Cathode coating for all-solid-state na-ion or k-ion battery

Abstract

The present invention relates generally to the field of storing electrical energy in rechargeable Na-ion or K-ion secondary batteries. More specifically, the invention relates to a cathode coating for an all-solid-state Na-ion or K-ion battery. The invention also relates to a method for preparing said coating. The invention also relates to a cathode coated with this coating, to a method for manufacturing such a cathode, and to the Na-ion or K-ion secondary batteries comprising such a cathode.

Description

[0001]DESCRIPTION TITLE: CATHODE COATING FOR ALL-SOLID NA-ION OR K-ION BATTERIES FIELD OF THE INVENTION The present invention relates generally to the field of electrical energy storage in rechargeable Na-ion or K-ion secondary batteries. More specifically, the invention concerns a cathode coating for an all-solid-state Na-ion or K-ion battery. The invention also relates to a method for preparing said coating. The invention also relates to a cathode coated with this coating, to the method for manufacturing such a cathode, and to Na-ion or K-ion secondary batteries comprising such a cathode. TECHNICAL BACKGROUND Demand for lithium-ion batteries has increased in recent years due to their application in a wide variety of electronic devices such as mobile phones and electric vehicles.However, lithium-based compounds are relatively expensive, and natural lithium sources are unevenly distributed and difficult to access, being located in only a small number of countries. Alternatives to lithium have been sought. To this end, sodium-ion batteries have been developed. Sodium is indeed very abundant and homogeneously distributed in the Earth's crust. It is advantageously non-toxic and more economically attractive. However, the redox potential of the Na+ / Na couple is -2.71 V relative to the standard hydrogen electrode (HEE), and is therefore higher than that of the Li+ / Li couple, whose potential is -3.05 V relative to the standard hydrogen electrode, for a molar mass three times greater. These characteristics make sodium-ion batteries less energy-dense. New active cathode materials of the oxide type make it possible to bridge this gap between these two technologies by increasing the voltage and specific capacity.Unfortunately, these new materials have the drawback of being basic and therefore poorly suited to the binders traditionally used in the solvent-based cathode manufacturing process for lithium batteries. For example, a sodium-ion battery with a cathode prepared from cathode material, PVDF, and carbon black is known by US2024079577. Existing secondary sodium batteries generally use liquid electrolytes containing an organic substance. These liquid electrolytes advantageously have high ionic conductivity but require additional safety features due to the risk of liquid leakage, fire, or explosion at high temperatures. To address the safety issues associated with liquid electrolytes, fully solid-state batteries using solid electrolytes have recently been developed.An all-solid-state battery typically comprises a positive electrode, a solid electrolyte, and a negative electrode. The positive electrode includes an active electrode material and a solid electrolyte, as well as an electronic conductor and a binder. Like the positive electrode, the negative electrode includes an active electrode material and a solid electrolyte, as well as a conductor and a binder. However, currently, no solid electrolyte meets the requirements for widespread use in all-solid-state batteries. Indeed, it is generally difficult to combine ionic conductivity, electrochemical stability, mechanical strength, and compatibility with anode and cathode materials for solid electrolytes. There remains a need to develop a solution that enables the compatibility of a cathode with a solid electrolyte in an all-solid-state Na-ion or K-ion battery.The invention aims to provide a coating that can be applied directly to the positive electrode of a Na-ion or K-ion battery, thereby enabling physical separation between the solid electrolyte and the electrode's active material and making it possible to use solid electrolytes that previously appeared unstable with respect to certain active materials. The invention also aims to provide a method for manufacturing said cathode coating. The invention further relates to a cathode having such a coating and to a method for manufacturing such a cathode. Finally, the invention aims to provide rechargeable Na-ion or K-ion secondary batteries comprising such a cathode. SUMMARY OF THE INVENTION The technical solution proposed by the present invention is to provide a cathode coating that makes the cathode compatible with a solid electrolyte in an all-solid-state battery.The invention relates firstly to a cathode coating comprising, preferably consisting of: a. at least one fluorinated polymer P1 (component A), b. at least one sodium or potassium salt (component B), and c. at least one conductivity additive (component C).According to a preferred embodiment, said at least one fluorinated polymer P1 comprising repeating units from a monomer M1a selected from the group consisting of vinyl fluoride, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, 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-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R. 1 CH2OCF=CF2 in which R 1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product has the formula R 2 OCF=CH2 in which R 2is F(CF2)p and p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture of these.According to a preferred embodiment, said fluorinated polymer P1 comprises repeating units from monomer M1a and repeating units from monomer M1b or repeating units from monomer M1c; said monomer M1a being vinylidene fluoride; said monomer M1b selected from the group consisting of vinyl fluoride; trifluoroethylene (TrFE); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); 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-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R. 1CH2OCF=CF2 in which R 1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product has the formula R 2 OCF=CH2 in which R 2 is F(CF2)p and p is 1, 2, 3 or 4; perfluorobutyl ethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof; said monomer M1c being selected from the group consisting of formula R 1 R 2 C=C(R 3 )((X 1 ) p HORN 4 ) in which the R substituents 1 , R 2 and R 3 are independently selected from the group consisting of H, CO2H and C1-C5 alkyl; R 4 is selected from the group consisting of –NHC(CH3)2CH2C(O)CH3 or –OR 5 with R 5selected from the group consisting of H and C1-C 18 alkyl optionally substituted by one or more –OH, -CO2H, -SO3H, -PO3H2, -OC(O)R groups 6 , -C(O)OR 6 or a heterocycle with five or ten members comprising at least one nitrogen atom in its cyclic chain; R 6 being selected from the group consisting of C1-C6 alkyl or C6-C 12 aryl optionally substituted by one or more –OH, -CO2H, -SO3H, -PO3H2 group(s); p is 0 or 1; X 1 is selected from the group consisting of –[-C(O)OC(R 7 (R 8 )C(R 9 (R 10 )-] w1 - and a C1-C hydrocarbon group 10 alkyl optionally bearing one or more -OH, -CO2H or ester group(s); with w1 being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R 7 , R 8 , R 9 , R 10are independently of each other, independently for each w1 unit, selected from the group consisting of H and C1-C5 alkyl. In a preferred embodiment, said at least one polymer P1 comprises monomeric units derived from a monomer M1a being vinylidene fluoride and monomeric units derived from a monomer M1b selected from the group consisting of trifluoroethylene, 1,1-chlorofluoroethylene, chlorotrifluoroethylene, hexafluoropropene, and tetrafluoroethylene, or a mixture thereof. In a preferred embodiment, said fluorinated polymer P1 comprises monomeric units bearing at least one of the following functional 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.According to a preferred embodiment, said sodium or potassium salt is selected from the group consisting of NaCF3SO3, NaPF6, NaClO4, NaBF4, NaB(C2O4)2, NaN(SO2F)2, NaN(SO2CF3)2, NaN(SO2C2F3)2, NaN(SO2CF2CF3)2, NaN(SO2F)(SO2CF3), NaN(SO2F)(SO2CF2CF3), NaN(SO2CF3)(SO2CF2CF3), NaAsF6, NaBF2C2O4, NaNO3, NaPF3(CF2CF3)3, NaTDI, KCF3SO3, KPF6, KClO4, KBF4, KB(C2O4)2, KN(SO2F)2, KN(SO2CF3)2, KN(SO2C2F3)2, KN(SO2CF2CF3)2, KN(SO2F)(SO2CF3), KN(SO2F)(SO2CF2CF3), KN(SO2CF3)(SO2CF2CF3), KAsF6, KBF2C2O4, KNO3, KPF3(CF2CF3)3 and KTDI or a mixture thereof. In a preferred embodiment, component C is selected from linear or cyclic ethers, esters, lactones, cyclic ketones, nitriles, carbonates, and ionic liquids. In a preferred embodiment, said