Binder solution for secondary battery

Abstract

The present invention relates to a binder solution for a secondary battery comprising at least one non-aqueous solvent and at least one fluoropolymer comprising recurring units derived from: a) vinylidene fluoride and b) at least one fluorinated olefin monomer comprising at least one-SO2X functional group, x is selected from X 'and OM, X' is selected from the group consisting of F, Cl, Br and I; and M is selected from the group consisting of H, an alkali metal and NH4 wherein the fluorinated olefin monomer b) is present in an amount of 0.1 to 10.0 mol%, the mol% being relative to the total number of moles of repeating units; to a solid composite electrolyte comprising at least one fluoropolymer according to the invention and at least one sulfide-based solid ion conducting inorganic particle; to a slurry for producing a solid composite electrolyte, comprising a binder solution according to the invention and at least one solid ion-conducting sulfide-based inorganic particle, optionally further comprising at least one electroactive material and / or at least one conductive agent; and to an electrode comprising at least one fluoropolymer according to the invention and at least one electroactive material, optionally further comprising at least one conductive agent and / or at least one sulfide-based solid ion-conducting inorganic particle. The present invention also relates to a secondary battery comprising a positive electrode, a negative electrode and a membrane located between the positive electrode and the negative electrode wherein at least one of the positive electrode, the negative electrode and the membrane comprises at least one fluoropolymer according to the present invention, optionally further comprising at least one sulfide-based solid ion conducting inorganic particle, at least one electroactive material and / or at least one conductive agent.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from European patent application No. 22189662.4 filed on August 10, 2022, the entire contents of which are incorporated by reference into this application for all purposes. Technical Field

[0003] The present invention relates to a binder solution for a secondary battery, the binder solution comprising at least one non-aqueous solvent and at least one fluoropolymer, the fluoropolymer comprising repeating units derived from: a) vinylidene fluoride and b) at least one fluorinated olefin monomer containing at least one -SO2X functional group, X is selected from X' and OM, X' is selected from the group consisting of F, Cl, Br and I; and M is selected from the group consisting of H, alkali metals and NH4, wherein the fluorinated olefin monomer b) is present in an amount of 0.1 to 10.0 mol%, the mol% being relative to the total molar number of the repeating units; to a solid composite electrolyte, the solid composite electrolyte comprising at least one fluoropolymer according to the present invention and at least one sulfide-based solid ion-conducting inorganic particle; to a slurry for preparing a solid composite electrolyte, the slurry comprising the binder solution according to the present invention and at least one sulfide-based solid ion-conducting inorganic particle, optionally further comprising at least one electroactive material and / or at least one conductive agent; and to an electrode, the electrode comprising at least one fluoropolymer according to the present invention and at least one electroactive material, optionally further comprising at least one conductive agent and / or at least one sulfide-based solid ion-conducting inorganic particle. The present invention also relates to a secondary battery comprising a positive electrode, a negative electrode and a membrane located between the positive electrode and the negative electrode, wherein at least one of the positive electrode, the negative electrode and the membrane comprises at least one fluoropolymer according to the present invention, optionally further comprising at least one sulfide-based solid ion-conducting inorganic particle, at least one electroactive material and / or at least one conductive agent. Background Art

[0004] Lithium-ion batteries have maintained their dominance in the rechargeable energy storage device market for decades due to their multiple advantages such as light weight, reasonable energy density, and good cycle life. Nevertheless, with the development of high-power applications such as electric vehicles, hybrid electric vehicles, grid energy storage, etc., there is a continuous demand for better safety and higher energy density.

[0005] First, solid-state battery has been considered as the energy storage device of next generation, wherein highly flammable liquid electrolyte is replaced by solid electrolyte, thus can substantially eliminate the risk of ignition and / or explosion.As solid electrolyte, organic polymer, inorganic matter and composite material have been actively studied, and each of them has its own advantages and disadvantages.Especially, considering the high ionic conductivity of solid electrolyte based on sulfide and good mechanical properties and easy processability of polymer, composite material (that is, inorganic electrolyte dispersed in polymer, for example comprising those of sulfide particles dispersed in polymer matrix) is considered as the most promising solution on industrial scale.However, there is the shortcoming to be further solved, such as poor solvent compatibility of sulfide material, which limits the selection of polymer that can be used to manufacture electrolyte, insufficient adhesion of current collector to electrode, the process of manufacturing solid composite electrolyte is quite complicated, the flexibility of solid composite electrolyte is relatively weak etc.

[0006] US2015 / 096169 A1 (Kureha Corp. and Toyota) discloses that a positive electrode for a sulfide-based solid-state battery exhibits good adhesion to a current collector, the positive electrode being formed with a slurry containing a fluorine-based copolymer having a specific amount of VDF units (between 40 and 70 mol %).

[0007] WO 2021 / 039950 (Fujifilm) describes a composition containing an inorganic solid electrolyte, comprising an inorganic solid electrolyte, a polymer binder and a dispersion medium, wherein the polymer binder comprises a fluorine-based copolymer containing a VDF component and 21 to 65 mol% of a hexafluoropropylene (HFP) component, exhibits more than 60% adsorption to the inorganic solid electrolyte and effectively controls excessive viscosity increase, recondensation or sedimentation of inorganic particles, thereby achieving a solid-state battery with excellent cycle characteristics. In particular, the polymer binder exhibits a tensile fracture strain of 500% or more.

[0008] Secondly, in parallel with the development of solid electrolytes for solid-state batteries, the use of lithium metal as anode has also been actively studied since the 1970s due to its favorable characteristics brought about by its low redox potential and high specific capacity. Lithium metal batteries generally use conventional liquid electrolytes such as carbonate-based electrolytes and / or ether-based electrolytes with low viscosity and high ionic conductivity. These liquid electrolytes decompose into a passivation layer at the beginning of the cycle, which ultimately leads to dendrite growth and subsequent further side reactions between the liquid electrolyte and the deposited reactive lithium ions. These have been key issues that have hindered the commercialization of lithium metal batteries.

[0009] The basic requirements for suitable electrolytes for lithium metal batteries are the same as those for conventional liquid electrolytes for lithium ion batteries, i.e., high ionic conductivity, low melting point and high boiling point, electrochemical stability and also safety. In addition to the basic requirements, suitable electrolytes for lithium metal batteries should also provide solutions for the above-mentioned shortcomings. In order to reduce or inhibit lithium dendrite formation and improve the cycle performance of lithium metal batteries, various approaches have been taken, such as uniformly coating a polymer layer on the surface of lithium metal.

[0010] WO 2018 / 054715 A1 (Solvay Specialty Polymers Italy) describes a specific multilayer assembly comprising a metal layer and a coating that uses a sulfonyl-containing fluoropolymer to inhibit the growth of lithium dendrites in a lithium metal anode, wherein the fluoropolymer comprises repeating units derived from at least one fluorinated olefin monomer bearing at least one -SO2X functional group, X being selected from the group consisting of H, an alkali metal and NH4, and the amount of the repeating unit is 5.0 to 50.0 mol%, preferably 10.0 to 25.0 mol%, relative to the total moles of repeating units in the fluoropolymer.

[0011] JP 2014 / 210929 (Daikin Industries, Ltd.) discloses a method for producing a fluorinated copolymer comprising repeating units derived from a fluorinated olefinic monomer and a monomer containing a -SO3Li group in its side chain, which exhibits high ionic conductivity and excellent stability when used in lithium metal batteries.

[0012] However, the demand for more reliable and safer secondary batteries based on lithium metal anodes still needs to be met, that is, there is still a continuous need for solutions in these areas to overcome the shortcomings of sulfide-based solid composite electrolytes and / or lithium metal batteries. In addition, regardless of the type and generation of batteries, the ultimate goal is always to meet the growing demand for batteries with higher energy density and higher reliability. Summary of the invention

[0013] A first object of the present invention is a binder solution for a secondary battery, the binder solution comprising at least one non-aqueous solvent and at least one fluoropolymer, the fluoropolymer comprising repeating units derived from: a) vinylidene fluoride (VDF) and b) at least one fluorinated olefin monomer containing at least one -SO2X functional group, X is selected from X' and OM, X' is selected from the group consisting of F, Cl, Br and I; and M is selected from the group consisting of H, alkali metals and NH4, wherein the fluorinated olefin monomer b) is present in an amount of 0.1 to 10.0 mol%, the mol% being relative to the total moles of the repeating units.

[0014] A second object of the invention is a solid composite electrolyte comprising at least one fluoropolymer according to the invention and at least one solid ion-conducting inorganic particle based on sulfides.

[0015] A third object of the present invention is a slurry for producing a solid composite electrolyte, the slurry comprising a binder solution according to the invention and at least one sulfide-based solid ion-conducting inorganic particle, optionally further comprising at least one electroactive material and / or at least one conductive agent.

[0016] A fourth object of the present invention is an electrode comprising at least one fluoropolymer according to the invention and at least one electroactive material, optionally further comprising at least one conducting agent and / or at least one solid ion-conducting inorganic particle based on sulfide.

