SOLID-STATE ANODE COATING FOR NA-ION OR K-ION BATTERIES

Abstract

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 relates to an anode 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 further relates to an anode coated with this coating, to the method for manufacturing such an anode, and to Na-ion or K-ion secondary batteries comprising such an anode.

Description

Title of the invention: Anode coating for all-solid-state Na-ion or K-ion batteries FIELD OF INVENTION

[0001] 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 relates to an anode 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 further relates to an anode coated with this coating, to the method for manufacturing such an anode, and to Na-ion or K-ion secondary batteries comprising such an anode. TECHNICAL BACKGROUND

[0002] 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 economical.

[0003] However, the redox potential of the Na+ / Na couple is -2.71 V relative to the standard hydrogen electrode (SHE) 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 oxide-type cathode materials 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 conventionally used in the solvent-based cathode manufacturing process for lithium batteries. For example, a sodium-ion battery comprising a cathode prepared from a cathode material, PVDF, and carbon black is known from US2024079577.

[0004] Secondary sodium batteries generally use liquid electrolytes containing an organic substance. These liquid electrolytes advantageously have high ionic conductivity, but require safety devices additional precautions due to the risk of liquid leakage, fire or explosion at high temperature.

[0005] In an attempt to solve the safety problems associated with liquid electrolytes, recently, all-solid batteries using solid electrolytes have been developed.

[0006] An all-solid-state battery generally comprises a positive electrode, a solid electrolyte, and a negative electrode. The positive electrode comprises a positive electrode active material and a solid electrolyte, and further comprises an electronically conductive material and a binder. Like the positive electrode, the negative electrode comprises a negative electrode active material and a solid electrolyte, and further comprises a conductive material and a binder.

[0007] However, there is currently no solid electrolyte that meets the specifications for widespread use of all-solid-state batteries. Indeed, for solid electrolytes, it is generally difficult to combine ionic conductivity, electrochemical stability, mechanical strength, and compatibility with anode or cathode materials.

[0008] There remains a need to develop a solution that makes an anode compatible with a solid electrolyte in an all-solid Na-ion or K-ion battery. In particular, there is a need to address the problem of anode volume variations during charge and discharge cycles. Finally, in the specific case of a sodium metal or potassium metal anode, there is a need to provide an anode protected by an effective means against dendrite formation.

[0009] The invention therefore aims to provide a coating that can be applied directly to a negative electrode of a Na-ion or K-ion battery, thereby enabling physical separation between the solid electrolyte and the active electrode material. Thus, the present invention provides a negative electrode comprising a first layer consisting of a conventional negative electrode and a second layer consisting of an anode coating according to the present invention.

[0010] The invention also aims to provide a method for manufacturing said anode coating. Finally, the invention relates to an anode having such a coating, and to the method for manufacturing such an anode.

[0011] Finally, the invention aims to provide rechargeable Na-ion or K-ion secondary batteries comprising such an anode. Summary of the invention

[0012] The technical solution proposed by the present invention is to provide an anode coating which makes it compatible with a solid electrolyte in an all-solid battery.

[0013] The invention relates primarily to an anode coating comprising, preferably consisting of: a. at least one PI fluorinated polymer (component A), b. at least one sodium or potassium salt (component B), and c. at least one conductivity additive (component C).

[0014] The invention also relates to a method of manufacturing an anode coating from an ink obtained by mixing all the constituents of the coating.

[0015] According to a preferred embodiment, said at least one PI fluorinated polymer comprising repeating units from a monomer Mla 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 R1CH2OCF=CF2 in which R1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product of formula R2OCF=CH2 in which R2 is 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-l-propene or a mixture thereof. ;

[0016] According to one embodiment, said PI fluorinated polymer comprises repeating units from monomer Mla and repeating units from monomer Mlb or repeating units from monomer Mlc; said monomer Mla being vinylidene fluoride; said monomer Mlb 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 R1CH2OCF=CF2 in which R1; is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product of formula R2 OCF=CH2 in which R2 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-l-propene or a mixture thereof; said monomer Mlc being selected from the group consisting of formula R1R2C=C(R3)((X1)PC(O)R4) in which the substituents R1, R2 and R3 are independently selected from the group consisting of H, CO2H and Ci-C5 alkyl;R4 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 or -OR5 with R5 selected from the group consisting of H and Ci-Ci8 alkyl optionally substituted by one or more -OH, -CO2H, -SO3H, -PO3H, -OC(O)R6, -C(O)O-R6 or a five- or ten-membered heterocycle comprising at least one nitrogen atom in its cyclic chain; R6 being selected from the group consisting of Ci-C6 alkyl or C6-Ci2 aryl optionally substituted by one or more -OH, -CO2H, -SO3H, -PO3H groups; p is 0 or 1; X1 is selected from the group consisting of -[-C(O)OC(R7)(R8)C(R9)(R10)-]wi- and an alkyl hydrocarbon group Ci-Cio optionally bearing one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5;R7, R8, R9, R10 are independently of each other, independently for each wl unit, selected from the group consisting of H and Ci-C5 alkyl. ;

