Fluoropolymer for secondary batteries

Abstract

The present invention relates to binder composition for use in the preparation of components for electrochemical devices comprising at least one fluoropolymer P1 having a peak to valley ratio greater than or equal to 0.80, said peak to valley ratio being calculated by dividing the maximum peak height Sp by maximum depth Sv obtained through atomic force microscopy measurement.

Description

[0001] Fluoropolymer for secondary batteries

[0002] Technical field

[0003] The present invention relates to a composition for preparing components for use in secondary batteries. In particular, the present invention relates to materials for use in manufacturing all solid-state batteries.

[0004] Background of the invention

[0005] Lithium-ion batteries with liquid electrolytes are currently dominating the market of rechargeable energy storage devices, despite some intrinsic limitations. Among them, severe safety concerns and intrinsic low energy densities for high power applications. Conventional Li-ion battery liquid electrolytes are indeed based on organic carbonates that undergo leakage, generate volatile gaseous species and are flammable. All solid-state batteries (ASSB) promise to be the next generation of energy storage devices as they provide higher energy density, longer cycle life, improved safety and lower costs. In a ASSB the highly flammable liquid electrolyte is replaced by a solid electrolyte, limiting the risk of ignition and / or explosion.

[0006] The use of polymeric binders in solid state batteries is also interesting at cathode side, where active materials, conductive agent and inorganic solid electrolytes (eg. sulfides) are kept together in a continuous matrix thanks to the binder itself.

[0007] The use of specific inorganic materials in composite electrolytes and in electrodes poses limitations in the choice of solvents as well as in that of binders: highly conductive sulfides, in particular, limit the range of available compatible solvents, which should not react with them, not reduce their ionic conductivity and not create by-products that could interfere with battery operation. Binders have to be also compatible with sulfides and soluble or dispersible in available solvents.

[0008] The dissolution of fluoropolymers in non-polar solvents are very slow or not soluble at all. Non-polar solvents are the standard material used in preparation of all solid-state batteries since the solid electrolytes are reactive against polar solvents which makes it not possible to use. Known materials that are easily soluble in non-polar solvents are rubber type like butadiene rubber, but these materials have low electrochemical stability and reduces the capacity of batteries. A fluoropolymer that can be dissolved in non-polar solvents at a fast rate are requested from the industry to be used as binders for all solid-state batteries.

[0009] Summary of the invention

[0010] The applicant surprisingly found specific fluoropolymers having an improved dissolution rate in non-polar solvents.

[0011] In a first aspect, the present invention relates to a binder composition for use in the preparation of components for electrochemical devices comprising at least one fluoropolymer Pl having a peak to valley ratio greater than or equal to 0.80, said peak to valley ratio being calculated by dividing the maximum peak height Sp by maximum depth Sv obtained through atomic force microscopy measurement.

[0012] In an embodiment, said at least one fluoropolymer Pl comprises recurring units derived from a monomer selected from the group consisting of vinylidene fluoride, hexafluoropropene, tetrafluoroethylene, chlorotrifluoroethylene, vinyl fluoride, pentafluoropropene, tetrafluoropropene, trifluoroethylene, 1,2-difluoroethylene and perfluoroalkyle vinyl ethers, perfluoro(l,3-dioxole), perfluoro(2,2-dimethyl-l,3-dioxole) (PDD), a monomer of formula CF2=CFOCF2CF(CF3)OCF2CF2X wherein X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; a monomer of formula CF2=CFOCF2CF2SO2F; a monomer of formula F(CF2)nCH2OCF=CF2 wherein n is 1, 2, 3, 4 or 5; a monomer of formula R1CH2OCF=CF2 wherein R1is hydrogen atom or F(CF2)m and m is 1, 2, 3 or 4; a monomer of formula R2OCF=CH2wherein R2is F(CF2)p et p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); trifluoropropene, hexafluoroisobutylene, perfluorobutylethylene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-l-propene or mixture thereof.

[0013] In a preferred embodiment, said at least one fluoropolymer Pl is a homopolymer of vinylidene fluoride or a polymer comprising recurring units derived from vinylidene fluoride and recurring units derived from at least one fluorinated monomer Ml; said at least one fluorinated monomer Ml being selected from the group consisting of hexafluoropropene, tetrafluoroethylene, chlorotrifluoroethylene, vinyl fluoride, pentafluoropropene, tetrafluoropropene, trifluoroethylene, 1,2-difluoroethylene and perfluoroalkyle vinyl ethers, perfluoro(l,3-dioxole), perfluoro(2,2-dimethyl-l,3-dioxole) (PDD), a monomer of formula CF2=CFOCF2CF(CF3)OCF2CF2X wherein X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; a monomer of formula CF2=CFOCF2CF2SO2F; a monomer of formula F(CF2)nCH2OCF=CF2 wherein n is 1, 2, 3, 4 or 5; a monomer of formula R1CH2OCF=CF2 wherein R1is hydrogen atom or F(CF2)m and m is 1, 2, 3 or 4; a monomer of formula R2OCF=CH2wherein R2is F(CF2)p et p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); trifluoropropene, hexafluoroisobutylene, perfluorobutylethylene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-l-propene or mixture thereof.

[0014] In a preferred embodiment, wherein said at least one fluoropolymer Pl comprises from 15wt% to 65wt% of recurring units derived from said at least one fluorinated monomer Ml based on the total weight of said fluoropolymer Pl.

[0015] In a preferred embodiment, said at least one fluoropolymer Pl comprises recurring units derived from vinylidene fluoride, recurring units derived from the fluorinated monomer Ml as defined in the present application, and recurring units derived from a hydrophilic monomer M2 of formula RaRbC=C(Rc)C(O)Rd(I) wherein Ra, Rband Rcare independently selected from the group consisting of H and C1-C5 alkyl; Rdis selected from the group consisting of -NHC(CH3)2CH2C(O)CH3, or ORd' wherein Rd' is selected from the group consisting of H and Ci-Ci8alkyl optionally substituted by one or more -OH, -CO2H, -SO3H, -PO3H2, -OC(O)Rd", -C(O)O-Rd" or a five- to six-membered heterocycle comprising at least nitrogen atom in the ring ; Rd" being selected from the group consisting of Ci-C6alkyl and C6-Ci2aryl optionally substituted with one or more -OH, -CO2H, -SO3H, -PO3H2functional group(s).

[0016] In a preferred embodiment, said at least one fluoropolymer Pl comprises from 0.05 mol% to 10 mol% of recurring units derived from said hydrophilic monomer M2 based on the total weight of said fluoropolymer Pl.

[0017] In a preferred embodiment, the peak to valley ratio is greater than or equal to 0.82, advantageously greater than or equal to 0.84, preferably greater than or equal to 0.86, more preferably greater than or equal to 0.88, most preferably greater than or equal to 0.90, in particular greater than or equal to 0.92. In a preferred embodiment, said at least one fluoropolymer comprises at least 35wt% of recurring units derived from vinylidene fluoride based on the total weight of said fluoropolymer Pl.

[0018] In another aspect, the present invention provides an electrode-forming composition for use in the preparation of electrodes for electrochemical devices comprising at least one electrode active material, a binder composition according to the present invention, and optionally at least one conductive agent. In another aspect, the present invention provides an electrode for electrochemical devices comprising at least one electrode active material, a binder composition according to the present invention, and optionally at least one conductive agent.

[0019] In another aspect, the present invention provides a secondary battery comprising an electrode according to the present invention.

