WO2024228000A1 - Composition in powder form based on a fluorinated polymer or a hydrophilic polymer - Google Patents

Abstract

The present invention relates to a composition in powder form comprising a polymer P1 comprising monomer units derived from a vinylidene fluoride monomer M0 or monomer units derived from a monomer M2 of formula R1R2C=C(R3)C(O)R, wherein the substituents R1, R2 and R3 are, independently of one another, chosen from the group consisting of H and C1-C5 alkyl; R is chosen from the group consisting of –NHC(CH3)2CH2C(O)CH3 or –OR' with R' is chosen from the group consisting of H and C1‐C18 alkyl optionally substituted by one or more –OH groups or a five- or six-membered heterocycle comprising at least one nitrogen atom in its cyclic chain; or a mixture of the M0 or M2 monomer units; characterised in that the polymer P1 has a Dv99 particle size distribution of less than 89 µm and a Dv10 size distribution of greater than 2.0 µm.

Description

DESCRIPTION

Title: Composition in powder form based on a fluorinated polymer or a hydrophilic polymer

Technical field

The present invention relates generally to the field of electrical energy storage in rechargeable secondary batteries of the Li-ion type. More specifically, the invention relates to a composition suitable for use as a coating for a separator.

Technological background of the invention

The market for separators for electrochemical devices is dominated by the use of polyolefins (e.g. Celgard® or Hipore®) produced by extrusion and/or stretching via dry or wet processes. The separators must have low thicknesses, an optimal affinity for the electrolyte and sufficient mechanical and temperature resistance. Among the most interesting alternatives to polyolefins, polymers with a better affinity for standard electrolytes have been proposed, in order to reduce the internal resistances of the system, such as poly(methylmethacrylate) (PMMA), poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-hexafluoropropene) (P(VDF-co-HFP)). Another option is to deposit a coating on one or both sides of the polyolefin separator. The main evaluation criteria for a separator coating are: dry adhesion, wet adhesion, ionic conductivity and heat stability.

Dry adhesion is measured after assembly, by pressing or lamination, of the coated separator with an electrode. This adhesion increases with the temperature and the pressure applied post coating. However, it is desirable to use mild pressing/lamination conditions: reduced pressure to avoid/limit pore closure and therefore minimize the impact on ionic conductivity, moderate temperature to limit energy consumption and maintain high line speed/productivity.

The wet adhesion of the coating to the separator is measured after impregnation with the electrolyte. This adhesion decreases when the coating is softened by the electrolyte solvents, leading to swelling of the polymer present in the coating, eventually to dissolution of the coating. The percentage of swelling or even dissolution or loss of integrity are used as a first indication of the wet adhesion performance.

Ionic conductivity represents the migration of Li ions through the separator and its coating, due to porosity. In aqueous coating, this porosity corresponds to the interstices between the solid particles that make up the coating: polymer particles (from latex or a powder redispersed in water) and/or ceramics. In solvent-based coating, this porosity is created by phase inversion (exposure to moisture of the acetone-based coating, for example) required before or during drying; without phase inversion, simple evaporation of the solvent forms a continuous non-porous coating. Gurley air permeability is used as a first indication of ionic conduction. Beyond the air permeability of the initial coated separator, other aspects can affect the ionic conductivity: the interaction with the electrolyte (favorable when a slight swelling of the polymer allows to improve the wettability/affinity for the electrolyte, unfavorable when too much swelling of the polymer leads to reduce/clog the pores), the effect of pressing or lamination (reduces/clogs the pores). The thermal stability is low for polyolefin separators alone (in PE or PP or PP/PE/PP multilayer), which present a significant shrinkage at temperature. The thermal stability can be significantly improved by a coating containing inorganic particles.

Polyvinylidene fluoride (PVDF) and its derivatives are of interest as the main constituent material of the separator and also as a coating of polyolefin separator, for their electrochemical stability, and for their high dielectric constant which promotes the dissociation of ions and therefore the conductivity. The copolymer P(VDF-co-HFP) (copolymer of vinylidene fluoride (VDF) and hexafluoropropylene (HFP)) has a lower crystallinity than PVDF. Therefore, the interest of these copolymers of P(VDF-co-HFP) is that they promote the conductivity.

There is still a need to develop new coatings for separators that are easy to implement and have a good compromise between dry adhesion, wet adhesion and ionic conductivity.

The invention therefore aims to remedy at least one of the drawbacks of the prior art, namely to propose a polymeric coating for a separator capable of preventing swelling or dissolution in one or more electrolyte solvents, while maintaining good adhesion properties and good ionic conductivity.

Summary of the invention

According to a first aspect, the present invention relates to a composition, preferably in powder form, comprising a polymer PI comprising monomeric units derived from a monomer MO being vinylidene fluoride or monomeric units derived from a monomer M2 of formula R ¹ R ² C=C(R ³ )C(O)R in which the substituents R ¹ , R ² and R ³ are independently of each other selected from the group consisting of H and C 1 -C ₅ alkyl; R is selected from the group consisting of -NHC(CH ₃ )2CH2C(O)CH3 OR -OR' with R' selected from the group consisting of H and C 1 -C ₈ alkyl optionally substituted by one or more -OH group(s) or a five- or six-membered heterocycle comprising at least one nitrogen atom in its cyclic chain; or a mixture of said monomeric units MO or M2; characterized in that said PI polymer has a particle size distribution Dv99 less than or equal to 89 pm and a particle size distribution DvlO greater than or equal to 2.0 pm.

Dv99 is the particle size at the 99th percentile (by volume) of the cumulative particle size distribution. This parameter can be determined by laser particle sizing. DvlO is the particle size at the 10th percentile (by volume) of the cumulative particle size distribution. This parameter can be determined by laser particle sizing. The particle size distribution is measured using a Microtrac S3500 particle size analyzer and using water as the dispersion medium or dry. It has been observed that particle size plays an important role in obtaining good adhesion, permeability or conductivity properties. Said PI polymer according to the present invention has a particle size distribution specifically selected to improve at least one of the above properties. Indeed, when the polymer particles have too large a size with a low grammage, the coverage of the separator is too low to achieve the desired properties. If the particles are too small, the transfer of ions within the separator is not sufficient. Furthermore, if the particle size distribution is too heterogeneous, the adhesion properties are reduced. By specifically choosing particles of said PI polymer with a size distribution as mentioned in the present application, the separator coatings comprising the composition according to the present invention have shown a good compromise between the different compositions targeted.

According to a preferred embodiment, said polymer PI is a homopolymer of vinylidene fluoride or a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units derived from a monomer M1 selected from the group consisting of vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, trifluoropropenes, tetrafluoropropenes, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropenes, perfluoroalkylvinylethers, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene and chlorotrifluoropropene or a mixture thereof; or a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units derived from a monomer M2 as defined in the present application. According to a preferred embodiment, said PI polymer has a particle size distribution Dv90 less than or equal to 50 pm, preferably less than or equal to 46 pm.

According to a preferred embodiment, said monomer Ml is hexafluoropropylene.

According to a preferred embodiment, the mass content of said monomer M1 in said polymer PI is between 0.5% and 20% based on the total weight of said polymer PI or the mass content of said monomer M2 in said polymer PI is between 0.01% and 10% based on the total weight of said polymer PI.

According to a preferred embodiment, the melt viscosity of said PI polymer is greater than or equal to 10 kP at 230°C and at a shear rate of 100 s-1 measured according to standard ASTM D3835.

According to a preferred embodiment, said PI polymer also comprises a functional group selected from the group consisting of carboxylic acid, carboxylic acid anhydride, carboxylic acid esters, epoxy, amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenolic, ester, ether, siloxane, sulfonic, sulfuric, phosphoric, or phosphonic groups; preferably carboxylic acid, carboxylic acid anhydride, carboxylic acid esters, hydroxyl, phosphoric and phosphonic.

According to a preferred embodiment, said PI polymer has a particle size distribution Dv99 less than or equal to 89 pm and a particle size distribution DvlO greater than or equal to 2.9 pm.

According to a preferred embodiment, said polymer PI contains monomeric units derived from a monomer M2 selected from the group consisting of acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, butyl acrylate, n-dodecyl, amyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, diacetone acrylamide, lauryl acrylate, n-octyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, methyl acrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-dodecyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, n-octyl methacrylate, ureido methacrylate and mixtures thereof of these.

According to a preferred embodiment, said PI polymer is free of fluorosurfactants.

According to another aspect, the present invention provides a separator comprising said composition according to the present invention.

According to a preferred embodiment, said separator comprises a porous support and said composition according to the present invention; said composition being deposited on one of the faces of the porous support.

According to another aspect, the present invention provides a Li-ion secondary battery comprising an anode, a cathode and a separator, wherein said separator is according to the present invention.

According to another aspect, the present invention provides a binder for a Li-ion battery comprising the composition according to the present invention.

According to another aspect, the present invention provides an electrode for a lithium-ion battery comprising a metal collector of which at least one face is covered with a substrate layer containing an active substance and a binder, characterized in that said binder is according to the present invention.

According to another aspect, the present invention provides a Li-ion secondary battery comprising an anode, a cathode and a separator, wherein the anode or the cathode is an electrode according to the present invention.

Detailed description of the present invention

According to a first aspect, the present invention provides a composition in powder form comprising a PI polymer.

Polymer PI

Said PI polymer may comprise monomeric units derived from a monomer MO being vinylidene fluoride.