[0017] According to a preferred embodiment, said at least one PI polymer comprises monomeric units derived from a monomer Mla being vinylidene fluoride and monomeric units derived from a monomer Mlb selected from the group consisting of trifluoroethylene, 1,1-chlorofluoroethylene, chlorotrifluoroethylene, hexafluoropropene and tetrafluoroethylene, or a mixture thereof.

[0018] According to a preferred embodiment, said at least one PI polymer 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.

[0019] According to a preferred embodiment, said sodium or potassium salt is selected from the group consisting of NaCF3SO3, NaPF6, NaC104, 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, KC104, KBF4, KB(C2O4)2, KN(SO2 F)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.

[0020] According to a preferred embodiment, component C is selected from linear or cyclic ethers, esters, lactones, cyclic ketones, nitriles, carbonates and ionic liquids.

[0021] According to a preferred embodiment, said coating has a thickness ranging from 0.1 to 100 pm, preferably from 0.1 to 50 pm and more preferably from 0.1 to 35 pm.

[0022] According to a preferred embodiment, said coating has a mass composition having the following mass composition:

[0023] - Component A with a ratio between 20 and 80%,

[0024] - Component B with a ratio between 1 and 40%,

[0025] - Component C with a ratio between 2 and 50%,

[0026] preferably the sum of these ratios being 100%.

[0027] The present invention also provides a method for manufacturing the anode coating according to the present invention from an ink obtained by mixing all the constituents of the coating in a solvent.

[0028] 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 their mixtures.

[0029] The invention also relates to an anode for an all-solid sodium-ion or potassium-ion battery, said anode consisting of at least one active material covered with a coating layer according to the present invention.

[0030] According to a preferred embodiment, said at least one active material is selected from the group consisting of graphite, soft carbon, hard carbon, sodium metal, potassium metal, sodium alloy, potassium alloy, Na2Ti3O7, Na4 Ti50i2, NaTi2(PO4)3, FeSe2, SnO2, FES, Sn, Sn3P4, phosphorus, Fe2O3, MoS2, SnS2, NiS2, Sb, K2Ti3O7, K2Ti40ç, K4Ti3C)|2, K2Ti8O[7, KTi2(PO4)3.

[0031] According to a preferred embodiment, said anode has a porosity of less than 10%, preferably less than 5%.

[0032] The invention also relates to a method for manufacturing a negative electrode for a Na-ion or K-ion battery, said method comprising the following operations:

[0033] - provide an anode,

[0034] - deposit a coating layer on said anode.

[0035] Another object of the invention is a secondary Na-ion or K-ion battery comprising an anode, a cathode and an all-solid electrolyte, wherein the anode is as described above.

[0036] The present invention overcomes the drawbacks of the prior art. It provides an ionically conductive coating with a homogeneous distribution of its dielectric constant while maintaining sufficient mechanical strength to prevent dendrite formation. This coating demonstrates good stability under reduction conditions and good flexibility, thus enabling it to withstand the volume variations of the anode during charge and discharge cycles.

[0037] In the specific case of a sodium or potassium anode, the coating according to the invention prevents the growth of dendrites that can cause short circuits, and the good homogeneity of the dielectric constant prevents the formation of areas with a high concentration of sodium or potassium ions. This coating also forms a stable and low-resistance solid-electrolyte interface (SEI) on the sodium or potassium metal, thus improving the performance and lifespan of all-solid-state batteries.

[0038] DESCRIPTION OF WAYS TO EMBODI THE INVENTION

[0039] The invention is now described in more detail and in a non-limiting manner in the following description.

[0040] According to a first aspect, the invention relates to an anode coating comprising, preferably consisting of: a. at least one PI fluorinated polymer (component A), b. at least one sodium or potassium salt (component B), and c. at least one conductivity additive (component C).

[0041] According to various embodiments, said coating comprises the following characteristics, possibly combined. The contents indicated are expressed by weight, unless otherwise stated. Component A

[0042] Said fluorinated polymer PI comprises in its chain at least monomeric units derived from a fluorinated monomer Mla 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 PI is semi-crystalline.

