Hybrid fluoropolymer electrolyte membrane

Abstract

The present invention relates to a method for producing a fluoropolymer electrolyte membrane comprising a fluoropolymer hybrid organic / inorganic composite for use in an electrochemical cell, to a polymer electrolyte membrane obtained by this method, and to films and membranes thereof, and to an electrochemical cell comprising a polymer electrolyte membrane between a positive electrode and a negative electrode. The present invention also relates to the use of a polymer electrolyte membrane obtained by the method according to the invention in an electrochemical device, in particular a secondary battery.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to European Patent Application No. 19197491.4, filed September 16, 2019, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to a method for producing a fluoropolymer electrolyte membrane comprising a fluoropolymer hybrid organic / inorganic composite for an electrochemical cell, to a polymer electrolyte membrane obtained by this method, and to an electrochemical cell comprising a polymer electrolyte membrane between a positive electrode and a negative electrode. The present invention also relates to the use of the polymer electrolyte membrane obtained by the method according to the invention in an electrochemical device, in particular in a secondary battery. [Background technology]

[0003] Hybrid organic / inorganic polymer composites, in which nanoscale or molecular-level inorganic materials are dispersed in organic polymers, have attracted great scientific, technological and even industrial interest due to their unique properties.

[0004] Hybridization of organic and inorganic compounds is an evolving method for creating polymer structures with improved mechanical properties, among others. In this regard, it is well known that the sol-gel process using metal alkoxides is the most useful and important approach for synthesizing hybrid organic / inorganic polymer composites. In particular, the proper control of hydrolysis and condensation of metal alkoxides in the presence of preformed organic polymers can lead to hybrid organic / inorganic polymer composites with improved properties compared to the original organic and inorganic compounds. The polymer as an organic compound can increase the toughness and processability of the inorganic material, i.e., the normally brittle metal alkoxide, and the inorganic network can increase the scratch resistance, mechanical properties, and surface properties of the resulting hybrid organic / inorganic polymer composites.

[0005] Hybrids made from fluoropolymers, in particular by the sol-gel technique starting from vinylidene fluoride polymers, are known in the art.

[0006] For example, WO 2011 / 121078 discloses that at least a portion of the hydroxyl groups of a fluoropolymer are converted in solution or in the molten state into a compound of formula X 4-m AY m A method for preparing a fluoropolymer hybrid organic / inorganic composite is disclosed, in which the fluoropolymer reacts with at least a portion of the hydrolyzable groups of a metal compound of the formula X, where X is a hydrocarbon group, Y is a hydrolyzable group, A is a metal selected from Si, Ti, and Zr, and m is an integer of 1 to 4. The choice of solvent used to dissolve the fluoropolymer is determined by the amount of the fluoropolymer and the amount of the hydrolyzable group of the metal compound of the formula X. 4-m AY m The solvent is not critical as long as it effectively solvates both the fluoropolymer and the metal compound and does not prevent the reaction between the hydroxyl groups of the fluoropolymer and the hydrolyzable groups of the metal compound. However, to produce the membrane, it is necessary to evaporate the solvent by drying. This patent document also mentions that swelling of the electrolyte solution containing a mixture of ethylene carbonate and propylene carbonate and LiPF6 occurs in the film made of the hybrid organic / inorganic composite. Furthermore, once the film is cast, swelling continues, which may result in a smaller final amount of liquid electrolyte that ultimately interpenetrates the film, and a corresponding decrease in ionic conductivity.

[0007] To address such shortcomings, WO 2013 / 160240 discloses the preparation of a fluoropolymer hybrid organic / inorganic composite in the presence of a liquid medium to provide a free-standing fluoropolymer film that stably contains and retains the liquid medium while having outstanding ionic conductivity. When the hybrid organic / inorganic composite is for use as a polymer electrolyte separator in an electrochemical device, it is made of a fluoropolymer, a fluoropolymer of formula X 4-m AY mThe resulting liquid mixture can then be processed into a film by casting.

[0008] However, the method described in WO 2013 / 160240 requires the use of process solvents such as acetone, N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), all of which need to be evaporated by drying / heating at the end of the process to produce the membrane, making them undesirable for industrial production processes.

[0009] WO 2015 / 169834 also describes a method for producing fluoropolymer hybrid organic / inorganic composites with exceptional crosslink density properties, excellent ion-conducting properties, and increased electrolyte retention in the polymer electrolyte membrane. However, this method also requires a process solvent to prepare the polymer solution, which then requires a process of evaporation of the process solvent to obtain the membrane.

[0010] In addition to the inconvenience of having an additional step to remove the process solvent used in the method, and the drawbacks from the point of view of processability and industrialization, such process solvents, especially acetone, are subject to the ATEX Directive 94 / 9 / EC, approved in 1994 by the European Union (EU). The ATEX Directive lays down technical and legal requirements for products intended for use in hazardous areas with potentially explosive atmospheres. The name of the ATEX Directive comes from the French title of the 94 / 9 / EC Directive, i.e. "(Appareils destines a etre utilises en) Atmospheres Explosibles". As of July 2003, it is mandatory to use products with ATEX type approval within the EU, and therefore products placed on the market or used in hazardous environments regulated by the ATEX Directive must meet the criteria laid down therein. The criteria vary depending on the classification of the hazardous area. Therefore, certain solvents, including acetone, which are believed to be capable of creating explosive atmospheres, are often of concern to manufacturers in the battery sector.

[0011] Therefore, there is a need in the art for a method to produce fluoropolymer hybrid organic / inorganic composites without the use of processing solvents.

[0012] To meet this demand from the sector, several solutions have been explored. One is to find alternative solvents with better ATEX properties without losing solubility characteristics, grafting rate, and other parameters that may affect the formation of the membrane. Another approach is to find alternative processes that do not require processing solvents to produce the polymer solution. Summary of the Invention

[0013] Accordingly, the present invention provides a method for producing a fluoropolymer electrolyte membrane comprising a fluoropolymer hybrid organic / inorganic composite for an electrochemical device, comprising the steps of: a) dissolving i) at least one fluoropolymer in ii) at least one liquid medium, wherein i) the at least one fluoropolymer is - at least one first repeat unit derived from at least one ethylenically unsaturated fluorinated monomer; - at least one second repeat unit derived from at least one ethylenically unsaturated monomer having at least one hydroxyl group; A process comprising: b) i) converting at least a portion of the hydroxyl groups of at least one fluoropolymer with iii) at least one metal compound of formula (I) X 4-m AY m (I) (wherein m is an integer from 1 to 3, A is a metal selected from the group consisting of Si, Ti, and Zr, Y is a hydrolyzable group, and X is a hydrocarbon group containing at least one isocyanate (-N=C=O) functional group). thereby reacting with a compound of the formula -OC(O)-NH-Z-AY m X 3-m obtaining a composition comprising at least one grafted fluoropolymer comprising at least one hydrogenated monomer having at least one pendant side chain comprising an end group of the formula: c) Formula -OC(O)-NH-Z-AY m X 3-m the terminal group of the formula (II) X' 4-m’ A'Y' m’ (II) (wherein m' is an integer from 1 to 4, A' is a metal selected from the group consisting of Si, Ti, and Zr, Y' is a hydrolyzable group optionally containing at least one functional group different from a -N=C=O group, and X' is a hydrocarbon group). thereby obtaining a composition comprising at least one fluoropolymer hybrid organic / inorganic composite; d) processing the composition from step c) into a polymer electrolyte membrane; wherein no drying step is present.