[0020] In another aspect, the present invention provides a solid electrolyte comprising the binder composition according to the present invention and sulfide-based inorganic particles and optionally a lithium salt. In another aspect, the present invention provides a solid-state battery comprising a solid electrolyte according to the present invention and / or an electrode according to the present invention.

[0021] Detailed description of the invention

[0022] The present invention relates to a binder composition comprising specific fluoropolymers having an improved dissolution rate in non-polar solvents. The applicant found that the morphology of the fluoropolymer influences the dissolution rate. In particular, the applicant found that the peak to valley ratio of the fluoropolymer is a parameter that can be useful to discriminate fluoropolymers having good dissolution rate or not in non-polar solvents.

[0023] In a first aspect of the present invention, a binder composition is provided. The binder composition is useful for the preparation of components for electrochemical devices. The binder composition comprising at least one fluoropolymer Pl having a peak to valley ratio greater than or equal to 0.80. The peak to valley ratio is calculated by dividing the maximum peak height Sp by maximum depth Sv obtained through atomic force microscopy measurement. The detailed method for measuring the peak to valley ratio is provided hereunder in the present application.

[0024] Preferably, the peak to valley ratio is greater than or equal to 0.81, advantageously greater than or equal to 0.82, preferably greater than or equal to 0.83, more preferably greater than or equal to 0.84, most preferably greater than or equal to 0.85, in particular greater than or equal to 0.86. More preferably, the peak to valley ratio is greater than or equal to 0.87, advantageously greater than or equal to 0.88, preferably greater than or equal to 0.89, more preferably greater than or equal to 0.90, most preferably greater than or equal to 0.91, in particular greater than or equal to 0.92. Most preferably, the peak to valley ratio is greater than or equal to 0.93, advantageously greater than or equal to 0.94, preferably greater than or equal to 0.95, more preferably greater than or equal to 0.96, most preferably greater than or equal to 0.97, in particular greater than or equal to 0.98. In particular, the peak to valley ratio is greater than or equal to 0.99, advantageously greater than or equal to 1.00, preferably greater than or equal to 1.01, more preferably greater than or equal to 1.02, most preferably greater than or equal to 1.03, in particular greater than or equal to 1.04.

[0025] Fluoropolymer Pl

[0026] As mentioned above, the fluoropolymer used in the present invention is a vinylic component bearing at least one fluorine atom.

[0027] The fluoropolymer Pl may comprise recurring units derived from a monomer selected from the group consisting of vinylidene fluoride, hexafluoropropene, tetrafluoroethylene, chlorotrifluoroethylene, vinyl fluoride, pentafluoropropene, tetrafluoropropene, trifluoroethylene, 1,2-difluoroethylene and perfluoroalkyle vinyl ethers, perfluoro(l,3-dioxole), perfluoro(2,2-dimethyl-l,3-dioxole) (PDD), a monomer of formula CF2=CFOCF2CF(CF3)OCF2CF2X wherein X isSO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; a monomer of formula CF2=CFOCF2CF2SO2F; a monomer of formula F(CF2)nCH2OCF=CF2 wherein n is 1, 2, 3, 4 or 5; a monomer of formula R1CH2OCF=CF2 wherein R1is hydrogen atom or F(CF2)m and m is 1, 2, 3 or 4; a monomer of formula R2OCF=CH2wherein R2is F(CF2)p et p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); trifluoropropene, hexafluoroisobutylene, perfluorobutylethylene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-l-propene or mixture thereof.

[0028] Preferably, the fluoropolymer Pl may be a homopolymer of vinylidene fluoride or a polymer comprising recurring units derived from vinylidene fluoride and recurring units derived from at least one fluorinated monomer Ml. The comonomers that is compatible and copolymerized with vinylidene fluoride can be halogenated (fluorinated, chlorinated or brominated) or non-halogenated.

[0029] Preferably, said fluorinated monomer Ml may be selected from the group consisting of hexafluoropropene, tetrafluoroethylene, chlorotrifluoroethylene, vinyl fluoride, pentafluoropropene, tetrafluoropropene, trifluoroethylene, 1,2-difluoroethylene and perfluoroalkyle vinyl ethers, perfluoro(l,3-dioxole), perfluoro(2,2-dimethyl-l,3-dioxole) (PDD), a monomer of formula CF2=CFOCF2CF(CF3)OCF2CF2X wherein X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; a monomer of formula CF2=CFOCF2CF2SO2F; a monomer of formula F(CF2)nCH2OCF=CF2wherein n is 1, 2, 3, 4 or 5; a monomer of formula R1CH2OCF=CF2 wherein R1is hydrogen atom or F(CF2)mand m is 1, 2, 3 or 4; a monomer of formula R2OCF=CH2wherein R2is F(CF2)Pet p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); trifluoropropene, hexafluoroisobutylene, perfluorobutylethylene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-l-propene or mixture thereof.

[0030] Examples of trifluoropropenes is in particular 3,3,3-trifluoropropene. Tetrafluoropropenes may be for example 2,3,3,3-tetrafluoropropene or 1,3,3,3-tetrafluoropropene. Pentafluoropropenes may be for example 1,1,3,3,3-pentafluoropropene or 1,2,3,3,3-pentafluoropropene. Perfluoroalkyl vinyl ethers are for example those of general formula Rf-O-CF=CF2, Rf being an alkyl group, preferably a C₁ to C₄ alkyl group (preferred examples being perfluoropropyl vinyl ether and perfluoromethyl vinyl ether). Chlorofluoroethylene can denote either 1-chloro-l-fluoroethylene or l-chloro-2-fluoroethylene. The 1-chloro-l-fluoroethylene isomer is preferred. Chlorotrifluoropropene is preferably l-chloro-3,3,3-trifluoropropene or 2-chloro-3,3,3-trifluoropropene.

[0031] Said fluorinated monomer Ml may be selected from the group consisting of vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl)ether (PMVE), perfluoro(ethylvinyl) ether and perfluoro(propyl vinyl) ether, perfluorobutylethylene, 3,3,3-trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene, chlorotrifluoropropene, ethylene and 2-trifluoromethyl-3,3,3-trifluoro-l-propene or mixtures thereof. Said fluorinated monomer Ml may be selected from the group consisting of vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropene, 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, 1,1,3,3,3-pentafluoropropene, 1,2,3,3,3-pentafluoropropene, perfluoro(propylvinyl ether), perfluoro(methyl vinyl ether), perfluoro(ethylvinyl ether), trifluoroethylene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene, chlorotrifluoropropene, ethylene and mixtures thereof.

[0032] Said fluorinated monomer Ml may be selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, perfluoro(propylvinyl ether), perfluoro(methyl vinyl ether), perfluoro(ethylvinyl ether), trifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene and mixtures thereof.

[0033] Said fluoropolymer Pl may contain at least 35wt% or at least 40wt% or at least 45wt% or at least 50 wt% of vinylidene fluoride, advantageously at least 55wt% of vinylidene fluoride, preferably at least 60wt% of vinylidene fluoride, more preferably at least 65wt% of vinylidene fluoride, in particular at least 70wt% of vinylidene fluoride based on the total weight of the fluoropolymer Pl. Preferably, said fluoropolymer Pl may contain less than 65wt% or less than 60wt% or less than 55wt% or less than 50 wt% of said fluorinated monomer Ml, advantageously less than 45 wt% of said fluorinated monomer Ml, preferably less than 40 wt% of said fluorinated monomer Ml, more preferably less than 35 wt% of said fluorinated monomer Ml based on the total weight of the fluoropolymer Pl. Preferably, said fluoropolymer Pl has a weight content in said fluorinated monomer Ml greater than 1 wt%, preferably greater than 5wt%, more preferably greater than 10wt%, in particular greater than 15 wt%, more particularly greater than 20wt%, most particularly greater than 25 wt% based on the total weight of the fluoropolymer Pl.