coating has a thickness ranging from 0.1 to 100 µm, preferably from 0.1 to 50 µm, and more preferably from 0.1 to 35 µm.According to a preferred embodiment, said coating has the following mass composition: - Component A with a ratio of between 20 and 80%, - Component B with a ratio of between 1 and 40%, - Component C with a ratio of between 2 and 50%, preferably, the sum of these ratios being 100%. The present invention also provides a method for manufacturing said cathode coating according to the present invention from an ink obtained by mixing all the constituents of the coating in a solvent.According to a preferred embodiment, said solvent is selected from the group consisting of acetone, acetyl triethyl citrate, γ-butyrolactone, cyclohexanone, cyclopentanone, dibutyl phthalate, dibutyl sebacate, diethyl carbonate, diethyl phthalate, dihydrolevoglucosenone, dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, 3-heptanone, hexamethyl phosphoramide, 3-hexanone, methyl ethyl ketone, N-methyl-2-pyrrolidinone, 3-octanone, 3-pentanone, propylene carbonate, tetrahydrofuran, tetramethylurea, triacetin, triethyl citrate, triethyl phosphate, Trimethyl phosphate, N,N′ tetrabutylsuccindiamide, and mixtures thereof. The present invention also provides a cathode for a solid-state sodium-ion or potassium-ion battery, said cathode consisting of an active material, a binder, and a conductive material, and having a coating layer according to the present invention.According to a preferred embodiment, said active material is selected from the group consisting of at least one active material of formula Na. x M y O2 or formula of formula K x M yO2; M comprising at least one metal or a mixture of metals; x is between 0 and 1; y is between 0 and 1. In a preferred embodiment, said conductive material is selected from carbon blacks, graphites, natural or synthetic, carbon fibers, carbon nanotubes, metal fibers and powders, and conductive metal oxides. In a preferred embodiment, said binder is a polymer selected from polyolefins, fluoropolymers, fluoropolymers with acidic functionalities, polyacrylic acids, polyacrylonitril, cellulose-type polymers, polyphenylsulfone, polyethersulfone, a phenolic resin, a vinyl ester resin, an epoxy resin, or a liquid crystal polymer. In a preferred embodiment, said cathode has a porosity of less than 10%, preferably less than 5%.The present invention also provides a method for manufacturing a positive electrode for a Na-ion or K-ion battery, said method comprising the steps of: - providing a cathode, - depositing a coating layer according to the present invention onto said cathode. The present invention also provides an all-solid-state secondary Na-ion or K-ion battery comprising an anode, a cathode according to the present invention, and an all-solid-state electrolyte. The present invention overcomes the drawbacks of the prior art. It provides an ionically conductive coating having a homogeneous distribution of its dielectric constant. Within the scope of the invention, the coating allows the use of positive electrodes without solid electrolytes mixed with the active material of the cathode. Indeed, the coating can be applied directly to a conventional positive electrode having a porosity between 15 and 45% before or after calendering.This coating then allows for physical separation between the solid electrolyte and the active material, thus enabling the use of solid electrolytes that previously appeared unstable with respect to certain active materials. The present invention therefore provides a positive electrode comprising a first layer consisting of a conventional positive electrode and a second layer consisting of a cathode coating according to the present invention. The invention provides a coating exhibiting a very good compromise between ionic conductivity, electrochemical stability, high-temperature stability, and mechanical strength. DESCRIPTION OF EMBODIMENTS OF THE INVENTION The invention is now described in more detail and in a non-limiting manner in the following description. According to a first aspect, the invention relates to a cathode coating comprising, preferably consisting of: a. at least one fluorinated polymer P1 (component A), b.at least one sodium or potassium salt (component B), and c. at least one conductivity additive (component C). In various embodiments, said coating comprises the following characteristics, possibly combined. The contents indicated are expressed by weight, unless otherwise stated. Component A Said fluorinated polymer P1 comprises in its chain at least monomeric units derived from a fluorinated monomer M1a selected from compounds containing a vinyl group capable of opening to polymerize and which contains, directly attached to this vinyl group, at least one fluorine atom, a fluoroalkyl group, or a fluoroalkoxy group. Preferably, said fluorinated polymer P1 is semi-crystalline.Preferably, said fluorinated polymer P1 comprises monomeric units derived from a monomer M1a selected from the group consisting of vinyl fluoride; vinylidene fluoride (VDF); 1,2-difluoroethylene; hexafluoropropylene (HFP); trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, 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-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R. 1 CH2OCF=CF2 in which R 1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product has the formula R 2 OCF=CH2 in which R 2is F(CF2)p and p is 1, 2, 3, or 4; perfluorobutylethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene, and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof. Examples of trifluoropropene include 3,3,3-trifluoropropene. Examples of tetrafluoropropene include 2,3,3,3-tetrafluoropropene and 1,3,3,3-tetrafluoropropene. Examples of pentafluoropropene include 1,1,3,3,3-pentafluoropropene and 1,2,3,3,3-pentafluoropropene. Chlorofluoroethylene can refer to 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.In particular, said fluorinated polymer P1 comprises at least monomeric units derived from a monomer M1a, being vinylidene fluoride. The fluorinated polymer P1 may be a homopolymer or a copolymer of vinylidene fluoride. In one particular embodiment, the fluorinated polymer P1 is a homopolymer of vinylidene fluoride. In another particular embodiment, the fluorinated polymer P1 is a polymer comprising monomeric units derived from a monomer M1a, being vinylidene fluoride, and monomeric units derived from a fluorinated monomer M1b copolymerizable with vinylidene fluoride, or monomeric units derived from a non-fluorinated monomer M1c, or a mixture of the two. In said fluorinated polymer P1, the mass percentage of the monomeric units M1a is at least 50%, preferably at least 60%, more preferably greater than 70%, and advantageously greater than 80%.Preferably, when the fluorinated monomer M1a is vinylidene fluoride, the mass percentage of vinylidene fluoride monomeric units in said fluorinated polymer P1 is at least 50%, preferably at least 60%, more preferably greater than 70% and advantageously greater than 80%.According to one embodiment, said fluorinated polymer P1 comprises monomeric units derived from a monomer M1a being vinylidene fluoride and monomeric units derived from a fluorinated monomer M1b selected from the group consisting of vinyl fluoride, 1,2-difluoroethylene, hexafluoropropylene (HFP), trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, 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-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R. 1 CH2OCF=CF2 in which R 1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product has the formula R 2OCF=CH2 in which R 2is F(CF2)p and p is 1, 2, 3 or 4; perfluorobutyl ethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof. Preferably, the fluorinated polymer P1 comprises monomeric units derived from a monomer M1a being vinylidene fluoride and monomeric units derived from a fluorinated monomer M1b selected from the group consisting of trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene; perfluoro(alkyl vinyl)ethers such as perfluoro(methyl vinyl)ether, perfluoro(ethyl vinyl)ether or perfluoro(propyl vinyl)ether; perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole); the product of the formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH,CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R'CH2OCF=CF2 in which R' is hydrogen or F(CF2)z and z is 1, 2, 3 or 4; the product of formula R''OCF=CH2 in which R'' is F(CF2)z and z is 1, 2, 3 or 4; trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene or 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof. In particular, the fluorinated polymer P1 comprises monomeric units derived from a monomer