[0014] A second object of the invention is a polymer electrolyte membrane obtainable as defined above.

[0015] A third object of the invention is an electrochemical device comprising a polymer electrolyte membrane as defined above between a positive electrode and a negative electrode.

[0016] A further object of the present invention is the use of a polymer electrolyte membrane as defined above in an electrochemical device, in particular in a secondary battery.

[0017] Applicants have now surprisingly discovered that it is possible to produce fluoropolymer electrolyte membranes comprising fluoropolymer hybrid organic / inorganic composites without the use of process solvents to dissolve the fluoropolymer, with the added advantage of avoiding the subsequent recovery and disposal of said solvents.

[0018] In particular, applicants have discovered that a liquid medium comprising at least one organic solvent can replace the processing solvent such that the fluoropolymer is dissolved therein, and thus a drying step to evaporate the processing solvent is not required to produce a fluoropolymer electrolyte membrane, and furthermore, multiple concerns regarding ATEX regulations are eliminated.

[0019] The fluoropolymer electrolyte membrane according to the invention is characterized in that it does not contain metal salts, for example lithium salts. As disclosed in WO 2017 / 216184, such a feature can be complemented by using the migration properties of metal salts from either the positive or negative electrode in an electrochemical device towards the electrolyte membrane, thereby ensuring excellent electrochemical performance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Throughout this specification, unless the context requires otherwise, the words "comprise" or "include" or variations such as "comprises", "comprising", "includes", "including" are understood to mean the inclusion of a stated element or method step or group of elements or method steps, but not to the exclusion of any other element or method step or group of elements or method steps. According to a preferred embodiment, the words "comprise" and "include" and variations thereof mean "consist exclusively of".

[0021] As used herein, the singular forms "a," "an," and "the" include plural aspects unless the context clearly indicates otherwise. The term "and / or" includes the meaning of "and," "or," and also all other possible combinations of the elements associated with this term.

[0022] The term "between" should be understood to be inclusive of the points.

[0023] As used herein, "alkyl" groups include saturated hydrocarbons having one or more carbon atoms, including straight-chain alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and the like; cyclic alkyl groups (or "cycloalkyl" or "alicyclic" or "carbocyclic" groups) such as cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl; branched-chain alkyl groups such as isopropyl, tert-butyl, sec-butyl, and isobutyl; and alkyl-substituted alkyl groups such as alkyl-substituted cycloalkyl groups and cycloalkyl-substituted alkyl groups.

[0024] The term "aliphatic group" includes organic moieties characterized by straight or branched chains, typically having between 1 and 18 carbon atoms. In complex structures, the chains may be branched, bridged, or cross-linked. Aliphatic groups include alkyl, alkenyl, and alkynyl groups.

[0025] As used herein, the terminology "(Cn-Cm)" with respect to organic groups, where n and m are each integers, indicates that the group may contain from n carbon atoms to m carbon atoms per group.

[0026] Ratios, concentrations, amounts, and other numerical data may be presented in a range format in this specification. Such range formats are used merely for convenience and brevity, and should be understood to be interpreted flexibly to include not only the numerical values ​​explicitly recited as the range endpoints, but also to include all individual numerical values ​​or subranges contained within the range as if each numerical value and subrange were explicitly recited. For example, a temperature range of about 120°C to about 150°C should be interpreted to include not only the explicitly recited endpoints of about 120°C to about 150°C, but also the subranges such as 125°C to 145°C, 130°C to 150°C, and individual amounts within the stated range, such as subquantities, e.g., 122.2°C, 140.6°C, and 141.3°C.

[0027] The components of the method for manufacturing fluoropolymer electrolyte membranes comprising fluoropolymer hybrid organic / inorganic composites for electrochemical devices according to the present invention are described in detail below.It should be understood that both the above summary and the following detailed description are illustrative and are intended to provide further explanation of the invention as claimed.Therefore, various changes and modifications described herein will be apparent to those skilled in the art.Furthermore, for the sake of clarity and conciseness, descriptions of well-known functions and structures may be omitted.

[0028] A first object of the present invention is a method for producing a fluoropolymer electrolyte membrane comprising a fluoropolymer hybrid organic / inorganic composite for an electrochemical device, comprising: a) dissolving i) at least one fluoropolymer in ii) at least one liquid medium, wherein i) the at least one fluoropolymer is - at least one first repeat unit derived from at least one ethylenically unsaturated fluorinated monomer; - at least one second repeat unit derived from at least one ethylenically unsaturated monomer having at least one hydroxyl group; A process comprising: b) i) converting at least a portion of the hydroxyl groups of at least one fluoropolymer with iii) at least one metal compound of formula (I) X 4-m AY m (I) (wherein m is an integer from 1 to 3, A is a metal selected from the group consisting of Si, Ti, and Zr, Y is a hydrolyzable group, and X is a hydrocarbon group containing at least one isocyanate (-N=C=O) functional group). thereby reacting with a compound of the formula -OC(O)-NH-Z-AY m X 3-m obtaining a composition comprising at least one grafted fluoropolymer comprising at least one hydrogenated monomer having at least one pendant side chain comprising an end group of the formula: c) Formula -OC(O)-NH-Z-AY m X 3-m the terminal group of the formula (II) X' 4-m’ A'Y' m’ (II) (wherein m' is an integer from 1 to 4, A' is a metal selected from the group consisting of Si, Ti, and Zr, Y' is a hydrolyzable group optionally containing at least one functional group different from a -N=C=O group, and X' is a hydrocarbon group). thereby obtaining a composition comprising at least one fluoropolymer hybrid organic / inorganic composite; d) processing the composition from step c) into a polymer electrolyte membrane; wherein no drying step is present.