[0034] Preferably, said fluoropolymer Pl contains from 35wt% to 80wt% and from 20wt% to 65wt% of said fluorinated monomer Ml based on the total weight of the fluoropolymer Pl or from 50wt% to 75wt% and from 25wt% to 50wt% of said fluorinated monomer Ml based on the total weight of the fluoropolymer Pl or from 60 wt% to 90 wt% of vinylidene fluoride and from 10 wt% to 40wt% of said fluorinated monomer Ml based on the total weight of the fluoropolymer Pl.

[0035] In a more specific embodiment, said polymer Pl comprise vinylidene fluoride recurring units and recurring units derived from hexafluoropropylene. Preferably, said fluoropolymer Pl may contain less than 65wt% or less than 60wt% or less than 55wt% or less than 50 wt% of hexafluoropropylene, advantageously less than 45 wt% of hexafluoropropylene, preferably less than 40 wt% of hexafluoropropylene, more preferably less than 35 wt% of hexafluoropropylene based on the total weight of the fluoropolymer Pl. Preferably, said fluoropolymer Pl has a weight content in hexafluoropropylene greater than 1 wt%, preferably greater than 5wt%, more preferably greater than 10wt%, in particular greater than 15 wt%, more particularly greater than 20wt%, most particularly greater than 25wt% based on the total weight of the fluoropolymer Pl. In a particular embodiment, said fluoropolymer Pl is a copolymer of vinylidene fluoride and hexafluoropropylene, wherein said fluoropolymer Pl contain at least 35wt% or at least 40wt% or at least 45wt% or at least 50 wt% of vinylidene fluoride, advantageously at least 55 wt% of vinylidene fluoride, preferably at least 60 wt% of vinylidene fluoride, more preferably at least 65 wt% of vinylidene fluoride, in particular from 60 to 90 wt% of vinylidene fluoride, more particularly from 60 to 85wt%, most particularly from 65 to 80 wt%; and less than 65wt% or less than 60wt% or less than 55wt% or less than 50 wt% of hexafluoropropylene, advantageously less than 45 wt% of hexafluoropropylene, preferably less than 40 wt% of hexafluoropropylene, more preferably less than 35 wt% of hexafluoropropylene, in particular from 10 to 40 wt% of hexafluoropropylene, more particularly from 15 to 40 wt%, most particularly from 20% to 35wt% or from 25wt% to 50wt% of hexafluoropropylene based on the total weight of the fluoropolymer Pl. In particular, said fluoropolymer Pl contains from 65 to 75 wt% of vinylidene fluoride and from 25 to 35 wt% of hexafluoropropylene or from 50 to 75 wt% of vinylidene fluoride and from 25 to 50 wt% of hexafluoropropylene or from 55 to 70 wt% of vinylidene fluoride and from 30 to 45 wt% of hexafluoropropylene.

[0036] Alternatively, said fluoropolymer Pl is a copolymer of vinylidene fluoride and tetrafluoroethylene. Preferably, said fluoropolymer Pl may contain less than 25 mol% of tetrafluoroethylene, advantageously less than 20 mol% of tetrafluoroethylene, preferably less than 15 mol% of tetrafluoroethylene, more preferably less than 10 mol% of tetrafluoroethylene, in particular less than 5 mol% of tetrafluoroethylene; and greater than 0,5 mol% of tetrafluoroethylene, preferably greater than 1 mol% of tetrafluoroethylene. In another embodiment, said fluoropolymer Pl is a copolymer of vinylidene fluoride and chlorotrifluoroethylene. Preferably, said fluoropolymer Pl may contain less than 25 mol% of chlorotrifluoroethylene, advantageously less than 20 mol% of chlorotrifluoroethylene, preferably less than 15 mol% of chlorotrifluoroethylene, more preferably less than 10 mol% of chlorotrifluoroethylene, in particular less than 5 mol% of chlorotrifluoroethylene; and greater than 0,5 mol% of chlorotrifluoroethylene, preferably greater than 1 mol% of chlorotrifluoroethylene.

[0037] Alternatively, said fluoropolymer Pl may 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 and a terpolymer of vinylidene fluoride, hexafluoropropene and tetrafluoroethylene.

[0038] In the fluoropolymer Pl according to the present invention, the molar content of trifluoroethylene can 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%, especially at least 15 mol%. Preferably, the molar content of trifluoroethylene can be between 15 and 50%, advantageously between 17 and 45 mol%, preferably between 20 and 40 mol%, especially between 20 and 35 mol%, especially between 20 and 30 mol%. In the fluoropolymer Pl according to the present invention, the molar content of chlorotrifluoroethylene can 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 l and 20%, advantageously between 2 and 17 mol%, preferably between 3 and 15 mol%, especially between 4 and 15 mol%, especially between 5 and 12 mol%.

[0039] In the fluoropolymer Pl according to the present invention, the molar content of tetrafluoroethylene can 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%, especially at least 20 mol%. Preferably, the molar content of tetrafluoroethylene can be between 1 and 60%, advantageously between 2 and 55 mol, preferably between 5 and 50 mol%, especially between 7 and 45 mol%, especially between 10 and 40 mol%.

[0040] In the fluoropolymer Pl according to the present invention, the molar content of 1,1-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 1,1-chlorofluoroethylene can be between 1 and 20%, advantageously between 2 and 17 mol%, preferably between 3 and 15 mol%, especially between 4 and 15 mol%, especially between 5 and 12 mol%. In a copolymer of vinylidene fluoride and trifluoroethylene, the molar content of vinylidene fluoride can be between 60 and 99 mol%, advantageously between 65 and 95 mol%, preferably between 65 and 90 mol%, more preferentially between 68 and 85 mol%, in particular between 70 and 82 mol%, more particularly between 73 and 82 mol%; and the molar content of trifluoroethylene can be between 1 and 40 mol%, advantageously between 5 and 35 mol%, preferably between 10 and 35 mol%, more preferably between 15 and 32 mol%, especially between 18 and 30 mol%, more particularly between 18 and 27 mol%. In the most preferred proportions, the copolymer has ferroelectric and ferroelectric relaxer properties.

[0041] In a copolymer of vinylidene fluoride and tetrafluoroethylene, the molar content of vinylidene fluoride can 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 can 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%.

[0042] In a copolymer of vinylidene fluoride and chlorotrifluoroethylene, the molar content of vinylidene fluoride can be between 60 and 99 mol%, advantageously between 65 and 98 mol%, preferably between 65 and 97 mol%, more preferentially between 70 and 96 mol%, in particular between 75 and 95 mol%; and the molar content of trifluoroethylene can be between 1 and 40 mol%, advantageously between 2 and 35 mol%, preferably between 3 and 35 mol%, more preferentially between 4 and 30 mol%, especially between 5 and 25 mol%.

[0043] In a terpolymer of vinylidene fluoride, chlorotrifluoroethylene and tetrafluoroethylene, 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 tetrafluoroethylene can be between 1 and 50 mol%, advantageously between 5 and 50 mol%, preferably between 5 and 40 mol%; and the molar content of chlorotrifluoroethylene can be between 1 and 30 mol%, advantageously between 1 and 15 mol%, preferably between 1 and 12 mol%.