M1a, being vinylidene fluoride, and monomeric units derived from a fluorinated monomer M1b selected from the group consisting of trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene,chlorofluoroethylene and hexafluoropropylene or a mixture thereof. Said polymer P1 may in particular be a copolymer of vinylidene fluoride and hexafluoropropylene. Preferably, said monomeric units derived from a fluorinated monomer M1b may be present in a mass content of 1 to 40% based on the total weight of polymer P1, advantageously from 3 to 35%, preferably from 3 to 30%, more preferably from 3 to 25%. Said polymer P1 may also comprise monomeric units derived from a monomer M1a selected from the group consisting of vinylidene fluoride (VDF); trifluoroethylene (TrFE); chlorotrifluoroethylene (CTFE), chlorofluoroethylene (CFE), 1,2-difluoroethylene, and tetrafluoroethylene (TFE). Preferably, said fluorinated polymer P1 comprises monomeric units derived from a monomer M1a being vinylidene fluoride and monomeric units derived from a fluorinated monomer M1b selected from the group consisting of trifluoroethylene,1,1-chlorofluoroethylene, chlorotrifluoroethylene, hexafluoropropene, and tetrafluoroethylene, or a mixture thereof. Said at least one polymer P1 may comprise monomeric units derived from vinylidene fluoride, trifluoroethylene, and optionally from 1,1-chlorofluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, or hexafluoropropene, or a mixture thereof; or monomeric units derived from vinylidene fluoride, tetrafluoroethylene, and optionally from 1,1-chlorofluoroethylene, trifluoroethylene, chlorotrifluoroethylene, or hexafluoropropene, or a mixture thereof. Said polymer P1 may, in particular, be a copolymer of vinylidene fluoride and trifluoroethylene, a copolymer of vinylidene fluoride and tetrafluoroethylene, a copolymer of vinylidene fluoride and chlorotrifluoroethylene, or a terpolymer of vinylidene fluoride, chlorotrifluoroethylene, and tetrafluoroethylene.a terpolymer of vinylidene fluoride, chlorotrifluoroethylene, and trifluoroethylene; a terpolymer of vinylidene fluoride, trifluoroethylene, and hexafluoropropene; a terpolymer of vinylidene fluoride, tetrafluoroethylene, and 1,1-chlorofluoroethylene; a terpolymer of vinylidene fluoride, trifluoroethylene, and 1,1-chlorofluoroethylene; or a terpolymer of vinylidene fluoride, hexafluoropropene, and tetrafluoroethylene. In polymer P1, the molar content of vinylidene fluoride may be at least 10 mol%, advantageously at least 20 mol%, preferably at least 30 mol%, more preferably at least 40 mol%, particularly at least 50 mol%, and more particularly at least 55 mol%. Preferably, the molar content of vinylidene fluoride may be between 55 and 99 mol%, advantageously between 55 and 95 mol%, preferably between 60 and 95 mol%, and in particular between 65 and 95 mol%. In polymer P1,The molar content of trifluoroethylene may be at least 1 mol%, advantageously at least 5 mol%, preferably at least 7 mol%, more preferably at least 10 mol%, in particular at least 12 mol%, more particularly at least 15 mol%. Preferably, the molar content of trifluoroethylene may be between 15 and 50%, advantageously between 17 and 45 mol%, preferably between 20 and 40 mol%, in particular between 20 and 35 mol%, more particularly between 20 and 30 mol%. In polymer P1, the molar content of chlorotrifluoroethylene may be at least 0.5 mol%, advantageously at least 1 mol%, preferably at least 2 mol%, more preferably at least 3 mol%, in particular at least 4 mol%, more particularly at least 5 mol%. Preferably, the molar content of chlorotrifluoroethylene may be between 1 and 20%, advantageously between 2 and 17 mol%, preferably between 3 and 15 mol%, in particular between 4 and 15 mol%,more particularly between 5 and 12 mol%. In polymer P1, the molar content of tetrafluoroethylene may be at least 1 mol%, advantageously at least 5 mol%, preferably at least 7 mol%, more preferably at least 10 mol%, in particular at least 15 mol%, more particularly at least 20 mol%. Preferably, the molar content of tetrafluoroethylene may be between 1 and 60%, advantageously between 2 and 55 mol%, preferably between 5 and 50 mol%, in particular between 7 and 45 mol%, more particularly between 10 and 40 mol%. In polymer P1, the molar content of chlorofluoroethylene may be at least 0.5 mol%, advantageously at least 1 mol%, preferably at least 2 mol%, more preferably at least 3 mol%, in particular at least 4 mol%, more particularly at least 5 mol%. Preferably, the molar content of chlorofluoroethylene may be between 1 and 20%, advantageously between 2 and 17 mol%, preferably between 3 and 15 mol%.in particular between 4 and 15 mol%, more particularly between 5 and 12 mol%. In a copolymer of vinylidene fluoride and trifluoroethylene, the molar content of vinylidene fluoride may be between 60 and 99 mol%, advantageously between 65 and 95 mol%, preferably between 65 and 90 mol%, more preferably between 70 and 85 mol%; and the molar content of trifluoroethylene may be between 1 and 40 mol%, advantageously between 5 and 35 mol%, preferably between 10 and 35 mol%, more preferably between 15 and 30 mol%. In a copolymer of vinylidene fluoride and tetrafluoroethylene, the molar content of vinylidene fluoride may be between 40 and 99 mol%, advantageously between 45 and 95 mol%, preferably between 50 and 90 mol%, more preferably between 55 and 85 mol%; and the molar content of tetrafluoroethylene may be between 1 and 60 mol%, advantageously between 5 and 55 mol%, preferably between 10 and 50 mol%,more preferably between 15 and 45 mol%. In a copolymer of vinylidene fluoride and chlorotrifluoroethylene, the molar content of vinylidene fluoride may be between 60 and 99 mol%, advantageously between 65 and 98 mol%, preferably between 65 and 97 mol%, more preferably between 70 and 96 mol%, in particular between 75 and 95 mol%; and the molar content of trifluoroethylene may be between 1 and 40 mol%, advantageously between 2 and 35 mol%, preferably between 3 and 35 mol%, more preferably between 4 and 30 mol%, in particular between 5 and 25 mol%. In a terpolymer of vinylidene fluoride, chlorotrifluoroethylene and tetrafluoroethylene, the molar content of vinylidene fluoride may be between 20 and 98 mol%, advantageously between 35 and 90 mol%, preferably between 50 and 90 mol%; and the molar content of tetrafluoroethylene may be between 1 and 50 mol%, advantageously between 5 and 50 mol%, preferably between 5 and 40 mol%,; and the molar content of chlorotrifluoroethylene may be between 1 and 30 mol%, advantageously between 1 and 15 mol%, preferably between 1 and 12 mol%. In a terpolymer of vinylidene fluoride, chlorotrifluoroethylene and trifluoroethylene, the molar content of vinylidene fluoride may be between 20 and 98 mol%, advantageously between 35 and 90 mol%, preferably between 50 and 90 mol%; and the molar content of trifluoroethylene may be between 1 and 50 mol%, advantageously between 5 and 50 mol%, preferably between 5 and 40 mol%; and the molar content of chlorotrifluoroethylene may be between 1 and 30 mol%, advantageously between 1 and 15 mol%, preferably between 1 and 12 mol%. In a terpolymer of vinylidene fluoride, trifluoroethylene and hexafluoropropene, the molar content of vinylidene fluoride can be between 20 and 98 mol%, advantageously between 35 and 90 mol%,preferably between 50 and 90 mol%; and the molar content of trifluoroethylene may be between 1 and 50 mol%, advantageously between 5 and 50 mol%, preferably between 5 and 40 mol%; and the molar content of hexafluoropropene may be between 1 and 30 mol%, advantageously between 1 and 15 mol%, preferably between 1 and 12 mol%. In a terpolymer of vinylidene fluoride, tetrafluoroethylene, and 1,1-chlorofluoroethylene, the molar content of vinylidene fluoride may be between 20 and 98 mol%, advantageously between 35 and 90 mol%, preferably between 50 and 90 mol%; and the molar content of tetrafluoroethylene may be between 1 and 50 mol%, advantageously between 5 and 50 mol%, preferably between 5 and 40 mol%; and the molar content of 1,1-difluoroethylene may be between 1 and 30 mol%, advantageously between 1 and 15 mol%, preferably between 1 and 12 mol%. In a terpolymer of vinylidene fluoride, trifluoroethylene, and 1,1- In chlorofluoroethylene, the molar content of vinylidene fluoride may be between 20 and 98 mol%, advantageously between 35 and 90 mol%, preferably between 50 and 90 mol%; and the molar content of trifluoroethylene may be between 1 and 50 mol%, advantageously between 5 and 50 mol%, preferably between 5 and 40 mol%; and the molar content of 1,1-difluoroethylene may be between 1 and 30 mol%, advantageously between 1 and 15 mol%, preferably