[0029] The fluoropolymer electrolyte membrane according to the invention advantageously does not contain one or more metal salts, such as, but not limited to, one ore metal salt selected from the group consisting of: - MeI, Me(PF6) n , Me(BF4) n , Me(ClO4) n , Me(bis(oxalato)borate) n ("Me (BOB) n ”), MeCF3SO3, Me[N(CF3SO2)2] n , Me[N(C2F5SO2)2] n , R F Me[N(CF3SO2)(R F SO2)] n , Me(AsF6) n , Me[C(CF3SO2)3] n , or Me2S n (wherein Me is a metal, preferably a transition metal, an alkali metal or an alkaline earth metal, more preferably Li, Na, K or Cs, even more preferably Li, and n is the valence of said metal, typically n is 1 or 2); - [ka] (In the formula, R' Fare F, CF3, CHF2, CH2F, C2HF4, C2H2F3, C2H3F2, C2F5, C3F7, C3H2F5, C3H4F3, C4F9, C4H2F7, C4H4F5, C5F 11 , C3F5OCF3, C2F4OCF3, C2H2F2OCF3 and CF2OCF3); and - A combination of them.

[0030] In one embodiment, step c) is carried out at room temperature or after heating to a temperature below 100°C.

[0031] In a preferred embodiment, step c) is carried out at a temperature of 50-100°C, preferably 70-90°C.

[0032] In step c), iv) the at least one metal compound of formula (II) as defined above is reacted with a compound of formula -OC(O)-NH-Z-AY from step b). m X 3-m is hydrolyzed and / or polycondensed with the terminal group of

[0033] In a preferred embodiment, the hydrolysis and / or polycondensation in step c) defined above is initiated by the addition of at least an acid catalyst. The choice of the acid catalyst is not particularly limited. The acid catalyst is typically selected from the group consisting of organic acids and inorganic acids. The acid catalyst is preferably selected from the group consisting of organic acids, such as, for example, citric acid and formic acid. In a preferred embodiment, the acid catalyst is formic acid.

[0034] In the present invention, the term "membrane" is intended to denote a discrete, usually thin, interface that moderates the permeation of chemical species in contact with it. This interface may be homogeneous, i.e. completely uniform in structure (dense membrane), or it may be chemically or physically heterogeneous, for example comprising gaps, pores or holes of finite dimensions (porous membrane).

[0035] In the present invention, the term "fluoropolymer" is intended to mean a (co)polymer in which at least one hydrogen atom has been replaced by fluorine. One, two, three or more hydrogen atoms may be replaced by fluorine.

[0036] Polyvinylidene fluoride (PVDF or VDF polymer) is one of the most widely used fluoropolymers in battery components due to its high anode stability and high dielectric constant, which favors the ionization of the lithium salt in lithium-ion batteries, allowing the flow of ions and thus improving the battery performance.

[0037] According to one embodiment, the first repeat unit derived from at least one ethylenically unsaturated fluorinated monomer is vinylidene fluoride (VDF), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), trifluoroethylene, and combinations thereof.

[0038] In one embodiment, the fluoropolymer of the present invention comprises two first repeat units derived from at least one ethylenically unsaturated fluorinated monomer. In a particular embodiment, the two first repeat units are VDF and CTFE. In another particular embodiment, the two first repeat units are VDF and TFE. In a preferred embodiment, the two first repeat units are VDF and HFP.

[0039] In one embodiment, the first repeat unit according to the present invention is a VDF (co)polymer.

[0040] In the present invention, a VDF polymer refers to a polymer consisting essentially of repeat units, more than 85 mol % of said repeat units being derived from VDF.

[0041] The VDF polymer is preferably (a) at least 85 mol % of repeat units derived from VDF; (b) optionally, 0.1 to 15 mol %, preferably 0.1 to 12 mol %, more preferably 0.1 to 10 mol % of repeat units derived from a fluorinated monomer other than VDF; (c) optionally, 0.1 to 5 mol %, preferably 0.1 to 3 mol %, more preferably 0.1 to 1 mol % of repeat units derived from one or more hydrogenated comonomers; Including, All of the above mole percentages are based on the total moles of repeat units of the VDF polymer.

[0042] i) Non-limiting examples of fluorinated monomers suitable as the first repeat unit different from VDF include, in particular: - C2-C8 perfluoroolefins such as tetrafluoroethylene and hexafluoropropylene (HFP); - C2-C8 hydrogenated fluoroolefins such as vinyl fluoride, 1,2-difluoroethylene and trifluoroethylene; -Formula CH2=CH-R f0 (In the formula, R f0 is a C1-C6 perfluoroalkyl) perfluoroalkylethylene, - chloro- and / or bromo- and / or iodo-C2-C6 fluoroolefins, for example chlorotrifluoroethylene; - Formula CF2=CFOR f1 (In the formula, R f1 is C1-C6 fluoro- or perfluoroalkyl, for example CF3, C2F5, C3F7), (per)fluoroalkyl vinyl ethers; - CF2 = CFOX0 (per)fluoro-oxyalkyl vinyl ether (wherein X0 is C1-C 12 Alkyl groups, C1-C 12 C1-C having one or more ether groups such as oxyalkyl groups or perfluoro-2-propoxy-propyl groups 12 (per)fluorooxyalkyl group; - Formula CF2=CFOCF2OR f2 (In the formula, R f2is a C1-C6 fluoro- or perfluoroalkyl group, for example a C1-C6 (per)fluorooxyalkyl group having one or more ether groups, such as CF3, C2F5, C3F7 or -C2F5-O-CF3; - Formula CF2 = CFOY0 (wherein Y0 is C1 to C 12 Alkyl group or (per)fluoroalkyl group, C1-C 12 C1-C having an oxyalkyl group or one or more ether groups 12 and Y0 comprises a carboxylic or sulfonic acid group in the form of its acid, acid halide or salt); Fluorodioxoles, preferably perfluorodioxoles.

[0043] In a preferred embodiment, said fluorinated monomer as the first repeat unit is advantageously selected from the group consisting of vinyl fluoride, trifluoroethylene, 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). Preferably, possible additional fluorinated monomers are selected from the group consisting of chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), trifluoroethylene (TrFE) and tetrafluoroethylene (TFE).

[0044] In a more preferred embodiment, the fluorinated monomer is hexafluoropropylene (HFP).

[0045] In another embodiment, non-limiting examples of VDF (co)polymers as the first repeat unit of the fluoropolymer of the present invention include, inter alia, homopolymers of VDF, VDF / TFE copolymers, VDF / TFE / HFP copolymers, VDF / TFE / CTFE copolymers, VDF / TFE / TrFE copolymers, VDF / CTFE copolymers, VDF / HFP copolymers, VDF / TFE / HFP / CTFE copolymers, etc. In particular, VDF / HFP copolymers have attracted much attention due to their excellent compatibility with electrodes, low transition temperature, and crystallinity, which can improve ionic conductivity.