[0017] A fifth object of the present invention is a secondary battery comprising a positive electrode, a negative electrode and a membrane located between the positive electrode and the negative electrode, wherein at least one of the positive electrode, the negative electrode and the membrane comprises at least one fluoropolymer according to the present invention, optionally further comprising at least one sulfide-based solid ion-conducting inorganic particle, at least one electroactive material and / or at least one conductive agent.

[0018] The inventors have surprisingly found that the fluoropolymers according to the present invention can provide a particularly advantageous combination of properties in secondary batteries, such as excellent adhesion to the current collector and better intra-membrane cohesion, while maintaining good ionic conductivity, especially in solid-state batteries with sulfide-based solid composite electrolytes and in current generation batteries with conventional liquid electrolytes (not limited to lithium metal batteries). BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Figure 1 is a cross-section of a pressure cell for AC impedance spectroscopy, developed in-house at Solvay to measure the ionic conductivity of membranes. In the pressure cell, the membrane is pressed between 2 stainless steel electrodes during impedance measurements.

[0020] Figure 2 represents the equivalent circuit used to simulate the conductivity behavior of the solid composite electrolyte, where R1 and R2 represent the bulk resistance and grain boundary resistance, respectively, and Q2 and Q3 represent the grain boundary and electrode contributions, respectively. DETAILED DESCRIPTION

[0021] Ratios, concentrations, amounts and other numerical data may be presented in the form of a range herein. It should be understood that the use of such a range format is only for convenience and brevity, and should be flexibly interpreted as including not only the numerical values ​​explicitly mentioned as range limits, but also all individual numerical values ​​or sub-ranges included within this range, as if each numerical value and sub-range were explicitly mentioned. In the context of the present invention, the term 'percent by weight' (wt%) indicates the content of a specific component in a mixture, which is calculated as the ratio between the weight of the component and the total weight of the mixture. As used herein, unless otherwise expressly stated, the concentration of repeating units in 'percent by mole' (mol%) refers to the concentration relative to the total number of repeating units in the polymer.

[0022] It should be understood that the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the claimed invention. Therefore, various changes and modifications described herein will be apparent to those skilled in the art. In addition, for the sake of clarity and brevity, descriptions of well-known functions and configurations may be omitted.

[0023] The present invention provides a binder solution for a secondary battery, the binder solution comprising at least one non-aqueous solvent and at least one fluoropolymer, the fluoropolymer comprising repeating units derived from:

[0024] a) vinylidene fluoride (VDF); and

[0025] b) at least one fluorinated olefin monomer containing at least one -SO2X functional group, X is selected from X' and OM, X' is selected from the group consisting of F, Cl, Br, and I; and M is selected from the group consisting of H, alkali metals, and NH4,

[0026] The fluorinated olefin monomer b) is present in an amount of 0.1 to 10.0 mol %, the mol % being relative to the total moles of the repeating units.

[0027] In one embodiment, the fluorinated olefin monomer b) containing at least one -SO2X functional group is present in an amount of at least 0.1 mol%, preferably at least 0.2 mol%, more preferably at least 0.3 mol%, and / or at most 10.0 mol%, preferably at most 5.0 mol%, more preferably at most 2.0 mol%, most preferably at most 1.5 mol%, the mol% being relative to the total moles of repeating units.

[0028] In a specific embodiment, the fluorinated olefin monomer b) containing at least one -SO2X functional group is present in an amount of 0.1 to 5.0 mol%, preferably 0.2 to 2.0 mol%, more preferably 0.2 to 1.5 mol%, the mol% being relative to the total moles of repeating units.

[0029] In another embodiment, the fluorinated olefin monomer b) containing at least one -SO2X functional group is present in an amount of 0.3 to 1.0 mol %, the mol % being relative to the total moles of repeating units.

[0030] In one embodiment, the fluorinated olefin monomer b) containing at least one -SO2X functional group is selected from the group consisting of:

[0031] -sulfonyl halofluoroolefin having the formula: CF2=CF(CF2) p SO2X', wherein p is an integer between 0 and 10, preferably between 1 and 6, more preferably p is equal to 2 or 3, and preferably X'=F;

[0032] -sulfonyl halide fluorovinyl ether having the formula: CF2=CF-O-(CF2) m SO2X', wherein m is an integer between 1 and 10, preferably between 1 and 6, more preferably between 2 and 4, even more preferably m is equal to 2, and preferably X'=F;

[0033] -sulfonyl halofluoroalkoxy vinyl ether having the formula: CF2=CF-(OCF2CF(R F1 )) w -O-CF2(CF(R F2 )) y SO2X', where w is an integer between 0 and 2, R F1 and R F2 , which are the same or different from each other, are independently F, Cl or C optionally substituted by one or more ether oxygen atoms. 1- C 10 fluoroalkyl, y is an integer between 0 and 6, preferably w is 1, R F1 is -CF3, y is 1 and R F2 is F, and preferably X'=F; and

[0034] - a sulfonyl halide aromatic fluoroolefin having the formula CF2=CF-Ar-SO2X' or CF2=CF-O-Ar-SO2X', wherein Ar is C 5- C 15 Aromatic or heteroaromatic substituents, and preferably X'=F.

[0035] In a preferred embodiment, the fluorinated olefin monomer b) containing at least one -SO2X functional group is selected from the group consisting of sulfonyl fluorides, i.e., wherein X'=F. More preferably, the fluorinated olefin monomer b) containing at least one -SO2X functional group is selected from the group consisting of sulfonyl fluoride vinyl ethers having the following formula: CF2=CF-O-(CF2) mSO2F, wherein m is an integer between 1 and 6, preferably between 2 and 4.

[0036] In a specific embodiment, the fluorinated olefin monomer b) containing at least one -SO2X functional group is perfluoro-5-sulfonyl fluoride-3-oxa-1-pentene (CF2=CF-O-CF2CF2-SO2F) (hereinafter "VEFS").

[0037] In a more preferred embodiment, the fluoropolymer is a copolymer of VDF-VEFS, wherein VEFS is present in an amount of 0.2 to 2.0 mol %, the mol % being relative to the total moles of repeating units.

[0038] In some embodiments, the fluoropolymer further comprises repeating units derived from c) at least one C2-C8 (per)fluoroolefin and / or C2-C8 chlorinated and / or brominated and / or iodinated fluoroolefin different from a) and b).

[0039] In a specific embodiment, the C2-C8 (per)fluoroolefin is selected from the group consisting of:

[0040] -C2-C8 perfluoroolefins, such as tetrafluoroethylene (TFE) and hexafluoropropylene (HFP);

[0041] - Hydrogen-containing C2-C8 fluoroolefins, such as vinyl fluoride (VF), trifluoroethylene (TrFE), hexafluoroisobutylene;

[0042] - having the formula CH2=CH-R f (per)fluoroalkylethylene, wherein R f is a C1-C6 (per)fluoroalkyl group;

[0043] -Has the formula CF2=CFOR f (per)fluoroalkyl vinyl ether (PAVE), where R f is a C1-C6 (per)fluoroalkyl group;

[0044] - (per)fluorooxy-alkyl vinyl ethers of the formula CF2=CFOX, wherein X is a C1-C ... 12 ((Per)fluoro)oxyalkyl;

[0045] - (per)fluorodioxole having the formula:

[0046]

[0047] Where R f3 , R f4 , R f5 and R f6are the same as or different from each other and are independently selected from fluorine atoms, and C1-C6 (per)fluoroalkyl groups optionally containing at least one oxygen atom; and

[0048] -Has the formula CFX2=CX2OCF2OR" f (per)fluoromethoxy-vinyl ether (MOVE), where R" f is selected from a linear or branched C1-C6 (per)fluoroalkyl group; a C5-C6 cyclic (per)fluoroalkyl group; a linear or branched C2-C6 (per)fluorooxyalkyl group containing 1 to 3 chain oxygen atoms, and X2=F or H; preferably, R" f It is -CF2CF3(MOVE1), -CF2CF2OCF3(MOVE2), or -CF3(MOVE3), and X2=F.

[0049] In more specific embodiments, the C2-C8 (per)fluoroolefin is selected from the group consisting of vinyl fluoride (VF), trifluoroethylene (TrFE), tetrafluoroethylene (TFE), hexafluoropropylene (HFP), hexafluoroisobutylene, and combinations thereof.

[0050] In a preferred embodiment, the C2-C8 (per)fluoroolefin is HFP.

[0051] In another preferred embodiment, the C2-C8 (per)fluoroolefin is TFE.

[0052] In another specific embodiment, the C2-C8 chlorinated and / or brominated and / or iodinated fluoroolefins are selected from the group consisting of 1,1-chlorofluoroethylene (CFE), chlorodifluoroethylene (CDFE), bromotrifluoroethylene, chlorotrifluoroethylene (CTFE), 1,2-dichloro-1,2-difluoroethylene, iodotrifluoroethylene, and combinations thereof.

[0053] In more specific embodiments, the C2-C8 chloro and / or brominated and / or iodinated fluoroolefin is cis-1,2-dichloro-1,2-difluoroethylene or trans-1,2-dichloro-1,2-difluoroethylene, preferably trans-1,2-dichloro-1,2-difluoroethylene.