between 1 and 12 mol%. In a terpolymer of vinylidene fluoride, hexafluoropropene, and tetrafluoroethylene, the molar content of vinylidene fluoride may be between 20 and 98 mol%, advantageously between 35 and 90 mol%, preferably between 50 and 90 mol%; and the molar content of tetrafluoroethylene may be between 1 and 50 mol%, advantageously between 5 and 50 mol%, preferably between 5 and 40 mol%; and the molar content of hexafluoropropene may be between 1 and 30 mol%.advantageously between 1 and 15 mol%, preferably between 1 and 12 mol%. Said fluorinated polymer P1 may comprise, in addition to monomeric units derived from the monomer M1a as defined above, in particular when M1a is vinylidene fluoride, monomeric units derived from a non-fluorinated monomer M1c of formula R, a R b C=C(R c )HORN d in which the R substituents a , R b and R c are independently selected from the group consisting of H and C1-C5 alkyl; R d is selected from the group consisting of –NHC(CH3)2CH2C(O)CH3 or –OR d 'with R d 'selected from the group consisting of H and C1-C 18 alkyl optionally substituted by one or more –OH, -CO2H, -SO3H, -PO3H2, -OC(O)R groups d '', -C(O)OR d or a five- or ten-membered heterocycle comprising at least one nitrogen atom in its cyclic chain; Rd '' being selected from the group consisting of C1-C6alkyl or C6-C 12 an aryl group optionally substituted by one or more –OH, -CO2H, -SO3H, or -PO3H2 groups. Said heterocycle may be saturated, unsaturated, or aromatic. Said heterocycle may be monocyclic or bicyclic. Said heterocycle may be a pyrrole, pyrrolidine, pyridine, piperidine, pyrimidine, pyrazine, 1,4-dihydropyridine, indole, oxindole, isatin, quinoline, isoquinoline, quinazoline, imidazoline, pyrazolidine, 2-pyrrolidone, delta-lactam, succinimide, 2-imidazolidinone, or 4-imidazolidinone ring. Said heterocycle may be substituted by one or more C1-C5 alkyl groups. As mentioned above, the C1-C 18The alkyl group is optionally substituted by said heterocycle. The latter may be linked to the alkyl chain by the nitrogen atom or any other atom forming the heterocycle. Preferably, the heterocycle is 2-pyrrolidone, delta-lactam, succinimide, 2-imidazolidinone, or 4-imidazolidinone. Said monomer M1c may have the formula R a R b C=C(R c )HORN d in which the R substituents a , R b and R c are independently selected from the group consisting of H and C1-C5 alkyl; R d is selected from the group consisting of –NHC(CH3)2CH2C(O)CH3 or –OR d 'with R d 'selected from the group consisting of H and C1-C 18 alkyl optionally substituted by one or more –OH, -CO2H, -SO3H, -PO3H2, -OC(O)R groups d '', - C(O)OR d or a five- or ten-membered heterocycle comprising at least one nitrogen atom in its cyclic chain; Rd '' being selected from the group consisting of C1-C6alkyl or C6-C 12 an aryl group optionally substituted with one or more –OH, -CO2H, -SO3H, or -PO3H2 groups. Preferably, the heterocycle is as defined above; in particular, the heterocycle is 2-pyrrolidone, deltalactam, succinimide, 2-imidazolidinone, or 4-imidazolidinone. Preferably, the R substituent d ' is selected from the group consisting of H, methyl, ethyl, propyl, n-butyl, isobutyl, t-butyl, n-dodecyl, amyl, isoamyl, hexyl, 2-ethylhexyl, lauryl, n-octyl, hydroxyethyl, hydroxybutyl, hydroxypropyl, ethyl substituted with a ureido group. In particular, said monomer M1c has the formula R a R b C=C(R c )HORN d in which the R substituents a and R b are H; R c is H or CH3; R d is –OR d 'with R d' selected from the group consisting of H, methyl, ethyl, propyl, n-butyl, isobutyl, t-butyl, hydroxypropyl, hydroxybutyl, 2-pyrrolidone, deltalactam, succinimide, 2-imidazolidinone, 4-imidazolidinone. More specifically, said monomer M1c may be acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-dodecyl acrylate, amyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, diacetone acrylamide, lauryl acrylate, n-octyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, methyl acrylic acid (or methacrylic acid), methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-Butyl methacrylate, isobutyl methacrylate,t-butyl methacrylate, n-dodecyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, n-octyl methacrylate, ureido methacrylate, monomers of formula CH2=CH(CO2CH2CH2CO2H), CH2=CH(CO2CH2CH2-OC(O)-CH2CH2CO2H), CH2=CH(CO2CH2CH2CH2-OC(O)-CH2CH2CO2H), CH2=CH(CO2CH(CH3)CH2-OC(O)-CH2CH2CO2H), CH2=CH(CO2CH2CH2-OC(O)-C6H4CO2H), CH2=CH(CO2CH2CH2CH2CH(CO2H)CH2CH2CO2H); and mixtures thereof. Among these, said monomer M1c with an alkyl group having from 1 to 8 carbon atoms is preferred, and an alkyl group having from 1 to 5 carbon atoms is more preferable. Said fluorinated polymer P1 may comprise one or more monomeric units derived from said monomer M1c as defined herein. In polymer P1, said monomeric units derived from said monomer M1c as defined herein may be present in a molar content of 0.05 to 10%.preferably from 0.1 to 5% by moles. According to another embodiment, said fluorinated polymer P1 comprises monomeric units derived from a monomer M1a being vinylidene fluoride, monomeric units derived from a fluorinated monomer M1b, monomeric units derived from a non-fluorinated monomer M1c of formula R, a R b C=C(R b )HORN d; said monomers M1b and M1c being as defined above. For example, said fluorinated polymer P1 comprises monomeric units derived from a monomer M1a being vinylidene fluoride, monomeric units derived from a fluorinated monomer M1b being hexafluoropropene and monomeric units derived from a non-fluorinated monomer M1c selected from the group consisting of acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, hydroxypropyl methacrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, methyl acrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, the monomers of formula CH2=CH(CO2CH2CH2CO2H), CH2=CH(CO2CH2CH2-OC(O)-CH2CH2CO2H), CH2=CH(CO2CH2CH2CH2-OC(O)-CH2CH2CO2H), CH2=CH(CO2CH(CH3)CH2-OC(O)-CH2CH2CO2H),CH2=CH(CO2CH2CH2-OC(O)-C6H4CO2H), CH2=CH(CO2CH2CH2CH2CH(CO2H)CH2CH2CO2H); and mixtures of these.In said fluorinated polymer P1, the mass percentage of monomeric units M1a is at least 50%, preferably at least 60%, more preferably greater than 70%, and advantageously greater than 80%. Preferably, when the fluorinated monomer M1a is vinylidene fluoride, the mass percentage of vinylidene fluoride monomeric units in said fluorinated polymer P1 is at least 50%, preferably at least 60%, more preferably greater than 70%, and advantageously greater than 80%. According to a particular embodiment, the fluorinated polymer P1 may be functionalized, in whole or in part, thereby improving its adhesion to metal.Thus, said fluorinated polymer P1 may comprise monomeric units bearing at least one of the following functional groups selected from the group consisting of carboxylic acids, carboxylic acid anhydrides, carboxylic acid esters, epoxy groups such as glycidyl, amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenolic, ester, ether, siloxane, sulfonic, sulfuric, phosphoric, and phosphonic; preferably at least one carboxylic acid or hydroxyl function. The function is introduced by a chemical reaction which may be grafting, or copolymerization of the fluorinated monomer with a monomer (for example, monomer M1c) bearing 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.In one embodiment, the functional group bears a carboxylic acid group, which is a (meth)acrylic acid type group selected from acrylic acid, methacrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyethylhexyl (meth)acrylate, and acryloyloxy propylsuccinate. In one embodiment, the units bearing the carboxylic acid group further comprise a heteroatom selected from oxygen, sulfur, nitrogen, and phosphorus. In one embodiment, the functionality is introduced via the transfer agent used in the synthesis process.The transfer agent is a polymer with a molecular mass of 20,000 g / mol or less, bearing functional groups selected from the following: 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, and phosphonic groups. An example of such a transfer agent is acrylic acid oligomers. In a preferred embodiment, the transfer agent is an acrylic acid oligomer with a molecular mass of 20,000 g / mol or less. Alternatively, the functional group may be introduced by an oligomeric or polymeric compound comprising said functional group and mixed with the fluorinated polymer P1. The oligomeric or polymeric compound can be impregnated in or mixed with the fluorinated polymer P1 or intimately mixed with it.In this case, the functional group can be derived from a (meth)acrylic acid compound selected from acrylic acid, methacrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyethylhexyl (meth)acrylate, and