Fluoropolymer membranes for electrochemical devices

Abstract

The present invention relates to a membrane for an electrochemical device, to a process for producing said membrane, and to the use of said membrane in a process for producing an electrochemical device.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to European Patent Application EP 17306762.0, filed December 13, 2017, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to a membrane for an electrochemical device, to a process for producing said membrane, and to the use of said membrane in a process for producing an electrochemical device. [Background technology]

[0003] Fluoropolymers, and in particular vinylidene fluoride polymers, are used in a wide variety of applications, including electrochemical applications.

[0004] For example, fluoropolymers are advantageously used as raw materials in the manufacture of electrodes or membranes suitable for use in electrochemical devices such as secondary batteries due to their resistance to chemicals and heat aging.

[0005] Alkaline or alkaline earth secondary batteries are typically formed by assembling a positive electrode (cathode), an ion-conducting membrane, and a negative electrode (anode). The ion-conducting membrane, often referred to as the separator, plays a vital role in the battery because it must provide high ionic conductivity while ensuring effective separation between the opposing electrodes.

[0006] Suitable electrolytes for use in electrochemical devices such as secondary batteries typically include liquid electrolytes and solid electrolytes. For electrolytes to be suitable for use in secondary batteries, they must exhibit high ionic conductivity, high chemical and electrochemical stability to the electrodes, and high thermal stability over a wide range of temperatures.

[0007] Liquid electrolytes suitable for use in lithium-ion secondary batteries typically comprise a metal salt, such as a lithium salt, dissolved in a suitable organic solvent.

[0008] However, serious safety issues can arise from overheating when the liquid electrolyte is heated above its flash point. In particular, thermal runaway can occur at high temperatures due to the chemical reaction between oxygen released by the cathode material and the organic liquid electrolyte as fuel.

[0009] To solve the safety issues of lithium-ion secondary batteries, gel polymer electrolytes have been investigated, which advantageously combine the advantages of both liquid electrolytes and solid polymer electrolytes, and thus are endowed with high ionic conductivity and high thermal stability.

[0010] Electrolyte membranes can be prepared based on the gel polymer electrolytes described above.

[0011] The preparation of membranes for use in secondary batteries is suitably carried out by a continuous process, but it is necessary to give the membrane good mechanical properties.

[0012] In the continuous process described above, the membrane is actually placed under tension in the coating machine, and in some cases, it is necessary to remove the membrane from the substrate before attaching it to the battery. The membrane must not be damaged in the process, and it must be an easy process to do so. Difficulty in handling the membrane may make industrialization of membrane preparation impossible.

[0013] Membranes known in the art prepared using gel electrolytes face the above problems when prepared by a continuous process.

[0014] Therefore, a need is felt for a gel electrolyte / membrane electrolyte that can be produced by a continuous process in a coating machine, and said membranes possess good mechanical properties and are suitable for use in electrochemical devices, particularly secondary batteries such as lithium ion batteries, exhibiting excellent capacity values ​​while adequately ensuring safety requirements. Summary of the Invention

[0015] It has now surprisingly been found that electrochemical devices, in particular secondary batteries, can be easily manufactured by using the membranes of the present invention.

[0016] It has also been surprisingly found that the membranes of the present invention can be produced in a continuous process on a coating machine without suffering from the deficiencies of membranes known in the art.

[0017] In a first object, the present invention provides a membrane for an electrochemical device, said membrane comprising: (a) at least one fluoropolymer hybrid organic / inorganic composite [polymer (Fh)] containing an inorganic domain (the aforementioned hybrid organic / inorganic composite is - (i) repeat units derived from at least one fluorinated monomer (FM); (ii) Formula: TIFF0007784228000001.tif29161 (wherein R1, R2, and R3 are equal to or different from each other and independently represent a hydrogen atom or a C1-C3 hydrocarbon group; R OH is a C1-C5 hydrocarbon moiety containing at least one hydroxyl group), and - (iii) optionally at least one fluoropolymer [polymer (F)] comprising repeat units derived from at least one fluorinated monomer (FM2) different from VDF. (wherein the polymer (F) has an intrinsic viscosity, measured in dimethylformamide at 25° C., of greater than 0.09 l / g and less than 0.6 l / g), Formula (I): X 4-m AY m (I) (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, and X is a hydrocarbon group, optionally containing one or more functional groups), with at least one metal compound [compound (M)], The inorganic domain is formed by the R of the (meth)acrylic monomer (MA) of at least one compound (M) described above. OH (obtained by grafting at least one compound (M) onto the polymer (F) through reaction with at least a portion of the groups), (b) a liquid medium [medium (L)], and preferably consists of these.

[0018] In a second object, the present invention provides a process for producing a membrane for an electrochemical device.

[0019] In a third object, the present invention provides an electrochemical device, preferably a secondary battery, comprising at least one film of the present invention between a positive electrode and a negative electrode. DETAILED DESCRIPTION OF THE INVENTION

[0020] For the purposes of the present invention, the term "membrane" is intended to mean a discrete, generally thin, interface that restricts 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, containing voids, pores, or holes of finite dimensions (porous membrane).

[0021] The polymer (F) is a fluoropolymer comprising repeating units derived from at least one monomer (FM) and repeating units derived from at least one monomer (MA).