[0043] Preferably, said fluorinated polymer PI comprises monomeric units derived from a monomer Mla selected from the group consisting of vinyl fluoride; vinylidene fluoride (VDF); 1,2-difluoroethylene; hexafluoropropylene (HFP); trifluoroethylene, 1,1-chlorofluoroethylene, 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 R1CH2OCF=CF2 in which R1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product of formula R2OCF=CH2 in which R2 is 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-l-propene or a mixture thereof. Among the trifluoropropenes, 3,3,3-trifluoropropene may be mentioned. Examples of tetrafluoropropenes include 2,3,3,3-tetrafluoropropene and 1,3,3,3-tetrafluoropropene. Examples of pentafluoropropenes 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.

[0044] In particular, said PI fluorinated polymer comprises at least monomeric units derived from a monomer Mla, namely vinylidene fluoride. The PI fluorinated polymer may be a homopolymer or a copolymer of vinylidene fluoride.

[0045] According to a particular embodiment, the PI fluorinated polymer is a vinylidene fluoride homopolymer.

[0046] According to another particular embodiment, the fluorinated polymer PI is a polymer comprising monomeric units derived from a monomer Mla being vinylidene fluoride and monomeric units derived from a fluorinated monomer Mlb copolymerizable with vinylidene fluoride, or monomeric units derived from a non-fluorinated monomer Mlc or a mixture of the two. In said fluorinated polymer PI, the mass percentage of the monomeric units Mla is at least 50%, preferably at least 60%, more preferably greater than 70% and advantageously greater than 80%. Preferably, in which the fluorinated monomer Mla is vinylidene fluoride vinylidene, the mass percentage in monomeric units of vinylidene fluoride in said fluorinated polymer PI is at least 50%, preferably at least 60%, more preferably greater than 70% and advantageously greater than 80%.

[0047] According to one embodiment, said fluorinated polymer PI comprises monomeric units derived from a monomer Mla being vinylidene fluoride and monomeric units derived from a fluorinated monomer Mlb selected from the group consisting of vinyl fluoride; 1,2-difluoroethylene; hexafluoropropylene (HFP); trifluoroethylene, chlorotrifluoroethylene, and 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(CF 3)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 R1CH2OCF=CF2 in which R1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4;the product of formula R2OCF=CH2 in which R2 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. Preferably, the fluoropolymer PI comprises monomeric units derived from a monomer M1 being vinylidene fluoride and monomeric units derived from a fluorinated monomer M1 selected from the group consisting of vinyl fluoride; 1,2-difluoroethylene, hexafluoropropylene; perfluoro(alkyl vinyl)ethers such as perfluoro(methyl vinyl)ether, perfluoro(ethyl vinyl)ether or perfluoro(propyl vinyl)ether; perfluoro(l,3-dioxole); perfluoro(2,2-dimethyl-l,3-dioxole); 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'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-l-propene or a mixture thereof. In particular, the fluorinated polymer PI comprises monomeric units derived from a monomer Mla being vinylidene fluoride and monomeric units derived from a fluorinated monomer Mlb selected from the group; consisting of 1,2-difluoroethylene and hexafluoropropylene, or a mixture thereof. This PI polymer may, in particular, be a copolymer of vinylidene fluoride and hexafluoropropylene. Preferably, the monomeric units derived from a fluorinated monomer Mlb may be present in a mass content of 1 to 40% based on the total weight of the PI polymer, advantageously from 3 to 35%, preferably from 3 to 30%, and more preferably from 3 to 25%.

[0048] Said PI polymer may also comprise monomeric units derived from a monomer Mla selected from the group consisting of vinylidene fluoride (VDF); trifluoroethylene (TrFE); chlorotrifluoroethylene (CTFE), chlorofluoroethylene (CFE), 1,2-difluoroethylene, and tetrafluoroethylene (TFE). Preferably, said fluorinated PI polymer comprises monomeric units derived from a monomer Mla being vinylidene fluoride and monomeric units derived from a fluorinated monomer Mlb selected from the group consisting of trifluoroethylene, 1,1-chlorofluoroethylene, chlorotrifluoroethylene, hexafluoropropene, and tetrafluoroethylene, or a mixture thereof.Said at least one PI polymer 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.The said PI polymer 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, 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 the PI polymer, 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%, in particular 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 the PI polymer, the molar content of trifluoroethylene may be... of 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 the PI polymer, 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 can 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 the PI polymer, 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%.