acryloyloxy propylsuccinate. For example, the functional group can be an oligomer or a polymer comprising monomeric units derived from a monomer selected from the group consisting of acrylic acid, methacrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyethylhexyl (meth)acrylate, and acryloyloxy propylsuccinate.According to one embodiment, the oligomer or polymer has a weight-average molecular weight less than or equal to 100,000 g / mol, advantageously less than 80,000 g / mol, preferably less than 60,000 g / mol, more preferably less than 40,000 g / mol, and in particular less than 20,000 g / mol. The weight-average molecular weight is determined by GPC using a Waters 2695e instrument coupled with a Wyatt NEON refractometer equipped with two PL Gel mixed C columns and a guard column (7.8 mm ID × 30 cm, 5 µm) under the following conditions: Temperature: 35°C; flow rate: 1.0 mL / min; injection volume: 100 µL. Samples are prepared at a concentration of 1 mg / ml in THF. Twelve samples of poly(methylmethacrylate) with a molecular mass ranging from 535 to 2,210,000 g / mol are used as calibration standards. This oligomer or polymer is preferably added during the production process of the fluorinated polymer P1.The functional group content of the PVDF is at least 0.01 mol%, preferably at least 0.1 mol%, and at most 15 mol%, preferably at most 10 mol%. Said fluorinated polymer P1 preferably has a high molecular weight. By high molecular weight, as used herein, is meant a fluorinated polymer P1 having a melt viscosity greater than 100 Pa·s, preferably greater than 500 Pa·s, and more preferably greater than 1000 Pa·s, according to ASTM D-3835 method measured at 232°C and 100 sec⁻¹. Said fluorinated polymer P1 used in the invention can be obtained by known polymerization methods such as emulsion or suspension polymerization. In a preferred embodiment, said fluorinated polymer P1 is prepared by an emulsion polymerization process in the presence of a non-fluorinated surfactant.Thus, said fluorinated polymer P1 may comprise between 10 ppm and 2 wt% of a non-fluorinated surfactant comprising polyethylene glycol or polypropylene glycol units. Preferably, said non-fluorinated surfactant has an HLB value of 1 to 20, in particular an HLB value of 1 to 5 or 10 to 15. In particular, said non-fluorinated surfactant comprises at least one polyethylene glycol segment and at least one polypropylene glycol segment, and has an HLB value of 1 to 5 and a weight-average molecular weight of 5000 to 10000 g·mol⁻¹. Alternatively, said surfactant comprises at least one polyethylene glycol segment and at least one polypropylene glycol segment, and has an HLB value of 10 to 15 and a weight-average molecular weight of 500 to 2500 g·mol⁻¹.The fluorinated polymer P1 may be in the form of a latex, generally having a solids content 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 20 nm, preferably at least 50 nm, and advantageously the weight-average size is in the range of 100 to 400 nm. The polymer particles may form agglomerates with a weight-average size of 1 to 30 micrometers, and preferably 2 to 10 micrometers. The agglomerates may break down into discrete particles during formulation and application to a substrate. In another preferred embodiment, the fluorinated polymer P1 is prepared by a suspension polymerization process. The said fluorinated polymer P1 can be in powder form.This is obtained from latex, which is subjected, for example, to a drying step and optionally to granulation. In some embodiments, the vinylidene fluoride contained in said P1 fluorinated polymer is bio-based. The term "bio-based" means "derived from biomass." This improves the polymer's environmental footprint. Bio-based VDF can be characterized by a renewable carbon content, i.e., carbon of natural origin from a biomaterial or biomass, of at least 1 atomic percent, 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 comes from a biomaterial (or biomass), as described below.According to some embodiments, the bio-carbon content of 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%. Said sodium or potassium salt is selected from the group consisting of NaCF3SO3, NaPF6, NaClO4, NaBF4, NaB(C2O4)2, NaN(SO2F)2, NaN(SO2CF3)2, NaN(SO2C2F3)2, NaN(SO2CF2CF3)2, NaN(SO2F)(SO2CF3), NaN(SO2F)(SO2CF2CF3), NaN(SO2CF3)(SO2CF2CF3), NaAsF6, NaBF2C2O4, NaNO3, NaPF3(CF2CF3)3, NaTDI, KCF3SO3, KPF6, KClO4, KBF4, KB(C2O4)2, KN(SO2F)2, KN(SO2CF3)2, KN(SO2C2F3)2, KN(SO2CF2CF3)2, KN(SO2F)(SO2CF3), KN(SO2F)(SO2CF2CF3), KN(SO2CF3)(SO2CF2CF3), KAsF6, KBF2C2O4, KNO3, KPF3(CF2CF3)3 and KTDI or a mixture of these.Preferably, said sodium or potassium salt is selected from the group consisting of: NaCF3SO3, NaPF6, NaClO4, NaBF4, NaB(C2O4)2, NaN(SO2F)2, NaN(SO2CF3)2, NaN(SO2C2F3)2, NaN(SO2CF2CF3)2, NaAsF6, NaBF2C2O4, NaNO3, NaPF3(CF2CF3)3, NaTDI, KCF3SO3, KPF6, KClO4, KBF4, KB(C2O4)2, KN(SO2F)2, KN(SO2CF3)2, KN(SO2C2F3)2, KN(SO2CF2CF3)2, KAsF6, KBF2C2O4, KNO3, KPF3(CF2CF3)3 and KTDI or a mixture thereof. The conductivity additive may be an organic molecule or a mixture of organic molecules capable of swelling the fluorinated polymer without dissolving it and having a dielectric constant greater than 1. According to one embodiment, component C is selected from linear or cyclic ethers, esters, lactones, cyclic ketones, nitriles, carbonates and ionic liquids.By way of non-limiting examples, examples of ethers include linear or cyclic ethers, such as dimethoxyethane (DME), methyl ethers of oligoethylene glycols with 2 to 5 oxyethylene units (e.g., dimethyl tetraethylene glycol ether), dioxolane, dioxane, dibutyl ether, tetrahydrofuran, and mixtures thereof. Examples of esters include phosphoric acid esters and sulfite esters. Examples include methyl formate, methyl acetate, methyl propionate, ethyl acetate, butyl acetate, and mixtures thereof. Examples of lactones include gamma-butyrolactone. Examples of cyclic ketones include cyclohexanone.Examples of nitriles include acetonitrile, pyruvonitrile, propionitrile, methoxypropionitrile, dimethylaminopropionitrile, butyronitrile, isobutyronitrile, valeronitrile, pivalonitrile, isovaleronitrile, glutaronitrile, methoxyglutaronitrile, 2-methylglutaronitrile, 3-methylglutaronitrile, adiponitrile, malononitrile, and mixtures thereof.Examples of carbonates include cyclic carbonates such as ethylene carbonate (EC) (CAS: 96-49-1), propylene carbonate (PC) (CAS: 108-32-7), butylene carbonate (BC) (CAS: 4437-85-8), dimethyl carbonate (DMC) (CAS: 616-38-6), diethyl carbonate (DEC) (CAS: 105-58-8), methyl ethyl carbonate (EMC) (CAS: 623-53-0), diphenyl carbonate (CAS 102-09-0), methyl phenyl carbonate (CAS: 13509-27-8), dipropyl carbonate (DPC) (CAS: 623-96-1), and methyl propyl carbonate (MPC). (CAS: 1333-41-1), ethyl propyl carbonate (EPC), vinylene carbonate (VC) (CAS: 872-36-6), fluoroethylene carbonate (FEC) (CAS: 114435-02-8), trifluoropropylene carbonate (CAS: 167951-80-6), or mixtures thereof. An ionic liquid is formed by the association of an organic cation and an anion.Examples of organic cations include ammonium, sulfonium, pyridinium, pyrrolidinium, imidazolium, imidazolinium, phosphonium, guanidinium, piperidinium, thiazolium, triazolium, oxazolium, pyrazolium, and mixtures thereof. In one embodiment, this cation may comprise a C1-C30 alkyl group, such as 1-butyl-1-methylpyrrolidinium, 1-ethyl-3-methylimidazolium, N-methyl-N-propylpyrrolidinium, or N-methyl-N-butylpiperidinium.Preferably, the anions associated with them are chosen from: imides, in particular bis(fluorosulfonyl)imide and bis(trifluoromethanesulfonyl)imide; borates; phosphates; phosphinates and phosphonates, in particular alkyl-phosphonates; amides, in particular dicyanamide; aluminates, in particular tetrachloroaluminate; halides (such as bromide, chloride, iodide anions); cyanates; acetates (CH3COO-), in particular trifluoroacetate; sulfonates, in particular methanesulfonate (CH3SO3-), trifluoromethanesulfonate; and sulfates, in particular hydrogen sulfate. According to one embodiment, the anions are chosen from tetrafluoroborate (BF4-), bis(oxalato)borate (BOB-), hexafluorophosphate (PF6-), hexafluoroarsenate (AsF6-), triflate or trifluoromethylsulfonate (CF3SO3-), bis(fluorosulfonyl)imide (FSI-), bis-(trifluoromethanesulfonyl)imide (TFSI-), nitrate (NO3-) and 4,5-dicyano-2-(trifluoromethyl)imidazole (TDI-).Preferably, the anion of the ionic liquid is selected from TDI-, FSI-, TFSI-, PF6-, BF4-, NO3-, and BOB-. In particular, the anion of the ionic liquid is FSI-. Among the ionic liquids, the following may be mentioned: EMIM:FSi, PYR:FSI, EMIM:TFSI, PYR:TFSI, EMIM:BOB, PYR:BOB, EMIM:TDI, PYR:TDI, EMIM:BF4, and PYR:BF4. The mass composition of the