[0022] The term "fluorinated monomer" is intended herein to mean an ethylenically unsaturated monomer containing at least one fluorine atom.

[0023] The term "at least one fluorinated monomer" is understood to mean that the polymer (F) may contain repeat units derived from one or more fluorinated monomers. In the remainder of the text, the expression "fluorinated monomers" is understood for the purposes of the present invention both in the plural and in the singular, i.e., it is understood to mean both one or more fluorinated monomers as defined above.

[0024] The term "at least one (meth)acrylic monomer (MA)" is understood to mean that the polymer (F) can comprise repeat units derived from one or more (meth)acrylic monomers (MA). In the remainder of the text, the expressions "(meth)acrylic monomers" are understood for the purposes of the present invention both in the plural and in the singular, i.e. they are understood to mean both one or more (meth)acrylic monomers as defined above.

[0025] When the fluorinated monomer (FM) contains at least one hydrogen atom, it is referred to as a hydrogen-containing fluorinated monomer.

[0026] If the fluorinated monomer does not contain any hydrogen atoms, it is referred to as a per(halo)fluorinated monomer.

[0027] The fluorinated monomer (FM) may further contain one or more other halogen atoms (Cl, Br, I).

[0028] Non-limiting examples of suitable fluorinated monomers (FM) include, among others: C2 to C8 perfluoroolefins such as tetrafluoroethylene and hexafluoropropylene, C2-C8 hydrogenated fluoroolefins such as vinylidene fluoride, 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, such as chlorotrifluoroethylene; -CF2=CFOX0(per)fluoro-oxyalkyl vinyl ether (wherein X0 is C1-C 12 Alkyl groups, C1-C 12 C1-C groups having one or more ether groups, such as oxyalkyl groups or perfluoro-2-propoxy-propyl groups 12 (per)fluorooxyalkyl groups), Formula CF2 = CFOY0 (wherein Y0 is C1 to C 12 Alkyl group or (per)fluoroalkyl group, C1-C 12 Oxyalkyl group or C1-C having one or more ether groups 12 (per)fluorooxyalkyl groups, Y0 containing a carboxylic or sulfonic acid group in the form of its acid, acid halide or salt), -fluorodioxoles, preferably perfluorodioxoles.

[0029] In a preferred embodiment according to the present invention, the polymer (F) is advantageously a random polymer [polymer (F) comprising a linear sequence of randomly distributed repeating units derived from at least one fluorinated monomer (MA)]. R )].

[0030] The expression "randomly distributed repeat units" is intended to mean representing the percentage ratio between the average number of sequences of at least one monomer (MA), said sequences being contained between two repeat units derived from at least one fluorinated monomer, and the total average number of repeat units derived from at least one monomer (MA).

[0031] When each repeat unit derived from at least one monomer (MA) is isolated, i.e., when a repeat unit derived from a monomer (MA) is contained between two repeat units of at least one fluorinated monomer, the average number of sequences of at least one monomer (MA) is equal to the average total number of repeat units derived from at least one monomer (MA), and therefore the percentage of randomly distributed repeat units derived from at least one monomer (MA) is 100%, which corresponds to a completely random distribution of repeat units derived from at least one monomer (MA). Thus, the greater the number of isolated repeat units derived from at least one monomer (MA) relative to the total number of repeat units derived from at least one monomer (MA), the higher the percentage of randomly distributed repeat units derived from at least one monomer (MA).

[0032] Polymer (F) may optionally further comprise repeat units derived from at least one hydrogenated monomer different from monomer (MA).

[0033] The term "hydrogenated monomer" is intended herein to mean an ethylenically unsaturated monomer containing at least one hydrogen atom and no fluorine atoms.

[0034] The term "at least one hydrogenated monomer" is intended to mean that the polymer (F) may contain repeat units derived from one or more hydrogenated monomers. In the remainder of the text, the expression "hydrogenated monomers" is understood for the purposes of the present invention both in the plural and in the singular, i.e., it is understood to mean both one or more hydrogenated monomers as defined above.

[0035] The polymer (F) can be amorphous or semi-crystalline.

[0036] The term "amorphous" is intended herein to mean a polymer (F) having a heat of fusion of less than 5 J / g, preferably less than 3 J / g, more preferably less than 2 J / g, as measured according to ASTM D-3418-08.

[0037] The term "semi-crystalline" is intended herein to mean a polymer (F) having a heat of fusion, measured according to ASTM D3418-08, of 10 to 90 J / g, preferably of 30 to 60 J / g, more preferably of 35 to 55 J / g.

[0038] The polymer (F) is preferably semi-crystalline.

[0039] The polymer (F) preferably comprises at least 0.01 mol %, more preferably at least 0.05 mol %, even more preferably at least 0.1 mol % of repeat units derived from at least one monomer (MA).

[0040] The polymer (F) preferably comprises at most 10 mol %, more preferably at most 5 mol %, even more preferably at most 3 mol % of repeat units derived from at least one monomer (MA).

[0041] The determination of the average molar percentage of repeat units derived from at least one monomer (MA) in the polymer (F) can be carried out by any suitable method, and in particular the acid-base titration method or the NMR method can be mentioned.

[0042] The polymer (F) is preferably a partially fluorinated fluoropolymer.