Said polymer PI may comprise monomeric units derived from a monomer M2 of formula R ¹ R ² C=C(R ³ )C(O)R in which the substituents R ¹ , R ² and R ³ are independently of each other selected from the group consisting of H and Ci-C ₅ alkyl; R is selected from the group consisting of -NHC(CH ₃ )2CH2C(O)CH3 OR -OR' with R' selected from the group consisting of H and Ci-Ci ₈ alkyl optionally substituted by one or more -OH group(s) or a five- or six-membered heterocycle comprising at least one nitrogen atom in its cyclic chain. Said polymer PI may comprise a mixture of said monomeric units MO and M2. Said heterocycle may be saturated or unsaturated or aromatic. Said heterocycle may be monocyclic or bicyclic. Said heterocycle may be a pyrrole, pyrrolidine, pyridine, piperidine, pyrimidine, pyrazine, 1,4-dihydropyridine, indole, oxindole, isatin, quinoline, isoquinoline, quinazoline, imidazoline, pyrazolidine, 2-pyrrolidone, deltalactam, succinimide, 2-imidazolidinone, 4-imidazolidinone ring. Said heterocycle may be substituted by one or more C 1 -C ₅ alkyl groups. As mentioned above, the C 1 -C 5 alkyl is optionally substituted by said heterocycle. The latter may be linked to the alkyl chain by the nitrogen atom or any other atoms forming the heterocycle. Preferably the heterocycle is 2-pyrrolidone, delta-lactam, succinimide, 2-imidazolidinone, 4-imidazolidinone.

Said monomer M2 may be of formula R ¹ R ² C=C(R ³ )C(O)R in which the substituents R ¹ , R ² and R ³ are independently of each other selected from the group consisting of H and C 1 -C ₅ alkyl; R is selected from the group consisting of -NHC(CH ₃ )2CH2C(O)CH3 or -OR' with R' selected from the group consisting of H and C 1 -C ₈ alkyl optionally substituted by one or more -OH group(s) a five- or ten-membered heterocycle comprising at least one nitrogen atom in its cyclic chain. Preferably, the heterocycle is as defined above, in particular the heterocycle is 2-pyrrolidone, deltalactam, succinimide, 2-imidazolidinone, 4-imidazolidinone. Preferably, the substituent R' is selected from the group consisting of H, methyl, ethyl, propyl, n-butyl, isobutyl, t-butyl, n-dodecyl, amyl, isoamyl, hexyl, 2-ethylhexyl, lauryl, n-octyl, hydroxyethyl, hydroxybutyl, hydroxypropyl, ethyl substituted by a ureido group. In particular, said monomer M2 is of formula R ¹ R ² C=C(R ³ )C(O)R in which the substituents R ¹ and R ² are H; R ³ is H or CH ₃ ; R is -OR' with R' selected from the group consisting of H, methyl, ethyl, propyl, n-butyl, isobutyl, t-butyl, hydroxy propyl, hydroxy butyl, 2-pyrrolidone, deltalactam, succinimide, 2-imidazolidinone, 4-imidazolidinone.

More particularly, said monomer M2 may be acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-dodecyl acrylate, amyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, diacetone acrylamide, lauryl acrylate, n-octyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, methyl acrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-dodecyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, n-octyl methacrylate, ureido methacrylate and mixtures thereof. Among these, said monomer M2 with an alkyl group having 1 to 8 carbon atoms is preferred, and an alkyl group having 1 to 5 carbon atoms is more preferable. Said polymer PI may comprise one or more monomeric units derived from said monomer M2 as defined herein.

Said polymer PI may comprise monomeric units derived from a monomer Ml copolymerizable with vinylidene fluoride.

The comonomers compatible with vinylidene fluoride may be halogenated (fluorinated, chlorinated or brominated) or non-halogenated. Said monomer Ml may be selected from the group consisting of vinyl fluoride; trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) and perfluoro(propyl vinyl) ether (PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the monomer of the formula CF2=CFOCF2CF(CF ₃ )OCF2CF ₂ X in which X is SO ₂ F, CO ₂ H, CH ₂ OH, CH ₂ OCN or CH ₂ OPO ₃ H; the monomer of the formula CF2=CFOCF2CF2SO ₂ F; the monomer of formula F(CF2)nCH ₂ OCF=CF2 in which n is 1, 2, 3, 4 or 5; the monomer of formula R ¹ CH ₂ OCF=CF2 in which R ¹ is hydrogen or F(CF ₂ )m and m is 1, 2, 3 or 4; the monomer of formula R ² OCF=CH ₂ in which R ² is F(CF ₂ )p and p is 1, 2, 3 or 4; perfluorobutyl ethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof. Among the trifluoropropenes, mention may be made of 3,3,3-trifluoropropene. Among the tetrafluoropropenes, mention may be made of 2,3,3,3-tetrafluoropropene, 1,3, 3, 3-tetrafluoropropene. Among the pentafluoropropenes, mention may be made of 1,1,3,3,3-pentafluoropropene or 1,2,3,3,3-pentafluoropropene. Chlorofluoroethylene may denote either 1-chloro-1-fluoroethylene or 1-chloro-2-fluoroethylene. The 1-chloro-1-fluoroethylene isomer is preferred. Chlorotrifluoropropene is preferably 1-chloro-3,3,3-trifluoropropene or 2-chloro-3,3,3-trifluoropropene.

Advantageously, said monomer Ml may be selected from the group consisting of vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) and perfluoro(propyl vinyl) ether (PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD), perfluorobutyl ethylene (PFBE), trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof.

Preferably, said monomer Ml may be selected from the group consisting of vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) and perfluoro(propyl vinyl) ether (PPVE); perfluorobutyl ethylene (PFBE), trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene and chlorotrifluoropropene or a mixture thereof.

More preferably, said monomer Ml may be selected from the group consisting of vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(methyl vinyl)ether, perfluoro(ethyl vinyl)ether, perfluoro(propyl vinyl)ether, perfluorobutylethylene, trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene and chlorotrifluoropropene or a mixture thereof. In particular, said monomer Ml may be selected from the group consisting of vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene and hexafluoropropylene or a mixture thereof.

According to one embodiment, in said polymer PI, the mass content of vinylidene fluoride units is preferably at least 50%, preferably at least 60%, more preferably greater than 70% and particularly greater than 80% based on the total weight of said polymer PI. Thus, the mass content of said monomer Ml in said polymer PI is less than 50%, advantageously less than 40%, preferably less than 30%, more preferably less than 20% based on the total weight of said polymer PI. According to a preferred embodiment, the mass content of said monomer Ml in said polymer PI is between 0.5% and 20%, advantageously between 0.5% and 19%, preferably between 0.5% and 18%, more preferably between 0.5% and 17%, in particular between 0.5% and 16%, more particularly between 0.5% and 15% based on the total weight of said polymer PI. The mass content of said monomer Ml in said polymer PI may also be between 1% and 20%, advantageously between 1% and 19%, preferably between 1% and 18%, more preferably between 1% and 17%, in particular between 1% and 16%, more particularly between 1% and 15% based on the total weight of said polymer PI. The mass content of said monomer Ml in said polymer PI may also be between 2% and 20%, advantageously between 2% and 19%, preferably between 2% and 18%, more preferably between 2% and 17%, in particular between 2% and 16%, more particularly between 2% and 15% based on the total weight of said polymer PI.

According to a preferred embodiment, said PI polymer is a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units derived from hexafluoropropylene; preferably the mass content of the monomeric units derived from vinylidene fluoride is at least 50%, preferably at least 60%, more preferably at least 70% and advantageously at least 80% based on the total weight of said PI polymer. More particularly, said PI polymer is a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units derived from hexafluoropropylene; the mass content of the vinylidene fluoride units is greater than 65% and the mass content of the hexafluoropropylene units is less than 35%. Preferably, the PI polymer is a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units derived from hexafluoropropylene; the mass content of vinylidene fluoride units is greater than 85% and the mass content of hexafluoropropylene units is less than 15%.

According to a particular embodiment, the polymer PI is a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units derived from hexafluoropropylene; the mass content of hexafluoropropylene is between 0.5% and 20%, advantageously between 0.5% and 19%, preferably between 0.5% and 18%, more preferably between 0.5% and 17%, in particular between 0.5% and 16%, more particularly between 0.5% and 15% based on the total weight of said polymer PI. Advantageously, the polymer PI is a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units derived from hexafluoropropylene; the mass content of hexafluoropropylene is between 1% and 20%, advantageously between 1% and 19%, preferably between 1% and 18%, more preferably between 1% and 17%, in particular between 1% and 16%, more particularly between 1% and 15% based on the total weight of said polymer PI. Preferably, the polymer PI is a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units derived from hexafluoropropylene; the mass content of hexafluoropropylene is between 2% and 20%, advantageously between 2% and 19%, preferably between 2% and 18%, more preferably between 2% and 17%, in particular between 2% and 16%, more particularly between 2% and 15% based on the total weight of said polymer PI. In particular, in this embodiment, the mass content of vinylidene fluoride units is preferably at least 50%, preferably at least 60%, more preferably greater than 70% and particularly greater than 80% based on the total weight of said PI polymer.