[0044] In a terpolymer of vinylidene fluoride, chlorotrifluoroethylene and trifluoroethylene, 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 can be between 1 and 50 mol%, advantageously between 5 and 50 mol%, preferably between 5 and 40 mol%; and the molar content of chlorotrifluoroethylene can be between 1 and 30 mol%, advantageously between 2 and 15 mol%, preferably between 4 and 12 mol%. In the most preferred proportions, the copolymer has ferroelectric and ferroelectric relaxer properties.

[0045] 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 can be between 1 and 50 mol%, advantageously between 5 and 50 mol%, preferably between 5 and 40 mol%; and the molar content of hexafluoropropene can be between 1 and 30 mol%, advantageously between 1 and 15 mol%, preferably between 1 and 12 mol%.

[0046] In a terpolymer of vinylidene fluoride, tetrafluoroethylene and 1,1-chlorofluoroethylene, 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 tetrafluoroethylene can 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-chlorofluoroethylene can be between 1 and 30 mol%, advantageously between 1 and 15 mol%, preferably between 1 and 12 mol%.

[0047] In a terpolymer of vinylidene fluoride, trifluoroethylene and 1,1-chlorofluoroethylene, 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 can 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-chlorofluoroethylene can be between 1 and 30 mol%, advantageously between 2 and 15 mol%, preferably between 4 and 12 mol%.

[0048] In a terpolymer of vinylidene fluoride, hexafluoropropene and tetrafluoroethylene, 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 tetrafluoroethylene can be between 1 and 50 mol%, advantageously between 5 and 50 mol%, preferably between 5 and 40 mol%; and the molar content of hexafluoropropene can be between 1 and 50 mol%, advantageously between 1 and 15 mol%, preferably between 1 and 12 mol%.

[0049] In a preferred embodiment, the fluoropolymer Pl preferably has melt viscosity of greater than 100 Pa.s, preferably of greater than 500 Pa.s, more preferably of greater than 1000 Pa.s, according to the ASTM D-3835 method, measured at 232°C and 100 sec⁻¹

[0050] Said fluoropolymer Pl may comprise recurring units derived from a hydrophilic monomer M2 of formula RaRbC=C(Rc)C(O)Rdin which the substituents Ra, Rband Rcare independently from each other selected from the group consisting of H and C1-C5 alkyl; Rdis selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 or-ORdwith Rdselected from the group consisting of H and Ci-Ci8alkyl optionally substituted by one or more group(s) -OH, -CO2H, -SO3H, -PO3H2, -OC(O)Rd", -C(O)O-Rdor a five- or ten-linked heterocycle comprising at least one nitrogen atom in its cyclic chain; Rdbeing selected from the group consisting of Ci-C6alkyl or aryl C6-Ci2optionally substituted by one or more group(s) -OH, -CO2H, -SO3H, -PO3H2. Said heterocycle can be saturated or unsaturated or aromatic. The said heterocycle can be monocyclic or bicyclic. Said heterocycle can be a pyrrole, pyrrolidine, pyridine, piperidine, pyrimidine, pyrazine, 1,4-dihydropyridine, indole, oxindole, isatine, quinoline, isoquinoline, quinazoline, imidazoline, pyrazolidine, 2-pyrrolidone, deltalactam, succinimide, 2-imidazolidinone, 4-imidazolidinone. The said heterocycle can be substituted by one or more C1-C5 groups alkyl. As mentioned above, Ci-Ci8alkyl is optionally substituted by the said heterocycle. The latter can 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.

[0051] Said hydrophilic monomer M2 may be of the formula RaRbC=C(Rc)C(O)Rdwherein Ra, Rband Rcare independently from each other selected from the group consisting of H and C1-C5 alkyl; Rdis selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 or -ORdwith Rdselected from the group consisting of H and Ci-Cis alkyl optionally substituted by one or more group(s) -OH, -CO2H, -SO3H, -PO3H2, -OC(O)Rd", -C(O)O-Rdor a five- or ten-linked heterocycle comprising at least one nitrogen atom in its cyclic chain; Rd being selected from the group consisting of Ci-C6alkyl or C6-Ci2aryl optionally substituted by one or more group(s) -OH, -CO2H, -SO3H, -PO3H2. Preferably, the heterocycle is as defined above, especially the heterocycle is 2-pyrrolidone, deltalactam, succinimide, 2-imidazolidinone, 4-imidazolidinone. Preferably, the Rdsubstituent 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 by a ureido group. In particular, said hydrophilic monomer M2 is of formula RaRbC=C(Rc)C(O)Rdwherein Raand Rbare H; Rcis H or CH3; Rdis — ORdwith Rd' selected from the group consisting of H, methyl, ethyl, propyl, n-butyl, isobutyl, t-butyl, hydroxy ethyl, hydroxy propyl, hydroxy butyl, 2-pyrrolidone, deltalactam, succinimide, 2-imidazolidinone, 4-imidazolidinone. More specifically, said hydrophilic monomer M2 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, 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 with the formula CH2=CH(CO2CH2CH2CO2H), CH2=CH(CO2CH2CH2-O-C(O)-CH2CH2CO2H), CH2=CH(CO2CH2CH2CH2-O-C(O)-CH2CH2CO2H), CH2=CH(CO2CH(CH3)CH2-O-C(O)-CH2CH2CO2H), CH2=CH(CO2CH2CH2-O-C(O)-CSH4CO2H), CH2=CH(CO2CH2CH2CH2CH(CO2H)CH2CH2CO2H); and mixtures thereof. Said fluoropolymer Pl may comprise one or more recurring units derived from said hydrophilic monomer M2 as defined herein. In the fluoropolymer Pl, said recurring units derived from said hydrophilic monomer M2 as defined herein may be present in a molar content of 0.05 to 10%, preferably 0.1 to 5% moles.

[0052] According to some embodiments, the fluoropolymer Pl (homopolymer or copolymers) are made of biobased vinylidene fluoride. The term "biobased" means "resulting from biomass". This makes it possible to improve the ecological footprint of the membrane. Biobased vinylidene fluoride can be characterized by a content of renewable carbon, that is to say of carbon of natural origin and originating from a biomaterial or from biomass, of at least 1 atom%, as determined by the content of 14C according to Standard NF EN 16640. The term "renewable carbon" indicates that the carbon is of natural origin and originates from a biomaterial (or from biomass), as indicated below. According to some embodiments, the biocarbon content of the VDF can be greater than 5 atom %, preferably greater than 10 atom %, preferably greater than 25 atom %, preferably greater than or equal to 33 atom %, preferably greater than 50 atom %, preferably greater than or equal to 66 atom %, preferably greater than 75 atom %, preferably greater than 90 atom %, preferably greater than 95 atom %, preferably greater than 98 atom %, preferably greater than 99 atom %, advantageously equal to 100 atom %.

[0053] Process for producing the fluoropolymer The fluoropolymer Pl used in the invention can be obtained by known polymerization methods, such as emulsion or suspension polymerization.