[0043] For the purposes of the present invention, the term "partially fluorinated fluoropolymer" is intended to mean a polymer comprising repeat units derived from at least one fluorinated monomer and repeat units derived from at least one monomer (MA), wherein the fluorinated monomer comprises at least one hydrogen atom.

[0044] According to a first embodiment of the present invention, the polymer (F) is preferably a partially fluorinated fluoropolymer comprising repeat units derived from vinylidene fluoride (VDF), at least one monomer (MA), and at least one fluorinated monomer (FM2).

[0045] The polymer (F) of this first embodiment of the invention is more preferably at least 60 mol%, preferably at least 75 mol%, more preferably at least 85 mol% vinylidene fluoride (VDF), 0.01 mol % to 10 mol %, preferably 0.05 mol % to 5 mol %, more preferably 0.1 mol % to 3 mol % of at least one monomer (MA), and It contains 0.1 mol % to 15 mol %, preferably 0.1 mol % to 12 mol %, and more preferably 0.1 mol % to 10 mol % of repeating units derived from at least one monomer (FM2) selected from vinyl fluoride (VF1), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE).

[0046] Non-limiting examples of monomers (MA) containing at least one hydroxyl end group include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyethylhexyl (meth)acrylate, among others.

[0047] The monomers (MA) are preferably chosen from: -formula: Hydroxyethyl acrylate (HEA) from TIFF0007784228000002.tif25161; formula: 2-hydroxypropyl acrylate (HPA) of any of TIFF0007784228000003.tif34161, - and mixtures thereof.

[0048] The polymer (F) can typically be obtained by polymerization of at least one fluorinated monomer, at least one monomer (MA) as defined above, and optionally a fluorinated monomer (FM2).

[0049] The polymer (F) can typically be obtained by emulsion polymerization or suspension polymerization.

[0050] Preferably, the intrinsic viscosity of the polymer (F), measured in dimethylformamide at 25° C., is less than 0.50 l / g, more preferably less than 0.45 l / g.

[0051] The polymer (Fh) typically comprises, and preferably consists of, fluoropolymer domains and inorganic domains.

[0052] The polymer (Fh) can be prepared, for example, according to the procedure described in WO 2015 / 169834.

[0053] In particular, the polymer (Fh) - R of the monomer (MA) of the polymer (F) in the presence of a liquid medium [medium (L)] OH with at least a portion of the compound (M), to form a compound of the formula -Y m-1 AX 4-m a first step resulting in a polymer (F) comprising pendant groups of a first step in which m, Y, A, and X have the same meanings as detailed above; - a second step of hydrolyzing and / or condensing at least one pendant group of the compound (M) and / or the polymer (F) obtained in the first step.

[0054] The polymer (Fh) is conveniently obtained in the form of a solution in a liquid medium (L).

[0055] In the second step, the process proceeds by reacting compound (M) and / or pendant-Y as detailed above. m-1 AX 4-m The method includes a step of hydrolyzing and / or polycondensing the groups to produce a polymer (Fh).

[0056] The hydrolysis / polycondensation can be carried out simultaneously with the reaction of the hydroxyl groups of the polymer (F) with the compound (M) in the first step, or can be carried out after said reaction has taken place.

[0057] Typically, this hydrolysis / polycondensation is initiated by the addition of a suitable catalyst / reactant, particularly for compounds where A=Si. Generally, water or a mixture of water and acid can be used to facilitate this reaction.

[0058] The choice of acid is not particularly limited, and both organic and inorganic acids can be used. Preferred acids that can be used in the process of the present invention are hydrochloric acid and formic acid.

[0059] When polymer (F) and compound (M) are reacted in the melt, the preferred method would be to inject water vapor, optionally in combination with a volatile acid, to promote hydrolysis / polycondensation.

[0060] When the reaction of the polymer (F) with the compound (M) is carried out in a solution, it would be preferable to add an aqueous medium, preferably an aqueous medium containing an acid, in order to promote hydrolysis / polycondensation.

[0061] While this hydrolysis / polycondensation can be carried out at room temperature, it is generally preferred to carry out this step at elevated temperatures above 50°C.

[0062] In the case of a reaction in a molten state, the temperature is in the range of 150 to 250°C, which corresponds to the melting point of the polymer (F), and in the case of a reaction in a solution, the temperature is selected taking into consideration the boiling point of the solvent. Generally, a temperature of 50 to 150°C, preferably 60 to 120°C, is preferred.

[0063] It is understood that in this step, the hydrolyzable groups of compound (M) react to produce a hybrid composite containing a polymer domain consisting of a chain of polymer (F) and an inorganic domain consisting of residues derived from compound (M).

[0064] The fluoropolymer hybrid organic / inorganic composite containing inorganic domains can be recovered by standard methods, which will vary depending on the techniques used for the various reaction steps.

[0065] The selection of the hydrolyzable group Y of the compound (M) of formula (I) as defined above is not particularly limited, provided that, under appropriate conditions, the hydrolyzable group Y can be obtained by the reaction of A of the compound (M) with R of the monomer (MA). OH The hydrolyzable group Y of compound (M) defined above is typically selected from the group consisting of halogen atoms, preferably chlorine atoms, hydrocarboxy groups, acyloxy groups and hydroxyl groups.