When said polymer PI has a mass content of vinylidene fluoride units of at least 50%, preferably at least 60%, more preferably greater than 70% and particularly greater than 80%, it may also comprise said monomer M2 in a mass content of 0.05% by weight to 10% by weight based on the total weight of said polymer PI and optionally comprises said monomer M1 according to any one of the embodiments detailed above. Preferably, in this embodiment, said monomer M2 is present in a mass content of 0.05% by weight to 5% by weight, particularly from 0.05 to 2% based on the total weight of said polymer PI.

When said polymer PI comprises at least 50% by weight of said monomer M2, the latter may also comprise monomeric units derived from a monomer M3. Said monomer M3 may be

- (A) an alkenyl compound containing a functional group, or

- (B) an alkenyl compound without a functional group.

The alkenyl compound (A) containing a functional group includes, for example, α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, crotonic acid, itaconic acid and the like; vinyl ester compounds such as vinyl acetate, vinyl neodecanoate and the like; amide compounds such as acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N,N-dialkylacrylamide, N,N-dialkylmethacrylamide, diacetone acrylamide and the like; acrylic acid esters such as 2-hydroxyethyl acrylate, N-dialkylaminoethyl acrylate, glycidyl acrylate, n-dodecyl acrylate, fluoroalkyl acrylate and the like; methacrylic acid esters such as dialkylaminoethyl methacrylate, fluoroalkyl methacrylate, 2-hydroxyethyl methacrylate, n-octyl methacrylate, t-butyl methacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate and the like; maleic anhydride, and alkenyl glycidyl ether compounds such as allyl glycidyl ether and the like. Among these, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, N-methylolacrylamide, N-methylolmethacrylamide, diacetone acrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and allyl glycidyl ether are preferred. These compounds may be used alone or as a mixture of two or more. The functional group-free alkenyl compound (B) includes, for example, conjugated dienes such as 1,3-butadiene, isoprene and the like; divinyl hydrocarbon compounds such as such as divinyl benzene and the like; and alkenyl cyanides such as acrylonitrile, methacrylonitrile and the like. Among these, preferred are 1,3-butadiene, and acrylonitrile. These compounds may be used alone or as a mixture of two or more. It is preferable that the functional alkenyl compound (A) is used in an amount of less than 50% by weight relative to the weight of the polymer PI and that the functional group-free alkenyl compound (B) is used in an amount of less than 30% by weight relative to the weight of the polymer PI.

As mentioned above, said PI polymer has a particular particle size distribution. This allows to achieve the targeted properties and to present a good compromise between adhesion and ionic conductivity.

Thus, said PI polymer has a particle size distribution Dv99 of less than 89 pm. The Dv99 is the particle size at the 99th percentile (by volume) of the cumulative particle size distribution. This parameter can be determined by laser particle size analysis. This applies to all Dv99 described in the present description. This particle size distribution is measured using a particle size analyzer and the measurement is carried out dry by laser diffraction on the powder. Advantageously, said PI polymer has a particle size distribution Dv99 less than or equal to 85 pm, preferably less than or equal to 80 pm, more preferably less than or equal to 75 pm, in particular less than or equal to 70 pm, more particularly less than or equal to 65 pm, preferably less than or equal to 60 pm, advantageously less than or equal to 55 pm, preferably less than or equal to 50 pm, particularly preferably less than or equal to 45 pm. Said PI polymer may have a particle size distribution Dv99 greater than or equal to 5 pm, preferably greater than or equal to 7 pm, more preferably greater than or equal to 9 pm, in particular greater than or equal to 11 pm, more particularly greater than or equal to 13 pm, preferably greater than or equal to 15 pm, advantageously more than or equal to 17 pm, preferably more than or equal to 19 pm, particularly more than or equal to 20 pm, more particularly more than or equal to 24 pm.

Thus, according to a particular embodiment, said polymer PI has a particle size distribution Dv99 less than or equal to 89 pm, advantageously less than or equal to 85 pm, preferably less than or equal to 80 pm, more preferably less than or equal to 75 pm, in particular less than or equal to 70 pm, more particularly less than or equal to 65 pm, preferably less than or equal to 60 pm, advantageously less than or equal to 55 pm, preferably less than or equal to 50 pm, particularly preferably less than or equal to 45 pm; and said PI polymer has a particle size distribution Dv99 greater than or equal to 5 pm, preferably greater than or equal to 7 pm, more preferably greater than or equal to 9 pm, in particular greater than or equal to 11 pm, more particularly greater than or equal to 13 pm, preferably greater than or equal to 15 pm, advantageously more than or equal to 17 pm, preferably more than or equal to 19 pm, particularly more than or equal to 20 pm, more particularly more than or equal to 24 pm. Said PI polymer may also have a particle size distribution DvlO greater than or equal to 2.0 pm. The DvlO is the particle size at the 10th percentile (by volume) of the cumulative particle size distribution. This parameter can be determined by laser particle size analysis as mentioned above. This particle size distribution is also measured using a particle size analyzer and the measurement is carried out dry by laser diffraction on the powder. This applies to all DvlOs described in the present description. Said PI polymer may have a particle size distribution DvlO greater than or equal to 2.1 pm, advantageously greater than or equal to 2.2 pm, preferably greater than or equal to 2.3 pm, more preferably greater than or equal to 2.4 pm, in particular greater than or equal to

2.5 pm, more particularly greater than or equal to 2.6 pm, preferably greater than or equal to 2.7 pm, advantageously greater than or equal to 2.8 pm, preferably greater than or equal to 2.9 pm, more preferably greater than or equal to 3.0 pm. However, it has been noted that when said PI polymer has a particle size distribution DvlO less than 2.9 this penalizes the ionic conductivity. Indeed, the pores of the separator support and the pores between the particles of said PI polymer tend to become clogged. It is therefore preferable to favor a particle size distribution DvlO greater than or equal to 3.0 pm.

Said PI polymer may have a particle size distribution DvlO greater than or equal to 3.1 pm, advantageously greater than or equal to 3.2 pm, preferably greater than or equal to 3.3 pm, more preferably greater than or equal to 3.4 pm, in particular greater than or equal to 3.5 pm, more particularly greater than or equal to 3.6 pm, preferably greater than or equal to 3.7 pm, advantageously greater than or equal to 3.8 pm, preferably greater than or equal to 3.9 pm, more preferably greater than or equal to 4.0 pm. Said PI polymer may have a particle size distribution DvlO less than or equal to 12 pm, advantageously less than or equal to 11 pm, preferably less than or equal to 10 pm, more preferably less than or equal to 9 pm, in particular less than or equal to 8 pm, more particularly less than or equal to 7 pm.

Thus, according to a particular embodiment, said polymer PI has a particle size distribution DvlO greater than or equal to 2.0 pm, advantageously greater than or equal to 2.1 pm, preferably greater than or equal to 2.2 pm, more preferably greater than or equal to 2.3 pm, in particular greater than or equal to 2.4 pm, more particularly greater than or equal to 2.5 pm, preferably greater than or equal to

2.6 pm, advantageously greater than or equal to 2.7 pm, preferably greater than or equal to 2.8 pm, more preferably greater than or equal to 2.9 pm, particularly preferably greater than or equal to 3.0 pm; and said PI polymer has a particle size distribution DvlO less than or equal to 12 pm, advantageously less than or equal to 11 pm, preferably less than or equal to 10 pm, more preferably less than or equal to 9 pm, in particular less than or equal to 8 pm, more particularly less than or equal to 7 pm. Thus, according to a particular embodiment, said PI polymer has a particle size distribution DvlO greater than or equal to 3.1 pm, advantageously greater than or equal to 3.2 pm, preferably greater than or equal to 3.4 pm. or equal to 3.3 pm, more preferably greater than or equal to 3.4 pm, in particular greater than or equal to 3.5 pm, more particularly greater than or equal to 3.6 pm, preferably greater than or equal to 3.7 pm, advantageously greater than or equal to 3.8 pm, preferably greater than or equal to 3.9 pm, more preferably greater than or equal to 4.0 pm; and said polymer PI has a particle size distribution Dv10 of less than or equal to 12 pm, advantageously less than or equal to 11 pm, preferably less than or equal to 10 pm, more preferably less than or equal to 9 pm, in particular less than or equal to 8 pm, more particularly less than or equal to 7 pm.

Said PI polymer may also have a particle size distribution Dv90 of less than 50 pm. The Dv90 is the particle size at the 90th percentile (by volume) of the cumulative particle size distribution. This parameter can be determined by laser particle size analysis as mentioned above. This particle size distribution is also measured using a particle size analyzer and the measurement is carried out dry by laser diffraction on the powder. This applies to all Dv90 described in the present description. Advantageously, said PI polymer has a particle size distribution Dv90 less than or equal to 48 pm, preferably less than or equal to 46 pm, more preferably less than or equal to 44 pm, in particular less than or equal to 42 pm, more particularly less than or equal to 40 pm, preferably less than or equal to 38 pm, advantageously less than or equal to 36 pm, preferably less than or equal to 34 pm, particularly less than or equal to 32 pm, more particularly less than or equal to 30 pm. Said PI polymer may have a particle size distribution Dv90 greater than or equal to 1 pm, advantageously greater than or equal to 2 pm, preferably greater than or equal to 3 pm, more preferably greater than or equal to 4 pm, in particular greater than or equal to 5 pm, more particularly greater than or equal to 6 pm, preferably greater than or equal to 7 pm, advantageously more than or equal to 8 pm, preferably more than or equal to 9 pm, particularly preferably more than or equal to 10 pm.