[0054] According to one embodiment, the fluoropolymer Pl is prepared by an emulsion polymerization process in the absence of a fluorinated surfactant. The surfactant may be non-ionic or ionic, preferably non-ionic. Preferably, the copolymer formed is fluorosurfactant-free, meaning that no fluoro-surfactants are used in making or processing the polymer. Preferably, the surfactant is a non-ionic surfactant. Hence, the surfactant is particularly non-ionic and non-fluorinated. Preferably, the surfactant comprises a polyethylene glycol segment and a polypropylene glycol segment. Preferably, said surfactant has a HLB value of 1 to 20, in particular a HLB value from 1 to 5 or from 10 to 15. In particular, the surfactant comprises a polyethylene glycol segment and a polypropylene glycol segment and has a HLB value of 1 to 5 and preferably a weight average molecular weight of from 2500 to 10000 g.mol-1, in particular from 5000 to 10000 g.mol-1(measured by GPC calibrated with polystyrene standard). Alternatively, the surfactant comprises a polyethylene glycol segment and a polypropylene glycol segment, has a HLB value of 10 to 15 and preferably a weight average molecular weight of from 500 to 2500 g.mol1(measured by GPC calibrated with polystyrene standard). In the present application, the HLB value of the surfactant refers to an HLB value calculated by the Griffin's method. The surfactant charge may be from 10 ppm to 2% by weight on the total monomer weight used, preferably from 10 ppm to 1.5 wt%, more preferably from 10 ppm to 1 wt% and most preferably the surfactant charge is from 100 ppm to 0.2% by weight on the total monomer weight used. Normally the surfactant is added during the initial filling of the reactor, but some portion may also be added after the reaction has begun. Surfactant may also be added as the reaction progresses if needed for further stabilization. Examples of emulsion processes are disclosed in W02008073685, WO2022 / 086775 or WO2006135543.

[0055] According to another embodiment, the fluoropolymer Pl is prepared by a suspension polymerization process. The process is carried out in the presence of a suspending agent. The latter may be polyvinyl alcohol (PVA) or a compound with a cellulose motif such as methylcellulose, hydroxypropyl methylcellulose, carboxymethylcellulose.

[0056] The polymerization of the fluoropolymer Pl results in a latex generally having a solids content of from 10% to 60% by weight, preferably from 10% to 50%, and having a volume-average particle size of less than 1 micrometer, preferably less than 1000 nm, preferably of less than 800 nm and more preferably of less than 600 nm. The volume-average size of the particles is generally at least 20 nm, preferably at least 50 nm, and advantageously the average size is within the range from 100 to 400 nm. The polymer particles can form agglomerates, the volume-average size of which is from 1 to 30 micrometers and preferably from 2 to 10 micrometers. Nicomp CW380 Particle Size Analyzer (light scattering) is used to measure the volume average particle size of the latex particles. The agglomerates can break up into discrete particles during the formulation and the application to a substrate.

[0057] Preferably, to obtain the fluoropolymer Pl according to the invention, the latex is dried at high temperature. The operational conditions to dry the fluoropolymer can be tuned to obtain the fluoropolymer according to the present invention, for example by drying at higher temperature (200°C or less) or for a longer time or under reduced pressure.

[0058] Electrode-forming composition & electrode prepared therefrom.

[0059] In another aspect of the present invention an electrode-forming composition is provided. The electrodeforming composition is suitable for use in the preparation of electrodes for electrochemical devices. Preferably, the electrode-forming composition comprises at least one electrode active material, a binder composition according to the present invention, and optionally at least one conductive agent.

[0060] In a preferred embodiment, the electrode-forming composition has the following mass composition: a. 50% to 99.95% electrode active material, preferably 50% to 99%,

[0061] b. 0% to 25% conductive agent, preferably 0.5% to 25%,

[0062] c. 0.05% to 25% of said binder depending on the invention, preferably 0.5% to 25%,

[0063] d. 0% to 25% of at least one additive selected from the group consisting of a plasticizer, an ionic liquid, a dispersing agent for a conductive additive, and a flow aid, preferably 0% to 5%; the sum of all these percentages being 100%.

[0064] The conductive agents in the electrode are composed of one or more materials that can improve conductivity. Some examples include carbon blacks such as acetylene black, Ketjen black; carbon fibers, such as carbon nanotube, carbon nanofiber, vapor phase growth carbon fiber; metal powders such as SUS (steel use stainless) powder, or aluminum powder.

[0065] The electrode active materials in electrode compositions are materials that are capable of storing and releasing lithium ions.

[0066] In particular, for a negative electrode, that electrode active material is selected from the group consisting of a lithium alloy, lithium metal, a metal oxide, a carbon material such as graphite or hard carbon, silicon and its derivatives SiOx, silicone, graphite-silicon composite, a silicon alloy and Li4Ti5O12or a mixture thereof. The shape of the negative electrode active material is not particularly limited but is preferably particulate.

[0067] In particular, for a positive electrode, said electrode active material is selected from the group consisting of LiCoO2, Li(Ni, Co, AI)O2, Li(1+x)NiaMnbCoc(x represents a real number of 0 or more, a = 0.9, 0.8, 0.6, 0.5, or 1 / 3, b = 0.05, 0.1, 0.2, 0.3, or 1 / 3, c = 0.05, 0.1, 0.2, or 1 / 3), LiNiO2, LiMn2O4, LiCoMnO4, Li3NiMn3O8, Li3Fe2(PO4)3, Li3V2(PO4)3, a spinel Li Mn substituted by a different element having a composition represented by Li1+xMn2-x-yMyO4, M representing at least one metal chosen from Al, Mg, Co, Fe, Ni, and Zn, x and y independently representing a real number between 0 and 2, lithium titanate LixTiOy- x and y independently representing a real number between 0 and 2, and a lithium metal phosphate having a composition represented by LiMPO4, with M representing Fe, Mn, Co, or Ni. The shape of the positive electrode active material is not particularly limited but is preferably particulate. In addition, the surface of each of the materials described above can be coated. The coating material is not particularly limited as long as it has lithium-ion conductivity and contains a material that can be held in the form of a coating layer on the surface of the active material. Examples of the coating material include LiNbO3, Li4Ti5O12, and Li3PO4.

[0068] Preferably, the electrode-forming composition may further comprise sulfide-based solid inorganic particles. Said sulfide-based solid inorganic particles may be selected from the group consisting of:

[0069] lithium sulfur tin phosphorous (« Isps ») such as Li10SnP2S12;

[0070] Lithium sulfur phosphorous (« Ips ») of formula (Li2S)x(P2S5)y, wherein x+ y=1 and 0 < x < 1, Li7P3S11, Li7PS6, Li4P2S6, Li9.6P3S12and Li3PS4;

[0071] Doped LPS such as Li2CuPS4, Li1+2xZn1-xPS4, wherein 0 < x < 1, Li3.33Mg0.33P2S6, and Li4-3xScxP2S6, wherein 0 < x < 1;

[0072] Lithium sulfur phosphorous oxygen (" LPSO") of formula LixPySzO, wherein 0,33 < x < 0,67, 0,07 < y < 0,2, 0,4 < z < 0,55, 0 < w < 0,15;

[0073] Lithium sulfur phosphorous (" LXPS") with x Si, Ge, Sn, As, Al, tel que Li10GeP2S12ou Li10SiP2S12

[0074] Lithium sulfur phosphorous oxygen (" LXPSO") with x Si, Ge, Sn, As, Al;

[0075] Lithium sulfur silica (" LSS") such as Li2S-P2S5-SiS2, Li2S-P2S5-SiS2-LiCl, Li2S-SiS2-P2S5, Li2S-SiS2-P2S5-LiI, Li9.54Si1.74P1.44S11.7Cl0.3;

[0076] Li4PS4Cl, Li15P3S16Cl3, Li7P2S8Cl et Li7P2S8I;

[0077] Material of formula Li6PS5Y wherein Y is Cl, Br or I such as Li6-xPS5-xY1+x, wherein 0 < x < 0,5; preferably Li6PS5Cl; And mixture thereof. Preferably, said sulfide-based solid inorganic particles may be material of formula Li6PS5Y wherein Y is Cl, Br or I such as Li6-xPS5-xY1+x, wherein 0 < x < 0,5; preferably Li6PS5Cl.