[0049] In the PI polymer, 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 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 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-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%.

[0050] Said fluorinated polymer PI may also comprise monomeric units derived from a monomer Mla being vinylidene fluoride and monomeric units derived from a non-fluorinated monomer Mlc of formula RaRbC=C(Rc)C(O)Rd in which the substituents Ra, Rb and Rc are independently selected from the group consisting of H and Ci-C5 alkyl; Rd is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 or -ORd' with Rd' selected from the group consisting of H and Ci-Ci8 alkyl optionally substituted by one or more -OH, -CO2H, -SO3H, -PO3H, -OC(O)Rd”, -C(O)O-Rd” group(s) 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 Ci-C6 alkyl or C6-Ci2 aryl optionally substituted by one or more -OH, -CO2H, -SO3H, -PO3H groups. Said heterocycle may be saturated or unsaturated or aromatic.The heterocycle may be monocyclic or bicyclic. It 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. The heterocycle may be substituted by one or more Ci-C5 alkyl groups. As mentioned above, the CrCi8 alkyl group is optionally substituted by the heterocycle. The heterocycle 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, 4-imidazolidinone.Said monomer Mlc may be of formula RaRbC=C(Rc)C(O)Rd in which the substituents Ra, Rb and Rc are independently selected from the group consisting of H and C1-C5 alkyl; Rd is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 or -ORd' with Rd' selected from the group consisting of H and CrCi8 alkyl optionally substituted by one or more -OH, -CO2H, -SO3H, -PO3H, -OC(O)Rd”, -C(O)O-Rd” group(s) 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 Ci-C6 alkyl or C6-Ci2 aryl optionally substituted with one or more -OH, -CO2H, -SO3H, or -PO3H groups. Preferably, the heterocycle is as defined above; in particular, the heterocycle is 2-pyrrolidone, deltalactam, succinimide, 2-imidazolidinone, or 4-imidazolidinone. Preferably, the substituent Rd' 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, or ethyl substituted with a ureido group. In particular, said monomer Mlc has the formula RaRbC=C(Rc)C(O)Rd in which the substituents Ra and Rb are H; Rc is H or CH3; Rd is -ORd' with Rd' 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 Mlc 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, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylate n-Butyl, 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 the 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 Mlc 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. The fluorinated polymer PI may comprise one or more monomeric units derived from the monomer Mlc as defined herein. In the polymer PI, the monomeric units derived from the monomer Mlc as defined herein may be present in a molar content of 0.05 to 10%, preferably 0.1 to 5% by mole.

[0051] According to another embodiment, said fluorinated polymer PI comprises monomeric units derived from a monomer Mla, being vinylidene fluoride, units monomeric units derived from a fluorinated monomer Mlb, monomeric units derived from a non-fluorinated monomer Mlc of formula RaRbC=C(Rb)C(O)Rd; said monomers Mlb and Mlc being as defined above.For example, said fluorinated polymer PI comprises monomeric units derived from a monomer Mla being vinylidene fluoride, monomeric units derived from a fluorinated monomer Mlb being hexafluoropropene, and monomeric units derived from a non-fluorinated monomer Mlc 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(CO2CH(CH3)CH2-OC(O)-CH2CH2CO2H),CH2=CH(CO2CH2CH2-OC(O)-C6 H4CO2H), CH2=CH(CO2CH2CH2CH2CH(CO2H)CH2CH2CO2H); and mixtures thereof.

[0052] In said fluorinated polymer PI, the mass percentage of monomeric units Mla is at least 50%, preferably at least 60%, more preferably greater than 70% and advantageously greater than 80%. Preferably, when the fluorinated monomer Mla is vinylidene fluoride, the mass percentage of vinylidene fluoride monomeric units in said fluorinated polymer PI is at least 50%, preferably at least 60%, more preferably greater than 70% and advantageously greater than 80%.

[0053] According to a particular embodiment, the fluorinated PI polymer can be functionalized in whole or in part, which allows it to improve adhesion to metal. Thus, said fluorinated PI polymer can comprise monomeric units bearing at least one of the functions selected from the group consisting of 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, phosphonic; preferably at least one carboxylic acid or hydroxyl function.

[0054] The function is introduced by a chemical reaction which may be grafting, or a copolymerization of the fluorinated monomer with a monomer (for example the monomer Mlc 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.