cathode coating according to the invention is: - Component A with a mass ratio between 20 and 80%; - Component B with a mass ratio between 1 and 40%; - Component C with a mass ratio between 2 and 50%; preferably the sum of these ratios being 100%. The invention also relates to a method of manufacturing the cathode coating described above from an ink obtained by mixing all the constituents of the coating in a solvent.The inks used for coatings can be prepared using any type of mixer known to those skilled in the art, such as a planetary mixer, centrifugal mixer, orbital mixer, stirrer shaft, or ultrathurax mixer. The various ink components are not added in a specific order. Ink production can be carried out at various temperatures, ranging from ambient temperature to the boiling point of the solvent used. The solvent used is preferably a polar solvent with a Hansen parameter greater than 2.By way of non-limiting example, one can cite in particular acetone, acetyl triethyl citrate (ATEC), γ-butyrolactone (GBL), cyclohexanone (CHO), cyclopentanone (CPO), dibutyl phthalate (DBP), dibutyl sebacate (DBS), diethyl carbonate (DEC), diethyl phthalate (DEP), dihydrolevoglucosenone (Cyrene), dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), 1,4-dioxane, 3-heptanone, hexamethyl phosphoramide (HMPA), 3-hexanone, methyl ethyl ketone (MEK), N-methyl-2-pyrrolidinone (NMP), 3-octanone, the 3−pentanone, propylene carbonate (PC), tetrahydrofuran (THF), tetramethylurea (TMU), triacetin, triethyl citrate (TEC), triethyl phosphate (TEP), trimethyl phosphate (TMP), N,N′ tetrabutylsuccindiamide (TBSA) or a mixture of two or more of the listed solvents.According to one embodiment, the porosity of the coated cathode according to the invention is less than 10%, preferably less than 5%. The porosity of the coated electrode (ER) is obtained according to the following calculation described in the publication by M.CAI, Nature Communications, 10, 2019, 4597:. where V ER represents the actual volume of the coated electrode and is calculated by multiplying the surface area of ​​the coated electrode by the thickness of the coated electrode. V denseER represents the volume occupied by each of the constituents without any porosity and is calculated according to the following formula: is the sum of the volume occupied by each component of the coated electrode. The thickness of this coating can range from 0.1 to 100 µm, preferably from 0.1 to 50 µm, and more preferably from 0.1 to 35 µm. The invention also relates to a cathode for a solid-state sodium-ion or potassium-ion battery, said cathode comprising, preferably consisting of, at least one active material, a binder, and a conductive material, and having a coating layer according to the invention. Said cathode is deposited on a metallic support. Said cathode thus forms a first layer on said metallic support. According to one embodiment, the active material at the positive electrode is chosen from the compounds described below. For a cathode of a sodium-ion battery, said at least one active material may have the formula Na x M yO2; M comprising at least one metal or a mixture of metals; x is between 0 and 1; y is between 0 and 1. Advantageously, M is selected from the group consisting of Ti, V, Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Au, Pt, Ir, Os, W, Ta, Al, Y, Ca, Li, Rb, Cs, Ce, Mo, Ba, Sc, B, and Hf. Preferably, M is selected from the group consisting of Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, and Hf. In particular, M is selected from the group consisting of Ni, Mn, Fe, Co, Cu, Zn, and Mg. Thus, the active material used in a positive electrode of a sodium-ion battery is selected from the group consisting of: Na 0.95 Neither 0.317 Mn 0.317 Mg 0.158 Ti 0.208 O2, Na 0.677 Neither 0.300 Mn 0.600 Mg 0.033 Ti 0.067 O2, Na 0.68 Cu 0.34 Mn 0.66 O2, Na 7 / 9 Cu 2 / 9 Fe 1 / 9 Mn 2 / 3 O2, Na 0.90 Cu 0.22 Fe 0.30 Mn 0.48O2, NaNi 1 / 3 Feb 1 / 3 Mr 1 / 3 O2, Na x MnO2, Na 0.67 Ni 1 / 3 Mr 2 / 3 O2, NaFe 0.5 Co 0.5 O2, Na x Feb 1 / 2 Mr 1 / 2 O2, Na x CrO2, NaNi 0.25 Feb 0.5 Mr 0.25 O2, Na 2 / 3 Mg 0.28 Mr 0.72 O2, Na 0.46 Co 0.5 Mr 0.5 O2, Na 0.67 Ni 0.15 Feb 0.2 Mr 0.65 O2, Na x FeO2, NaFe 0.3 Ni 0.7 O2, NaLi 0.05 (Ni 0.25 Feb 0.25 Mr 0.5 ) 0.95 O2, Na 0.7 Feb 0.4 Mr 0.4 Co 0.2 O2, Na 0.97 Feb 0.5 Mr 0.5 O2, Na 0.7 (Fe 0.5 Mr 0.5 ) 0.8 Co 0.2 O2, Na x CoO2, Na x NiO2, Na 1 / 3 Ni 1 / 3 Mr 2 / 3 O2, Na 0.67 Ni 0.2 Mg 0.1 Mr 0.7 O2, Na 2 / 3 Ni 1 / 3−x Zn x Mr 2 / 3 O2, Na0.7 Mn 0.6 Neither 0.3 Co 0.1 O2, Na 0.7 Mn 0.65 Neither 0.15 Fe 0.2 O2, Na 0.85 Li 0.17 Neither 0.21 Mn 0.64 O2, Na x TiO2, NaNi 0.5 Ti 0.5 O2, Na x VO2, Na x V2O5, Na 1+x V3O8. The active material used in a positive electrode can also have the formula Na 1+a Neither x Mn y Fe z HAS m B n O2 in which -0.35 ≤ a ≤ 0.20, 0.08 <x≤0,5, 0,05≤y≤0,48, 0,03<z<0,4, 0,03<m<0,24, 0,001<n<0,06, x+y+z+m+n=1 ; avec A sélectionné parmi le groupe consistant en Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P et Cu, ou un mélange de ceux-ci ; B sélectionné parmi le groupe consistant en Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P et Cu, ou un mélange de ceux-ci. Ladite au moins une matière active peut être de formule Na x M y(XO z ) a ·nH2O, where M represents a transition metal such as Ti, V, Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Au, Pt, Ir, Os, W, Ta, Al, Y, Mo, Sc; and X is a non-metallic element such as P, S, Si, As, Mo, or W. Examples in the phosphate family, where X=P, include NaFePO4, Na3V2(PO4)3, NaMnPO4, NaCoPO4, NaTi2(PO4)3, Na2FeP2O7, Na2MnP2O7, Na2CoP2O7, Na7V3(P2O7)4, or a combination thereof. Examples in the sulfate family, where X=S, include Na2Fe2(SO4)3, NaFe(SO4)2, or a combination thereof. In the silicate family, where X = Si, examples include Na₂MnSiO₄, Na₂FeSiO₄, or combinations thereof. In the molybdenate family, where X = Mo, examples include Fe₂(MoO₄)₃, Ag₂Mo₂O₇, or combinations thereof. This active ingredient may also have the formula Na₂. x M y (XO z ) a Y b.nH2O, where M represents a transition metal such as Ti, V, Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Au, Pt, Ir, Os, W, Ta, Al, Y, Mo, Sc, and X is a non-metallic element such as P, S, Si, As, Mo, or W, and Y is a halogen such as F, Cl, or Br. Examples of fluorophosphates include Na2FePO4F, Na3V2(PO4)3F3, Na3V2O2(PO4)2F, Na2CoPO4F, Na 1,5 VPO 4,8 F 0,7 or a combination thereof. At least one active ingredient may also have the formula Na x M 1 [M 2 (CN)6] y where M 1 is a transition metal such as Ti, V, Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Au, Pt, Ir, Os, W, Ta, Al, Y, Mo, Sc, and M 2 is also a transition metal such as Ti, V, Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Au, Pt, Ir, Os, W, Ta, Al, Y, Mo, Sc. M 1 may be the same as or different from M 2One example is Na 2- x Fe[Fe(CN)6], Na 2-x Mn[Mn(CN)6], Na 2-x Mn[Fe(CN)6], Na4Fe(CN)6, Na x Fe[Co(CN)6], Na2Zn3[Fe(CN)6]2 or a combination thereof. For a cathode of a potassium-ion battery, said at least one active material has the formula K x M yO2; M comprising at least one metal or a mixture of metals; x is between 0 and 1; y is between 0 and 1. Advantageously, M is selected from the group consisting of Ti, V, Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Au, Pt, Ir, Os, W, Ta, Al, Y, Ca, Li, Rb, Cs, Ce, Mo, Ba, Sc, B, and Hf. Preferably, M is selected from the group consisting of Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, and Hf. In particular, M is selected from the group consisting of Ni, Mn, Fe, Co, Cu, Zn, and Mg. Thus, the active material used in a positive electrode of a potassium-ion battery is selected from the group consisting of: K 0.95 Neither 0.317 Mn 0.317 Mg 0.158 Ti 0.208 O2, K 0.677 Neither 0.300 Mn 0.600 Mg 0.033 Ti 0.067 O2, K 0.68 Cu 0.34 Mn 0.66 O2, K 7 / 9 Cu 2 / 9 Fe 1 / 9 Mn 2 / 3 O2, K 0.90 Cu 0.22 Fe 0.30 Mn 0.48O2, KNi 1 / 3 Feb 1 / 3 Mr 1 / 3 O2, K x MnO2, K 0.67 Ni 1 / 3 Mr 2 / 3 O2, KFe 0.5 Co 0.5 O2, K x Feb 1 / 2 Mr 1 / 2 O2, K x CrO2, KNi 0.25 Feb 0.5 Mr 0.25 O2, K 2 / 3 Mg 0.28 Mr 0.72 O2, K 0.46 Co 0.5 Mr 0.5 O2, K 0.67 Ni 0.15 Feb 0.2 Mr 0.65 O2, K x FeO2, KFe 0.3 Ni 0.7 O2, KLi 0.05 (Ni 0.25 Feb 0.25 Mr 0.5 ) 0.95 O2, K 0.7 Feb 0.4 Mr 0.4 Co 0.2 O2, K 0.97 Feb 0.5 Mr 0.5 O2, K 0.7 (Fe 0.5 Mr 0.5 ) 0.8 Co 0.2 O2, K x CoO2, K x NiO2, K 1 / 3 Ni 1 / 3 Mr 2 / 3 O2, K 0.67 Ni 0.2 Mg 0.1 Mr 0.7 O2, K 2 / 3 Ni 1 / 3−x Zn x Mr 2 / 3 O2, K 0.7 Mr 0.6Neither 0.3 Co 0.1 O2, K 0.7 Mn 0.65 Neither 0.15 Fe 0.2 O2, K 0.85 Li 0.17 Neither 0.21 Mn 0.64 O2, K x TiO2, K x MnO2, KNi 0.5 Ti 0.5 O2, K x VO2, K x V2O5, K 1+x V3O8, K x Co 0,5 Mn 0,5 O2. The active material used in a positive electrode can also have the formula K 1+a Neither x Mn y Fe z HAS m B nO2 in which -0.35 ≤ a ≤ 0.20, 0.08 <x≤0,5, 0,05≤y≤0,48, 0,03<z<0,4, 0,03<m<0,24, 0,001<n<0,06, x+y+z+m+n=1 ; avec A sélectionné parmi le groupe consistant en Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P et Cu, ou un mélange de ceux-ci ; B sélectionné parmi le groupe consistant en Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P et Cu, ou un mélange de ceux-ci. Ladite au moins une matière active peut être de formule K x M y (XO z ) a·nH2O, where M represents a transition metal such as Ti, V, Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Au, Pt, Ir, Os, W, Ta, Al, Y, Mo, Sc, and X is a non-metallic element such as P, S, Si, As, Mo, or W. Examples in the phosphate family, where X=P, include KFePO4, K3V2(PO4)3, KMnPO4, KCoPO4, KTi2(PO4)3, K2FeP2O7, K2MnP2O7, K2CoP2O7, K7V3(P2O7)4, or a combination thereof. Examples in the sulfate family, where X=S, include K2Fe2(SO4)3, KFe(SO4)2, or a combination thereof. In the silicate family, where X = Si, examples include K₂MnSiO₄, K₂FeSiO₄, or combinations thereof. In the molybdenate family, where X = Mo, examples include Fe₂(MoO₄)₃, Ag₂Mo₂O₇, or combinations thereof. This active ingredient may also have the formula K x M y (XO z ) a Y b.nH2O, where M represents a transition metal such as Ti, V, Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Au, Pt, Ir, Os, W, Ta, Al, Y, Mo, Sc, and X is a non-metallic element such as P, S, Si, As, Mo, or W, and Y is a halogen such as F, Cl, or Br. Examples of fluorophosphates include K2FePO4F, K3V2(PO4)3F3, K3V2O2(PO4)2F, K2CoPO4F, K 1,5 VPO 4,8 F 0,7 or a combination thereof. This at least one active ingredient may also have the formula K x M 1 [M 2 (CN)6] y where M 1 is a transition metal such as Ti, V, Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Au, Pt, Ir, Os, W, Ta, Al, Y, Mo, Sc, and M 2 is also a transition metal such as Ti, V, Cr, Mn, Fe, Mg, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Au, Pt, Ir, Os, W, Ta, Al, Y, Mo, Sc. M 1 may be the same as or different from M 2One example is K. 2-x Fe[Fe(CN)6], K 2-x Mn[Mn(CN)6], K 2-x Mn[Fe(CN)6], K4Fe(CN)6, K x Fe[Co(CN)6], K2Zn3[Fe(CN)6]2, K 2-x Ni[Fe(CN)6] yor a combination thereof. The electronically conductive material is preferably selected from carbon blacks, natural or synthetic graphites, carbon fibers, carbon nanotubes, metal fibers and powders, and conductive metal oxides. The binder used to fabricate the cathode is preferably a polymer selected from polyolefins (e.g., polyethylene or polypropylene), fluoropolymers (PVDF) that may contain acidic functional groups, polyacrylic acids (PAAs), polyacrylonitril (PANs), cellulose-type polymers, polyphenylsulfone, polyethersulfone, a phenolic resin, a vinyl ester resin, an epoxy resin, or a liquid crystal polymer. At the cathode, this coating is electrochemically stable up to 5V.Preferably, said cathode forming said first layer comprises less than 3% by weight, advantageously less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.1% by weight, and is in particular free of solid electrolyte based on the total weight of said cathode; said solid electrolyte being preferably present in said coating layer according to the present invention. The invention also relates to a method for manufacturing a positive electrode for a Na-ion or K-ion battery, said method comprising the following operations: - providing a cathode, - depositing a coating layer according to the invention onto said cathode. This coating can be produced by any deposition methods known to those skilled in the art, such as solvent coating, dip-shrink methods, centrifugal coating, spray coating, or calendering.These deposition techniques can be performed at various temperatures ranging from 5°C to 180°C. In one embodiment, the coating can be applied directly to a standard positive electrode with a porosity between 15% and 45%, either before or after calendering. This coating then enables physical separation between the solid electrolyte and the active material, thus allowing the use of solid electrolytes that previously appeared unstable with certain active materials.According to one embodiment, the manufacturing process for a positive electrode of a Na-ion or K-ion battery comprises, prior to the deposition of the coating according to the invention, the following steps: - mixing the active charge, the polymer binder, and the conductive charge using a process that yields an electrode formulation applicable to a metallic substrate; - deposition of said electrode formulation onto the metallic substrate; - consolidation of said electrode by heat treatment (application of a temperature up to 50°C above the polymer's melting point, without mechanical pressure), and / or thermomechanical treatment such as calendering. The metallic substrates of the electrodes are generally made of aluminum for the cathode. The metallic substrates may be surface-treated and have a conductive primer with a thickness of 5 µm or more. The substrates may also be woven or nonwoven carbon fibers.Thus, the positive electrode comprises a metallic support on which is deposited a first layer comprising, preferably, an active material, a binder, and a conductive material, and a second layer deposited on said first layer; said second layer comprising said cathode coating according to the present invention. Another object of the invention is an all-solid Na-ion or K-ion secondary battery comprising a negative electrode, a positive electrode, and an all-solid electrolyte, in which the cathode is as described above. EXAMPLES The following examples illustrate, in a non-limiting manner, the scope of the invention. Preparation of fluorinated polymer solution (P1) 149.92 g of VDF-HFP copolymer with an HFP mass percentage of 23% is dissolved in 857.53 g of acetone using a planetary mixer at 2000 rpm for six 1-minute intervals to achieve complete dissolution.Preparation of Coating Ink I: P1 / NaFSI 80 / 20. Dissolve 0.589 g of NaFSI (NaN(SO2F)2) in 14.524 g of the polymer solution (P1). The solution is stirred using a magnetic stirrer at 21°C for 30 min. Preparation of Coating Ink II: P1 / NaFSI / S160 / 20 / 20. Dissolve 0.882 g of NaFSI in 0.898 g of tetraethylene glycol dimethyl ether (CAS 143-24-8) using a magnetic stirrer for 10 min at 21°C. Then add 17.652 g of a 15% solution of P1 in acetone. Preparation of ink III for coating: P1 / NaFSI / S160 / 20 / 20. Dissolve 0.882 g of NaFSI in 0.449 g of tetraethylene glycol dimethyl ether (Cas 143-24-8) and 0.449 g of 1-Butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide (Cas 1057745-51-3) using a magnetic stirrer for 10 min at 21°C. Then add 17.652 g of a 15% PF solution in acetone.Preparation of ink IV for P1 / NaFSI / S140 / 30 / 30 coating: Dissolve 0.528 g of NaFSI in 0.528 g of tetraethylene glycol dimethyl ether (CAS 143-24-8) using a magnetic stirrer for 10 min at 21°C. Then add 4.675 g of a 15% P1 solution in acetone. Preparation of ink V for P1 / NaFSI / S150 / 15 / 35 coating: Dissolve 0.568 g of NaFSI in 1.232 g of tetraethylene glycol S1 dimethyl ether (CAS 143-24-8) using a magnetic stirrer for 10 min at 21°C. Then 7.04 g of a 25% P1 solution in acetone is added. Coating of a porous NaNi cathode. 0,4 Fe 0,2 Mn 0,4 O2 by ink I: A cathode with the following formulation NaNi 0,4 Fe 0,2 Mn 0,4O2 / HSV1810 / C65 97 / 1.5 / 1.5 is coated with ink B. The electrode before coating has an average porosity of 43% and a density of 2.22 g / cm³. The coating is applied by sizing. After drying at room temperature, the coating has a mass of 18.24 mg / cm², allowing it to completely fill the electrode's porosity. The ionic conductivity of the electrode was measured by impedance spectroscopy at 0.056 mS / cm. Coating of a porous NaNi cathode 0,4 Fe 0,2 Mn 0,4 O2 by the ink V A NaNi cathode 0,4 Fe 0,2 Mn 0,4A 31 µm thick O2 electrode is coated with V ink using a bar coater. The wet thickness deposited is 200 µm. The coating is dried using a heater at 35°C. The coated electrode is then calendered to achieve a total thickness of 51 µm. Power Test: A power test was performed to compare an electrode coated with V ink to a standard electrode. Method: The method consists of charging a battery at a slow rate of C / 10 and discharging it at different rates, thus measuring the capacity that can be delivered by the battery at different discharge rates. System used: Cathode: Coated or uncoated electrode; Electrolyte: 1M NaPF6 in EC / EMC 3 / 7 by volume; Fiberglass separator; Anode: Sodium metal. Table 1 shows the capacity delivered during discharge by the two batteries for two different rates.[Table 1] Technology Capacity at C / 5 Capacity at C Bare electrode 115 mAh / g 95 mAh / g Coated electrode 120 mAh / g 102 mAh / g.