[0046] The hydrogenated comonomer is not particularly limited, and may be an α-olefin, a (meth)acrylic monomer, a vinyl ether monomer, or a styrene monomer.

[0047] Therefore, the VDF polymer is more preferably (a) at least 85 mol % of repeat units derived from VDF; (b) optionally 0.1 to 15 mol %, preferably 0.1 to 12 mol %, more preferably 0.1 to 10 mol % of a fluorinated monomer different from VDF, said fluorinated monomer being preferably selected from vinyl fluoride, chlorotrifluoroethylene (CTFE), hexafluoropropene (HFP), tetrafluoroethylene (TFE), perfluoromethylvinylether (MVE), trifluoroethylene (TrFE) and mixtures thereof; a polymer consisting essentially of All of the above mole percentages are based on the total moles of repeat units in the VDF polymer.

[0048] In addition to said repeating units, defects, end chains, impurities, chain inversions or branches etc. may further be present in the VDF polymer, without these constituents substantially modifying the behaviour and properties of the VDF polymer.

[0049] According to one embodiment, the second repeat unit is derived from a (meth)acrylic acid ester having a hydroxyl group.

[0050] According to one embodiment, the (meth)acrylic acid ester having a hydroxyl group includes 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate, 2-hydroxymethyl acrylate, 2-hydroxymethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl acrylate, 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl acrylate, 8-hydroxyoctyl methacrylate, 2-hydroxyethylene glycol acrylate, 2-hydroxyethylene glycol methacrylate, 2-hydroxypropylene glycol acrylate, 2-hydroxypropylene glycol methacrylate, 2,2,2-trifluoroethyl acrylate, and 2,2,2-trifluoroethyl methacrylate.

[0051] In a preferred embodiment, the second repeat unit is a HEA.

[0052] In one embodiment, the fluorinated copolymer comprises 0.1 to 20.0 mol %, preferably 0.1 to 15.0 mol %, more preferably 0.1 to 10.0 mol % of a second repeat unit derived from at least one ethylenically unsaturated monomer having a hydroxyl group.

[0053] In a preferred embodiment, the fluorinated copolymer is 90.0 mol % to 99.9 mol % of a first repeat unit derived from at least one ethylenically unsaturated fluorinated monomer; and 0.1 to 10.0 mol % of a second repeating unit derived from at least one ethylenically unsaturated monomer having a hydroxyl group.

[0054] In a preferred embodiment, the fluorinated copolymer is 80.0 mol% to 99.8 mol% of VDF and 0.1 mol% to 10.0 mol% of HEP as a first repeat unit derived from at least one ethylenically unsaturated fluorinated monomer; and a HEA as a second repeating unit derived from at least one ethylenically unsaturated monomer having 0.1 to 10.0 mol % of a hydroxyl group.

[0055] liquid medium In the present invention, the term "liquid medium" is intended to mean a composition comprising one or more substances that are in the liquid state at 20° C. under atmospheric pressure.

[0056] The liquid medium typically comprises at least one organic solvent and optionally at least one ionic liquid.

[0057] The choice of organic solvent is not particularly limited, as long as it is suitable for solubilizing the fluoropolymer according to the invention and does not fall within the explosive atmospheres defined in the ATEX Directive 94 / 9 / EC, which defines an explosive atmosphere as a mixture of: i) combustible substances in the form of gas, vapor, mist or dust; ii) containing air; iii) under atmospheric conditions; iv) where combustion after ignition spreads throughout the unburned mixture;

[0058] Non-limiting examples of suitable organic solvents include, inter alia: aliphatic, cycloaliphatic or aromatic ether oxides, more particularly dibutyl oxide, dipentyl oxide, diisopentyl oxide, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether benzyl oxide; - glycol ethers, such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, etc.; - glycol ether esters, such as ethylene glycol methyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, etc.; - alcohols, such as diacetone alcohol; - ketones, such as methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, isophorone, etc.; - linear or cyclic esters, such as n-butyl acetate, methyl acetoacetate, dimethyl phthalate, gamma-butyrolactone, etc.; - linear or cyclic amides, such as N,N-diethylacetamide, N,N-dimethylacetamide, N,N-dimethylformamide, and N-methyl-2-pyrrolidone; - Dimethyl sulfoxide: Examples include:

[0059] In one embodiment, the organic solvent comprises at least one organic carbonate compound.

[0060] In the present invention, the organic carbonate compound may be a partially or fully fluorinated carbonate compound. The organic carbonate compound according to the present invention may be either a cyclic carbonate or an acyclic carbonate.

[0061] Non-limiting examples of organic carbonate compounds include ethylene carbonate (1,3-dioxolan-2-one), propylene carbonate, 4-methylene-1,3-dioxolan-2-one, 4,5-dimethylene-1,3-dioxolan-2-one, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, methyl propyl carbonate, methyl butyl carbonate, ethyl butyl carbonate, propyl butyl carbonate, dibutyl carbonate, di-tert-butyl carbonate, and butylene carbonate, among others.

[0062] The fluorinated carbonate compound may be monofluorinated or polyfluorinated. Suitable examples of fluorinated carbonate compounds include, but are not limited to, monofluorinated ethylene carbonate (4-fluoro-1,3-dioxolane-2-one) and difluorinated ethylene carbonate, monofluorinated and difluorinated propylene carbonate, monofluorinated and difluorinated butylene carbonate, 3,3,3-trifluoropropylene carbonate, fluorinated dimethyl carbonate, fluorinated diethyl carbonate, fluorinated ethyl methyl carbonate, fluorinated dipropyl carbonate, fluorinated dibutyl carbonate, fluorinated methyl propyl carbonate, and fluorinated ethyl propyl carbonate.

[0063] In a preferred embodiment, the organic carbonate compound is a mixture of ethylene carbonate and propylene carbonate.

[0064] In another preferred embodiment, the organic carbonate compound is a mixture of ethylene carbonate, propylene carbonate, and 4-fluoro-1,3-dioxolan-2-one.

[0065] In another embodiment, the organic solvent comprises at least one organic carbonate compound and at least one sulfone compound. The sulfone compound according to the present invention can be either a cyclic sulfone or a non-cyclic sulfone.

[0066] Non-limiting examples of sulfone compounds include tetramethylene sulfone (sulfolane), butadiene sulfone (sulfolene), pentamethylene sulfone, hexamethylene sulfone, thiazolidine 1,1-dioxide, thiomorpholine 1,1-dioxide, dimethyl sulfone, diethyl sulfone, ethyl methyl sulfone, and mixtures thereof, among others.