[0054] In a preferred embodiment, the C2-C8 chlorinated and / or brominated and / or iodinated fluoroolefin is chlorotrifluoroethylene (CTFE).

[0055] In a more preferred embodiment, the fluoropolymer is a terpolymer of VDF-HFP-VEFS, wherein HFP is present in an amount of 10.0 to 30.0 mol%, preferably 13.0 to 25.0 mol%, more preferably 15.0 to 20.0 mol%, and VEFS is present in an amount of 0.1 to 10.0 mol%, preferably 0.1 to 5.0 mol%, more preferably 0.2 to 1.5 mol%, the mol% being relative to the total moles of the repeating units.

[0056] In another more preferred embodiment, the fluoropolymer is a terpolymer of VDF-CTFE-VEFS, wherein CTFE is present in an amount of 10.0 to 30.0 mol%, preferably 13.0 to 25.0 mol%, more preferably 15.0 to 20.0 mol%, and VEFS is present in an amount of 0.1 to 10.0 mol%, preferably 0.1 to 5.0 mol%, more preferably 0.2 to 1.5 mol%, the mol% being relative to the total moles of the repeating units.

[0057] In some embodiments, the fluoropolymer is a fluoroelastomer.

[0058] In the present invention, the term "fluoroelastomer" is intended to designate the fluoropolymer resins serving as the base component for obtaining true elastomers. True elastomers are defined by ASTM, Special Technical Bulletin, No. 184, as materials that can be stretched to twice their intrinsic length at room temperature and, after holding them under tension for 5 minutes, recover within the same time to within 10% of their initial length once they are released.

[0059] Typically, fluoroelastomers are amorphous, exhibit low crystallinity (i.e., have less than 20 vol% crystalline phase), and have a glass transition temperature (T g In most cases, the fluoroelastomer advantageously has a T below 10°C, preferably below 5°C, more preferably below 0°C, and even more preferably below -5°C. g .

[0060] The term "amorphous" herein is intended to mean a polymer having a heat of fusion of less than 5.0 J / g, preferably less than 3.0 J / g, and more preferably less than 2.0 J / g, as measured by differential scanning calorimetry (DSC) according to ASTM D3418 at a heating rate of 10°C / min.

[0061] With regard to the nonaqueous solvent, no particular limitation is imposed as long as the nonaqueous solvent can dissolve the fluoropolymer of the present invention.

[0062] However, if a non-aqueous solvent is used in the presence of sulfide-based solid ion-conducting inorganic particles in addition to the fluoropolymer, the non-aqueous solvent should be compatible with the sulfide-based solid ion-conducting inorganic particles, which means that the solvent has no negative impact on the ionic conductivity of the sulfide-based solid composite electrolyte. For this reason, although the solvent is required to exhibit high polarity, preferably with a high dielectric constant, in order to dissolve the fluoropolymer, it is preferred that no electrophilic moiety is present in the solvent to limit the interaction between the solvent and the sulfide particles in order to avoid their degradation.

[0063] In specific embodiments, the non-aqueous solvent is selected from the group consisting of nitrile-containing solvents, ethers, esters, thiols, thioethers, ketones, and tertiary amines.

[0064] In a preferred embodiment, the non-aqueous solvent is a nitrile-containing solvent having the general formula R-CN, wherein R represents an alkyl group. Non-limiting examples of nitrile-containing solvents are acetonitrile, butyronitrile, valeronitrile, isobutyronitrile, and the like.

[0065] In another preferred embodiment, the non-aqueous solvent is an ether with the general formula R1-O-R2, wherein R1 and R2 independently represent an alkyl group. Ether solvents include cyclic ethers based on 3, 5 or 6 rings. Cyclic ethers can be substituted by alkyl, can have unsaturation and can have additional functional elements such as nitrogen or oxygen atoms inside the ring. Non-limiting examples of (cyclic) ether solvents are diethyl ether, 1,2-dimethoxy ether, cyclopentyl methyl ether, diethyl ether, dibutyl ether, 1,3-dioxolane, 1,3-dioxane, anisole, tetrahydrofuran, methyltetrahydrofuran, tetrahydropyran, etc.

[0066] In another preferred embodiment, the non-aqueous solvent is an ester with the general formula R3-COO-R4, wherein R3 and R4 independently represent an alkyl group. Non-limiting examples of ester solvents are butyl butyrate, ethyl benzoate, etc. In a more preferred embodiment, the non-aqueous solvent is butyl butyrate.

[0067] In another preferred embodiment, the non-aqueous solvent is a thiol with the general formula R5=SH or a thioether with the general formula R6-S-R7, wherein R5, R6 and R7 are independently alkyl. The thioether solvent includes a cyclic thioether based on a 3, 5 or 6-membered ring. The cyclic thioether can be substituted by an alkyl group, can have unsaturation and can have additional functional elements such as nitrogen or oxygen atoms in the ring. Non-limiting examples of thiol solvents are ethanethiol, tert-dodecyl mercaptan, thiophenol, tert-butyl mercaptan, octanethiol, dimethyl sulfide, ethyl methyl sulfide, methyl benzyl sulfide, etc.

[0068] In another preferred embodiment, the non-aqueous solvent is a ketone having the general formula R8R9C=O, wherein R8 and R9 independently represent an alkyl group. Non-limiting examples of ketone solvents are methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, acetophenone, benzophenone, and the like. In a more preferred embodiment, the non-aqueous solvent is methyl isobutyl ketone.

[0069] In another preferred embodiment, the non-aqueous solvent is a solvent having the general formula R 10 R 11 R 12 N tertiary amine, where R 10 , R 11 and R 12 and independently represent an alkyl group. The N atom of the tertiary amine may be embedded in a 3-, 5-, or 6-membered ring. Non-limiting examples of tertiary amine solvents are triethylamine, dimethylbutylamine, tributylamine, cyclohexyldimethylamine, N-ethylpiperidine, and the like.

[0070] In the present invention, R1 to R 12 The alkyl groups of the present invention refer to "alkyl" including saturated hydrocarbons having one or more carbon atoms, including: straight chain alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, cyclic alkyl groups (or "cycloalkyl" or "alicyclic" or "carbocyclyl") such as cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl, branched alkyl groups such as isopropyl, tert-butyl, sec-butyl and isobutyl, and alkyl-substituted alkyl groups such as alkyl-substituted cycloalkyl and cycloalkyl-substituted alkyl groups, as defined above. In addition, the alkyl group may include functional groups such as one or more unsaturated, ether, carbonyl, carboxyl, hydroxyl, sulfhydryl, thiol, sulfoxyl, sulfonic acid, nitrile, nitro, nitroso, azo, amide, imide, amino, imine or halogen.

[0071] In another specific embodiment, the non-aqueous solvent is an organic carbonate, which may be partially or fully fluorinated. In the present invention, the organic carbonate may be cyclic or acyclic. Non-limiting examples of organic carbonates notably include ethylene carbonate (1,3-dioxolane-2-one), propylene carbonate, 4-methylene-1,3-dioxolane-2-one, 4,5-dimethylene-1,3-dioxolane-2-one, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, methyl propyl carbonate, methyl butyl carbonate, ethyl butyl carbonate, propyl butyl carbonate, dibutyl carbonate, di-tert-butyl carbonate, butylene carbonate, monofluorinated and difluorinated ethylene carbonate, monofluorinated and difluorinated propylene carbonate, monofluorinated and difluorinated butylene carbonate, 3,3,3-trifluoropropylene carbonate, fluorinated dimethyl carbonate, fluorinated diethyl carbonate, fluorinated methyl ethyl carbonate, fluorinated dipropyl carbonate, fluorinated dibutyl carbonate, fluorinated methyl propyl carbonate, and fluorinated ethyl propyl carbonate.

[0072] In another specific embodiment, the non-aqueous solvent is selected from the group consisting of: acyclic amides, lactams, lactones, cyclic sulfones, sulfoxides and tertiary phosphines. The non-limiting examples of non-aqueous solvents include dimethylformamide, N,N-dimethylacetamide, N-Methyl pyrrolidone, N-ethyl pyrrolidone, gamma-butyrolactone, gamma-valerolactone, cyclopentane, dimethyl sulfoxide and hexamethylphosphoramide. In a preferred embodiment, the non-aqueous solvent is N-Methyl pyrrolidone.

[0073] A second object of the present invention is a solid composite electrolyte comprising at least one fluoropolymer and at least one sulfide-based solid ion-conducting inorganic particle, wherein the fluoropolymer comprises repeating units derived from:

[0074] a) vinylidene fluoride (VDF); and

[0075] b) at least one fluorinated olefin monomer containing at least one -SO2X functional group, X is selected from X' and OM, X' is selected from the group consisting of F, Cl, Br, and I; and M is selected from the group consisting of H, alkali metals, and NH4,

[0076] The fluorinated olefin monomer b) is present in an amount of 0.1 to 10.0 mol %, the mol % being relative to the total moles of the repeating units.

[0077] Fluoropolymer is as defined in the present invention.