Claims

CLAIMS 1. Cathode coating comprising, preferably consisting of: a. at least one fluorinated polymer P1 (component A), b. at least one sodium or potassium salt (component B), and c. at least one conductivity additive (component C). 2.Coating according to the preceding claim characterized in that said at least one fluorinated polymer P1 comprising repeating units derived from a monomer M1a selected from the group consisting of vinyl fluoride, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, 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-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R. 1 CH2OCF=CF2 in which R 1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product has the formula R 2 OCF=CH2 in which R 2is F(CF2)p and p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof.

3. Coating according to any one of the preceding claims characterized in that said fluorinated polymer P1 comprises repeating units from monomer M1a and repeating units from monomer M1b or repeating units from monomer M1c; said monomer M1a being vinylidene fluoride; said monomer M1b selected from the group consisting of vinyl fluoride; trifluoroethylene (TrFE); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP);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-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R; 1 CH2OCF=CF2 in which R 1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product has the formula R 2 OCF=CH2 in which R 2 is F(CF2)p and p is 1, 2, 3 or 4; perfluorobutyl ethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof; said monomer M1c being selected from the group consisting of formula R 1 R 2 C=C(R 3 )((X 1 ) p HORN 4 ) in which the R substituents 1 , R 2 and R 3 are independently selected from the group consisting of H, CO2H and C1-C5 alkyl; R 4 is selected from the group consisting of –NHC(CH3)2CH2C(O)CH3 or –OR 5 with R 5 selected from the group consisting of H and C1-C 18 alkyl optionally substituted by one or more –OH, -CO2H, -SO3H, -PO3H2, -OC(O)R groups 6 , -C(O)OR 6 or a heterocycle with five or ten members comprising at least one nitrogen atom in its cyclic chain; R 6 being selected from the group consisting of C1-C6alkyl or C6-C 12aryl optionally substituted by one or more –OH, -CO2H, -SO3H, -PO3H2 group(s); p is 0 or 1; X 1 is selected from the group consisting of –[-C(O)OC(R 7 (R 8 )C(R 9 (R 10 )-] w1 - and a C1-C hydrocarbon group 10 alkyl optionally bearing one or more -OH, -CO2H or ester group(s); with w1 being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R 7 , R 8 , R 9 , R 10are independently of each other, independently for each unit w1, selected from the group consisting of H and C1-C5 alkyl.

4. Coating according to any one of the preceding claims characterized in that said at least one polymer P1 comprises monomeric units derived from a monomer M1a being vinylidene fluoride and monomeric units derived from a monomer M1b selected from the group consisting of trifluoroethylene, 1,1-chlorofluoroethylene, chlorotrifluoroethylene, hexafluoropropene and tetrafluoroethylene, or a mixture thereof. 5.Coating according to any one of the preceding claims characterized in that said fluorinated polymer P1 comprises monomeric units bearing at least one of the following functions: 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. 6.Coating according to any one of the preceding claims characterized in that said sodium or potassium salt is selected from the group consisting of NaCF3SO3, NaPF6, NaClO4, NaBF4, NaB(C2O4)2, NaN(SO2F)2, NaN(SO2CF3)2, NaN(SO2C2F3)2, NaN(SO2CF2CF3)2, NaN(SO2F)(SO2CF3), NaN(SO2F)(SO2CF2CF3), NaN(SO2CF3)(SO2CF2CF3), NaAsF6, NaBF2C2O4, NaNO3, NaPF3(CF2CF3)3, NaTDI, KCF3SO3, KPF6, KClO4, KBF4, KB(C2O4)2, KN(SO2F)2, KN(SO2CF3)2, KN(SO2C2F3)2, KN(SO2CF2CF3)2, KN(SO2F)(SO2CF3), KN(SO2F)(SO2CF2CF3), KN(SO2CF3)(SO2CF2CF3), KAsF6, KBF2C2O4, KNO3, KPF3(CF2CF3)3 and KTDI or a mixture thereof.

7. A coating according to any one of the preceding claims, wherein component C is selected from linear or cyclic ethers, esters, lactones, cyclic ketones, nitriles, carbonates, and ionic liquids.

8. A coating according to any one of the preceding claims, having a thickness from 0.1 to 100 µm, preferably from 0.1 to 50 µm, and more preferably from 0.1 to 35 µm.

9. A coating according to any one of the preceding claims, having the following mass composition: - Component A with a ratio from 20 to 80%, - Component B with a ratio from 1 to 40%, - Component C with a ratio from 2 to 50%, preferably the sum of these ratios being 100%.

10. A method for manufacturing the cathode coating according to any one of the preceding claims from an ink obtained by mixing all the constituents of the coating in a solvent. 11.A method according to the preceding claim, wherein said solvent is selected from the group consisting of acetone, acetyl triethyl citrate, γ-butyrolactone, cyclohexanone, cyclopentanone, dibutyl phthalate, dibutyl sebacate, diethyl carbonate, diethyl phthalate, dihydrolevoglucosenone, dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, 3-heptanone, hexamethyl phosphoramide, 3-hexanone, methyl ethyl ketone, N-methyl-2-pyrrolidinone, 3-octanone, 3-pentanone, propylene carbonate, tetrahydrofuran, tetramethylurea, triacetin, triethyl citrate, and triethyl phosphate, trimethyl phosphate, N,N′ tetrabutylsuccindiamide and mixtures thereof. 12.Cathode for a solid sodium-ion or potassium-ion battery, said cathode consisting of at least one active material, a binder and a conductive material, and having a coating layer according to any one of the preceding claims 1 to 9.

13. Cathode according to the preceding claim, wherein said at least one active material is selected from the group consisting of an active material of formula Na. x M y O2 or formula of formula K x M y O2; M comprising at least one metal or mixture of metals; x is between 0 and 1; y is between 0 and 1.

14. Cathode according to any one of the preceding claims 12 or 13, wherein said conductive material is selected from carbon blacks, graphites, natural or synthetic, carbon fibers, carbon nanotubes, metal fibers and powders, and conductive metal oxides.

15. Cathode according to any one of the preceding claims 12 to 14, wherein said binder is a polymer selected from polyolefins, fluoropolymers, fluoropolymers with acid functions, polyacrylic acids, polyacrylonitril, cellulose-type polymers, polyphenylsulfone, polyethersulfone, a phenolic resin, a vinyl ester resin, an epoxy resin, or a liquid crystal polymer.

16. Cathode according to any one of the preceding claims 12 to 15, having a porosity of less than 10%, preferably less than 5%. 17.Method for manufacturing a positive electrode of a Na-ion or K-ion battery, said method comprising the steps of: - providing a cathode, - depositing on said cathode a coating layer according to any one of the preceding claims 1 to 9.

18. All-solid Na-ion or K-ion secondary battery comprising an anode, a cathode according to any one of the preceding claims 12 to 16 and an all-solid electrolyte.

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