[0067] In a preferred embodiment, the organic solvent is a mixture of ethylene carbonate, propylene carbonate, 4-fluoro-1,3-dioxolan-2-one, and sulfolane.

[0068] Ionic Liquids The term "ionic liquid" as used herein refers to compounds that contain positively charged cations and negatively charged anions and are in the liquid state at atmospheric pressure and temperatures below 100° C. While ordinary liquids such as water are composed primarily of electrically neutral molecules, ionic liquids are composed primarily of ions and short-lived ion pairs. As used herein, the term "ionic liquid" refers to compounds that do not contain a solvent.

[0069] As used herein, the term "cationic atom" refers to at least one non-metallic atom that carries a positive charge.

[0070] The term "onium cation," as used herein, refers to a positively charged ion with at least a portion of its charge localized on at least one non-metallic atom, such as O, N, S, or P.

[0071] In the present invention, the ionic liquid is n- Q l+ (n / l) (In the formula, - A n- represents an anion; - Q l+ (n / l) represents a cation; n and l are independently selected from 1 to 5, each of which represents an anion An- and cation Q l+ (n / l) represents the charge of It has the general formula:

[0072] The cations may be selected, independently of one another, from metal cations and organic cations. The cations may be monovalent or polyvalent cations.

[0073] Preferred examples of the metal cation include alkali metal cations, alkaline earth metal cations, and cations of d-block elements.

[0074] In the present invention, Q l+ (n / l) may represent an onium cation. An onium cation is a cation formed by elements of groups VB and VIB (as defined in the old European IUPAC system according to the Periodic Table of Elements) with three or four hydrocarbon chains. Group VB includes N, P, As, Sb and Bi atoms. Group VIB includes O, S, Se, Te and Po atoms. An onium cation may in particular be a cation formed by an atom selected from the group consisting of N, P, O and S, more preferably N and P, and three or four hydrocarbon chains.

[0075] Onium Cation Q l+ (n / l) teeth, heterocyclic onium cations; in particular those selected from the group consisting of: [ka] - unsaturated cyclic onium cations; in particular those selected from the group consisting of: [ka] - saturated cyclic onium cations; in particular those selected from the group consisting of: [ka] and - acyclic onium cations, especially those of the general formula + L-R' s (wherein L represents an atom selected from the group consisting of N, P, O and S, more preferably N and P; s represents the number of R' groups selected from 2, 3 or 4 depending on the valence of the element L, each R' independently represents a hydrogen atom or a C1-C8 alkyl group; L + and R' may be a single bond or a double bond.

[0076] In the above formula, each "R" symbol represents, independently of one another, a hydrogen atom or an organic group. Preferably, each "R" symbol in the above formula represents, independently of one another, a hydrogen atom or a saturated or unsaturated, linear, branched or cyclic C1-C alkoxy group, optionally substituted one or more times with a halogen atom, an amino group, an imino group, an amide group, an ether group, an ester group, a hydroxyl group, a carboxyl group, a carbamoyl group, a cyano group, a sulfone group or a sulfite group. 18 It may represent a hydrocarbon group.

[0077] Cation Q l+ (n / l) may more specifically be selected from ammonium, phosphonium, pyridinium, pyrrolidinium, pyrazolinium, imidazolium, arsenic, quaternary phosphonium, and quaternary ammonium cations.

[0078] The quaternary phosphonium or ammonium cation may more preferably be selected from tetraalkylammonium or tetraalkylphosphonium cations, trialkylbenzylammonium or trialkylbenzylphosphonium cations, or tetraarylammonium or tetraarylphosphonium cations, the alkyl groups of which may be the same or different and represent a linear or branched alkyl chain having 4 to 12 carbon atoms, preferably 4 to 6 carbon atoms, and the aryl groups of which may be the same or different and represent a phenyl group or a naphthyl group.

[0079] In certain embodiments, Q l+ (n / l) represents a quaternary phosphonium or quaternary ammonium cation.

[0080] In a preferred embodiment, Q l+ (n / l) represents a quaternary phosphonium cation. Non-limiting examples of quaternary phosphonium cations include trihexyl(tetradecyl)phosphonium and tetraalkylphosphonium cations, in particular the tetrabutylphosphonium (PBu4) cation.

[0081] In another embodiment, Q l+ (n / l) represents the imidazolium cation. Non-limiting examples of imidazolium cations include 1,3-dimethylimidazolium, 1-(4-sulfobutyl)-3-methylimidazolium, 1-allyl-3H-imidazolium, 1-butyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, and 1-octyl-3-methylimidazolium.

[0082] In another embodiment, Q l+ (n / l) are, in particular, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, trimethylbenzylammonium, methyltributylammonium, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium, N,N-dimethyl-N-ethyl-N-(3-methoxypropyl)ammonium, N,N-dimethyl-N-ethyl-N-benzylammonium, N,N-dimethyl-N-ethyl-N-phenylethylammonium, N-tributyl-N-methylammonium, N-trimethyl-N-butylammonium, N-trimethyl-N-hexylammonium, N-trimethyl-N-propylammonium, and Aliquat 336 (methyltri(C8-C 10 represents a quaternary ammonium cation selected from the group consisting of (a mixture of alkyl) ammonium compounds.

[0083] In one embodiment, Q l+ (n / l) represents a piperidinium cation, in particular N-butyl-N-methylpiperidinium, N-propyl-N-methylpiperidinium.

[0084] In another embodiment, Q l+ (n / l) represents a pyridinium cation, in particular N-methylpyridinium.

[0085] In a more preferred embodiment, Q l+ (n / l) represents a pyrrolidinium cation. Among the specific pyrrolidinium cations, mention may be made of the following: 1~12 Alkyl-C 1~12 Alkyl-pyrrolidinium, more preferably C 1~4 Alkyl-C 1~4 Alkyl-pyrrolidinium. Examples of pyrrolidinium cations include, but are not limited to, N,N-dimethylpyrrolidinium, N-ethyl-N-methylpyrrolidinium, N-isopropyl-N-methylpyrrolidinium, N-methyl-N-propylpyrrolidinium, N-butyl-N-methylpyrrolidinium, N-octyl-N-methylpyrrolidinium, N-benzyl-N-methylpyrrolidinium, N-cyclohexylmethyl-N-methylpyrrolidinium, and N-[(2-hydroxy)ethyl]-N-methylpyrrolidinium. More preferred are N-methyl-N-propylpyrrolidinium (PYR13) and N-butyl-N-methylpyrrolidinium (PYR14).