[0066] According to a preferred embodiment, X of compound (M) is R A and Y is OR B where R A and R B are equal to or different from each other, and for each occurrence, C1 to C 18 R is independently selected from hydrocarbon groups; A optionally includes at least one functional group.

[0067] If the compound (M) defined above contains at least one functional group at X, it is designated as a functional compound (M1), and if none of the Xs of the compound (M) defined above contains a functional group, the compound (M) is designated as a non-functional compound (M2).

[0068] Non-limiting examples of functional groups that may be present on X include, inter alia, epoxy groups, carboxylic acid groups (in the form of their acids, esters, amides, anhydrides, salts or halides), sulfonic groups (in the form of their acids, esters, salts or halides), hydroxyl groups, phosphate groups (in the form of their acids, esters, salts or halides), thiol groups, amine groups, quaternary ammonium groups, ethylenically unsaturated groups (such as vinyl groups), cyano groups, urea groups, organo-silane groups, aromatic groups.

[0069] According to a more preferred embodiment, the compound (M) is a compound (M1) in which m is an integer from 1 to 3, A is a metal selected from the group consisting of Si, Ti and Zr, and X is R A’ and Y is OR B’ where R A’ is a C1-C group containing at least one functional group 12 is a hydrocarbon group, R B’ is a C1 to C5 linear or branched alkyl group, preferably a methyl or ethyl group.

[0070] Examples of functional compounds (M1) are in particular vinyltriethoxysilane, vinyltrimethoxysilane, vinyltrismethoxyethoxysilane of formula CH2=CHSi(OC2H4OCH3)3, vinyltrismethoxyethoxysilane of formula: 2-(3,4-epoxycyclohexylethyltrimethoxysilane) from TIFF0007784228000004.tif23161, formula: Glycidoxypropylmethyldiethoxysilane from TIFF0007784228000005.tif25161, formula: Glycidoxypropyltrimethoxysilane from TIFF0007784228000006.tif18161, formula: Methacryloxypropyltrimethoxysilane from TIFF0007784228000007.tif19161, formula: Aminoethylaminepropylmethyldimethoxysilane from TIFF0007784228000008.tif18161, formula: TIFF0007784228000009.tif14161 aminoethylaminepropyltrimethoxysilane, 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, of the formula: TIFF0007784228000010.tif22161 triethoxysilylpropyl maleic acid, 3-(trihydroxysilyl)-1-propane-sulfonic acid of formula HOSO2-CH2CH2CH2-Si(OH)3, N-(trimethoxysilylpropyl)ethylene-diaminetriacetic acid, and its sodium salt, of formula: TIFF0007784228000011.tif32161 3-(triethoxysilyl)propylsuccinic anhydride, acetamidopropyltrimethoxysilane of formula H3C-C(O)NH-CH2CH2CH2-Si(OCH3)3, 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 t+y=4.

[0071] Examples of non-functional compounds (M2) are in particular 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 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.

[0072] According to another preferred embodiment, X of compound (M) is a C1-C aryl group containing at least one -N=C=O functional group. 12 is a hydrocarbon group, and A and Y are as defined above, in which case compound (M) is represented as compound (M').

[0073] According to an even more preferred embodiment, in compound (M'), Y is OR D where R D is a C1 to C5 linear or branched alkyl group, preferably R D is a methyl or ethyl group.

[0074] Non-limiting examples of suitable compounds (M′) according to this embodiment include the following: 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.

[0075] According to a preferred embodiment, the at least one polymer (Fh) contained in the membrane of the invention is at least one [polymer (F)] as defined above, at least one metal compound (M') as defined above, and - obtained by reaction of at least one metal compound (M2) as defined above.

[0076] For the purposes of the present invention, the term "liquid medium [medium (L)]" is intended to mean a medium comprising one or more substances that are in the liquid state at 20° C. under atmospheric pressure.

[0077] The medium (L) comprises at least one metal salt (MS).

[0078] The medium (L) typically does not include one or more solvents (S).

[0079] The choice of medium (L) is not particularly limited, provided that it is suitable for solubilizing the metal salt (MS).

[0080] The amount of medium (L) in the membrane of the present invention is typically at least 40% by weight, preferably at least 50% by weight, more preferably at least 60% by weight, based on the total weight of said medium (L) and at least one polymer (Fh).

[0081] According to a preferred embodiment of the invention, the liquid medium (L) comprises at least one organic carbonate.

[0082] Non-limiting examples of suitable organic carbonates include, among others, ethylene carbonate, propylene carbonate, mixtures of ethylene carbonate and propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl-methyl carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, fluoropropylene carbonate, and mixtures thereof.

[0083] Other suitable liquid media (L) may include esters, preferably ethyl propionate or propyl propionate, acetonitrile, γ-butyrolactone, dimethyl ether, 1,2 dimethoxyethane, and fluorocarbonates.