Thus, according to a particular embodiment, said polymer PI has a particle size distribution Dv90 less than or equal to 50 pm, advantageously less than or equal to 48 pm, preferably less than or equal to 46 pm, more preferably less than or equal to 44 pm, in particular less than or equal to 42 pm, more particularly less than or equal to 40 pm, preferably less than or equal to 38 pm, advantageously less than or equal to 36 pm, preferably less than or equal to 34 pm, particularly less than or equal to 32 pm, more particularly less than or equal to 30 pm; and said PI polymer has a particle size distribution Dv90 greater than or equal to 1 pm, advantageously greater than or equal to 2 pm, preferably greater than or equal to 3 pm, more preferably greater than or equal to 4 pm, in particular greater than or equal to 5 pm, more particularly greater than or equal to 6 pm, preferably greater than or equal to 7 pm, advantageously more preferably greater than or equal to 8 pm, in a preferentially preferred manner greater than or equal to 9 pm, in a particularly preferred manner greater than or equal to 10 pm.

According to a preferred embodiment, said PI polymer has a particle size distribution

Dv99 less than or equal to 89 pm, advantageously less than or equal to 85 pm, preferably less than or equal to 80 pm, more preferably less than or equal to 75 pm, in particular less than or equal to 70 pm, more particularly less than or equal to 65 pm, preferably less than or equal to 60 pm, advantageously less than or equal to 55 pm, preferably less than or equal to 50 pm, particularly preferably less than or equal to 45 pm;

DvlO greater than or equal to 2.0 pm, advantageously greater than or equal to 2.1 pm, preferably greater than or equal to 2.2 pm, more preferably greater than or equal to 2.3 pm, in particular greater than or equal to 2.4 pm, more particularly greater than or equal to 2.5 pm, preferably greater than or equal to 2.6 pm, advantageously greater than or equal to 2.7 pm, preferably greater than or equal to 2.8 pm, more preferably greater than or equal to 2.9 pm, particularly preferably greater than or equal to 3.0 pm or DvlO greater than or equal to 3.1 pm, advantageously greater than or equal to 3.2 pm, preferably greater than or equal to 3.3 pm, more preferably greater than or equal to 3.4 pm, in particular greater than or equal to 3.5 pm, more particularly greater than or equal to 3.6 pm, preferably greater than or equal to 3.7 pm, advantageously greater than or equal to 3.8 pm, preferably greater than or equal to 3.9 pm, more preferably greater than or equal to 4.0 pm; and Dv90 less than or equal to 50 pm, advantageously less than or equal to 48 pm, preferably less than or equal to 46 pm, more preferably less than or equal to 44 pm, in particular less than or equal to 42 pm, more particularly less than or equal to 40 pm, preferably less than or equal to 38 pm, advantageously less than or equal to 36 pm, preferably less than or equal to 34 pm, particularly preferably less than or equal to 32 pm, more particularly preferably less than or equal to 30 pm.

According to another preferred embodiment, said polymer PI has a particle size distribution Dv99 less than or equal to 89 pm, advantageously less than or equal to 85 pm, preferably less than or equal to 80 pm, more preferably less than or equal to 75 pm, in particular less than or equal to 70 pm, more particularly less than or equal to 65 pm, preferably less than or equal to 60 pm, advantageously less than or equal to 55 pm, preferably less than or equal to 50 pm, particularly preferably less than or equal to 45 pm; and greater than or equal to 5 pm, preferably greater than or equal to 7 pm, more preferably greater than or equal to 9 pm, in particular greater than or equal to 11 pm, more particularly greater than or equal to 13 pm, of preferred manner greater than or equal to 15 pm, advantageously preferred manner greater than or equal to 17 pm, preferentially preferred manner greater than or equal to 19 pm, particularly preferred manner greater than or equal to 20 pm, more particularly preferred manner greater than or equal to 24 pm;

DvlO greater than or equal to 2.0 pm, advantageously greater than or equal to 2.1 pm, preferably greater than or equal to 2.2 pm, more preferably greater than or equal to 2.3 pm, in particular greater than or equal to 2.4 pm, more particularly greater than or equal to 2.5 pm, preferably greater than or equal to 2.6 pm, advantageously greater than or equal to 2.7 pm, preferably greater than or equal to 2.8 pm, more preferably greater than or equal to 2.9 pm, particularly preferably greater than or equal to 3.0 pm or DvlO greater than or equal to 3.1 pm, advantageously greater than or equal to 3.2 pm, preferably greater than or equal to 3.3 pm, more preferably greater than or equal to 3.4 pm, in particular greater than or equal to 3.5 pm, more particularly greater than or equal to 3.6 pm, preferably greater than or equal to 3.7 pm, advantageously greater than or equal to 3.8 pm, preferably greater than or equal to 3.9 pm, more preferably greater than or equal to 4.0 pm; and less than or equal to 12 pm, advantageously less than or equal to 11 pm, preferably less than or equal to 10 pm, more preferably less than or equal to 9 pm, in particular less than or equal to 8 pm, more particularly less than or equal to 7 pm;

Dv90 less than or equal to 50 pm, advantageously less than or equal to 48 pm, preferably less than or equal to 46 pm, more preferably less than or equal to 44 pm, in particular less than or equal to 42 pm, more particularly less than or equal to 40 pm, preferably less than or equal to 38 pm, advantageously less than or equal to 36 pm, preferably less than or equal to 34 pm, particularly less than or equal to 32 pm, more particularly less than or equal to 30 pm; and greater than or equal to 1 pm, advantageously greater than or equal to 2 pm, preferably greater than or equal to 3 pm, more preferably greater than or equal to 4 pm, in particular greater than or equal to 5 pm, more particularly greater than or equal to 6 pm, preferably greater than or equal to 7 pm, advantageously more than or equal to 8 pm, preferably more than or equal to 9 pm, particularly preferably more than or equal to 10 pm.

Said polymer PI may have a melt viscosity greater than or equal to 10 kP at 230°C and at a shear rate of 100 s-1 measured according to ASTM D3835, advantageously greater than or equal to 12 kP, preferably greater than or equal to 14 kP, in particular greater than or equal to 15 kP at 230°C and at a shear rate of 100 s-1 measured according to ASTM D3835. Preferably, when the polymer PI comprises monomeric units MO, at least 50% by weight based on the total weight thereof, and optionally Ml, the melt viscosity of said polymer PI is greater than or equal to 10 kP at 230°C and at a shear rate of 100 s-1 measured according to ASTM D3835; advantageously, the melt viscosity of said polymer PI is greater than or equal to 12 kP, preferably greater than or equal to 14 kP, more preferably greater than or equal to 15 kP at 230°C and at a shear rate of 100 s-1 measured according to ASTM D3835. Preferably, when the polymer PI comprises monomeric units derived from vinylidene fluoride and monomeric units derived from hexafluoropropene Ml, the melt viscosity of said polymer PI is greater than or equal to 10 kP at 230°C and at a shear rate of 100 s-1 measured according to ASTM D3835; advantageously, the melt viscosity of said PI polymer is greater than or equal to 12 kP, preferably greater than or equal to 14 kP, more preferably greater than or equal to 15 kP at 230°C and at a shear rate of 100 s-1 measured according to standard ASTM D3835.

According to a preferred embodiment, when the polymer PI comprises monomeric units MO, at least 50% by weight based on the total weight thereof, and optionally Ml, the melt viscosity of said polymer PI is greater than or equal to 40 kP at 230°C and at a shear rate of 100 s-1 measured according to the ASTM D3835 standard. Advantageously, the melt viscosity of said polymer PI is greater than or equal to 45 kP, preferably greater than or equal to 50 kP, more preferably greater than or equal to 55 kP, in particular greater than or equal to 60 kP at 230°C and at a shear rate of 100 s-1 measured according to the ASTM D3835 standard.