[0078] In the present invention, the term "sulfide-based solid ion-conductive inorganic particles" is not particularly limited as long as it is a solid electrolyte material containing one or more sulfur atoms in the molecular structure or composition.

[0079] The sulfide-based solid ion-conductive inorganic particles preferably contain Li, S, and an element of Groups 13 to 15 (e.g., P, Si, Sn, Ge, Al, As, Sb, or B) to increase Li ion conductivity.

[0080] The sulfide-based solid ion-conducting inorganic particles according to the present invention are preferably selected from the group consisting of:

[0081] - Lithium tin phosphide ("LSPS") materials, such as Li 10 SnP2S 12 ;

[0082] - Lithium phosphosulfide ("LPS") materials, such as glasses, crystals or glass-ceramics of those having the formula: (Li2S) x -(P2S5) y , where x+y=1 and 0≤x≤1; Li7P3S 11;Li7PS6;Li4P2S6;Li 9.6 P3S 12 and Li3PS4;

[0083] - doped LPS, such as Li2CuPS4; Li 1+2x Zn 1-x PS4, where 0≤x≤1; Li 3.33 Mg 0.33 P2S6; and Li 4- 3x Sc x P2S6, where 0≤x≤1;

[0084] -With formula Li x P y S z A lithium phosphorus sulfide oxygen ("LPSO") material of O, wherein 0.33≤x≤0.67, 0.07≤y≤0.2, 0.4≤z≤0.55;

[0085] - Lithium phosphide materials containing X ("LXPS"), wherein X is Si, Ge, Sn, As, or Al, such as Li 10 SnP2S 12 , Li 10 GeP2S 12 , Li 10 SiP2S 12 , and Li2S-P2S5-SnS;

[0086] - lithium phosphorus oxysulfide containing X ("LXPSO"), wherein X is Si, Ge, Sn, As or Al;

[0087] -Lithium silicon sulfide ("LSS") materials, such as Li2SiS3, Li2S-P2S5-SiS2, Li2S-P2S5-SiS2-LiCl, Li2S-SiS2-P2S5, Li2S-SiS2-P2S5-LiI, Li2S-SiS2-LiI, Li2S-SiS2, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , and Li2S-SiS2-Al2S3;

[0088] -Lithium boron sulfide materials, such as Li3BS3 and Li2S-B2S3-LiI;

[0089] -Lithium tin sulfide materials and lithium arsenide materials, such as Li 0.8 Sn 0.8 S2, Li4SnS4, Li 3.833 Sn0.833 As 0.166 S4, Li3AsS4-Li4SnS4, and Ge-substituted Li3AsS4; and

[0090] -Has the general formula Li a PS b X c A lithium phosphorus sulfide material, wherein X represents at least one halogen element selected from the group consisting of Cl, Br and I or a combination thereof; and a represents a number from 2.0 to 7.0, b represents a number from 3.5 to 6.0, and c represents a number from 0 to 3.0, such as Li4PS4Cl 、 Li7P2S8Cl, and Li7P2S8I.

[0091] In a more preferred embodiment, the sulfide-based solid ion-conducting inorganic particles are of the general formula Li a PS b X c Lithium phosphide materials, more particularly Argyrodite-type sulfide materials having the formula Li6PS5X, wherein X is Cl, Br, or I.

[0092] In another preferred embodiment, the argyrodite-type sulfide material having the formula Li6PS5X lacks sulfur and / or lithium, such as Li6-xPS5-xCl 1+x (where 0≤x≤0.5), or doped with heteroatoms.

[0093] Particularly preferred sulfide-based solid ion-conducting particles are lithium tin phosphide ("LSPS") materials (e.g., Li 10 SnP2S 12 ) and argyrodite-type sulfide materials (e.g. Li6PS5Cl).

[0094] In one embodiment, the amount of sulfide-based solid ion-conducting inorganic particles is at least 40.0 wt%, preferably at least 60.0 wt%, more preferably at least 70.0 wt%, even more preferably at least 80.0 wt%, and most preferably at least 90.0 wt%, and / or at most 99.8 wt%, preferably at most 99.5 wt%, more preferably at most 99.0 wt%, and most preferably at most 98.0 wt%, based on the total weight of the solid composite electrolyte.

[0095] In a specific embodiment, the amount of the sulfide-based solid ion-conductive inorganic particles is 40.0 to 99.8 wt %, preferably 60.0 to 99.5 wt %, more preferably 70.0 to 99.0 wt %, even more preferably 80.0 to 99.0 wt %, and most preferably 90.0 to 99.0 wt %, based on the total weight of the solid composite electrolyte.

[0096] In a more specific embodiment, the amount of the sulfide-based solid ion-conductive inorganic particles is 95.0 to 99.0 wt % based on the total weight of the solid composite electrolyte.

[0097] In the present invention, the sulfide-based solid ion-conductive inorganic particles are different from lithium salts conventionally used as an essential element of lithium secondary batteries.

[0098] The term "lithium salt" is intended herein to mean a substance that needs to be dissolved in a solvent to ensure ion conduction.

[0099] In lithium secondary batteries, the liquid electrolyte is mainly composed of lithium salts in non-aqueous organic solvents, in which lithium ions (i.e., Li + cations) act as charge carriers, so that the liquid electrolyte acts as a cation (i.e., Li + The conductive pathway for the movement of cations from the cathode to the anode during discharge. The dissolution of lithium salts is through the solvent - Li + The interaction is carried out, that is, Li + The dissociation of cation-(counter) anion interactions is critical. Therefore, many simple lithium salts are excluded from use in electrolytes because their strong cation-anion interactions result in high lattice energies and thus poor solubility in relevant aprotic solvents (e.g., LiCl, LiF, Li2O, etc.). Non-limiting examples of lithium salts notably include lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluoroantimonate (LiSbF6), lithium hexafluorotantalate (LiTaF6), lithium tetrachloroaluminate (LiAlCl4), lithium tetrafluoroborate (LiBF4), lithium chloroborate (Li2B 10 Cl 10 ), lithium fluoroborate (Li2B 10 F 10 ), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(fluorosulfonyl)imide Li(FSO2)2N (LiFSI), lithium bis(trifluoromethanesulfonyl)imide Li(SO2CF3)2N (LiTFSI), and mixtures thereof.

[0100] Li + Cationic conductivity is derived from both the total ionic conductivity and the cation transfer number. Considering that the cation transfer number in non-aqueous organic solvents is low, for example, typically less than 0.5, ionic conductivity plays a key role in battery performance.

[0101] In short, a liquid electrolyte in which at least one lithium salt is dissolved in at least one non-aqueous organic solvent plays a key role as one of the main components of a conventional lithium secondary battery.

[0102] In this regard, recent advances in the field of batteries involve the use of solid substances as electrolyte materials, and among others, solid ion-conducting inorganic particles based on sulfides are promising materials. In such solid-state batteries, the solid electrolyte replaces the function / role of the liquid electrolyte. Although many efforts have been made to understand the ion transport mechanism in solid electrolytes, the Li+ transport mechanism within the solid electrolyte (i.e., the interface between the electrode and the electrolyte (electrode / solid electrolyte interface and the active material / solid electrolyte interface within the electrode)) is still unclear. + The cation diffusion behavior still lacks a deep understanding.

[0103] Like liquid electrolytes, solid electrolytes are ionic conductors that deliver ions between two electrodes. However, unlike liquid electrolytes, solid electrolytes do not need to dissociate / dissolve into Li + The solid electrolyte is conductive by the presence of cations. For example, the lithium cations in lithium argyrodite Li6PS5X (X = Cl, Br or I) are + The cation diffusion mechanism plays a role as Li + However, it dissociates into Li in the non-aqueous solvent that constitutes the liquid electrolyte. + Different from the lithium salts of the cations and the corresponding counteranions, it is understood that the lithium sites within Li6PS5X form local cages, in which multiple hopping processes may occur, namely bimodal hopping, intracage hopping, and intercage hopping, thereby generating Li + Cation diffusion / transport (Reddy et al., Sulfide and oxide inorganic solid electrolytes for All-Solid-State LiBatteries: Nanomaterials 2020, 10, 1606; doi: 10.3390 / nano10081606). That is, unlike liquid electrolytes, only one species in solid electrolytes is mobile and these structures have the mobile species (i.e., Li + cations), corresponding to a cooperative conduction mechanism.

[0104] In view of the above, lithium salts are significantly different from sulfide-based solid ion-conducting inorganic particles containing lithium species in their inorganic structure, because lithium salts need to be dissolved in a solvent to ensure ion conduction, while sulfide-based solid ion-conducting inorganic particles have an intrinsic ionic conductivity higher than 0.1 mS / cm at room temperature, which is due to the diffusion of sublattices of mobile lithium species in their inorganic skeletons.

[0105] In the present invention, the solid composite electrolyte does not contain a lithium salt.

[0106] The solid composite electrolyte of the present invention is characterized by its high adhesion property to a current collector when used for manufacturing an electrode (notably a positive electrode) of a solid-state battery.