[0084] The metal salt (MS) is typically (a)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 , Me[N(CF3SO2)(R F SO2)] n (In the formula, R F is C2F5, C4F9 or CF3OCF2CF2), Me(AsF6) n , Me[C(CF3SO2)3] n , Me2S n wherein Me is a metal, preferably a transition metal, alkali metal or alkaline earth metal, more preferably Me is Li, Na, K, Cs, Mg, Ca and Al, even more preferably Me is Li, and n is the valence of said metal, (b) TIFF0007784228000012.tif23161(in the formula, R' F are F, CF3, CHF2, CH2F, C2HF4, C2H2F3, C2H3F2, C2F5, C3F7, C3H2F5, C3H4F3, C4F9, C4H2F7, C4H4F5, C5F 11 , C3F5OCF3, C2F4OCF3, C2H2F2OCF3 and CF2OCF3), and (c) selected from the group consisting of combinations thereof.

[0085] Preferably, the metal salt is LiPF6.

[0086] The concentration of metal salt (MS) in the medium (L) of the membrane of the invention is advantageously at least 0.01M, preferably at least 0.025M and more preferably at least 0.05M.

[0087] The concentration of metal salt (MS) in the medium (L) of the membrane of the invention is advantageously at most 5M, preferably at most 2M, more preferably at most 1M.

[0088] In a second object, the present invention provides a process for producing a membrane for an electrochemical device, said process comprising: (A) preparing a solution of at least one defined polymer (Fh) in a liquid medium (L); (B) treating the solution obtained in step (A) to form a polymer electrolyte membrane; (C) drying the polymer electrolyte membrane prepared in step (B).

[0089] In step (B), the solution of polymer (Fh) in liquid medium (L) can be treated in a continuous or discontinuous process.

[0090] In a continuous process, the solution is fed into a coating machine onto which the sheet material can be placed, such as a roll-to-roll slot die coating machine.

[0091] The continuous process in the coater is preferably carried out at room temperature in a controlled environment.

[0092] In a non-continuous process, the solution is suitably cast at a consistent thickness onto an inert substrate using a tape casting machine such as a doctor blade in a dry chamber.

[0093] Membranes for electrochemical devices of the invention can be advantageously obtained by a process according to this second object of the invention.

[0094] The membranes of the present invention are particularly suitable for use in electrochemical devices, especially secondary batteries.

[0095] For the purposes of the present invention, the term "secondary battery" is intended to mean a rechargeable battery.

[0096] The secondary battery of the present invention is preferably a secondary battery based on any of lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), zinc (Zn), aluminum (Al), and yttrium (Y).

[0097] The secondary battery of the present invention is more preferably a lithium ion secondary battery.

[0098] In a third object, the present invention provides an electrochemical device, preferably a secondary battery, comprising at least one film of the present invention between a positive electrode and a negative electrode.

[0099] To the extent that the disclosure of any patent, patent application, and publication incorporated herein by reference contradicts the statement of this application to the extent that the term may be unclear, the statement shall control.

[0100] The present invention will now be described in more detail with reference to the following examples, the purpose of which is illustrative only and not intended to limit the scope of the invention. [Example]

[0101] raw materials Polymer 1: VDF-AA (0.9 mol %)-HFP (2.4 mol %) polymer with an intrinsic viscosity of 0.30 l / g in DMF at 25°C. Polymer 2 - Comparison: VDF-HEA (0.8 mol %)-HFP (2.4 mol %) polymer with an intrinsic viscosity of 0.077 l / g in DMF at 25°C. Polymer (FA): VDF-HEA (0.6 mol%)-HFP (2.5 mol%) polymer with an intrinsic viscosity of 0.097 l / g in DMF at 25°C. LiPF6: lithium hexafluorophosphate salt. NMC: commercially available from Umicore, LiNi 0.33 Mn 0.33 Co 0.33 O2. Liquid medium (LA): Solution of LiPF6 (1 mol / L) in ethylene carbonate (EC) / propylene carbonate (PC) (1 / 1 by volume) containing vinylene carbonate (VC) (2 wt%). Graphite: 75% SMG HE2-20 (Hitachi Chemical Co., Ltd.) / 25% TIMREX® SFG6. DBTDL: Dibutyltin dilaurate. TEOS: tetraethoxysilane. TSPI: 3-(triethoxysilyl)propyl isocyanate.

[0102] Synthesis of Polymer 1 (not according to the invention): An 80-liter reactor equipped with an impeller rotating at 250 rpm was sequentially charged with 50.4 kg of demineralized water and 0.6 g / kg of ethylhydroxyethylcellulose derivative MnT (commercially available from AkzoNobel as Bermocoll® E230 FQ). The reactor was sequentially purged with vacuum (30 mmHg) and nitrogen at 20°C. Next, 3.0 g / kg of t-amyl perpivalate MnT in isododecane (a 75 wt% solution of t-amyl perpivalate, commercially available from Arkema) was added. The stirring speed was increased to 300 rpm. Finally, acrylic acid (AA, initial amount) and hexafluoropropylene (HFP) monomer were introduced into the reactor, followed by vinylidene fluoride (VDF). The monomer amounts and temperature conditions are shown in Table 1. The reactor was gradually heated to the set-point temperature at a fixed temperature as indicated in the table, and the pressure was fixed at 120 bar. The pressure was kept constant at 120 bar by feeding a constant amount of AA (feed amount) diluted with an aqueous solution of AA ([AA] in water) with the concentration of AA indicated in Table 1. After this feeding, no further aqueous solution was introduced and the pressure began to decrease. The polymerization was then stopped by venting the reactor until atmospheric pressure was reached. The polymer thus obtained was then recovered, washed with demineralized water, and oven-dried at 65°C.