[0055] According to one embodiment, the functional group bears a carboxylic acid function which is a (meth)acrylic acid type group chosen from acrylic acid, methacrylic acid, methyl (meth)acrylate, (meth)ethyl acrylate, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, hydroxybutyl(meth)acrylate, hydroxyethylhexyl(meth)acrylate and acryloyloxy propylsuccinate.

[0056] According to one embodiment, the units bearing the carboxylic acid function further comprise a heteroatom selected from oxygen, sulfur, nitrogen and phosphorus.

[0057] 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 less than or equal to 20,000 g / mol and 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 less than or equal to 20,000 g / mol. Alternatively, the functional group may be introduced by an oligomeric or polymeric compound comprising said functional group and mixed with the fluorinated polymer PI.The oligomeric or polymeric compound may be impregnated in, mixed with, or intimately blended with the fluoropolymer PI. In this case, the functional group may 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 may 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, said 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 x 30 cm, 5 µm) under the following conditions: Temperature: 35°C; flow rate: 1.0 mL / min; injection volume: 100 pL. The samples are prepared at a concentration of of 1 mg / ml in THF. Twelve samples of poly(methylmethacrylate) having a molecular weight of 535 to 2,210,000 g / mol are used as calibration standards. Said oligomer or polymer is preferably added during the production process of the fluorinated polymer PI. The functional group content of PVDF is at least 0.01 mol%, preferably at least 0.1 mol%, and at most 15 mol%, preferably at most 10 mol%.

[0058] Said PI fluorinated polymer preferably has a high molecular weight. By high molecular weight, as used here, is meant a PI fluorinated polymer having a melt viscosity greater than 100 Pa.s, preferably greater than 500 Pa.s, more preferably greater than 1000 Pa.s, according to the ASTM D-3835 method measured at 232°C and 100 sec-1.

[0059] The fluorinated PI polymer used in the invention can be obtained by known polymerization methods such as emulsion or suspension polymerization. In a preferred embodiment, the fluorinated PI polymer is prepared by an emulsion polymerization process in the presence of a non-fluorinated surfactant. Thus, the fluorinated PI polymer may comprise between 10 ppm and 2 wt% of a non-fluorinated surfactant comprising polyethylene glycol or polypropylene glycol units. Preferably, the 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, the 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 segment of polyethylene glycol and at least one segment of polypropylene glycol, and has an HLB value of 10 to 15 and a weight-average molecular weight of 500 to 2500 g·mol⁻¹. Said fluoropolymer PI 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 average size is in the range of 100 to 400 nm. Polymer particles can form agglomerates with an average size by weight of 1 to 30 micrometers, and preferably 2 to 10 micrometers.Agglomerates can break down into discrete particles during formulation and application to a substrate.

[0060] According to a preferred embodiment, said fluorinated PI polymer is prepared by a suspension polymerization process. Said fluorinated PI polymer may be in powder form. This powder is obtained from latex which is subjected, for example, to a drying step and optionally to granulation.

[0061] According to certain embodiments, the vinylidene fluoride contained in said PI 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 certain 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%. Component B 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, KC1O4, KBF4, KB(C2O4)2, KN(SO2F)2, KN(SO2CF3)2, KN(SO2C2F3)2, KN(SO2CF2CF3)2, KN(SO2F)(SO2CF3), KN(SO2F)(SO2CF2CF3), KN(SO2CF3)(SO2CF2 CF3), KAsF6, KBF2C2O4, KNO3, KPF3(CF2CF3)3 and KTDI or a mixture thereof.

[0063] Preferably, said sodium or potassium salt is selected from the group consisting of: NaCF3SO3, NaPF6, NaC104, 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, KC1O4, KBF4, KB(C2O4)2, KN(SO2F)2, KN(SO2CF3)2, KN(SO2C2F3)2, KN(SO2CF2CF3)2, KAsF6, KBF2C2O4, KNO3, KPF3(CF2 CF3)3 and KTDI or a mixture of these. Component C

[0064] 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 chosen from linear or cyclic ethers, esters, lactones, cyclic ketones, nitriles, carbonates and ionic liquids.

[0065] By way of non-limiting examples, among ethers, one may cite linear or cyclic ethers, such as, for example, dimethoxyethane (DME), methyl ethers of oligoethylene glycols of 2 to 5 oxyethylene units (for example, dimethyl ether of tetraethylene glycol), dioxolane, dioxane, dibutyl ether, tetrahydrofuran, and mixtures thereof.

[0066] Examples of esters include phosphoric acid esters and sulfite esters. Examples include methyl formate, methyl acetate, methyl propionate, ethyl acetate, butyl acetate, or mixtures thereof.