According to a particular embodiment, when the polymer PI comprises monomeric units MO, at least 50% by weight based on the total weight thereof, and optionally Ml, the polymer PI comprises a functional group which makes it possible to improve adhesion to metal. Thus, said polymer PI may comprise monomeric units carrying at least one of the functions selected from the group consisting of carboxylic acid, carboxylic acid anhydride, carboxylic acid esters, epoxy groups such as glycidyl, amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenolic, ester, ether, siloxane, sulfonic, sulfuric, phosphoric, phosphonic; preferably carboxylic acid, carboxylic acid anhydride, carboxylic acid esters, hydroxyl, phosphoric and phosphonic; in particular at least one carboxylic acid function, carboxylic acid anhydride, carboxylic acid esters,. The functional group can be introduced by a chemical reaction which can be grafting, or a copolymerization with a monomer carrying at least one of said functional groups and a vinyl function capable of copolymerizing with vinylidene fluoride or the monomer Ml, according to techniques well known to those skilled in the art. The functionality can be introduced via the transfer agent used during the process for synthesizing said polymer PI. The transfer agent may be a polymer with a molar mass of less than or equal to 20,000 g/mol and carrying functional groups chosen from the groups: carboxylic acid, carboxylic acid anhydride, carboxylic acid esters, epoxy groups (such as glycidyl), amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenolic, ester, ether, siloxane, sulfonic, sulfuric, phosphoric, phosphonic. An example of a transfer agent of this type is acrylic acid oligomers. According to a preferred embodiment, the transfer agent is an acrylic acid oligomer with a molar mass of less than or equal to 20,000 g/mol. Alternatively, the functional group may be introduced by an oligomeric or polymeric compound comprising said functional group and mixed with the polymer PI. The oligomeric or polymeric compound may be impregnated in or mixed with the polymer PI or intimately mixed therewith. In this case, the functional group may be derived from a (meth)acrylic acid compound selected from acrylic acid, methacrylic acid, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, hydroxyethylhexyl(meth)acrylate and acryloyloxy propylsuccinate. For example, the functional group may be an oligomer or a polymer comprising monomeric units derived from a monomer selected from the group consisting of acrylic acid, methacrylic acid, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, hydroxyethylhexyl(meth)acrylate and acryloyloxy propylsuccinate. According to one embodiment, said oligomer or polymer has a weight average molecular mass less than or equal to 100,000 g/mol, advantageously less than 80,000 g/mol, preferably less than 60,000 g/mol, more preferably less than 40,000 g/mol, in particular less than 20,000 g/mol. The weight average molecular mass is determined by GPC using a Waters 2695e device coupled with a Wyatt NEON refractometer equipped with two PL Gel mixed C columns and a guard column (7.8 mm LD. x 30 cm, 5 μm) under the following conditions: Temperature: 35°C; flow rate: 1.0 mL/min; injection volume: 100 pL. The samples are prepared at a concentration of 1 mg/ml in THF. Twelve samples of poly(methylmethacrylate) having a molecular weight of 535 to 2,210,000 g/mol are used as a calibration standard. When containing a functional group as mentioned above, the content thereof in said PI polymer is at least 0.01 mol%, preferably at least 0.1 mol%, and at most 15 mol%, preferably at most 10 mol%.

According to a particular embodiment, when said polymer PI comprises monomeric units derived from a monomer M2, at least 50% by weight based on the total weight thereof, said polymer PI has a pH of between 1.5 and 4.0, advantageously between 1.6 and 3.9, preferably between 1.7 and 3.8, more preferably between 1.8 and 3.7, in particular between 1.9 and 3.6, more particularly between 2.0 and 3.5, measured in water at room temperature. To measure the pH, a Mettler Toledo SevenEasy brand pH meter or equivalent and an Electrode In Lab Routine Pro are used. Before calibration, the cleanliness of the electrode is ensured. If necessary, clean the electrode with hot soapy water. It is ensured that the pH electrode is always kept filled with KCI filling solution. The device is calibrated with buffer solutions of pH 10, 7 and 4. To calibrate, dip the electrode in the pH 10 buffer solution and press Cal, once the pH has stabilized repeat the operation with the pH 7 then 4 buffer. Rinse with distilled water and dry the electrode between each buffer. The electrode is prepared beforehand before measurement by soaking in a 0.1M HCI solution for one to two hours then rinsed with deionized water. To measure the pH, dip the electrode in the product to be tested and shake for a few seconds. Let the measurement stabilize for 15 minutes and read the value displayed by the pH meter. The measurement is taken at room temperature.

Preferably, when said polymer PI comprises monomeric units derived from a monomer M2, at least 50% by weight based on the total weight thereof, said polymer PI has a transition temperature glass transition temperature less than or equal to 230°C. Advantageously, said PI polymer has a glass transition temperature less than or equal to 220°C, preferably less than 200°C, more preferably less than 180°C, in particular less than 160°C, more particularly less than or equal to 150°C. The glass transition temperatures indicated here are calculated using the Fox equation. The Fox equation is an equation used to predict the glass transition temperature of statistical copolymers:

1 / Tg,copo = i œi / Tg,i

Tg,copo is the glass transition temperature of the copolymer,

Tg,i are those of the homopolymers i corresponding to each comonomer, œi are the mass fractions of the monomers i composing this copolymer.

Mass fractions are expressed without units. Glass transition temperatures are expressed in degrees Kelvin. The temperature is then converted to degrees Celsius.

As mentioned above, said PI polymer is free of fluorosurfactants. Said PI polymer may comprise between 10 ppm and 2 wt% of a surfactant comprising polyethylene glycol or polypropylene glycol units. Preferably, said surfactant has an HLB value of 1 to 20, in particular an HLB value of 1 to 5 or 10 to 15. In particular, said surfactant comprises a polyethylene glycol segment and a polypropylene glycol segment, and has an HLB value of 1 to 5 and a weight average molecular weight of 5000 to 10000 g.mol-1. Alternatively, said surfactant comprises a polyethylene glycol segment and a polypropylene glycol segment, and has an HLB value of 10 to 15 and a weight average molecular weight of 500 to 2500 g.mol-1.

Composition

Preferably, said composition according to the present invention comprises at least 50%, advantageously at least 60%, preferably at least 70%, more preferably at least 80%, in particular at least 90%, more particularly at least 95% by weight of said PI polymer according to the present invention based on the total weight of said composition.

According to a particular embodiment, when the polymer PI comprises monomeric units MO, at least 50% by weight based on the total weight thereof, and optionally M1, said composition may optionally comprise a polymer P2 comprising monomeric units derived from a monomer selected from the group consisting of acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-dodecyl acrylate, amyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, diacetone acrylamide, lauryl acrylate, n-octyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, methyl acrylic acid, methacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-dodecyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, n-octyl methacrylate and ureido methacrylate. According to a particular embodiment, when the polymer PI comprises monomeric units M2, at least 50% by weight based on the total weight thereof, said composition may optionally comprise a polymer P3 comprising monomeric units comprising monomeric units derived from a monomer selected from the group consisting of vinylidene fluoride or a monomer M1 as defined in the present application or a mixture thereof.

Said PI polymer can be obtained by an emulsion or suspension polymerization process according to the usual techniques known to those skilled in the art. The PI polymer is generally obtained in the form of a latex, a dispersion or an aqueous solution. The composition according to the present invention can be obtained from a latex comprising said PI polymer by a drying step followed by a step for achieving the desired size distribution. The drying step can be carried out by atomization or co-atomization, preferably at a temperature of 100°C to 220°C, or lyophilization. The powder can also be obtained by grinding techniques, such as cryogrinding, where the mixture is brought to a temperature below room temperature, using liquid nitrogen for example, before grinding. At the end of the powder manufacturing step, i.e. after the drying step, the particle size can be adjusted and optimized by selection or screening processes and/or by grinding, granulating, sieving, compacting or shearing. One or more of these techniques can be used to achieve the desired size distribution.

When the composition comprises, in addition to polymer PI, said polymer P2 or said polymer P3, said polymers may be mixed in powder form, or in the form of an aqueous dispersion followed by drying. Said polymer PI may also form an interpenetrating polymer network (IPN or semi-IPN) with said polymer P2 or said polymer P3.

Preferably, said polymer P2 and said polymer P3 have a size distribution in the same range as that of said polymer PI. Thus, said polymer P2 or said polymer P3 has a particle size distribution Dv99 of less than 89 pm. The Dv99 is the particle size at the 99th percentile (by volume) of the cumulative particle size distribution. This parameter can be determined by laser particle size analysis. This applies to all Dv99 described in the present description. This particle size distribution is measured using a particle size analyzer and the measurement is carried out dry by laser diffraction on the powder. Advantageously, said polymer P2 or said polymer P3 has a particle size distribution Dv99 less than or equal to 85 pm, preferably less than or equal to 80 pm, more preferably less than or equal to 75 pm, in particular less than or equal to 70 pm, more particularly less than or equal to 65 pm, preferably less than or equal to 60 pm, advantageously less than or equal to 55 pm, preferably less than or equal to 50 pm, particularly preferably less than or equal to 45 pm.

Said polymer P2 or said polymer P3 may have a particle size distribution Dv99 greater than or equal to 5 pm, preferably greater than or equal to 7 pm, more preferably greater than or equal to 9 pm, in particular greater than or equal to 11 pm, more particularly greater than or equal to 13 pm, preferably greater than or equal to 15 pm, advantageously preferably greater than or equal to 17 pm, in a preferentially preferred manner greater than or equal to 19 pm, in a particularly preferred manner greater than or equal to 20 pm, in a more particularly preferred manner greater than or equal to 24 pm.

Thus, according to a particular embodiment, said polymer P2 or said polymer P3 has a particle size distribution Dv99 less than or equal to 89 pm, advantageously less than or equal to 85 pm, preferably less than or equal to 80 pm, more preferably less than or equal to 75 pm, in particular less than or equal to 70 pm, more particularly less than or equal to 65 pm, preferably less than or equal to 60 pm, advantageously less than or equal to 55 pm, preferably less than or equal to 50 pm, particularly preferably less than or equal to 45 pm; and said polymer P2 or said polymer P3 has a particle size distribution Dv99 greater than or equal to 5 pm, preferably greater than or equal to 7 pm, more preferably greater than or equal to 9 pm, in particular greater than or equal to 11 pm, more particularly greater than or equal to 13 pm, preferably greater than or equal to 15 pm, advantageously more than or equal to 17 pm, preferably more than or equal to 19 pm, particularly more than or equal to 20 pm, more particularly more than or equal to 24 pm.