[0078] Preferably, the electrode-forming composition may further comprise a solvent. The solvent may be used to disperse all the components for the preparation of the electrode made thereof.

[0079] When the composition comprises sulfide-based solid inorganic particles, the solvent may be, for example, without limitation: octyl acetate, pentyl acetate, acetone, methyl isobutyl ketone (MIBK), diisobutyl ketone, cyclopentanone, isobutyl isobutyrate (IBIB), ethyl acetate, propylene glycol monomethyl ether acetate, l,3,2-dioxathiolan-2-oxide, 1,2-dimethoxyethane, l,3,3-trimethyl-2-oxabicyclo[2.2.2]octane, 1,3-dimethyl-2-imidazolidinone,, l,3-dioxolan-2-one, 1,3-dioxolane, 2,2,2-trifluoro-N, N-dimethylacetamide, 2,2,4,4-tetramethyl-3-pentanone, 2,2,4- trimethylpenta n-3-one, 2,2,5,5-tetramethylhexan-3-one, 2, 2,6,6-tetramethyl-4-heptanone, 2,2-dimethylpentan-3-one, 2,3-butanedione, 2,4-dimethyl-3-pentanone, 2,6-dimethyl-4-heptanone, 2-butanone, 2-methylpentan-3-one, 2-methylpropanenitrile, 2-methyltetrahydrofuran, 2-pentanone, 2-phenylacetonitrile, 3,3-dimethyl-2-butanone, 3-methyl-2-butanone, 3-pentanone, 4-methyl-2-oxo- 1,3-dioxolane, 4-methyl-2-pentanone, acetonitrile, acetophenone, benzaldehyde, benzonitrile, benzophenone, bis(2-chloroethyl) ether, butanenitrile, butyl acetate, chloroacetonitrile, cyclohexanone, cyclopentanone, dibenzyl ether, dibutyl ether, diethyl carbonate, diethyl ether, diisopropyl ether, dimethyl carbonate, dimethylcyanamide, dioxane, diphenylphosphinic chloride, dipropyl ether, ethyl 2,2-dimethylpropanoate, ethyl 2-methylpropanoate, ethyl acetate, ethyl benzoate, ethyl butanoate, ethyl chloroacetate, ethyl chloroformate, ethyl formate, ethyl propanoate, formamide, isopropyl 2,2-dimethylpropanoate, isopropyl acetate, isopropyl pivalate, methyl 2,2-dimethylpropanoate, methyl acetate, methyl benzoate, methyl propanoate, methyl propyl ether, N, N-dimethylbenzylamine, N, N-dimethylcarbamoyl chloride, N, N-dimethylformamide, N, N-dimethyltrifluoroacetamide, N, N-dimethylurethane, N-methylpyrrolidone, oxane, oxolan-2-one, phenylphosphonic dichloride, phenylphosphonic difluoride, phosphorus oxychloride, propanenitrile, propyle acetate, sulfolane, tetra hydrofurane, tributyle phosphate, triethyl phosphate, trimethyle phosphate, tripyrrolidinophosphine oxide, l-butyl-3-methylimidazolium tetrafluoroborate, l-butyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)imide, butyl-methylpyrrolidinium bis-(trifluoromethylsulfonyl)imide, butyl-methylpiperidinium bis-(trifluoromethylsulfonyl)imide, ethyl-dimethyl-propylammonium bis-(trifluoromethylsulfonyl)imide, triethylsulfonium bis-(trifluoromethylsulfonyl) imide.

[0080] The electrode can be prepared by a process comprising the following steps:

[0081] A) providing an electrode-forming composition comprising the binder composition according to the present invention; at least one electrode active material and a solvent and optionally, at least one electrically conductive additive;

[0082] B) providing a metallic substrate with at least one surface;

[0083] C) Applying the electrode-forming composition provided in step a) to said at least one surface of the metallic substrate provided in step B), thereby providing an assembly comprising a metal substrate coated with said electrode-forming composition on at least one surface; and

[0084] D) drying of the assembly provided for in step C) to form the electrode.

[0085] Solid electrolyte

[0086] In another aspect of the present invention, a solid electrolyte is provided. The solid electrolyte comprises the binder composition according to the present invention and sulfide-based inorganic particles and optionally a lithium salt.

[0087] The lithium salt may be selected from the group consisting of LiCF3SO3, LiPF6, LiClO4, LiBF4, LiB(C2O4)2, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2C2F3)2, LiN(SO2C2F5)2, LiN(SO2F)(SO2CF3), LiN(SO2F)(SO2C2F5), LiN(SO2CF3)(SO2C2F5), LiAsF6, LiBF2C2O4, LiNO3, LiPF3(CF2CF3)3, LiTDI or mixture thereof. Preferably, the lithium salt may be selected from the group consisting of LiCF3SO3, LiPF6, LiClO4, LiBF4, LiB(C2O4)2, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2C2F3)2, LiN(SO2C2F5)2, LiTDI or mixture thereof. In particular, the lithium salt may be selected from the group consisting of LiCF3SO3, LiPF6, LiClO4, LiBF4, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2C2F3)2, LiTDI or mixture thereof.

[0088] The solid electrolyte may also sulfide-based inorganic particles. The latter may be selected from the group consisting of:

[0089] lithium sulfur tin phosphorous (« Isps ») such as Li10SnP2S12; Lithium sulfur phosphorous (« Ips ») of formula (Li2S)x(P2S5)y, wherein x+ y=1 and 0 < x < 1, Li7P3S11, Li7PS6, Li4P2S6, Li9.6P3S12and Li3PS4

[0090] Doped LPS such as Li2CuPS4, Li1+2xZn1-xPS4, wherein 0 < x < 1, Li3.33Mg0.33P2S6, and Li4-3xScxP2S6, wherein 0 < x < 1;

[0091] Lithium sulfur phosphorous oxygen (" LPSO") of formula LixPySzO, wherein 0,33 < x < 0,67, 0,07 < y < 0,2, 0,4 < z < 0,55, 0 < w < 0,15;

[0092] Lithium sulfur phosphorous (" LXPS") with x Si, Ge, Sn, As, Al, tel que Li10GeP2S12ou Li10SiP2S12

[0093] Lithium sulfur phosphorous oxygen (" LXPSO") with x Si, Ge, Sn, As, Al;

[0094] Lithium sulfur silica (" LSS") such as Li2S-P2S5-SiS2, Li2S-P2S5-SiS2-LiCl, Li2S-SiS2-P2S5, Li2S-SiS2-P2S5-LiI, Li9.54Si1.74P1.44S11.7Cl0.3;

[0095] Li4PS4Cl, Li15P3S16Cl3, Li7P2S8Cl et Li7P2S8I;

[0096] Material of formula Li6PS5Y wherein Y is Cl, Br or I such as Li6-xPS5-xYi+x, wherein 0 < x < 0,5; preferably Li6PS5CI;

[0097] And mixture thereof.