[0067] Among the lactones, gamma butyrolactone can be mentioned in particular.

[0068] Among the cyclic ketones, cyclohexanone can be mentioned in particular.

[0069] 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.

[0070] 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), ethyl methyl 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 carbonate. propyl (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.

[0071] 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 associated anions are selected from: imides, in particular bis(fluorosulfonyl)imide and bis(trifluoromethanesulfonyl)imide; borates; and phosphates. phosphinates and phosphonates, in particular alkylphosphonates; amides, in particular dicyanamide; aluminates, in particular tetrachloroaluminate; halides (such as bromide, chloride, iodide anions); cyanates; Acetates (CH3COO), particularly trifluoroacetate; sulfonates, particularly methanesulfonate (CH3SO3), trifluoromethanesulfonate; and sulfates, particularly hydrogen sulfate. In one embodiment, the anions are selected 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, said anion of the ionic liquid is selected from TDI, FSI, TFSI, PF6, BF4, NO3, and BOB. In particular, said anion of the ionic liquid is FSI. Among the ionic liquids, we can notably mention EMIM:FSi, PYR:FSI, EMIM:TFSI, PYR:TFSI, EMIM:BOB, PYR:BOB, EMIM:TDI, PYR:TDI, EMIM:BF4, PYR:BF4.

[0072] The mass composition of the anode 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%,

[0073] Preferably, the sum of these ratios being 100%.

[0074] The invention also relates to a solvent-based method for manufacturing the anode coating described above, from an ink obtained by mixing all the constituents of the coating in a solvent.

[0075] The inks used to make the coatings can be produced by any type of mixer known to those skilled in the art, such as a planetary mixer, centrifugal mixer, orbital mixer, agitator shaft, or ultrathurax. The various constituents of the ink are not added in a specific order. The ink can be manufactured at various temperatures, ranging from ambient temperature up to the boiling point of the solvent used to manufacture the ink.

[0076] The solvent used is preferably a polar solvent with a Hansen parameter greater than 2. By way of non-limiting example, acetone, acetyl triethyl citrate (ATEC), γ-butyrolactone (GBL), cyclohexanone (CHO), cyclopentanone (CPO), dibutyl phthalate (DBP), dibutyl sebacate (DBS), diethyl carbonate (DEC), diethyl phthalate (DEP), dihydrolevoglucosinone (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, 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.

[0077] According to one embodiment, the porosity of the coated anode according to the invention is less than 10%, preferably less than 5%.

[0078] 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:

[0079] _ VER ^denseER P “ y FR

[0080] where VER 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. VdenSeER represents the volume occupied by each of the components without any porosity and is calculated according to the following formula:

[0081] y denser DJ

[0082] VdenSeER is the sum of the volume occupied by each constituent of the coated electrode.

[0083] The thickness of this coating can range from 0.1 to 100 pm, preferably from 0.1 to 50 pm and more preferably from 0.1 to 35 pm.

[0084] The invention also relates to an anode for a solid-state sodium-ion or potassium-ion battery, said anode comprising, preferably consisting of, at least one active material covered with a coating layer according to the invention. Preferably, said active material of the anode is deposited on a metallic support.

[0085] According to one embodiment, said at least one anode active material is selected from the group consisting of graphite, soft carbon, hard carbon, sodium metal, potassium metal, sodium alloy, potassium alloy, Na2Ti3O7, Na4 Ti50i2, NaTi2(PO4)3, FeSe2, SnO2, FES, Sn, Sn3P4, phosphorus, Fe2O3, MoS2, SnS2, NiS2, Sb, K2Ti3O7, K2Ti4O2, K4Ti3C2, K2Ti8O7, KTi2(PO4)3.; preferably graphite, soft carbon, hard carbon, Na2Ti3O7, Na4Ti5O2, NaTi2(PO4)3, FeSe2, SnO2, FES, Sn, Sn3P4, phosphorus, Fe2O3, MoS2, SnS2, NiS2, Sb, K2Ti3O7, KpOg, K4Ti5O12, K2Ti8O[7, KTi2(PO4)3. More particularly, for an electrode used in a sodium-ion battery, said at least one active material is selected from the group consisting of graphite, soft carbon, hard carbon, sodium metal, sodium alloy, Na2Ti3O7, Na4Ti5O2, NaTi2(PO4)3, FeSe2, SnO2, FES, Sn, Sn3P4, phosphorus, Fe2O3, MoS2, SnS2, NiS2, Sb.More specifically, for an electrode used in a potassium-ion battery, said at least one active material is selected from the group consisting of graphite, soft carbon, hard carbon, potassium metal, potassium alloy, FeSe2, SnO2, FES, Sn, Sn3P4, phosphorus, Fe2O3, MoS2, SnS2, NiS2, Sb, K2Ti3O7, K2Ti4O9, K4Ti 5O12, K2Ti8O17, KTi2(PO4)3. .