Said polymer P2 or said polymer P3 may also have a particle size distribution DvlO greater than or equal to 2.0 pm. The DvlO is the particle size at the 10th percentile (by volume) of the cumulative particle size distribution. This parameter can be determined by laser particle size analysis as mentioned above. This particle size distribution is also measured using a particle size analyzer and the measurement is carried out dry by laser diffraction on the powder. This applies to all DvlOs described in the present description. Said polymer P2 or said polymer P3 may have a particle size distribution DvlO greater than or equal to 2.1 pm, advantageously greater than or equal to 2.2 pm, preferably greater than or equal to 2.3 pm, more preferably greater than or equal to 2.4 pm, in particular greater than or equal to 2.5 pm, more particularly greater than or equal to 2.6 pm, preferably greater than or equal to 2.7 pm, advantageously greater than or equal to 2.8 pm, preferably greater than or equal to 2.9 pm, more preferably greater than or equal to 3.0 pm.

Said polymer P2 or said polymer P3 may have a particle size distribution DvlO greater than or equal to 3.1 pm, advantageously greater than or equal to 3.2 pm, preferably greater than or equal to 3.3 pm, more preferably greater than or equal to 3.4 pm, in particular greater than or equal to 3.5 pm, more particularly greater than or equal to 3.6 pm, preferably greater than or equal to 3.7 pm, advantageously greater than or equal to 3.8 pm, preferably greater than or equal to 3.9 pm, more preferably greater than or equal to 4.0 pm. Said polymer P2 or said polymer P3 may have a particle size distribution DvlO less than or equal to 12 pm, advantageously less than or equal to 11 pm, preferably less than or equal to 10 pm, more preferably greater than or equal to 11 pm. preferably less than or equal to 9 pm, in particular less than or equal to 8 pm, more particularly less than or equal to 7 pm.

Thus, according to a particular embodiment, said polymer P2 or said polymer P3 has a particle size distribution Dv10 greater than or equal to 2.0 pm, advantageously greater than or equal to 2.1 pm, preferably greater than or equal to 2.2 pm, more preferably greater than or equal to 2.3 pm, in particular greater than or equal to 2.4 pm, more particularly greater than or equal to 2.5 pm, preferably greater than or equal to 2.6 pm, advantageously greater than or equal to 2.7 pm, preferably greater than or equal to 2.8 pm, more preferably greater than or equal to 2.9 pm, particularly preferably greater than or equal to 3.0 pm; and said polymer P2 or said polymer P3 has a particle size distribution DvlO less than or equal to 12 pm, advantageously less than or equal to 11 pm, preferably less than or equal to 10 pm, more preferably less than or equal to 9 pm, in particular less than or equal to 8 pm, more particularly less than or equal to 7 pm.

Thus, according to a particular embodiment, said polymer P2 or said polymer P3 has a particle size distribution Dv10 greater than or equal to 3.1 pm, advantageously greater than or equal to 3.2 pm, preferably greater than or equal to 3.3 pm, more preferably greater than or equal to 3.4 pm, in particular greater than or equal to 3.5 pm, more particularly greater than or equal to 3.6 pm, preferably greater than or equal to 3.7 pm, advantageously greater than or equal to 3.8 pm, preferably greater than or equal to 3.9 pm, more preferably greater than or equal to 4.0 pm; and said polymer P2 or said polymer P3 has a particle size distribution DvlO less than or equal to 12 pm, advantageously less than or equal to 11 pm, preferably less than or equal to 10 pm, more preferably less than or equal to 9 pm, in particular less than or equal to 8 pm, more particularly less than or equal to 7 pm.

Said polymer P2 or said polymer P3 may also have a particle size distribution Dv90 of less than 50 pm. The Dv90 is the particle size at the 90th percentile (by volume) of the cumulative particle size distribution. This parameter can be determined by laser particle size analysis as mentioned above. This particle size distribution is also measured using a particle size analyzer and the measurement is carried out dry by laser diffraction on the powder. This applies to all Dv90 described in the present description. Advantageously, said polymer P2 or said polymer P3 has a particle size distribution Dv90 less than or equal to 48 pm, preferably less than or equal to 46 pm, more preferably less than or equal to 44 pm, in particular less than or equal to 42 pm, more particularly less than or equal to 40 pm, preferably less than or equal to 38 pm, advantageously less than or equal to 36 pm, preferably less than or equal to 34 pm, particularly preferably less than or equal to 32 pm, more particularly preferably less than or equal to 30 pm. Said polymer P2 or said polymer P3 may have a particle size distribution Dv90 greater than or equal to 1 pm, advantageously greater than or equal to 2 pm, preferably greater than or equal to 3 pm, more preferably greater than or equal to 4 pm, in particular greater than or equal to 5 pm, more particularly greater than or equal to 6 pm, preferably greater than or equal to 7 pm, advantageously more preferably greater than or equal to 8 pm, preferentially more preferably greater than or equal to 9 pm, particularly more preferably greater than or equal to 10 pm.

Thus, according to a particular embodiment, said polymer P2 or said polymer P3 has a particle size distribution Dv90 less than or equal to 50 pm, advantageously less than or equal to 48 pm, preferably less than or equal to 46 pm, more preferably less than or equal to 44 pm, in particular less than or equal to 42 pm, more particularly less than or equal to 40 pm, preferably less than or equal to 38 pm, advantageously less than or equal to 36 pm, preferably less than or equal to 34 pm, particularly less than or equal to 32 pm, more particularly less than or equal to 30 pm; and said polymer P2 or said polymer P3 has a particle size distribution Dv90 greater than or equal to 1 pm, advantageously greater than or equal to 2 pm, preferably greater than or equal to 3 pm, more preferably greater than or equal to 4 pm, in particular greater than or equal to 5 pm, more particularly greater than or equal to 6 pm, preferably greater than or equal to 7 pm, advantageously more than or equal to 8 pm, preferably more than or equal to 9 pm, particularly preferably more than or equal to 10 pm.

According to a preferred embodiment, said polymer P2 or said polymer P3 has a particle size distribution

Dv99 less than or equal to 89 pm, advantageously less than or equal to 85 pm, preferably less than or equal to 80 pm, more preferably less than or equal to 75 pm, in particular less than or equal to 70 pm, more particularly less than or equal to 65 pm, preferably less than or equal to 60 pm, advantageously less than or equal to 55 pm, preferably less than or equal to 50 pm, particularly preferably less than or equal to 45 pm;

DvlO greater than or equal to 2.0 pm, advantageously greater than or equal to 2.1 pm, preferably greater than or equal to 2.2 pm, more preferably greater than or equal to 2.3 pm, in particular greater than or equal to 2.4 pm, more particularly greater than or equal to 2.5 pm, preferably greater than or equal to 2.6 pm, advantageously greater than or equal to 2.7 pm, preferably greater than or equal to 2.8 pm, more preferably greater than or equal to 2.9 pm, particularly preferably greater than or equal to 3.0 pm or DvlO greater than or equal to 3.1 pm, advantageously greater than or equal to 3.2 pm, preferably greater than or equal to 3.3 pm, more preferably greater than or equal to 3.4 pm, in particular greater than or equal to 3.5 pm, more particularly greater than or equal to 3.6 pm, preferably greater than or equal to 3.7 pm, advantageously greater than or equal to 3.8 pm, preferably greater than or equal to 3.9 pm, more preferably greater than or equal to 4.0 pm; and Dv90 less than or equal to 50 pm, advantageously less than or equal to 48 pm, preferably less than or equal to 46 pm, more preferably less than or equal to 44 pm, in particular less than or equal to 42 pm, more particularly less than or equal to 40 pm, preferably less than or equal to 38 pm, advantageously less than or equal to 36 pm, preferably less than or equal to 34 pm, particularly less than or equal to 32 pm, more particularly less than or equal to 30 pm.

According to another preferred embodiment, said polymer P2 or said polymer P3 has a particle size distribution

Dv99 less than or equal to 89 pm, advantageously less than or equal to 85 pm, preferably less than or equal to 80 pm, more preferably less than or equal to 75 pm, in particular less than or equal to 70 pm, more particularly less than or equal to 65 pm, preferably less than or equal to 60 pm, advantageously less than or equal to 55 pm, preferably less than or equal to 50 pm, particularly preferably less than or equal to 45 pm; and greater than or equal to 5 pm, preferably greater than or equal to 7 pm, more preferably greater than or equal to 9 pm, in particular greater than or equal to 11 pm, more particularly greater than or equal to 13 pm, preferably greater than or equal to 15 pm, advantageously more preferably greater than or equal to 17 pm, preferably more preferably greater than or equal to 19 pm, particularly more preferably greater than or equal to 20 pm, more particularly more preferably greater than or equal to 24 pm;

DvlO greater than or equal to 2.0 pm, advantageously greater than or equal to 2.1 pm, preferably greater than or equal to 2.2 pm, more preferably greater than or equal to 2.3 pm, in particular greater than or equal to 2.4 pm, more particularly greater than or equal to 2.5 pm, preferably greater than or equal to 2.6 pm, advantageously greater than or equal to 2.7 pm, preferably greater than or equal to 2.8 pm, more preferably greater than or equal to 2.9 pm, particularly preferably greater than or equal to 3.0 pm or DvlO greater than or equal to 3.1 pm, advantageously greater than or equal to 3.2 pm, preferably greater than or equal to 3.3 pm, more preferably greater than or equal to 3.4 pm, in particular greater than or equal to 3.5 pm, more particularly greater than or equal to 3.6 pm, preferably greater than or equal to 3.7 pm, advantageously greater than or equal to 3.8 pm, preferably greater than or equal to 3.9 pm, more preferably greater than or equal to 4.0 pm; and less than or equal to 12 pm, advantageously less than or equal to 11 pm, preferably less than or equal to 10 pm, more preferably less than or equal to 9 pm, in particular less than or equal to 8 pm, more particularly less than or equal to 7 pm; Dv90 less than or equal to 50 pm, advantageously less than or equal to 48 pm, preferably less than or equal to 46 pm, more preferably less than or equal to 44 pm, in particular less than or equal to 42 pm, more particularly less than or equal to 40 pm, preferably less than or equal to 38 pm, advantageously less than or equal to 36 pm, preferably less than or equal to 34 pm, particularly less than or equal to 32 pm, more particularly less than or equal to 30 pm; and greater than or equal to 1 pm, advantageously greater than or equal to 2 pm, preferably greater than or equal to 3 pm, more preferably greater than or equal to 4 pm, in particular greater than or equal to 5 pm, more particularly greater than or equal to 6 pm, preferably greater than or equal to 7 pm, advantageously more than or equal to 8 pm, preferably more than or equal to 9 pm, particularly preferably more than or equal to 10 pm.