[0086] Non-limiting examples of anions of ionic liquids include iodide, bromide, chloride, hydrogen sulfate, dicyanamide, acetate, diethyl phosphate, methyl phosphate, fluorinated anions such as hexafluorophosphate (PF6 - ) and tetrafluoroborate (BF4 - ), as well as the following formula: [ka] The oxaloborate includes

[0087] In one embodiment, A n- is a fluorinated anion. Among the fluorinated anions that can be used in the present invention, the fluorinated sulfonimide anion can be particularly advantageous. This organic anion is in particular of the general formula: (E a -SO2)N - R (In the formula, -E a represents a fluorine atom or a group having preferably 1 to 10 carbon atoms selected from fluoroalkyl, perfluoroalkyl, and fluoroalkenyl; - R represents a substituent. The anion may be selected from those having the following formula:

[0088] Preferably, E a may represent F or CF3.

[0089] According to a first embodiment, R represents a hydrogen atom.

[0090] According to a second embodiment, R preferably represents a linear or branched, cyclic or acyclic hydrocarbon-based group having 1 to 10 carbon atoms, optionally having one or more unsaturations and optionally substituted one or more times with halogen atoms, a nitrile functional group or an alkyl group, optionally substituted one or more times with halogen atoms. Furthermore, R may represent a nitrile group -CN.

[0091] According to a third embodiment, R represents a sulfinate group. In particular, R is a is as defined above a In this case, the fluorinated anion is symmetric, i.e., the two E a The groups may be identical or asymmetric, i.e., the two E a The groups may be different.

[0092] Furthermore, R may represent the group -SO2-R', where R' preferably represents a linear or branched, cyclic or acyclic hydrocarbon-based group having 1 to 10 carbon atoms, which may optionally have one or more unsaturations and which may optionally be substituted one or more times with halogen atoms, a nitrile functional group or an alkyl group, which is optionally substituted one or more times with halogen atoms. In particular, R' may comprise a vinyl or allyl group. Furthermore, R may represent the group -SO2-N-R', where R' is as defined above or alternatively R' represents a sulfonate functional group -SO3.

[0093] The cyclic hydrocarbon group may preferably refer to a cycloalkyl group or an aryl group. "Cycloalkyl" refers to a monocyclic hydrocarbon chain having 3 to 8 carbon atoms. Preferred examples of cycloalkyl groups are cyclopentyl and cyclohexyl. "Aryl" refers to a monocyclic or polycyclic aromatic hydrocarbon group having 6 to 20 carbon atoms. Preferred examples of aryl groups are phenyl and naphthyl. When the group is a polycyclic group, the rings may be fused or bonded by a σ (sigma) bond.

[0094] According to a fourth embodiment, R represents a carbonyl group. R may in particular be represented by the formula -CO-R', where R' is as defined above.

[0095] The organic anion that can be used in the present invention is advantageously CF3SO2N - SO2CF3 (bis(trifluoromethanesulfonyl)imide anion, commonly referred to as TFSI), FSO2N - SO2F (bis(fluorosulfonyl)imide anion, commonly referred to as FSI), CF3SO2N - SO2F and CF3SO2N - SO2N - It may be selected from the group consisting of SO2CF3.

[0096] In a preferred embodiment, the ionic liquid is - One or more C1-C 30a positively charged cation selected from the group consisting of imidazolium, pyridinium, pyrrolidinium and piperidinium ions, optionally containing alkyl groups; a negatively charged anion selected from the group consisting of halides, fluorinated anions and borates; Contains:

[0097] C1~C 30 Non-limiting examples of alkyl groups include methyl, ethyl, propyl, iso-propyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl, 2,2-dimethyl-propyl, hexyl, 2,3-dimethyl-2-butyl, heptyl, 2,2-dimethyl-3-pentyl, 2-methyl-2-hexyl, octyl, 4-methyl-3-heptyl, nonyl, decyl, undecyl, and dodecyl groups, among others.

[0098] In the present invention, (iii) X in at least one metal compound of formula (I) defined above is the same or different from each other and is, in each occurrence, a linear or branched C1-C aryl group containing at least one -N=C=O functional group. 12 is a hydrocarbon group, Y are the same or different and are OR in each occurrence, and R is a linear or branched C1-C5 alkyl group, preferably a methyl group or an ethyl group.

[0099] (iii) Non-limiting examples of the at least one metal compound of formula (I) defined above include trimethoxysilylmethyl isocyanate, triethoxysilylmethyl isocyanate, trimethoxysilylethyl isocyanate, triethoxysilylethyl isocyanate, trimethoxysilylpropyl isocyanate, triethoxysilylpropyl isocyanate, trimethoxysilylbutyl isocyanate, triethoxysilylbutyl isocyanate, trimethoxysilylpentyl isocyanate, triethoxysilylpentyl isocyanate, trimethoxysilylhexyl isocyanate, and triethoxysilylhexyl isocyanate.

[0100] In a preferred embodiment, (iii) the at least one metal compound of formula (I) as defined above is triethoxysilylpropyl isocyanate.

[0101] (iv) The hydrolyzable group Y' of at least one metal compound of formula (II) defined above is not particularly limited, provided that it allows the formation of the fluoropolymer hybrid organic / inorganic composite of the present invention under suitable conditions.The hydrolyzable group Y' is typically selected from the group consisting of a halogen atom, preferably a chlorine atom, a hydrocarboxy group, an acyloxy group and a hydroxyl group.

[0102] (iv) If the at least one metal compound of formula (II) as defined above contains at least one functional group different from the -N=C=O functional group on the groups X', it is designated as a functional compound. If none of the groups X' contains a functional group different from the -N=C=O functional group, it is designated as a non-functional compound.

[0103] A mixture of one or more functional compounds and one or more non-functional compounds may be used in the process of the present invention as (iv) the at least one metal compound of formula (II) defined above.

[0104] The functional compounds can advantageously further modify the chemistry and properties of the grafted fluoropolymer relative to the neat fluoropolymer and the neat inorganic phase.

[0105] Non-limiting examples of functional groups different from the -N=C=O functional group include epoxy groups, carboxylic acid groups (in its acid, ester, amide, anhydride, salt or halide form), sulfonic acid groups (in its acid, ester, salt or halide form), hydroxyl groups, phosphate groups (in its acid, ester, salt or halide form), thiol groups, amine groups, quaternary ammonium groups, ethylenically unsaturated groups (such as vinyl groups), cyano groups, urea groups, organosilane groups, aromatic groups, among others.