[0098] The solid eletrolyte may be in the form of a film. The film can be prepared following a process comprising the steps of:

[0099] a) dissolving the binder composition in an organic solvent to form a solution,

[0100] b) adding said sulfide-based inorganic particles and optionally a lithium salt to form a composition, c) coating the composition formed in step b) on a support to form a film,

[0101] d) drying the film so obtained.

[0102] The organic solvent may be, without limitation, octyl acetate, pentyl acetate, acetone, methyl isobutyl ketone (MIBK), diisobutyl ketone, cyclopentanone, isobutyl isobutyrate (IBIB), ethyl acetate, propylene glycol monomethyl ether acetate, l,3,2-dioxathiolan-2-oxide, 1,2-dimethoxyethane, l,3,3-trimethyl-2-oxabicyclo[2.2.2]octane, l,3-dimethyl-2-imidazolidinone,, l,3-dioxolan-2-one, 1,3-dioxolane, 2,2,2-trifluoro-N, N-dimethylacetamide, 2,2,4,4-tetramethyl-3-pentanone, 2,2,4- trimethylpentan-3-one, 2,2,5,5-tetramethylhexan-3-one, 2,2,6,6-tetramethyl-4-heptanone, 2,2-dimethylpentan-3-one, 2,3-butanedione, 2,4-dimethyl-3-pentanone, 2,6-dimethyl-4-heptanone, 2-butanone, 2-methylpentan-3-one, 2-methylpropanenitrile, 2- methyltetra hydrofuran, 2-pentanone, 2-phenylacetonitrile, 3,3-dimethyl-2-butanone, 3-methyl-2-butanone, 3-pentanone, 4-methyl-2-oxo- 1,3-dioxolane, 4-methyl-2-pentanone, acetonitrile, acetophenone, benzaldehyde, benzonitrile, benzophenone, bis(2-chloroethyl) ether, butanenitrile, butyl acetate, chloroacetonitrile, cyclohexanone, cyclopentanone, dibenzyl ether, dibutyl ether, diethyl carbonate, diethyl ether, diisopropyl ether, dimethyl carbonate, dimethylcyanamide, dioxane, diphenylphosphinic chloride, dipropyl ether, ethyl 2,2-dimethylpropanoate, ethyl 2-methylpropanoate, ethyl acetate, ethyl benzoate, ethyl butanoate, ethyl chloroacetate, ethyl chloroformate, ethyl formate, ethyl propanoate, formamide, isopropyl 2,2-dimethylpropanoate, isopropyl acetate, isopropyl pivalate, methyl 2,2-dimethylpropanoate, methyl acetate, methyl benzoate, methyl propanoate, methyl propyl ether, N, N-dimethylbenzylamine, N, N-dimethylcarbamoyl chloride, N, N-dimethylformamide, N, N-dimethyltrifluoroacetamide, N, N-dimethylurethane, N-methylpyrrolidone, oxane, oxolan-2-one, phenylphosphonic dichloride, phenylphosphonic difluoride, phosphorus oxychloride, propanenitrile, propyle acetate, sulfolane, tetrahydrofurane, tributyle phosphate, triethyl phosphate, trimethyle phosphate, tripyrrolidinophosphine oxide, l-butyl-3-methylimidazolium tetrafluoroborate, l-butyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)imide, butyl-methylpyrrolidinium bis-(trifluoromethylsulfonyl)imide, butyl-methylpiperidinium bis-(trifluoromethylsulfonyl)imide, ethyl-dimethyl-propylammonium bis-(trifluoromethylsulfonyl)imide, triethylsulfonium bis-(trifluoromethylsulfonyl) imide.

[0103] Preferably, said solution formed in step a) may have a solution viscosity greater than 80 cP, advantageously greater than 90 cP, preferably greater than 95 cP, in particular greater than 100 cP measured at 25°C at a shear rate of 10 sec-1. According to a preferred embodiment, said solution has a viscosity of less than 600 cP, advantageously less than 550 cP, preferably less than 500 cP, in particular less than 450 cP measured at 25°C and a shear rate of 10 sec-1.

[0104] A solution viscosity greater than 80 cP may be preferred to allow good suspension of the sulfide-based inorganic particles.

[0105] Preferably, step a) is performed at a temperature of from 20°C to 80°C, preferably of from 20°C to 70°C. The support can be removed after the drying stage to obtain a self-supporting film. The support may be, for example, mylar, glass, aluminum, or aluminum coated with a polymer layer.

[0106] Alternatively, the support can be a fibrous reinforcement. When the support is a fibrous reinforcement, it is not removed. According to a particular embodiment, the fibrous reinforcement is made of any material (porous membrane, woven or non-woven) that improves the mechanical properties compared to the composition alone. This may include, but is not limited to:

[0107] - a microporous film based on polyolefins, such as polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), Celgard® Li-ion separator,

[0108] - a porous film based on PVDF, polyethersulfone (PES) or polysulfone (PSU),

[0109] - a woven substrate (e.g. PP, PE, PET, PVDF, PES, PSU, inorganic fibers),

[0110] - a non-woven substrate of the melt blown type (e.g. PP, PET, PVDF, PES, PSU), a spunbond substrate (e.g. PP, PET, PVDF, PES, PSU),

[0111] - a cellulosic separator,

[0112] - staples short fibers, or

[0113] - of fibers spun in a molten state.

[0114] - a metal (copper or aluminum)

[0115] According to one embodiment, the fibrous reinforcement is a multilayer material with at least one layer of polyolefin and at least one inorganic layer, e.g. Celgard® PP coated with an alumina layer on both sides. Fibrous reinforcement can be selected from polymers (e.g. polyolefin, PVDF, PTFE, polyamide, polyimide, polyaramid, polybenzoaxoles, polybenzimidazoles, polybenzthiazoles, polyphosphazenes, PEKK, PEEK, PES, PSU), carbon fibers (e.g. vapor grown carbon fibers (VGCF®)), carbon nanotubes (CNTs), inorganic fibers (e.g. glass fibers), and plant fibers (e.g. paper, lignin, cellulose, cellulose nanowhiskers).

[0116] Examples

[0117] Method of measurement of peak to valley ratio

[0118] Samples were cryo-microtomed following the following steps: Cut a small piece of the film with scissors, place the piece of film into a microtome holder, install the cryogenic sample holder box onto the microtome and fix the sample into the box, put a diamond knife into a knife holder and fix the knife holder into the cryogenic box, fill the cryogenic box with liquid nitrogen allowing the sample to cool, use the diamond knife to cut roughly 10-50um into the sample.

[0119] The atomic force microscopy (AFM) images were then collected by a Nanosurf Drive AFM using Dynamic Force Mode. The AFM probe used to collect the images was a Budger Sensors Tap300AL-G and the software used to analyze the images was Gwyddion.

[0120] The "mean height" is calculated as the arithmetic mean of the Z (height values) of the Atomic Force = i

[0121] Microscopy (AFM) image, which can be written as:

[0122]

[0123] R, where p is the average, n is the total number of Z values, i iterates over the pixels, and Zi is the height values of the pixel i from the AFM image. As is common practice in AFM data processing, Z is defined so that the lowest height pixel of the image is 0 nanometers, and all other values are positive heights relative to that.

[0124] Sp (maximum peak height) is then defined as the maximum peak height relative to the mean value. Mathematically,

[0125]

[0126] — max(^) AT, where max(Z) is the maximum Z height of the AFM image, and p is the average Z height.