Said composition according to the present invention can be used as one of the materials for preparing a separator in an electrochemical device. Said composition is preferably used in the coating for a separator. In addition to said composition, the coating for a separator may contain inorganic particles which serve to form micropores in the coating (the interstices between inorganic particles). The addition of inorganic particles may also contribute to heat resistance or improve wettability. According to one embodiment, said coating comprises from 50 to 99 weight percent of inorganic particles, based on the weight of the coating. These inorganic particles must be electrochemically stable (not subject to oxidation and/or reduction in the range of voltages used). In addition, the powdery inorganic materials preferably have high ionic conductivity. Materials with a low density are preferred over materials with a higher density, since the weight of the produced battery can be reduced. The dielectric constant is preferably equal to or greater than 5. According to one embodiment, said inorganic particles are selected from the group consisting of: BaTiO3, Pb(Zr,Ti)03, Pb 1-x LaxZryO3 (0<x<l, 0<y<l), PBMg3Nb2/3)3,PbTiO3, hafnia (HfO (HfO2), SrTiO 3, SnO2, CeO2, MgO, NiO, CaO, ZnO, Y2O3, bohemite (y-AIO(OH)), AI2O3, TiO2, SiC, ZrO2, boron silicate, BaSO4, nano-clays, or mixtures thereof. In this case, the ratio of the solids of the polymer PI, and optionally P2 and P3, to the inorganic particles is from 0.5 to 40 parts by weight of solids of the total composition for 60 to 99.5 parts by weight of inorganic particles. Advantageously, the ratio of solids of the polymer PI, and optionally P2 and P3, to the inorganic particles is from 0.5 to 35 per 65 to 99.5 parts by weight of inorganic particles. Preferably, the ratio of solids of the polymer PI, and optionally P2 and P3, to the inorganic particles is from 0.5 to 30 per 70 to 99.5 parts by weight of inorganic particles. The separator coating may optionally comprise from 0 to 15% by weight based on the polymer, and preferably 0.1 to 10% by weight of additives, selected from thickeners, pH adjusting agents, anti-sedimentation agents, surfactants, wetting agents, fillers, antifoaming agents and fugitive or non-fugitive adhesion promoters. The fillers mentioned here in the additives are different from the inorganic particles mentioned above.

Said separator according to the present invention comprises a coating, as described above, optionally arranged on one or both faces of a porous support. In this case, the coating is used to coat the support of the separator, on at least one face, in the form of a single layer or multilayers. There is no particular limitation in the choice of the support which is coated with the coating of the invention, as long as it is a porous substrate having pores. Said support may comprise a single layer or several distinct layers. When it comprises several layers, the coating as described in the present invention is arranged on the external face of the support, that is to say on the face which will first be in contact with the electrolytic composition used in the battery. Advantageously, the application of the coating on the support is done by aqueous means or by solvent means. The porous substrate may take the form of a membrane or a fibrous fabric. When the porous substrate is fibrous, it may be a nonwoven web forming a porous web, such as a web obtained by direct spinning or melt blowing (of the "spunbond" or "melt blown" type) or electro-spinning. Examples of porous substrates useful in the invention as a support include, but are not limited to: polyolefins, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, poly(phenylene oxide), poly(phenylene sulfide), polyethylene naphthalene or mixtures thereof. However, other heat-resistant engineering plastics may be used without particular limitation. Nonwoven materials made of natural and synthetic materials may also be used as the substrate of the separator. The porous substrate generally has a thickness of 1 to 50 µm, and are typically membranes obtained by extrusion and stretching (wet or dry processes) or casting of nonwovens. The porous substrate preferably has a porosity of between 5% and 95%. The average pore size (diameter) is preferably between 0.001 and 50 µm, more preferably between 0.01 and 10 µm.

According to another embodiment, said separator comprises a porous support as described above on which a first layer of inorganic particles as defined in the present application is deposited. On said first layer, a second layer comprising said composition according to the present invention.

According to an alternative embodiment, said separator does not comprise a porous support. In this case, said separator consists of the coating as described above and comprising said composition; the latter is deposited directly on the cathode or on the anode of the electrochemical device. The absence of a porous support makes it possible to limit the production costs of the electrochemical device and the dimensions thereof. In this case, said coating replaces the porous support. In this embodiment, said composition preferably has a porosity of 5 to 95%. The coating for separator of the invention has an excellent compromise of properties for the application of coating for separator: good adhesion in dry and wet state, good resistance to electrolyte solvent(s) characterized by good retained integrity and moderate swelling. Electrode

Said composition can also be used as a binder for an electrode, preferably for a cathode. The electrode comprises said composition of the present invention, a conductive agent and an active material.

In a preferred embodiment, the electrode has the following mass composition: a. 50% to 99.9% of active material, preferably 50% to 99%, b. 25% to 0% of conductive agent, preferably 25% to 0.5%, c. 25% to 0.05% of said composition according to the invention, preferably 25% to 0.5%, d. 0% to 5% of at least one additive selected from the group consisting of a plasticizer, an ionic liquid, a dispersing agent for conductive additive, and a flow aid; the sum of all these percentages being 100%.

The conductive agents in the electrode are composed of one or more materials that can enhance the conductivity. Some examples include carbon blacks such as acetylene black, Ketjen black; carbon fibers, such as carbon nanotube, carbon nanofiber, vapor-grown carbon fiber; metal powders such as SUS powder, and aluminum powder.

Active materials are materials that are capable of storing and releasing lithium ions.

In a preferred embodiment, said electrode is a negative electrode. In particular, for a negative electrode, said active material is selected from the group consisting of a lithium alloy, a metal oxide, a carbon material such as graphite or hard carbon, silicon, a silicon alloy and _Li4Ti5O12 . The shape of the negative electrode active material is not particularly limited but is preferably particulate.

In another preferred embodiment, said electrode is a positive electrode. Preferably, for a cathode, said active material is selected from the group consisting of LiCoO2, Li(Ni, Co, AI)O2, Li( 1+ x), NiaMnbCoc (x represents a real number of 0 or more, a = 0.8, 0.6, 0.5, or 1/3, b = 0.1, 0.2, 0.3, or 1/3, c = 0.1, 0.2, or 1/3), LiNiO2, LiMn2O4, LiCoMnO4, Li3NiMn3O3, Li3Fe2(PO4)3, Li3V2(PO4)3, a Li Mn spinel substituted by a different element having a composition represented by Lil+xMn2-x-yMyO4, M representing at least one metal selected from Al, Mg, Co, Fe, Ni, and Zn, x and y independently representing a real number between 0 and 2, lithium titanate LixTiOy - x and y independently represent a real number between 0 and 2, and a lithium metal phosphate having a composition represented by LiMPO4, M representing Fe, Mn, Co, or Ni. In addition, the surface of each of the materials described above can be coated. The coating material is not particularly limited as long as it has lithium ion conductivity and contains a material capable of being maintained as a coating layer on the surface of the active material. Examples of the coating material include LiNbO3, Li4Ti5O12, and Li3PO4. The shape of the cathode active material is not particularly limited but is preferably particulate. Said electrode can be prepared by a process with or without solvent. Said process comprising the following steps:

- mixing the active filler, said composition according to the invention, the conductive filler and any additives using a process which makes it possible to obtain an electrode formulation applicable to a metal support by a process without solvent or in the presence of a solvent;

- depositing said electrode formulation on the metal substrate by a solvent-free process or in the presence of a solvent to obtain a Li-ion battery electrode,

- optionally a solvent evaporation step; and

- consolidation of said electrode by heat treatment (application of a temperature of up to 50°C above the melting temperature of the polymer, without mechanical pressure), and/or thermo-mechanical treatment such as calendering or thermo-compression.

A “solventless” process is understood to mean a process that does not require a residual solvent evaporation step downstream of the deposition step.

When a solvent is used, it may be water or an organic solvent, in particular a polar organic solvent having a dipole moment greater than 1.5 Debye. By organic solvent, mention may be made, without limitation, of N-methyl pyrrolidone, dimethylformamide, dimethylacetamide, N,N-dimethylaminopropylamine, tetra hydrofuran, dimethyl sulfoxide, acetone, methyl ethyl ketone, cyclohexanone, gamma-butyrolactone and gamma-valerolactone.