[0106] Examples of functional compounds are, inter alia, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltrismethoxyethoxysilane of formula CH2=CHSi(OC2H4OCH3)3, vinyltrismethoxyethoxysilane of formula: [ka] 2-(3,4-epoxycyclohexylethyltrimethoxysilane), The formula: [ka] glycidoxypropylmethyldiethoxysilane, The formula: [ka] glycidoxypropyltrimethoxysilane, The formula: [ka] methacryloxypropyltrimethoxysilane, The formula: [ka] of aminoethylaminopropylmethyldimethoxysilane, The formula: H2NC2H4NHC3H6Si(OCH3)3 aminoethylaminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-chloroisobutyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, n-(3-acryloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane, (3-acryloxypropyl)dimethylmethoxysilane, (3-acryloxypropyl)methyldichlorosilane, (3-acryloxypropyl)methyldimethoxysilane, 3-(n-allylamino)propyltrimethoxysilane, 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane, 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane, carboxyethylsilanetriol, and sodium salts thereof, the following formula: [ka] triethoxysilylpropylmaleamic acid, 3-(trihydroxysilyl)-1-propane-sulfonic acid of the formula HOSO2-CH2CH2CH2-Si(OH)3, N-(trimethoxysilylpropyl)ethylene-diaminetriacetic acid and its sodium salt of the formula: [ka] 3-(triethoxysilyl)propylsuccinic anhydride of the formula H3C-C(O)NH-CH2CH2CH2-Si(OCH3)3, acetamidopropyltrimethoxysilane of the formula Ti(L) X (OR) Y where L is an amine substituted alkoxy group, such as OCH2CH2NH2, R is an alkyl group, and x and y are integers such that x+y=4.

[0107] Examples of non-functional compounds are, inter alia, trimethoxysilane, triethoxysilane, tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), tetramethyl titanate, tetraethyl titanate, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-isobutyl titanate, tetra-tert-butyl titanate, tetra-n-pentyl titanate, tetra-n-hexyl titanate, tetraisooctyl titanate, tetra tetra-n-lauryl zirconate, tetraethyl zirconate, tetra-n-propyl zirconate, tetraisopropyl zirconate, tetra-n-butyl zirconate, tetra-sec-butyl zirconate, tetra-tert-butyl zirconate, tetra-n-pentyl zirconate, tetra-tert-pentyl zirconate, tetra-tert-hexyl zirconate, tetra-n-heptyl zirconate, tetra-n-octyl zirconate, and tetra-n-stearyl zirconate.

[0108] In a preferred embodiment, (iv) the at least one metal compound of formula (II) is tetraethoxysilane (TEOS).

[0109] At least one acid catalyst may be added in step c) of the process according to the invention.

[0110] The selection of the acid catalyst is not particularly limited.The acid catalyst is typically selected from the group consisting of organic acids and inorganic acids, preferably from the group consisting of organic acids.Among them, formic acid is the preferred acid that can be used in the process according to the present invention.

[0111] A second object of the invention is the polymer electrolyte membrane obtainable by the method according to the invention.

[0112] A third object of the invention is an electrochemical device comprising, between a positive electrode and a negative electrode, a polymer electrolyte membrane obtained by the method according to the invention.

[0113] In one embodiment, at least one of the positive and negative electrodes comprises a metal salt, preferably a transition metal salt, an alkali metal salt or an alkaline earth metal salt, more preferably a Li salt, a Na salt, a K salt or a Cs salt, even more preferably a Li salt.

[0114] Yet another object of the present invention is the use of a polymer electrolyte membrane obtained by the method according to the invention in an electrochemical device, in particular in a secondary battery.

[0115] To the extent that the disclosures of any patents, patent applications, and publications incorporated herein by reference conflict with the statements of this application to the extent that a term may be unclear, this statement shall control.

[0116] The invention will now be described in more detail with reference to the following examples, the purpose of which is merely illustrative and not intended to limit the scope of the invention. EXAMPLES

[0117] raw materials Fluoropolymer: Solef® VDF / HEA / HFP copolymer, available from Solvay Specialty Polymers Italy SpA TSPI: 3-(triethoxysilyl)propyl isocyanate Tetraethoxysilane (TEOS): Commercially available as a liquid from Aldrich Chemistry (>99% purity) Organic solvents: - Ethylene Carbonate (EC) - Propylene Carbonate (PC) - Fluoroethylene carbonate (FEC) - Sulfolane (SL)

[0118] Example 1 (Ex.1) The fluoropolymer was pre-dried overnight under vacuum at 80°C. The fluoropolymer (5.0 g, 10.0 parts by weight relative to the total weight of the organic solvent used) was dissolved in a mixture of EC / PC (1:1 w / w; 45.0 g). After the fluoropolymer was completely dissolved, 106 mg (1.1 mol% relative to the total moles of the fluoropolymer) of TSPi was added to the solution, which was then stirred for mixing at 80°C for 60 minutes. To this was added TEOS (1.6 g) with stirring for 5 minutes, followed by 360 mg (1 equivalent relative to TEOS) of formic acid, also with stirring for 5 minutes, while maintaining the temperature at 80°C. The amount of TEOS was determined to be 10% by weight (m), assuming that the TEOS was totally converted to SiO2. SiO2 / m フルオロポリマー ) was calculated.

[0119] After adding formic acid, the resulting solution was spread to a certain thickness on a HALAR® 9414 film substrate using a tape casting device (Doctor Blade). The film thus prepared was left at 50° C. for 30 minutes to allow the sol-gel reaction to proceed.

[0120] Although N,N-dimethylformamide (DMF) is a good solvent for fluoropolymers, the fluoropolymer electrolyte membrane containing the hybrid organic / inorganic composite prepared above is insoluble in such a solvent. The higher the crosslink density of the membrane, the lower the solubility of the membrane in DMF. Therefore, by using this feature, it is possible to confirm whether a hybrid organic / inorganic composite has been formed or not using a dissolution test in DMF. For this purpose, the membrane was placed in about 5 mL of DMF at room temperature for about 1 minute.

[0121] Examples 2 to 5 (Ex. 2 to 5) Ex2-5 were prepared in the same manner as Ex1, with the only difference being the amount of organic solvent used and the amount of F-polymer (for Ex2 only). For example, in Ex5, a mixture of EC / PC / FEC / SL (20:10:10:60 w / w) was used instead.