[0127] Sv (maximum depth) is defined as the minimum pit depth relative to the mean and is positive. Mathematically,

[0128]

[0129] —, where min(Z) is the minimum Z height of the AFM image (which by definition is zero) and p is the average Z height.

[0130] Peak to valley ratio was calculated by dividing Sp by Sv. The AFM measurement has been done at room temperature.

[0131] Dissolution Time measurement

[0132] The solid were cut into 2cm square and added to octyl acetate at 8wt% solid and mixed at 50°C, 110 rpm in a mix rotor. The time until all the solid disappeared and could not see by naked eye were measured.

[0133] Example 1

[0134] A fluoropolymer having vinylidene fluoride - hexafluoropropene weight ratio 70 / 30 was prepared by emulsion polymerization according to known methods disclosed in the present application, in particular following the procedure disclosed in the comparative example of WO2022 / 086775. The latex were dried in an oven heated at 200°C for 2hours to obtain a solid. The peak to valley ratio was 0.953.

[0135] Example 2

[0136] The same fluoropolymer latex as in example 1 was prepared and dried at 110°C for 8 hours. The peak to valley ratio was 0.939.

[0137] Comparative example 1

[0138] The same fluoropolymer latex as in example 1 was prepared and dried at 50°C for 5 hours. The peak to valley ratio was 0.657.

[0139] Comparative example 2

[0140] The same fluoropolymer latex as in example 1 was prepared and dried at 100°C for 2 hours. The peak to valley ratio was 0.64.

[0141] Comparative example 3

[0142] The same fluoropolymer latex as in example 1 was prepared and dried at room temperature overnight. The peak to valley ratio was 0.584.

[0143] Table 1 hereunder reports the dissolution time measured for each example.

[0144] Table 1

[0145] Examples Peak to valley ratio Dissolution time

[0146] Example 1 0.953 15h

[0147] Example 2 0.939 18h

[0148] Comparative example 1 0.657 > 20h

[0149] Comparative example 2 0.64 > 20h

[0150] Comparative example 3 0.584 > 20h

[0151]

[0152] As demonstrated with the present data, the peak to valley ratio greater than 0.8 allows to significantly decrease the dissolution time of the fluoropolymer.

Claims

Claims1. A binder composition for use in the preparation of components for electrochemical devices comprising at least one fluoropolymer Pl having a peak to valley ratio greater than or equal to 0.80, said peak to valley ratio being calculated by dividing the maximum peak height Sp by maximum depth Sv obtained through atomic force microscopy measurement.

2. The binder composition according to claim 1 wherein said at least one fluoropolymer Pl comprises recurring units derived from a monomer selected from the group consisting of vinylidene fluoride, hexafluoropropene, tetrafluoroethylene, chlorotrifluoroethylene, vinyl fluoride, pentafluoropropene, tetrafluoropropene, trifluoroethylene, 1,2-difluoroethylene and perfluoroalkyle vinyl ethers, perfluoro(l,3-dioxole), perfluoro(2,2-dimethyl-l,3-dioxole) (PDD), a monomer of formula CF2=CFOCF2CF(CF3)OCF2CF2X wherein X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; a monomer of formula CF2=CFOCF2CF2SO2F; a monomer of formula F(CF2)nCH2OCF=CF2wherein n is 1, 2, 3, 4 or 5; a monomer of formula R1CH2OCF=CF2wherein R1is hydrogen atom or F(CF2)m and m is 1, 2, 3 or 4; a monomer of formula R2OCF=CH2wherein R2is F(CF2)p et p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); trifluoropropene, hexafluoroisobutylene, perfluorobutylethylene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-l-propene or mixture thereof.

3. The binder composition according to any one of the previous claims wherein said at least one fluoropolymer Pl is a homopolymer of vinylidene fluoride or a polymer comprising recurring units derived from vinylidene fluoride and recurring units derived from at least one fluorinated monomer Ml; said at least one fluorinated monomer Ml being selected from the group consisting of hexafluoropropene, tetrafluoroethylene, chlorotrifluoroethylene, vinyl fluoride, pentafluoropropene, tetrafluoropropene, trifluoroethylene, 1,2-difluoroethylene and perfluoroalkyle vinyl ethers, perfluoro(l,3-dioxole), perfluoro(2,2-dimethyl-l,3-dioxole) (PDD), a monomer of formula CF2=CFOCF2CF(CF3)OCF2CF2X wherein X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; a monomer of formula CF2=CFOCF2CF2SO2F; a monomer of formula F(CF2)nCH2OCF=CF2wherein n is 1, 2, 3, 4 or 5; a monomer of formula R1CH2OCF=CF2wherein R1is hydrogen atom or F(CF2)m and m is 1, 2, 3 or 4; a monomer of formula R2OCF=CH2wherein R2is F(CF2)p et p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); trifluoropropene, hexafluoroisobutylene, perfluorobutylethylene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-l-propene or mixture thereof.

4. The binder composition according to the previous claims wherein said at least one fluoropolymer Pl comprises from 15wt% to 65wt% of recurring units derived from said at least one fluorinated monomer Ml based on the total weight of said fluoropolymer Pl.

5. The binder composition according to any one of the previous claims wherein said at least one fluoropolymer Pl comprises recurring units derived from vinylidene fluoride, recurring units derived from the fluorinated monomer Ml as defined in claim 3, and recurring units derived from a hydrophilic monomer M2 of formula RaRbC=C(Rc)C(O)Rd(I) wherein Ra, Rband Rcare independently selected from the group consisting of H and C1-C5 alkyl; Rdis selected from the group consisting of -NHC(CH3)2CH2C(O)CH3, or ORd' wherein Rd' is selected from the group consisting of H and Ci-Ci8alkyl optionally substituted by one or more -OH, -CO2H, -SO3H, -PO3H2, -OC(O)Rd", -C(O)O-Rd" or a five- to six-membered heterocycle comprising at least nitrogen atom in the ring; Rd” being selected from the group consisting of Ci-C6alkyl and C6-Ci2aryl optionally substituted with one or more -OH, -CO2H, -SO3H, -PO3H2functional group(s).

6. The binder composition according to the previous claims wherein said at least one fluoropolymer Pl comprises from 0.05 mol% to 10 mol% of recurring units derived from said hydrophilic monomer M2 based on the total weight of said fluoropolymer Pl.

7. The binder composition according to any one of the previous claims wherein the peak to valley ratio is greater than or equal to 0.82, advantageously greater than or equal to 0.84, preferably greater than or equal to 0.86, more preferably greater than or equal to 0.88, most preferably greater than or equal to 0.90, in particular greater than or equal to 0.92.

8. The binder composition according to any one of the previous claims wherein said at least one fluoropolymer comprises at least 35wt% of recurring units derived from vinylidene fluoride based on the total weight of said fluoropolymer Pl.

9. An electrode-forming composition for use in the preparation of electrodes for electrochemical devices comprising at least one electrode active material, a binder composition according to any one of the previous claims, and optionally at least one conductive agent.

10. An electrode for electrochemical devices comprising at least one electrode active material, a binder composition according to any one of the previous claims 1 to 8, and optionally at least one conductive agent.

11. A secondary batery comprising an electrode according to the previous claim.

12. A solid electrolyte comprising the binder composition according to any one of the previous claims 1 to 8 and a lithium salt and / or sulfide-based inorganic particles.

13. A solid-state battery comprising a solid electrolyte according to the previous claim and / or an electrode according to previous claim 10.

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