s in NMP.

[0077] Homopolymer 2: Homopolymer of vinylidene fluoride characterized by a solution viscosity of 5000 mPa.s in NMP.

[0078] Homopolymer 3: Homopolymer of vinylidene fluoride characterized by a solution viscosity of 2000 mPa.s in NMP.

[0079] Homopolymer 4: Homopolymer of vinylidene fluoride characterized by a solution viscosity of 11000 mPa.s in NMP.

[0080] Homopolymer 5: Homopolymer of vinylidene fluoride characterized by a solution viscosity of 10000 mPa.s in NMP.

[0081] Functional copolymer 1: Copolymer of vinylidene fluoride and acrylic acid characterized by a solution viscosity of 6000 mPa.s in NMP.

[0082] Functional copolymer 2: Copolymer of vinylidene fluoride and acrylic acid characterized by a solution viscosity of 2000 mPa.s in NMP.

[0083] For all these products, the dry extract rate is 8%.

[0084] Measurement of the solution viscosity of the polymer binder dissolved in NMP:

[0085] Viscosity measurements are carried out with a BROOKFIELD® viscometer DV2T, equipped with the SC4 chamber and the 25 mobile, the temperature is regulated with a HUBER® bath at 25°C. Turbidity measurement

[0086] The turbidity of the polymer binder is measured by dissolving the polymer in N-methylpyrrolidone (NMP) at a mass concentration of 77.5 g / L and at a temperature of 25°C.

[0087] The determination of the turbidity value is carried out using a Hach 2100 Q turbidimeter, previously calibrated using several Stablcal formazin standard solutions ranging from 10 to 800 NTU. Measurement of adhesion

[0088] The adhesion between the layer formed by the mixture of active materials coated with carbon / carbon black / binder and the aluminum foil is measured. To do this, a 25 mm wide strip is cut. This strip is then stuck to a rigid aluminum plate using a double-sided adhesive, the adhesive being deposited on the side of the active materials coated with carbon / carbon black / binder coating. The peel test is carried out using an Instron® type 34SC1 dynamometer by fixing the rigid aluminum plate in one jaw and the flexible aluminum foil on which the deposit has been made in the other jaw. In this configuration, the peel angle is 180°. The speed of movement of the jaws is set at 100 mm / min.

[0089] Measurement of the viscosity of the electrode formulation applicable on a metal support

[0090] The viscosity of the electrode formulations was measured at 23°C, using a TA HR 10 rheometer. The ink which contains by weight 94 parts of active materials coated with carbon, 3 parts of carbon black and 3 parts of binder for 100 parts of the mixture of active materials coated with carbon / carbon black / binder is deposited between 2 parallel plates (diameter of 40mm) separated by 1mm (=gap of 1mm). The viscosity values ​​are obtained at different shear rates ranging from 0.1s 1 to 100 s1. The value of 10s 1 is taken as a comparison between the different formulations.

[0091] Table 1 shows the performances in terms of cathode adhesion and viscosity of the electrode formulations having compositions according to the invention (examples 1, 2 and 7) versus comparative examples 3, 4 and 5.

[0092] [Tables 1] N° Binder Turbidity Adhesion (N / m) Viscosity T=0 (mPa.s) @ 10s i Viscosity t=24H (mPa.s) @ 10s 1 1 Homopolymer e 1 130 22.5 3300 4470 2 Homopolymer e 2 290 43.2 5540 7450 3 Homopolymer e3 40 17.8 1720 2590 4 Homopolymer e 4 2 38.3 7720 9310 5 Homopolymer e 5 400 46.6 6100 12300 6 Functional copolymer 1 3 160 6700 18000 7 Functional copolymer 2 134 40.7 2500 5220

Claims

Claims

1. A cathode composition for a battery, said composition comprising: - a fluorinated polymer binder (component A), - an electrode active material (component B), and - a conductive material (component C), wherein said polymer binder has an initial turbidity of the polymer binder of between 45 and 390 NTU, preferably of between 100 and 300 NTU, and said electrode active material is coated with a carbon layer.

2. A cathode composition according to claim 1 wherein said carbon-coated active material comprises inorganic lithium insertion compounds coated with a graphitic layer ranging from 5 nm to 1 pm.

3. A cathode composition according to either of claims 1 or 2, wherein said carbon-coated active material is formed from elementary particles of size between 100 nm and 5 pm, as measured by laser granulometry.

4. A cathode composition according to one of claims 1 to 3, wherein said active material is selected from manganese dioxide, iron oxide, copper oxide, nickel oxide, lithium composite oxides, lithium-nickel composition oxides, lithium-cobalt composition oxides, lithium-nickel-cobalt composite oxides, lithium-nickel-cobalt-manganese composite oxides, lithium-enriched lithium-nickel-cobalt-manganese composite oxides, lithium-transition metal composite oxides, lithium-manganese-nickel composite oxides of spinel structure, high-voltage nickel-manganese composite oxides, vanadium oxides, S8-type sulfur oxides and mixtures thereof.

5. A cathode composition according to one of claims 1 to 3, wherein said active material is selected from LiFePO4, LiMnPO4, LiFexMnyPO4, LiFePO4F, LiMnPO4F and LiFexMnyPO4F where x+y =1.

6. Cathode composition according to one of claims 1 to 5, wherein said component A is selected from poly(vinylidene fluoride) homopolymers and copolymers of vinylidene difluoride with at least one comonomer selected from the list: vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropene, 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, 1,1,3,3,3-pentafluoropropene, 1,2,3,3,3-pentafluoropropene, perfluoropropylvinylether, perfluoromethylvinylether, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene, chlorotrifluoropropene, ethylene, and mixtures thereof.

7. A cathode composition according to claim 6, wherein the PVDF comprises monomer units carrying at least one of the following functionalities: carboxylic acid, carboxylic acid anhydride, carboxylic acid esters, epoxy groups (such as glycidyl), amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenolic, ester, ether, siloxane, sulfonic, sulfuric, phosphoric, or phosphonic.

8. Cathode composition according to one of claims 1 to 7, in which component C is chosen from carbon blacks, graphites, natural or synthetic, carbon fibers, carbon nanotubes, metal fibers and powders, and conductive metal oxides.

9. Cathode composition according to one of claims 1 to 8, having the following mass composition: - Component A with a ratio of between 80 and 99%, - Component B with a ratio of between 1 and 5%, - Component C with a ratio of between 1 and 5%, the sum of these ratios being 100%.

10. A method of manufacturing the cathode composition according to one of claims 1 to 9, said method using active materials coated with carbon (component B), a conductive material (component C) and a fluorinated polymer binder (component A), said method comprising the following steps: - preparing a polymer binder solution by dissolving component A in N-methylpyrrolidone (NMP) at a dry extract level of 2 to 20%, preferably 2 to 15%, advantageously 4 to 14%; - adding component B and component C to said polymer binder solution, and mixing to obtain an electrode formulation applicable to a metal support.

11. A Li-ion secondary battery comprising an anode, a cathode according to one of claims 1 to 9 and an electrolyte.