[0107] In the present invention, the nature of the "current collector" depends on whether the electrode provided thereby is a positive electrode or a negative electrode. If the electrode of the present invention is a positive electrode, the current collector typically comprises at least one metal selected from the group consisting of aluminum (Al), nickel (Ni), titanium (Ti), and their alloys, preferably Al. If the electrode of the present invention is a negative electrode, the current collector typically comprises at least one metal selected from the group consisting of lithium (Li), sodium (Na), zinc (Zn), magnesium (Mg), copper (Cu), and their alloys, preferably Cu.

[0108] The solid composite electrolyte of the present invention is further characterized by the high cohesion between the fluoropolymer and the sulfide-based solid ion-conducting inorganic particles when used for manufacturing a film located between the positive electrode and the negative electrode.

[0109] A third object of the present invention is a slurry for manufacturing a solid composite electrolyte, the slurry comprising an adhesive solution according to the present invention and at least one sulfide-based solid ion-conducting inorganic particle, optionally further comprising at least one electroactive material and / or at least one conductive agent.

[0110] In the present invention, the term "electroactive material" is intended to denote a material that can incorporate or insert lithium ions into its structure and release a large amount of lithium ions therefrom during the charging and discharging stages of a battery.

[0111] In the case of forming a positive electrode, the electroactive material for the positive electrode is not particularly limited. It may include composite metal chalcogenides having the formula LiMQ2, where M is at least one metal selected from transition metals such as Co, Ni, Fe, Mn, Cr, and V and Q is a chalcogen element such as O and S. Among these, it is preferred to use lithium-based composite metal oxides having the formula LiMO2, where M is the same as defined above. Preferred examples thereof may include LiCoO2, LiNiO2, LiNi x Co 1-x O2 (0 < x < 1) and spinel-structured LiMn2O4. Another preferred example may include lithium-nickel-manganese-cobalt-based metal oxides having the formula LiNi x Mn y Co z O2 (x + y + z = 1, referred to as NMC), for example LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, LiNi0.6 Mn 0.2 Co 0.2 O2, and LiNi x Co y Al z O2 (x+y+z=1, called NCA) based on lithium-nickel-cobalt-aluminum metal oxides, such as LiNi 0.8 Co 0.15 Al 0.05 O2.

[0112] As an alternative, still in the case of forming a positive electrode, the electroactive material of the positive electrode may include a material having the formula M1M2(JO4) f E 1-f An electroactive material based on lithiated or partially lithiated transition metal oxyanions, wherein M1 is lithium, which may be partially substituted by another alkali metal accounting for less than 20% of the M1 metal; M2 is a transition metal selected from Fe, Mn, Ni or a mixture thereof at an oxidation level of +2, which may be partially substituted by one or more additional metals, which are at an oxidation level between +1 and +5 and account for less than 35% of the M2 metal, including 0; JO4 is any oxygen anion, wherein J is P, S, V, Si, Nb, Mo or a combination thereof; E is a fluoride anion, a hydroxide anion or a chloride anion; f is the mole fraction of the JO4 oxygen anion, generally included between 0.75 and 1.

[0113] M1M2(JO4) as defined above f E 1-f The electroactive material is preferably phosphate based and may have an ordered or altered olivine structure.

[0114] More preferably, the electroactive material of the positive electrode has the formula Li 3-x M' y M” 2-y (JO4)3, wherein 0≤x≤3, 0≤y≤2, M' and M" are the same or different metals, at least one of which is a transition metal; JO4 is preferably PO4, which may be partially substituted by another oxygen anion, wherein J is S, V, Si, Nb, Mo or a combination thereof. Still more preferably, the electroactive material is of the formula Li(Fe x Mn 1-x )PO4, wherein 0≤x≤1, preferably x=1, i.e., lithium iron phosphate having the formula LiFePO4.

[0115] In a preferred embodiment, the electroactive material of the positive electrode is selected from the group consisting of: LiMQ2, wherein M is at least one metal selected from Co, Ni, Fe, Mn, Cr and V and Q is O or S; LiNix Co 1-x O2(0 < x < 1); spinel-structured LiMn2O4; lithium-nickel-manganese-cobalt-based metal oxide (NMC) having the formula LiNi x Mn y Co z O2 (x + y + z = 1), lithium-nickel-cobalt-aluminum-based metal oxide (NCA) having the formula LiNi x Co y Al z O2 (x + y + z = 1), lithium-cobalt-based metal oxide (LCO), lithium-nickel-manganese-based metal oxide (LNMO), and LiFePO4.

[0116] In a more preferred embodiment, the electroactive material of the positive electrode is selected from the group consisting of NMC, NCA, LCO, and LNMO.

[0117] In the present invention, the term "conductive agent" is intended to particularly denote a material used to ensure that the electrode has good charge and discharge performance and to provide additional conductivity. Non-limiting examples of conductive agents are carbonaceous materials and metal powders or fibers, such as carbon black, carbon nanotubes (CNT), vapor-grown carbon fibers (VGCF), graphite, graphene, graphite fibers, etc. Examples of carbon black include Ketjen black and acetylene black. Metal powders or fibers include nickel and aluminum powders or fibers.

[0118] In one embodiment, the amount of fluoropolymer in the slurry is such that an electrode containing a certain amount of fluoropolymer is provided, and this amount ranges from at least 1.0 wt%, preferably at least 1.5 wt%, more preferably 2.0 wt%, and / or at most 20.0 wt%, preferably at most 15.0 wt%, more preferably at most 10.0 wt%, most preferably at most 5.0 wt% relative to the total weight of the fluoropolymer, sulfide-based solid ion-conducting inorganic particles, electroactive material, and optionally the conductive agent.

[0119] In a specific embodiment, the amount of fluoropolymer in the slurry is such that an electrode containing a certain amount of fluoropolymer is provided, and this amount ranges from 1.0 to 20.0 wt%, preferably 1.5 to 15.0 wt%, more preferably 2.0 to 10.0 wt%, and most preferably 2.0 to 5.0 wt% relative to the total weight of the fluoropolymer, sulfide-based solid ion-conducting inorganic particles, electroactive material, and optionally the conductive agent. Thus, the resulting electrode exhibits excellent adhesion to the current collector.

[0120] The slurry according to the present invention is typically applied to the foil of at least one inert flexible carrier by a technique selected from the following: casting, spraying, spin spraying, roller coating, blade coating, slot coating, gravure coating, inkjet printing, spin coating and screen printing. In one embodiment, the wet film thus obtained typically has a thickness of 10 to 400 μm, preferably 50 to 200 μm. The wet film is then dried at a temperature between 10°C and 200°C, preferably between 20°C and 80°C. An additional drying step can be suitably performed in an oven under vacuum at a temperature between 20°C and 150°C, preferably between 50°C and 80°C, to completely remove the solvent. Those skilled in the art can select the optimal duration and temperature of the drying step according to the boiling point of the solvent. The dry film thus obtained can be further subjected to an additional compression step, such as calendaring, uniaxial or isostatic compression method, to reduce porosity and increase the density of the solid composite electrolyte.

[0121] A fourth object of the present invention is an electrode comprising at least one fluoropolymer according to the invention and at least one electroactive material, optionally further comprising at least one conducting agent and / or at least one solid ion-conducting inorganic particle based on sulfide.

[0122] In one embodiment, the electroactive material is used in a positive electrode.

[0123] In a specific embodiment, the electrode comprises at least one fluoropolymer according to the invention and at least one electroactive material for the positive electrode.

[0124] In another specific embodiment, an electrode comprises at least one fluoropolymer according to the invention, at least one electroactive material for a positive electrode, and at least one sulfide-based solid ion-conducting inorganic particle.

[0125] In the present invention, the positive electrode is characterized by high adhesion properties to the current collector in the secondary battery.

[0126] In a specific embodiment, the positive electrode comprises a VDF-VEFS copolymer as the fluoropolymer. 、 LiNi as electroactive material for positive electrode 0.6 Mn 0.2 Co 0.2 O2, and optionally carbon black as a conductive agent.

[0127] In another specific embodiment, the positive electrode comprises a VDF-CTFE-VEFS terpolymer as a fluoropolymer, LiNi as an electroactive material for the positive electrode. 0.6 Mn 0.2 Co 0.2 O2, and optionally carbon black as a conductive agent.

[0128] In another specific embodiment, the positive electrode comprises a VDF-HFP-VEFS terpolymer as a fluoropolymer, LiNi as an electroactive material for the positive electrode. 0.6 Mn 0.2 Co 0.2 O2, and optionally carbon black as a conductive agent.

[0129] In some embodiments, an electrode comprises a fluoropolymer according to the present invention, at least one sulfide-based solid ion-conducting inorganic particle, at least one electroactive material, and optionally at least one conductive agent.

[0130] In a more specific embodiment, the positive electrode comprises a VDF-VEFS copolymer as a fluoropolymer, Li6PS5Cl as a sulfide-based solid ion-conducting inorganic particle, LiNi as an electroactive material for the positive electrode. 0.6 Mn 0.2 Co 0.2 O2, and optionally carbon black as a conductive agent.