[0103] TIFF0007784228000013.tif67161

[0104] Polymer 2 - Comparative Synthesis: An 80-liter reactor equipped with an impeller rotating at 300 rpm was sequentially charged with 58,242 g of demineralized water and 11.1 g of METHOCEL® K100 GR suspending agent (available from Dow). The reactor was sequentially purged with vacuum (30 mmHg) and nitrogen at 14°C. Next, 149.9 g of a 75 wt. % solution of t-amyl perpivalate initiator in isododecane was charged to the reactor, followed by 21.6 g of hydroxyethyl acrylate (HEA) and 1,873 g of hexafluoropropylene (HFP) monomer. Finally, 16,597 g of vinylidene fluoride (VDF) was charged to the reactor. The reactor was gradually heated to a set-point temperature of 57°C, and the pressure was fixed at 110 bar. During the polymerization, the pressure was kept constant at 110 bar by feeding 13 kg of an aqueous solution containing 240.6 g of HEA. After this feeding, no more aqueous solution was introduced and the pressure began to drop to 80 bar. The polymerization was then stopped by venting the reactor until atmospheric pressure was reached. In general, a conversion of approximately 75% of the monomers was obtained. The polymer thus obtained was then recovered, washed with demineralized water and oven-dried at 65°C.

[0105] Synthesis of polymer (FA): An 80-liter reactor equipped with an impeller rotating at 250 rpm was sequentially charged with 49,992 g of demineralized water and 15.2 g of METHOCEL® K100 GR suspending agent. The reactor was sequentially purged with vacuum (30 mmHg) and nitrogen at 20°C. Next, 204.4 g of a 75 wt. % solution of t-amyl perpivalate initiator in isododecane was charged. The stirring speed was increased to 300 rpm. Finally, 20.4 g of hydroxyethyl acrylate (HEA) and 2,555 g of hexafluoropropylene (HFP) monomer were charged into the reactor, followed by 22,735 g of vinylidene fluoride (VDF). The reactor was gradually heated to a set-point temperature of 55°C, and the pressure was fixed at 120 bar. During the polymerization, the pressure was kept constant at 120 bar by feeding 16.9 kg of an aqueous solution containing 235 g of HEA. After this feeding, no more aqueous solution was introduced and the pressure began to drop to 90 bar. The polymerization was then stopped by venting the reactor until atmospheric pressure was reached. In general, a conversion of approximately 76% of the monomers was obtained. The polymer thus obtained was then recovered, washed with demineralized water and oven-dried at 65°C.

[0106] Mechanical property procedures The mechanical properties are measured at room temperature on dumbbell specimens using a Shimadzu Autograph AG-X Plus at a speed of 50 mm / min.

[0107] Determination of the intrinsic viscosity of the polymer (F) The intrinsic viscosity (η) [dl / g] was calculated using an Ubbelhode viscometer based on the dropwise addition time at 25°C of a solution obtained by dissolving the polymer (F) in N,N-dimethylformamide at a concentration of about 0.2 g / dl, according to the following equation: TIFF0007784228000014.tif20161 (where c is the polymer concentration [g / dl] and η r is the relative viscosity, i.e., the ratio between the dropping time of the sample solution and the dropping time of the solvent, and η sp is the specific viscosity, i.e., η r-1, and Γ is an empirical factor, which is equal to 3 for polymer (F). was measured using

[0108] General procedure for producing electrodes by a continuous process at pilot scale using liquid media (LA). Anode: A solution of polymer 1 in acetone was prepared at 60°C and then brought to room temperature in an argon glove box (O<2 ppm, H<2 ppm). In the next step, the liquid medium (LA) was added to the solution thus obtained. The weight ratio [m 媒体(L-A) / (m 媒体(L-A) +m ポリマー1 )]×100 was 75%. Graphite was added to the solution thus obtained in a weight ratio of 90 / 10 (graphite / polymer 1). Cathode: Add the liquid medium (LA) to the acetone solution of polymer 1 in a weight ratio [mm 媒体(LA) / (m 媒体(LA) +m ポリマー1 )] × 100 was 76.7%.

[0109] A composition containing 50 wt% C-NERGY® SUPER C65 carbon black and 50 wt% VGCF® carbon fiber (CF) and NMC blend was added to the resulting solution in a weight ratio of 92.8 / 7.2 ((CF+LFP) / polymer 1). The CF / NMC weight ratio was 7.7 / 92.3.

[0110] Electrode coating procedure The solution mixture was fed into a roll-to-roll slot die coating machine (Ingecal - custom made) in a controlled dry environment (22°C with a dew point of -20°C). The machine parameters in use were as follows: - Line speed: 0.5m / min - Drying section: 1st and 2nd zones at 40°C, 3rd zone at 50°C and 4th zone at 60°C

[0111] Slot die: 195 microns average for anodes deposited on Cu substrates, 390 microns average for cathodes deposited on Al substrates.

[0112] Electrode densification procedure The electrodes are then densified by calendering, so that the final thickness of the anode is 71 μm, while the cathode is 76 μm.