[0122] Comparative example 1 (Comp.Ex1) The fluoropolymer was pre-dried overnight at 80°C under vacuum. The fluoropolymer (5.0 g, 10.0 parts by weight relative to the total weight of the organic solvent used) was dissolved in acetone (45.0 g). After the fluoropolymer was completely dissolved, the solution was homogenous and clear after homogenization at room temperature. 106 mg (1.1 mol% relative to the total moles of the fluoropolymer) of TSPi was added to the solution, which was then stirred for mixing at 60°C for 90 minutes. Then, 1 M LiPF6 dissolved in a mixture of EC / MC (50:50) was added to the solution. Subsequently, TEOS (1.6 g) was added to this with stirring for 5 minutes, and then 360 mg of formic acid (1 equivalent relative to TEOS) was also added with stirring for 5 minutes while maintaining the temperature at 60°C to produce a polymer electrolyte membrane of Comp.Ex.1. An additional drying step was performed to evaporate the acetone.

[0123] However, the membranes thus produced still contained residual acetone, the amount of which varied from 600 ppm to 0.65 wt % relative to the total weight of the membrane, which ultimately adversely affected the battery cycling performance.

[0124] The detailed composition is shown in Table 1 below.

[0125] [Table 1]

[0126] *The residual amount of acetone was measured multiple times using a gas chromatograph (Agilent system) equipped with a DB-WAX Ultra Inert Column [30 m (length) * 0.32 mm (inner diameter) * 0.5 μm (membrane)] at temperature conditions starting from 40°C up to 160°C (in 8 min) or 240°C (in 15 min) with a 2 min rest time.

[0127] All experiments were performed under a protected environment (flushed with N2).

Claims

1. 1. A method for producing a fluoropolymer electrolyte membrane comprising a fluoropolymer hybrid organic / inorganic composite for an electrochemical device, comprising: a) dissolving i) at least one fluoropolymer in ii) at least one liquid medium, wherein i) the at least one fluoropolymer is at least one first repeat unit derived from at least one ethylenically unsaturated fluorinated monomer; at least one second repeat unit derived from at least one ethylenically unsaturated monomer having at least one hydroxyl group; a process comprising: b) i) converting at least a portion of said hydroxyl groups of at least one fluoropolymer with iii) at least one metal compound of formula (I): X ４－ｍ AY ｍ (I) (wherein m is an integer from 1 to 3; A is a metal selected from the group consisting of Si, Ti, and Zr; Y is a hydrolyzable group; and X is a hydrocarbon group containing at least one isocyanate (—N═C═O) functional group.) whereby a compound of the formula -O-C(O)-NH-Z-AY is reacted with ｍ X ３－ｍ obtaining a composition comprising at least one grafted fluoropolymer comprising at least one hydrogenated monomer having at least one pendant side chain comprising an end group of the formula: c) Formula -OC(O)-NH-Z-AY ｍ X ３－ｍ the terminal group of iv) at least one metal compound of formula (II) ︸' ４－ｍ’ _'] ｍ’ (=) wherein m' is an integer from 1 to 4; A' is a metal selected from the group consisting of Si, Ti, and Zr; Y' is a hydrolyzable group optionally containing at least one functional group different from a -N=C=O group; and X' is a hydrocarbon group. thereby obtaining a composition comprising at least one fluoropolymer hybrid organic / inorganic composite; d) processing the composition from step c) into a polymer electrolyte membrane; and wherein there is no drying step of the liquid medium, and wherein the at least one liquid medium is aliphatic, cycloaliphatic or aromatic ether oxides; - glycol ethers; - glycol ether esters; - alcohol; - methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, isophorone; - linear or cyclic esters; linear or cyclic amides; - dimethyl sulfoxide; - organic carbonate compounds; and - Sulfone compounds and optionally at least one ionic liquid.

2. The method of claim 1 , wherein the fluoropolymer electrolyte membrane is free of metal salts.

3. The process according to claim 1 or 2, wherein step c) is carried out at a temperature between 50°C and 100°C, preferably between 70°C and 90°C.

4. The method according to any one of claims 1 to 3, wherein said ii) at least one liquid medium comprises at least one ionic liquid.

5. The method of any one of claims 1 to 4, wherein the at least one first repeat unit is derived from vinylidene fluoride (VDF), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), trifluoroethylene, and combinations thereof.

6. The method of any one of claims 1 to 5, wherein the at least one second repeat unit is derived from a (meth)acrylic acid ester having at least one hydroxyl group.

7. 7. The method of claim 6, wherein the (meth)acrylic acid ester having a hydroxyl group comprises 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate, 2-hydroxymethyl acrylate, 2-hydroxymethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl acrylate, 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl acrylate, 8-hydroxyoctyl methacrylate, 2-hydroxyethylene glycol acrylate, 2-hydroxyethylene glycol methacrylate, 2-hydroxypropylene glycol acrylate, 2-hydroxypropylene glycol methacrylate, and mixtures thereof.

8. iii) X in at least one metal compound of formula (I) is the same or different from one another and, in each occurrence, is a linear or branched C ring containing at least one -N=C=O functional group. １～ C １２ Y is the same or different from each other and is OR in each occurrence, R is a straight or branched C １ ~C ５ The method according to any one of claims 1 to 7, wherein the alkyl group is an alkyl group, preferably a methyl group or an ethyl group.

9. 9. The method of claim 8, wherein the at least one metal compound of formula (I) is selected from the group consisting of trimethoxysilylmethyl isocyanate, triethoxysilylmethyl isocyanate, trimethoxysilylethyl isocyanate, triethoxysilylethyl isocyanate, trimethoxysilylpropyl isocyanate, triethoxysilylpropyl isocyanate, trimethoxysilylbutyl isocyanate, triethoxysilylbutyl isocyanate, trimethoxysilylpentyl isocyanate, triethoxysilylpentyl isocyanate, trimethoxysilylhexyl isocyanate, triethoxysilylhexyl isocyanate, and mixtures thereof.

10. The at least one metal compound of formula (II) is selected from the group consisting of trimethoxysilane, triethoxysilane, tetramethoxysilane, tetraethoxysilane (TEOS), tetramethyl titanate, tetraethyl titanate, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-isobutyl titanate, tetra-tert-butyl titanate, tetra-n-pentyl titanate, tetra-n-hexyl titanate, tetraisooctyl titanate, tetra-n-lauryl titanate, 10. The method of any one of claims 1 to 9, comprising tetraethyl zirconate, tetra-n-propyl zirconate, tetraisopropyl zirconate, tetra-n-butyl zirconate, tetra-sec-butyl zirconate, tetra-tert-butyl zirconate, tetra-n-pentyl zirconate, tetra-tert-pentyl zirconate, tetra-tert-hexyl zirconate, tetra-n-heptyl zirconate, tetra-n-octyl zirconate, tetra-n-stearyl zirconate, and mixtures thereof.

11. Use of a polymer electrolyte membrane obtainable by the method according to any one of claims 1 to 10 in an electrochemical device, in particular in a secondary battery.

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