As solvent-free mixing processes of the various constituents of the electrode formulation, the following may be mentioned, without being exhaustive: mixing by agitation, mixing by air jet, high shear mixing, mixing by V mixer, mixing by screw mass mixer, mixing by double cone, mixing by drum, conical mixing, mixing by double Z arm, mixing in a fluidized bed, mixing in a planetary mixer, mixing by mechanical fusion, mixing by extrusion, mixing by calendering, mixing by grinding.

As another mixing method, mention may be made of mixing routes using a liquid such as water such as spray drying (co-atomization or "spray drying") or a method of spraying a liquid containing the binder and/or the conductive filler onto a fluidized powder bed of the active filler.

The metal supports of the electrodes are generally made of aluminum for the cathode and copper for the anode. The metal supports can be surface treated and have a conductive primer with a thickness of 5 pm or more. The supports can also be carbon fiber woven or nonwoven. The consolidation of said electrode is done by heat treatment by passing it through an oven, under an infrared radiation lamp, in a calender with heated rollers or in a press with heated plates. Another alternative consists of a two-step process. First, the electrode undergoes heat treatment in an oven, under an infrared radiation lamp or in contact with pressureless heating plates. Then a compression step at room temperature or hot is carried out using a calender or a press with plates. This step makes it possible to adjust the porosity of the electrode and to improve adhesion to the metal substrate. Examples

Three samples of polymers Al, A2 and A3 were tested. The three polymers Al, A2 and A3 are copolymers of vinylidene fluoride with hexafluoropropylene and comprising a carboxylic acid functional group and having a melt viscosity of 74.25 kP measured at 230°C and a shear rate of 100 s-1 measured according to ASTM D3835. In all three cases, the hexafluoropropylene content is 4.5% by weight. Two other samples according to the invention were prepared, A4 and A5. Sample A4 is a copolymer of vinylidene fluoride with 10% hexafluoropropylene having a melt viscosity of 16.0 kP measured at 230°C and a shear rate of 100 s-1 measured according to ASTM D3835. Sample A5 is a copolymer of vinylidene fluoride with 6.1 wt% hexafluoropropylene having a melt viscosity of 49.1 kP measured at 230°C and a shear rate of 100 s-1 measured according to ASTM D3835.

The size distribution of the three samples is shown below in Table 1.

[Table 1]

From these three powder samples, separator coatings were prepared according to the protocol below. For each coating, the adhesion and Gurley value were measured and reported as a function of the copolymer loading used (hereinafter "loading") to prepare the separators. In the tests carried out with sample Al, the loading was 1.2 g/m ² . In the tests carried out with sample A2, the loading was 1.6 g/m ² . In the tests carried out with sample A3, the loading was 2.8 g/m ² .

Preparation of redispersed powder compositions

The powdered samples (100g) and the dispersant (BYK-21486, 2g) are added into a CMC solution (Nippon Paper F04HC, 4.5g in 900g of deionized water) and the powder is then dispersed and possibly deagglomerated using a Filmix mixer operated at 10m/s and 20°C for 1h. The dispersion is then added with a binder (BYK-LPC-22346, 6g) and a wetting agent (BYK-LPX-20990, 1.8g), and then homogenized with a magnetic stirrer at 1000 rpm for 20min.

Measurement of particle size distribution The specific particle diameters DIO, D90, D99 represent volume average values of the diameter at 10%, 90%, 99% respectively of the cumulative volume in the particle size distribution, measured with Microtrac S3500 bluewave and using water as dispersion medium. The analysis can be done directly for redispersed powder compositions. To analyze the powder, the following protocol is followed: 0.5g of powder is placed in a 100mL jar with 2mL of surfactant (10% Triton X-100) and 60mL of demineralized water. The mixture is stirred with a magnetic bar for 10 min at 200rpm then for 5min in the ultrasonic tank. The mixture is analyzed with a Microtrac S3500 bluewave particle size analyzer in wet mode.

Coating of the separator

This formulation is then applied to a Celgard® C210 SP separator using a bar coater equipped with a 50 pim opening doctor blade and at a speed of 30mm/s. The coated separator is dried at 60°C for 5min.

Weight

The weight of the coating deposited is determined with a precision balance by weighing 24mm diameter discs cut with a die, by the difference between the coated separator and the bare separator.

Dry adhesion

Two samples of separators are assembled with their coated face in contact using a roller press operated at 90°C, 1.5MPa, 2.4m/min. In this assembly, a 22.5cm strip is cut, one face of which is then glued to an aluminum plate (3x10cm) with double-sided tape. At one end of the sample, the double layer of separators is peeled off by hand by about 5mm. The sample is installed in the 180° tensile test with this part of the separator peeled off in one of the jaws and the aluminum plate in the other jaw. The peel force is measured at 50mm/min then reported to the sample width and normalized by the coating weight.

Gurley Measure

The Gurley permeability (Gurley 4110N densometer with 4320EN auto-timer) of each coated separator is measured, then the permeability of the substrate (measured at 415sec/100cc) is subtracted to obtain the Gurley permeability value of the coating, which is then normalized by the coating weight.

The results are presented in Table 2 below.

[Table 2]

As demonstrated by the above examples, the use of a composition according to the present invention makes it possible to obtain better adhesion while maintaining an ionic conductivity acceptable for the intended applications. The selection of a polymer having a particular size distribution as mentioned in claim 1 has a significant advantage over a polymer whose size distribution is too high or too heterogeneous.

Claims

Claims 1. Composition, preferably in powder form, comprising a polymer PI comprising monomeric units derived from a monomer MO being vinylidene fluoride or monomeric units derived from a monomer M2 of formula R ¹ R ² C=C(R ³ )C(O)R in which the substituents R ¹ , R ² and R ³ are independently of each other selected from the group consisting of H and Ci-C ₅ alkyl; R is selected from the group consisting of - NHC(CH ₃ )2CH2C(O)CH ₃ OR -OR' with R' selected from the group consisting of H and Ci-Ci ₈ alkyl optionally substituted by one or more -OH group(s) or a five- or six-membered heterocycle comprising at least one nitrogen atom in its cyclic chain; or a mixture of said monomeric units MO or M2; characterized in that said PI polymer has a particle size distribution Dv99 less than or equal to 89 pim and a particle size distribution DvlO greater than or equal to 2.0 pm. 2. Composition according to the preceding claim, characterized in that said polymer PI is a homopolymer of vinylidene fluoride or a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units derived from a monomer M1 selected from the group consisting of vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, trifluoropropenes, tetrafluoropropenes, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropenes, perfluoroalkylvinylethers, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene and chlorotrifluoropropene or a mixture thereof; or a copolymer comprising monomeric units derived from vinylidene fluoride and monomeric units derived from a monomer M2 as defined in the preceding claim. 3. Composition according to the preceding claim, characterized in that said monomer Ml is hexafluoropropylene. 4. Composition according to any one of the preceding claims 2 or 3, characterized in that the mass content of said monomer M1 in said polymer PI is between 0.5% and 20% based on the total weight of said polymer PI or the mass content of said monomer M2 in said polymer PI is between 0.01% and 10% based on the total weight of said polymer PI. 5. Composition according to any one of the preceding claims 2 to 4, characterized in that the viscosity in the molten state of said polymer PI is greater than or equal to 10 kP at 230°C and at a shear rate of 100 s-1 measured according to standard ASTM D3835. 6. Composition according to any one of the preceding claims 2 to 5 characterized in that said PI polymer also comprises a functional group selected from the group consisting of carboxylic acid, carboxylic acid anhydride, carboxylic acid esters, epoxy, amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenolic, ester, ether, siloxane, sulfonic, sulfuric, phosphoric, and phosphonic groups; preferably carboxylic acid, carboxylic acid anhydride, carboxylic acid esters, hydroxyl, phosphoric and phosphonic. 7. Composition according to any one of the preceding claims 2 to 6, characterized in that said polymer PI has a particle size distribution Dv99 less than or equal to 89 pm and a particle size distribution DvlO greater than or equal to 2.9 pm. 8. Composition according to claim 1 characterized in that said polymer PI contains monomeric units derived from a monomer M2 selected from the group consisting of acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-dodecyl acrylate, amyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, diacetone acrylamide, lauryl acrylate, n-octyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, methyl acrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, methacrylate isobutyl methacrylate, t-butyl methacrylate, n-dodecyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, n-octyl methacrylate, ureido methacrylate and mixtures thereof. 9. Composition according to any one of the preceding claims, characterized in that said PI polymer has a particle size distribution Dv90 less than or equal to 50 pm, preferably less than or equal to 46 pm. 10. Composition according to any one of the preceding claims, characterized in that said PI polymer is free of fluorosurfactants. 11. Separator comprising said composition according to any one of the preceding claims 1 to 9. 12. Separator according to the preceding claim, characterized in that it comprises a porous support and said composition according to any one of the preceding claims 1 to 9; said composition being deposited on one of the faces of the porous support. 13. Li-ion secondary battery comprising an anode, a cathode and a separator, wherein said separator is according to the preceding claim. 14. Binder for Li-ion battery comprising said composition according to any one of the preceding claims 1 to 9. 15. Electrode for a lithium-ion battery comprising a metal collector of which at least one face is covered with a layer of substrate containing an active substance and a binder, characterized in that said binder is according to the preceding claim. 16. Li-ion secondary battery comprising an anode, a cathode and a separator, in which the anode or the cathode is an electrode according to the preceding claim.