[0113] General procedure for producing membranes by a non-continuous process (batchwise) on a laboratory scale using a liquid medium (LA). 1.5 g of Polymer 2-Comparative or Polymer (FA) was dissolved in 8.5 g of acetone at 60°C, thereby obtaining a solution containing 15 wt% of the aforementioned polymer. The solution was homogenous and transparent after homogenization at room temperature. Then, DBTDL (0.015 g) was added. The solution was homogenized at 60°C. TSPI (0.060 g) was added thereto. The solution was kept at 60°C for about 90 minutes to allow the isocyanate functional groups of TSPI to react with the hydroxyl groups of the polymer. In the next step, a liquid medium (LA) was added to the thus obtained solution. The weight ratio [m 媒体(L-A) / (m 媒体(L-A) +m ポリマー) After homogenization at 60°C, formic acid was added. Then, TEOS was added to it. Assuming that TEOS was completely converted to SiO2, the amount of TEOS was calculated by the weight ratio (m SiO2 / m ポリマー ) This ratio was 10%. The amount of formic acid was calculated using the following formula: ギ酸 / n TEOS = 7.8. All components were added to the resulting solution mixture under an argon atmosphere. The solution mixture was cast onto a PET substrate at a constant thickness using a tape casting machine (doctor blade) in a dry room (dew point: -40°C). The thickness was controlled by the distance between the knife and the PET film. The solvent rapidly evaporated from the solution mixture, resulting in a film. After several hours, the film was removed from the PET substrate. The film thus obtained had a constant thickness of 32 μm.

[0114] General procedure for producing membranes by a continuous process at pilot scale using a liquid medium (LA). Preparation of solutions 10 g of polymer 2 or polymer (FA) was dissolved in 67 g of acetone at 60°C, thereby obtaining a solution containing 13 wt% of the aforementioned polymer. The solution was homogenous and transparent after homogenization at room temperature. Then, DBTDL (0.10 g) was added. The solution was homogenized at 60°C. TSPI (0.40 g) was added thereto. The solution was kept at 60°C for about 90 minutes to allow the isocyanate functional groups of TSPI to react with the hydroxyl groups of the polymer. In the next step, liquid medium (LA) was added to the thus obtained solution. The weight ratio [m 媒体(L-A) / ( 媒体(L-A) +m ポリマー After homogenization at 60°C, formic acid was added. Then, TEOS was added to it. Assuming that TEOS was completely converted to SiO2, the amount of TEOS was calculated by the weight ratio (m SiO2 / m ポリマー ) This ratio was 10%. The amount of formic acid was calculated using the following formula: ギ酸 / n TEOS = 3.27 All components were added to the solution mixture thus obtained under an argon atmosphere.

[0115] Roll-to-roll slot die coating machine (Ingecal - custom made) The solution mixture prepared above was fed into the coating machine at room temperature. The La machine is in a controlled environment (22°C with a dew point of -20°C). Machine parameters in use: -Line speed: 1m / min Drying section: 1st and 2nd zones at 40°C, 3rd zone at 50°C and 4th zone at 60°C. -Slot die: average 300 microns producing a film of about 50 microns deposited on the PET substrate.

[0116] Example 1: A membrane made by a continuous process on a pilot scale using the polymer (FA) of the present invention is prepared according to the procedure described above. The obtained membrane has a thickness of 60 microns, is easily removed from the substrate, and is easy to handle due to the membrane's good mechanical properties. The mechanical properties in both directions were recorded. The MD (machine direction) and TD (transverse direction) are shown in Table 2.

[0117] Example 2: Films made by a continuous process on a pilot scale using Polymer 2-Comparative were prepared according to the procedure described above. The resulting films were 55 microns thick and difficult to remove from the substrate. They were also difficult to handle and could be easily damaged due to their lack of good mechanical properties.

[0118] Example 3: A laboratory-scale, batch-type, non-continuous membrane made using the polymer (FA) of the present invention was prepared according to the procedure described above. The resulting membrane had a thickness of 41 microns and was easily removed from the substrate. The mechanical properties of the membrane are shown in Table 2.

[0119] Comparative Example 4: A laboratory-scale, batch-type, non-continuous membrane made using Polymer 2-Comparative was prepared according to the procedure described above. The resulting membrane had a thickness of 48 microns and was removed from the substrate with difficulty to avoid any damage. The mechanical properties of the membrane are shown in Table 2.

[0120] TIFF0007784228000015.tif72161

[0121] Example 5: Fabrication of a lithium-ion battery with the membrane of Example 1. A pouch cell (4 × 4 cm) was charged with a membrane prepared according to the general procedure detailed above at the cathode (2.2 mAh / cm 2 ) and anode (2.8mAhcm 2) The pouch cell has a capacity of 35.3 mA / hr. The pouch cell was cycled between 2.8 V and 4.15 V. After two cycles at C / 20-D / 20, the test protocol was carried out following a consecutive series of five cycles at C / 10-D / 10, C / 5-D / 5, C / 2-D / 2, C / 2-D, and C / 2-2D. The discharge capacity values ​​of the pouch cell thus obtained at different discharge rates are shown in Table 3 herein below.

[0122] TIFF0007784228000016.tif100161

[0123] The secondary battery of the present invention was found to function adequately.