[0131] In another more specific embodiment, the positive electrode comprises a VDF-CTFE-VEFS terpolymer as a fluoropolymer, Li6PS5Cl as a sulfide-based solid ion-conducting inorganic particle, LiNi as an electroactive material for the positive electrode. 0.6 Mn 0.2 Co 0.2 O2, and optionally carbon black as a conductive agent.

[0132] In another more specific embodiment, the positive electrode comprises a VDF-HFP-VEFS terpolymer as a fluoropolymer, Li6PS5Cl as a sulfide-based solid ion-conducting inorganic particle, LiNi as an electroactive material for the positive electrode. 0.6 Mn 0.2 Co 0.2 O2, and optionally carbon black as a conductive agent.

[0133] A fifth object of the present invention is a secondary battery comprising a positive electrode, a negative electrode and a membrane located between the positive electrode and the negative electrode, wherein at least one of the positive electrode, the negative electrode and the membrane comprises at least one fluoropolymer according to the present invention, optionally further comprising at least one sulfide-based solid ion-conducting inorganic particle, at least one electroactive material and / or at least one conductive agent.

[0134] In some embodiments, the secondary battery is a solid-state battery.

[0135] In the present invention, the term "membrane" is intended to mean in particular an ion-permeable membrane placed between the positive electrode and the negative electrode. Its function is to allow lithium ions to pass through while blocking electrons and ensuring physical isolation between the electrodes.

[0136] Should the disclosure of any patents, patent applications, and publications incorporated herein by reference conflict with the description of the present application to the extent that it might render a term unclear, the present invention shall take precedence.

[0137] The present invention will now be described in more detail with reference to the following examples, which are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0138] Examples

[0139] raw materials

[0140] - Crystalline sulfide-based solid ion-conducting inorganic particles LPSCl (Li6PS5Cl), commercially available from NEI Corporation;

[0141] -NMC622( NMC KHX12), commercially available from Umicore;

[0142] -Conductive carbon black (C-NERGY TM SUPER C65T), commercially available from Imerys;

[0143] - butyl butyrate (BB), commercially available from Sigma Aldrich;

[0144] - methyl isobutyl ketone (MIBK), commercially available from Sigma-Aldrich; and

[0145] - N-methylpyrrolidone (NMP), commercially available from Sigma-Aldrich.

[0146] Fluoropolymers:

[0147] -Polymer 1: VDF-CTFE-VEFS (79.5 / 20.0 / 0.5 in mol%), synthesized in-house at Solvay Specialty Polymers Italy SpA

[0148] -Polymer 2: VDF-CTFE (80.0 / 20.0 in mol%), synthesized in-house at Solvay Specialty Polymers Italy

[0149] - Polymer 3: VDF-HFP (in mol % 78.5 / 21.5), N935, commercially available from Solvay Specialty Polymers Italy (T g =-19℃)

[0150] -Polymer 4: VDF-CTFE-HFP (80.0 / 10.0 / 10.0 in mol%), synthesized in-house at Solvay Specialty Polymers Italy

[0151] -Polymer 5: VDF-CTFE-HFP (79.0 / 15.0 / 6.0 in mol%), synthesized in-house at Solvay Specialty Polymers Italy

[0152] Synthesis of polymers 1-2 and 4-5

[0153] Polymer 1:

[0154] In a steel vertical autoclave equipped with baffles and a stirrer operating at 550 rpm, 1.3 L of demineralized water were introduced. The temperature was brought to a reaction temperature of 75° C. and then 6.0×10 5 Pa (absolute pressure) of VDF. Subsequently, a gaseous mixture of VDF-CTFE with a nominal molar ratio of 80 / 20 was added by using a compressor until a pressure of 26.0×10 5 The pressure is Pa (absolute pressure).

[0155] Before starting the reaction, the composition of the gaseous mixture present in the head of the autoclave as analyzed by gas chromatography was 83.5 mol% of VDF and 16.5 mol% of CTFE. 30.0 cc of an ethyl acetate solution (3% w / w) of ammonium persulfate ((NH4)2S2O8) was fed into the autoclave.

[0156] The polymerization pressure was maintained constant by first adding 2.0 mL of VEFS to the gaseous mixture when 25.0 g of the gaseous mixture was introduced, followed by continued addition of 2.0 mL of VEFS each time an additional 12.5 g of the gaseous mixture was further added until the polymerization was complete. When 250.0 g of the mixture had been fed, the feed was stopped, the reactor was cooled to room temperature and then degassed to remove residual (i.e., unreacted) monomers. The latex as produced was discharged and further degassed with nitrogen for 24 hours. The resulting polymer was separated with aluminum sulfate (Al2(SO4)3) using standard separation procedures and then dried in a ventilated oven at 90°C for 24 hours.

[0157] Polymer 2:

[0158] In a steel vertical autoclave equipped with baffles and a stirrer operating at 550 rpm, 1.3 L of demineralized water were introduced. The temperature was brought to a reaction temperature of 75° C. and 3.5×105 Pa (absolute pressure) of VDF. A gaseous mixture of VDF-CTFE with a nominal molar ratio of 80 / 20 was added by using a compressor until a pressure of 20.0×10 5 The pressure is Pa (absolute pressure).

[0159] Before starting the reaction, the composition of the gaseous mixture present in the head of the autoclave as analyzed by gas chromatography was 83.5 mol% VDF and 16.5 mol% CTFE. 45.0 cc of ammonium persulfate solution in ethyl acetate (3% w / w) and 2 mL of pure ethyl acetate were fed into the autoclave.

[0160] The polymerization pressure was maintained constant by feeding the monomer mixture. When 300.0 g of the mixture had been fed, the feed was stopped, the reactor was cooled to room temperature and degassed to remove unreacted monomer. The latex as produced was discharged and further degassed with nitrogen for 24 hours. The resulting polymer was separated with aluminum sulfate using a standard separation procedure, and then dried in a ventilated oven at 90 ° C for 24 hours.

[0161] Polymer 4:

[0162] Polymer 4 was synthesized in a similar manner to Polymer 1.

[0163] In a steel vertical autoclave equipped with baffles and a stirrer operating at 550 rpm, 1.3 L of demineralized water were introduced. The temperature was brought to a reaction temperature of 75°C. 4.0×10 5 Pa (absolute pressure) VDF and 3.0×10 5 Pa (absolute pressure) of HFP. A gaseous mixture of VDF-CTFE-HFP with a nominal molar ratio of 80.0 / 10.0 / 10.0 was added by using a compressor until a pressure of 20.0×10 5 The pressure is Pa (absolute pressure).

[0164] Before starting the reaction, the composition of the gaseous mixture present in the head of the autoclave as analyzed by gas chromatography was 72.6 mol% of VDF, 14.2 mol% of CTFE and 13.2 mol% of HFP. 2.0 mL of pure ethyl acetate was fed into the autoclave.

[0165] The polymerization pressure was maintained constant until the polymerization was completed. When 200.0 g of the mixture had been fed, the feed was stopped, the reactor was cooled to room temperature and degassed to remove residue. The latex as produced was discharged and further degassed with nitrogen for 24 hours. The resulting polymer was separated with aluminum sulfate using a standard separation procedure and then dried in a ventilated oven at 90 ° C for 24 hours.

[0166] Polymer 5:

[0167] Polymer 5 was synthesized in a similar manner to Polymer 4.

[0168] In a steel vertical autoclave equipped with baffles and a stirrer operating at 550 rpm, 1.3 L of demineralized water were introduced. The temperature was brought to a reaction temperature of 75°C. 3.8×10 5 Pa (absolute pressure) VDF and 4.0×10 5 Pa (absolute pressure) of HFP. A gaseous mixture of VDF-CTFE-HFP with a nominal molar ratio of 79.0 / 15.0 / 6.0 was added by using a compressor until a pressure of 20.0×10 5 The pressure is Pa (absolute pressure).

[0169] Before starting the reaction, the composition of the gaseous mixture present in the head of the autoclave as analyzed by gas chromatography was 78.3 mol% of VDF, 14.6 mol% of CTFE and 7.1 mol% of HFP. 45.0 cc of an ethyl acetate solution of ammonium persulfate (3% w / w) and 3 mL of pure ethyl acetate were fed into the autoclave.

[0170] The polymerization pressure was maintained constant until the polymerization was completed. When 300.0 g of the mixture had been fed, the feed was stopped, the reactor was cooled to room temperature and then degassed to remove the residue. The latex as produced was discharged and further degassed with nitrogen for 24 hours. The resulting polymer was then separated with aluminum sulfate using a standard separation procedure and dried in a ventilated oven at 90 ° C for 24 hours.

[0171] Preparation of solid composite electrolytes E1 and CE1-CE4

[0172] Example 1 (E1) of the present invention

[0173] A solid composite electrolyte composed of 95.0 parts by weight (pbw) of LPSCl and 5.0 pbw of polymer 1 was produced in the form of a film as follows:

[0174] A 10.0 wt% polymer solution was prepared by weighing 1.0 g of polymer 1 and 9.0 g of BB. Subsequently, 3.705 g of LPSCl, 1.95 g of the 10.0 wt% polymer solution and 0.345 g of BB were mixed with 4 glass balls under magnetic stirring at 400 rpm for a minimum of 6 hours. The solid content of the slurry and the casting speed were adjusted so that the slurry viscosity was maintained between 2.0 and 10.0 Pa.s during casting. The obtained slurry was cast on a flexible support ( FN). The wet film was dried on a hot plate at 50°C for one hour and then placed in an oven under vacuum at 80°C during the night. The samples were stored in mini grip bags and then placed in sealed bags. All experiments were performed in an argon-filled glove box.