[0086] 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.

[0087] The binder used to manufacture the anode is a polymer chosen from among polyolefins (for example: polyethylene or polypropylene), fluorinated polymers (PVDF) which may have acid functions, polyacrylic acids (PAA), polyacrylonitril (PAN), cellulose-type polymers, polyphenylsulfone, polyethersulfone, a phenolic resin, a vinyl ester resin, an epoxy resin, PTFE or a liquid-crystal polymer.

[0088] Thus, said anode comprises, preferably consists of, an active material covered with a coating layer according to the present invention comprising, preferably consisting of: a) at least one fluorinated polymer PI (component A), b) at least one sodium or potassium salt (component B) and at least one conductivity additive (component C). Preferably said anode has a porosity as defined in this application.

[0089] The invention also relates to a method for manufacturing a negative electrode for a Na-ion or K-ion battery, said method comprising the following operations:

[0090] - provide an anode,

[0091] - deposit on said anode a coating layer according to the invention.

[0092] Thus, the present invention provides a negative electrode comprising, preferably consisting of, a metallic support on which is deposited an active material covered with a coating layer according to the present invention comprising, preferably consisting of: a) at least one fluorinated polymer PI (component A), b) at least one sodium or potassium salt (component B) and at least one conductivity additive (component C).

[0093] This coating can be applied by any deposition method 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 carried out at various temperatures ranging from 5°C to 180°C.

[0094] The metallic support of the anode is generally made of copper. The metallic supports may be surface-treated and have a conductive primer 5 µm or more thick. The supports may also be woven or non-woven carbon fiber.

[0095] 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, wherein the anode is as described above.

[0096] According to one embodiment, the cathode of said battery is also covered with a coating layer according to the invention.

[0097] EXAMPLES

[0098] The following examples illustrate, in a non-limiting manner, the scope of the invention. Preparation of fluorinated polymer (PI) solution

[0099] 149.92 g of VDF-HFP copolymer with a mass percentage of HFP of 23% is dissolved in 857.53 g of acetone using a planetary mixer at 2000 rpm for six times 1 min to obtain complete dissolution.

[0100] Preparation of ink I for coating: Pl / NaFSI 80 / 20

[0101] 0.589 g of NaFSI (NaN(SO2F)2) is dissolved in 14.524 g of the polymer solution (PI). The solution is stirred using a magnetic stir bar at 21°C for 30 min.

[0102] Preparation of ink II for coating: Pl / NaFSI / Sl 60 / 20 / 20

[0103] 0.882 g of NaFSI is dissolved in 0.898 g of tetraethylene glycol dimethyl ether (Cas 143-24-8) using a magnetic stirrer for 10 min at 21°C. Then 17.652 g of a 15% PI solution in acetone is added.

[0104] Preparation of ink III for coating: Pl / NaFSI / Sl 60 / 20 / 20

[0105] 0.882 g of NaFSI is dissolved 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 143-24-8) using a magnetic stirrer for 10 min at 21°C. Then 17.652 g of a 15% PI solution in acetone is added. Sodium metal coating with ink III#:

[0106] A 350 µm thick sheet of sodium metal is coated with ink III using a coating plate. The wet thickness deposited is 50 µm. After drying at room temperature for 2 hours, the deposited film thickness is measured at 28 µm. The electrode is then calendered to obtain a 5 µm deposit on the sodium metal. The ionic conductivity is measured by impedance spectroscopy. The value obtained is 0.659 mS / cm. Dendrite tests#:

[0107] A dendrite test was performed to compare the coating on the Na metal from ink III with respect to a standard liquid electrolyte.

[0108] Method: The method consists of charging and discharging a symmetrical Na metal / Na metal battery, and the battery potential is then measured. This potential is proportional to the surface area of ​​the electrodes, so the appearance of dendrites results in an increase in potential.

[0109] System used:

[0110] Cathode: Coated or uncoated metal sodium

[0111] Anode: Sodium metal

[0112] The battery is charged using a positive current of 0.25 mA to an energy density of 0.25 mAh. The battery is then discharged using a negative current of 0.25 mA to an energy density of 0.25 mAh.