Claims

1. 1. A method for producing a membrane for an electrochemical device by a continuous process, the continuous process comprising: (A) (b) Providing at least one solution of (a) at least one fluoropolymer hybrid organic / inorganic composite [polymer (Fh)] comprising inorganic domains in a liquid medium [medium (L)] (The hybrid is at least one fluoropolymer [polymer (F)], (i) at least 60 mol %, preferably at least 75 mol %, more preferably at least 85 mol % vinylidene fluoride (VDF); (ii) 0.01 mol % to 10 mol %, preferably 0.05 mol % to 5 mol %, more preferably 0.1 mol % to 3 mol % of at least one of the formula (wherein R1, R2, and R3 are each equal to or different from each other and independently represent a hydrogen atom or C １ ~C ３ is a hydrocarbon group, R ＯＨ is a C containing at least one hydroxyl group １ ~C ５ a repeating unit derived from a (meth)acrylic monomer [monomer (MA)] of the formula (I) (which is a hydrocarbon moiety); (iii) 0.1 mol% to 15 mol%, preferably 0.1 mol% to 12 mol%, more preferably 0.1 mol% to 10 mol% of vinyl fluoride (VF １ ), repeating units derived from at least one fluorinated monomer (FM2) selected from chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE); At least one fluoropolymer [polymer (F)] comprising wherein the polymer (F) has an intrinsic viscosity, measured in dimethylformamide at 25° C., of greater than 0.09 l / g and less than 0.6 l / g; Formula (I): X ４－ｍ AY ｍ (I) 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, and X is a hydrocarbon group, optionally containing one or more functional groups. and at least one metal compound [compound (M)] of is obtained by the reaction The inorganic domain is formed by the R of the (meth)acrylic monomer (MA) of at least one compound (M). ＯＨ by grafting said at least one compound (M) onto said polymer (F) through reaction with at least a portion of the groups The liquid medium (L) comprises at least one organic carbonate and at least one metal salt (MS), the metal salt being preferably LiPF ６ ) and (B) treating the solution obtained in step (A) to form a polymer electrolyte membrane; (C) drying the polymer electrolyte membrane prepared in step (B).

2. 2. The method of claim 1, wherein the fluorinated monomer (FM2) is selected from the group consisting of chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP) and tetrafluoroethylene (TFE), preferably selected from the group consisting of HFP and TFE.

3. The monomer (MA) is -formula: hydroxyethyl acrylate (HEA), formula: 2-hydroxypropyl acrylate (HPA) of any one of the above 3. The method according to claim 1 or 2, wherein the hydroxybenzoate is selected from the group consisting of hydroxybenzoates, ...

4. 4. The method according to claim 1, wherein the polymer (F) is a vinylidene fluoride (VDF)-hydroxyethyl acrylate (HEA)-hexafluoropropylene (HFP) terpolymer.

5. 5. The process according to any one of claims 1 to 4, wherein the intrinsic viscosity of the polymer (F), measured in dimethylformamide at 25°C, is less than 0.50 l / g, more preferably less than 0.45 l / g.

6. X in compound (M) is R Ａ and Y is OR Ｂ wherein R Ａ and R Ｂ are equal to or different from each other, and for each occurrence, C １～ C １８ R is independently selected from hydrocarbon groups; Ａ The method of any one of claims 1 to 5, wherein optionally comprises at least one functional group.

7. The compound (M) is a functional compound (M1), and the functional compound (M1) is vinyltriethoxysilane, vinyltrimethoxysilane, a compound of the formula CH ２ = CHSi(OC ２ H ４ OCH ３ ) ３ vinyltrismethoxyethoxysilane of the formula: 2-(3,4-epoxycyclohexylethyltrimethoxysilane), formula: glycidoxypropylmethyldiethoxysilane, formula: glycidoxypropyltrimethoxysilane, formula: methacryloxypropyltrimethoxysilane, formula: aminoethylamine propylmethyl dimethoxysilane, formula: aminoethylaminepropyltrimethoxysilane, 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 formula: of triethoxysilylpropyl maleate, Formula HOSO ２ -CH ２ CH ２ CH ２ -Si(OH) ３ 3-(trihydroxysilyl)-1-propane-sulfonic acid, N-(trimethoxysilylpropyl)ethylene-diaminetriacetic acid, and its sodium salt, of the formula: 3-(triethoxysilyl)propylsuccinic anhydride, Formula H ３ C-C(O)NH-CH ２ CH ２ CH ２ -Si(OCH ３ ) ３ acetamidopropyltrimethoxysilane of formula Ti(L) ｔ (OR) ｚ wherein L is an amine-substituted alkoxy group, e.g., OCH ２ CH ２ NH ２ wherein R is an alkyl group, and t and z are integers such that t+z=4.

8. The compound (M) is a non-functional compound (M2), and the non-functional compound (M2) 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, and tetra-n-lauryl 7. The method of any one of claims 1 to 6, wherein the carboxylic acid ester is selected from the group consisting of titanate, 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.

9. The method according to any one of claims 1 to 6, wherein compound (M) is compound (M'), and compound (M') 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, and triethoxysilylhexyl isocyanate.

10. The method according to claim 1, wherein the solution of polymer (Fh) in medium (L) is fed to a coating machine onto which a sheet material can be placed.

11. The method of claim 1, wherein the continuous process is carried out at room temperature.

Images