[0175] Comparative Example 1 (CE1)

[0176] CE1 was prepared in the same manner as E1 except that polymer 2 was used instead of polymer 1.

[0177] Comparative Example 2 (CE2)

[0178] The solid composite electrolyte of CE2 was prepared in the same manner as E1, except that polymer 3 was used instead of polymer 1.

[0179] Comparative Example 3 (CE3) and Comparative Example 4 (CE4)

[0180] The solid composite electrolytes of CE3 and CE4 were prepared in the same manner as CE2, except that polymer 4 and polymer 5 were used instead of polymer 3, respectively.

[0181] Cohesion within solid composite electrolytes E1 and CE1-CE4

[0182] A strip of dry, self-supporting solid composite electrolyte was fixed to a rigid Al plate (2.6 cm * 10 cm) using double-sided tape (width 25 mm; thickness 0.24 mm). Using an electric tensile / compression test bench (ESM303, from Mark-10 Corporation) equipped with a flat circular tip, a second double-sided tape (fixed at the bottom of the circular tip) with a diameter of 1 cm and a thickness of 0.24 mm was pressed to the second surface of the solid composite electrolyte with a force of 200 N for 1 min. In the second step, the tip was removed (pulled off) from the surface of the solid composite electrolyte at a constant speed of 100 mm / s. As a result, the solid composite electrolyte was damaged (torn) and a portion of it remained on the rigid Al support, while the other portion remained on the tip connected to the test bench. The force required to separate the membrane into two parts is recorded in Table 1 as the average of 5 independent pull-off measurements. The pull-off test was carried out in a dry room with a dew point of -40 ° C.

[0183] Ionic conductivity of solid composite electrolytes E1 and CE1-CE4

[0184] The ionic conductivity of the solid composite electrolytes of E1 and CE1-CE4 in membrane form was measured by AC impedance spectroscopy using an in-house developed pressure cell, where the membrane was pressed between two stainless steel electrodes during the impedance measurement. The cross section of the pressure cell is Figure 1 Shown in.

[0185] The impedance spectrum was measured at a pressure of 370 MPa and a temperature of 20° C. AC impedance measurements were performed with a potentiostat (VMP-300, BioLogic Science Instruments SAS, France) in the frequency range of 1000 Hz to 4.7 MHz.

[0186] The Nyquist plot of solid composite electrolytes shows the typical behavior of solid electrolytes (inorganic, polymer or composite materials) with semicircular and Warburg type impedances in the high frequency region and low frequency region, respectively. According to the equivalent circuit R1(R2 / Q2)Q3 (see Figure 2 ) is used to simulate the conductive behavior of the composite electrolyte, where R is the resistance and Q is the constant phase element, where R1 and R2 represent the bulk resistance and grain boundary resistance, respectively, and Q2 and Q3 represent the grain boundary and electrode contributions, respectively.

[0187] The intercept of the semicircle with the real axis at high frequencies is attributed to the bulk resistance (R1), while the intercept with the real axis at low frequencies is attributed to the total resistance of the membrane (R1+R2). This total resistance R is conventionally used to calculate the conductivity of solid composite electrolytes. Therefore, the ionic conductivity σ is obtained using the equation σ=d / (R x A), where d is the thickness of the membrane and A is the area of ​​the stainless steel electrode. The SI unit of ionic conductivity is Siemens / meter (S / m), where S is ohm -1 , and 1 millisiemens / centimeter (mS / cm) is the decimal part of the SI unit, that is, 1 mS / cm=0.1 S / m.

[0188] Preparation of positive electrode

[0189] E1 and CE1-CE4 with LPSCl

[0190] The positive electrodes of E1 and CE1-CE4 composed of 74.0 pbw NMC622, 20.0 pbw LPSCl, 2.0 pbw conductive carbon black, and 4.0 pbw fluoropolymer (selected from polymers 1 to 5) were produced as follows:

[0191] A 10.0 wt% binder solution was prepared by weighing 1.0 g of fluoroelastomer and 9.0 g of BB. Subsequently, 1.0 g of LPSCl, 0.1 g of conductive carbon, 3.7 g of NMC622 and 2.0 g of 10.0 wt% binder solution were mixed with 4 glass balls under magnetic stirring at 400 rpm for at least 6 hours. The slurry obtained was cast on an aluminum (Al) current collector using an automatic film applicator from ECO. The solid content and casting speed of the slurry were adjusted so that the slurry viscosity was maintained between 2.0 and 10.0 Pa.s during casting and so as to obtain 25.0 to 30.0 mg / cm 2 The wet film was dried on a hot plate at 50°C for one hour, placed in an oven under vacuum at 80°C during the night, stored in a mini grip bag, and then placed in a sealed bag. The experiments were performed in an argon-filled glove box.

[0192] E2 and CE5-CE6 without LPSCl

[0193] The positive electrodes of E2 and CE5-CE6 composed of 96 pbw NMC622, 2.0 pbw conductive carbon black, and 2.0 pbw fluoropolymer (selected from polymers 1 to 3) were produced as follows:

[0194] A 10.0 wt% binder solution was prepared by weighing 1.0 g of fluoropolymer and 9.0 g of NMP. Subsequently, 0.1 g of conductive carbon, 4.8 g of NMC622 and 1.0 g of a 10.0 wt% binder solution were mixed with 4 glass balls under magnetic stirring at 400 rpm for a minimum of 6 hours. The slurry obtained was cast on an Al current collector using an automatic film applicator from ECO. The solid content and casting speed of the slurry were adjusted so that the slurry viscosity was maintained between 2.0 and 10.0 Pa.s during casting and so as to obtain 25.0 to 30.0 mg / cm 2 The wet film was dried on a hot plate at 50°C for one hour, placed in an oven under vacuum at 80°C during the night, stored in a mini grip bag, and then placed in a sealed bag. The experiments were performed in an argon-filled glove box.

[0195] Adhesion of positive electrode to Al current collector (peel test)

[0196] The adhesion strength of the positive electrode to the Al current collector is evaluated using a 180° peel test. The electrode strips (2cm*10cm) of the dried electrode are fixed on a rigid Al plate (2.6cm*10cm) with the electrode facing down and the current collector facing up using double-sided tape (width 25mm; thickness 0.24mm). Using an electric tension / compression tester (ESM303, from Mark-10), an angle of 180° is maintained and the Al current collector is peeled off from the electrode at a constant speed of 300mm / min. The force required to remove the Al current collector from the electrode is recorded in Table 1, which is the average value of 3 independent strips generated by 3 independent electrodes using 3 independent slurries with the same composition. The peel test was carried out in a dry room with a dew point of -40°C.

[0197] In all positive electrodes of E1 and E2, whether or not they have sulfide-based solid ion-conducting inorganic particles, excellent adhesion properties to the Al current collector (distinct from those of CE1 to CE6) are clearly observed, while exhibiting good ionic conductivity. In particular, as shown in Table 1 below, E1 exhibits the best adhesion to the current collector and also the best cohesion compared to CE1-CE4, suitable for sulfide-based solid-state batteries. In addition, when MIBK is used instead of BB as a solvent when manufacturing the positive electrode E1 using polymer 1, the adhesion properties are measured to be higher than 245 N / m, far exceeding the 214 N / m of E1. Similarly, E2 shows excellent adhesion properties compared to CE5 and CE6, which can be applied to the current generation of batteries with conventional liquid electrolytes.

[0198] Table 1

[0199]

Claims

1. A binder solution for a secondary battery, comprising at least one non-aqueous solvent and at least one fluoropolymer, the fluoropolymer comprising repeating units derived from: a) vinylidene fluoride (VDF); and b) at least one fluorinated olefin monomer containing at least one -SO2X functional group, X is selected from X' and OM, X' is selected from the group consisting of F, Cl, Br, and I; and M is selected from the group consisting of H, alkali metals, and NH4, The fluorinated olefin monomer b) is present in an amount of 0.1 to 10.0 mol %, wherein the mol % is relative to the total moles of the repeating units.