[0113] In the case of the liquid electrolyte, a porous PE separator is soaked with an electrolyte solution containing IM NaFSI in EC / EMC 3 / 7 by volume.

[0114] Table 1 shows the time required for the initial potential of the battery to double.

[0115] [Tables 1] Technology Time Coating Ink III >230H Liquid Electrolyte 16H

Claims

Demands

1. Anode coating comprising, preferably consisting of: a. at least one PI fluorinated polymer (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 PI fluoropolymer comprising repeating units derived from a monomer Mla 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(l,3-dioxole); perfluoro(2,2-dimethyl-l,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2 X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2 OPO3H; 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 R1CH2OCF=CF2 in which R1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4;the product of formula R2OCF=CH2 in which R2 is 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-l-propene or a mixture thereof.;

3. A coating according to any one of the preceding claims, characterized in that said PI fluoropolymer comprises repeating units derived from monomer Mla and repeating units derived from monomer Mlb or repeating units derived from monomer Mlc; said monomer Mla being vinylidene fluoride; said monomer Mlb selected from the group consisting of vinyl fluoride; trifluoroethylene (VF3); 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

4. 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 R1CH2OCF=CF2 in which R1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product of formula R2OCF=CH2 in which R2 is F(CF2)P and p is 1, 2, 3 or 4; perfluorobutyl ethylene (PFBE); trifluoropropene, tetrafluoropropene, 1' hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof;said monomer Mlc being selected from the group consisting of formula R'R2C=C(R 3)((X')pC(O)R4) in which the substituents R1, R2 and R3 are independently selected from the group consisting of H, CO2H and Ci-C5 alkyl; R4 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 or -OR5 with R5 selected from the group consisting of H and Ci-Ci8 alkyl optionally substituted by one or more -OH, -CO2H, -SO3H, -PO3H, -OC(O)R6, -C(O)O-R6 or a five- or ten-membered heterocycle comprising at least one nitrogen atom in its cyclic chain; R6 being selected from the group consisting of Ci-C6 alkyl or C6-Ci2 aryl optionally substituted by one or more -OH, -CO2H, -SO3H, -PO3H group(s); p is 0 or 1;X1 is selected from the group consisting of -[-C(O)OC(R7)(R8)C(R9)(R10)-]wi- and an alkyl Ci-Cio hydrocarbon group optionally bearing one or more -OH, -CO2H or ester(s) group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R7, R8, R9, R10 are independently of each other, independently for each wl unit, selected from the group consisting of H and CrC5 alkyl. A coating according to any one of the preceding claims, characterized in that said at least one PI polymer comprises monomeric units derived from a monomer Mla, where Mla is fluoride. of vinylidene and monomeric units derived from an Mlb monomer 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 at least one PI polymer 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, NaC1O4, 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, KC1O4, 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, kbf2c 2O4, KNO3, KPF3(CF2CF3)3 and KTDI or a mixture of these.

7. 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. Coating according to any one of the preceding claims, having a thickness from 0.1 to 100 pm, preferably from 0.1 to 50 pm and more preferably from 0.1 to 35 pm.

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

10. Method for manufacturing the anode coating according to any one of the preceding claims from an ink obtained by mixing all the components of the coating in a solvent.

11. A process 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, triethyl phosphate, trimethyl phosphate, N,N' tetrabutylsuccindiamide and their mixtures.

12. Anode for a solid sodium-ion or potassium-ion battery, said anode consisting of at least one active material covered with a coating layer according to any one of claims 1 to 9.

13. Anode according to the preceding claim, wherein said at least one active material is selected from the group consisting of graphite, soft carbon, hard carbon, sodium metal, potassium metal, sodium alloy, potassium alloy, Na2Ti3O7, Na4Ti50i2, NaTi2(PO4)3, FeSe2, SnO2, FES, Sn, Sn3P4, phosphorus, Fe2O3, MoS2, SnS2, NiS2, Sb, K2Ti3O7, K2Ti4O9, K4Ti5O12, K2Ti8O17, KTi2(PO4)3.

14. Anode according to any one of the preceding claims 12 or 13, having a porosity of less than 10%, preferably less than 5%.

15. Method for manufacturing a negative electrode for a Na-ion or K-ion battery, said method comprising the following operations: - providing an anode, - depositing on said anode a coating layer according to any one of claims 1 to 9.

16. All-solid Na-ion or K-ion secondary battery comprising a cathode, an anode according to any one of claims 12 to 14 and an all-solid electrolyte.

17. Battery according to the preceding claim, wherein the cathode is covered with a coating layer according to any one of claims 1 to 9.