2. The binder solution according to claim 1, wherein The fluorinated olefin monomer b) containing at least one -SO2X functional group is selected from the group consisting of: -sulfonyl halofluoroolefin having the formula: CF2=CF(CF2) p SO2X', wherein p is an integer between 0 and 10, preferably between 1 and 6, more preferably p is equal to 2 or 3, and preferably X'=F; -sulfonyl halide fluorovinyl ether having the formula: CF2=CF-O-(CF2) m SO2X', wherein m is an integer between 1 and 10, preferably between 1 and 6, more preferably between 2 and 4, even more preferably m is equal to 2, and preferably X'=F; -sulfonyl halofluoroalkoxy vinyl ether having the formula: CF2=CF-(OCF2CF(R F1 )) w -O-CF2(CF(R F2 )) y SO2X', where w is an integer between 0 and 2, R F1 and R F2 , which are the same or different from each other, are independently F, Cl or C optionally substituted by one or more ether oxygen atoms 1- C 10 fluoroalkyl, y is an integer between 0 and 6, preferably w is 1, R F1 is -CF3, y is 1 and R F2 is F, and preferably X'=F; and - a sulfonyl halide aromatic fluoroolefin having the formula CF2=CF-Ar-SO2X' or CF2=CF-O-Ar-SO2X', wherein Ar is C 5- C 15 Aromatic or heteroaromatic substituents, and preferably X'=F.

3. The binder solution according to claim 2, wherein: The fluorinated olefin monomer b) containing at least one -SO2X functional group is a sulfonyl halide fluorovinyl ether, in particular perfluoro-5-sulfonyl fluoride-3-oxa-1-pentene (CF2=CF-O-CF2CF2-SO2F).

4. The binder solution according to any one of claims 1 to 3, wherein The fluoropolymer further comprises additional repeating units derived from c) at least one C2-C8 (per)fluoroolefin and / or C2-C8 chlorinated and / or brominated and / or iodinated fluoroolefin different from a) and b).

5. The binder solution according to claim 4, wherein The C2-C8 (per)fluoroolefin is selected from the group consisting of: -C2-C8 perfluoroolefins, such as tetrafluoroethylene (TFE) and hexafluoropropylene (HFP); - Hydrogen-containing C2-C8 fluoroolefins, such as vinyl fluoride (VF), trifluoroethylene (TrFE), hexafluoroisobutylene; - having the formula CH2=CH-R f (per)fluoroalkylethylene, wherein R f is a C1-C6 (per)fluoroalkyl group; -Has the formula CF2=CFOR f (per)fluoroalkyl vinyl ether (PAVE), where R f is a C1-C6 (per)fluoroalkyl group; - (per)fluorooxy-alkyl vinyl ethers of the formula CF2=CFOX, wherein X is a C1-C2-alkylene group containing at least one catenary oxygen atom 12 ((Per)fluoro)oxyalkyl; - (per)fluorodioxole having the formula: Where R f3 , R f4 , R f5 and R f6 are the same as or different from each other and are independently selected from fluorine atoms and C1-C6 (per)fluoroalkyl groups optionally containing at least one oxygen atom; and -Has the formula CFX2=CX2OCF2OR" f (per)fluoromethoxy-vinyl ether (MOVE), wherein R" f is selected from a linear or branched C1-C6 (per)fluoroalkyl group; a C5-C6 cyclic (per)fluoroalkyl group; a linear or branched C2-C6 (per)fluorooxyalkyl group containing 1 to 3 chain oxygen atoms, and X2=F or H; preferably, R" f is -CF2CF3(MOVE1), -CF2CF2OCF3(MOVE2), or -CF3(MOVE3), and X2 is F.

6. The binder solution according to claim 4, wherein The C2-C8 chlorinated and / or brominated and / or iodinated fluoroolefins are selected from the group consisting of 1,1-chlorofluoroethylene (CFE), chlorodifluoroethylene (CDFE), bromotrifluoroethylene, chlorotrifluoroethylene (CTFE), 1,2-dichloro-1,2-difluoroethylene, iodotrifluoroethylene, and combinations thereof.

7. The binder solution according to any one of claims 1 to 6, wherein The fluoropolymer has a heat of fusion as measured according to ASTM D3418 of less than 5.0 J / g, preferably less than 3.0 J / g, more preferably less than 2.0 J / g.

8. The binder solution according to any one of claims 1 to 7, wherein The non-aqueous solvent is selected from the group consisting of nitrile-containing solvents, ethers, esters, thiols, thioethers, ketones, and tertiary amines, preferably butyl butyrate and / or methyl isobutyl ketone.

9. A solid composite electrolyte comprising at least one fluoropolymer and at least one sulfide-based solid ion-conducting inorganic particle, wherein the fluoropolymer comprises repeating units derived from: a) vinylidene fluoride (VDF); and b) at least one fluorinated olefin monomer containing at least one -SO2X functional group, X is selected from X' and OM, X' is selected from the group consisting of F, Cl, Br, and I; and M is selected from the group consisting of H, alkali metals, and NH4, The fluorinated olefin monomer b) is present in an amount of 0.1 to 10.0 mol %, the mol % being relative to the total moles of the repeating units.

10. The solid composite electrolyte according to claim 9, wherein: The sulfide-based solid ion-conducting inorganic particles are selected from the group consisting of: -Lithium tin phosphide ("LSPS") materials, such as Li 10 SnP2S 12 ; - Lithium phosphosulfide ("LPS") materials, such as glasses, crystals or glass ceramics having the formula: (Li2S) x -(P2S5) y , where x+y=1 and 0≤x≤1; Li7P3S 11 ;Li7PS6;Li4P2S6;Li 9.6 P3S 12 and Li3PS4; -doped LPS, such as Li2CuPS4; Li Li 1+2x Zn 1-x PS4, where 0≤x≤1; Li 3.33 Mg 0.33 P2S6; and Li 4- 3x Sc x P2S6, where 0≤x≤1; -With formula Li x P y S z A lithium phosphorus sulfide oxygen ("LPSO") material of O, wherein 0.33≤x≤0.67, 0.07≤y≤0.2, 0.4≤z≤0.55, 0≤w≤0.15; - Lithium phosphide materials containing X ("LXPS"), where X is Si, Ge, Sn, As, Al, such as Li 10 GeP2S 12 and Li 10 SiP2S 12 ; - lithium phosphorus oxysulfide containing X ("LXPSO"), wherein X is Si, Ge, Sn, As, Al; - lithium silicon sulfide ("LSS") materials; -Lithium boron sulfide materials, such as Li3BS3 and Li2S-B2S3-LiI; -Lithium tin sulfide materials and lithium arsenide materials, such as Li 0.8 Sn 0.8 S2, Li4SnS4, Li 3.833 Sn 0.833 As 0.166 S4, Li3AsS4-Li4SnS4, Ge-substituted Li3AsS4; and -Has the general formula Li a PS b X c A lithium phosphorus sulfide material, wherein X represents at least one halogen element selected from the group consisting of Cl, Br and I or a combination thereof; and a represents a number from 2.0 to 7.0, b represents a number from 3.5 to 6.0, and c represents a number from 0 to 3.

0.

11. A slurry for making a solid composite electrolyte, comprising a binder solution according to any one of claims 1 to 8 and at least one sulfide-based solid ion-conducting inorganic particle, optionally further comprising at least one electroactive material and / or at least one conductive agent.

12. The slurry according to claim 11, wherein The electroactive material is for the positive electrode and is selected from the group consisting of: having the formula LiNi x Mn y Co z O2 (x + y + z = 1) based on lithium-nickel-manganese-cobalt metal oxide, having the formula LiNi x Co y Al z O2 (x+y+z=1)-based lithium-nickel-cobalt-aluminum metal oxide, lithium-cobalt metal oxide, and lithium-nickel-manganese metal oxide.

13. An electrode comprising at least one fluoropolymer and at least one electroactive material, optionally further comprising at least one conductive agent and / or at least one sulfide-based solid ion-conducting inorganic particle, wherein the fluoropolymer comprises repeating units derived from: a) vinylidene fluoride (VDF); and b) at least one fluorinated olefin monomer containing at least one -SO2X functional group, X is selected from X' and OM, X' is selected from the group consisting of F, Cl, Br, and I; and M is selected from the group consisting of H, alkali metals, and NH4, The fluorinated olefin monomer b) is present in an amount of 0.1 to 10.0 mol %, the mol % being relative to the total moles of the repeating units.

14. The electrode according to claim 13, wherein The electroactive material is for the positive electrode and is selected from the group consisting of: having the formula LiNi x Mn y Co z O2 (x + y + z = 1) based on lithium-nickel-manganese-cobalt metal oxide, having the formula LiNi x Co y Al z O2 (x+y+z=1)-based lithium-nickel-cobalt-aluminum metal oxide, lithium-cobalt metal oxide, and lithium-nickel-manganese metal oxide.

15. A secondary battery comprising a positive electrode, a negative electrode and a membrane located between the positive electrode and the negative electrode, wherein at least one of the positive electrode, the negative electrode and the membrane comprises at least one fluoropolymer, optionally further comprising at least one sulfide-based solid ion-conducting inorganic particle, at least one electroactive material and / or at least one conductive agent, wherein the fluoropolymer comprises repeating units derived from: a) vinylidene fluoride (VDF); and b) at least one fluorinated olefin monomer containing at least one -SO2X functional group, X is selected from X' and OM, X' is selected from the group consisting of F, Cl, Br, and I; and M is selected from the group consisting of H, alkali metals, and NH4, The fluorinated olefin monomer b) is present in an amount of 0.1 to 10.0 mol %, the mol % being relative to the total moles of the repeating units.

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