Binder composition for secondary batteries

Abstract

The present invention relates to a binder composition comprising a specific amorphous (per)fluorinated polymer powder with improved solubility and its use for preparing secondary and solid-state battery components.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to European Patent Application Publication No. 21186199.2, filed July 16, 2021, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to a binder composition comprising a specific amorphous (per)fluorinated polymer powder having improved solubility in solvents and its use for preparing secondary and solid-state battery components. [Background technology]

[0003] Lithium-ion batteries with liquid electrolytes currently dominate the rechargeable energy storage device market, despite some inherent limitations, among which are challenging safety concerns for high power applications and inherent low energy density. Conventional Li-ion battery liquid electrolytes are in fact based on organic carbonates, which leak, produce volatile gaseous species, and are flammable.

[0004] Solid-state batteries (SSBs) promise to be the next generation of energy storage devices because they offer higher energy density, longer cycle life, improved safety, and lower cost. In SSBs, highly flammable liquid electrolytes are replaced by solid-state electrolytes, eliminating virtually all risk of fire and / or explosion. Despite these inherent theoretical advantages over conventional batteries, ease of operation and scalable processing are also required for their successful commercialization.

[0005] Among solid electrolytes, solid ions (Li) dispersed in a polymer binder are + ) Composite electrolytes composed of conducting inorganic materials offer the possibility of combining high ionic conductivity with good mechanical properties.

[0006] Prior art composite electrolytes are typically produced by a wet casting method, in which inorganic powder is dispersed in a solution of a binder in a solvent to form a slurry, which is cast onto a support and subsequently dried to remove the solvent used.

[0007] The use of polymer binders in solid-state batteries is also interesting on the cathode side, where the active material, the conductive agent and the inorganic solid electrolyte (e.g. sulfide) are held together in a continuous matrix due to the binder itself.

[0008] Among the processing routes, tape casting is the most widely adopted, both for electrodes and solid electrolytes, due to both its similarity to conventional battery component processing and its inherent versatility, allowing thickness and other processing parameters to be finely tuned. In this method, a slurry is prepared by dispersing inorganic conductive particles in a polymer solution and casting the resulting dispersion onto the desired layer.

[0009] The use of certain inorganic materials in the composite electrolyte and electrodes brings about limitations in the choice of solvent and in the choice of binder. Highly conductive sulfides in particular limit the range of available compatible solvents, which should not react with the highly conductive sulfides, reduce their ionic conductivity, and produce by-products that may interfere with the battery operation. The binder must also be compatible with the sulfides and soluble or dispersible in the available solvents.

[0010] Some reports have suggested the use of fluorinated binders for sulfide composites, but the use of commercially adopted crystalline fluorinated binders is limited by solubility problems in the few solvents that are compatible with inorganics.

[0011] As an example, U.S. Patent Application Publication No. 2019 / 296393 discloses the preparation of a solid electrolyte layer for an SSB, containing a sulfide solid electrolyte, polyvinylidene fluoride (PVdF), ethyl cellulose (EC), and butyl butyrate as a solvent.

[0012] In contrast, amorphous fluorinated polymers (e.g., Tecnoflon® FKM) can be solubilized in some compatible solvents. However, the use of these polymers as binders has inherent drawbacks that may limit their real application in solid-state battery components, paving the way for the development and use of new and alternative products. In particular, amorphous fluorinated polymers are mainly produced in the form of slabs, which must be cut into small pieces before the dissolution process takes place. This results in the loss of time and operational costs of further processing, as well as problems in obtaining polymer fine dispersions in the selected compatible solvent.

[0013] Several amorphous fluorinated polymers in powder form are currently on the market, such as Tecnoflon® NM powder. Nevertheless, the usual additives present in said powders, such as organic anti-sticking agents, are not stable at the voltages at which the battery operates, resulting in by-products and adversely affecting battery operation.

[0014] In the document US 2010 / 174011, especially in sections

[0042] to

[0047] , cryogenic grinding is described as a technique for reducing the size of fluoroelastomer fragments or pellets. In this case, the addition of an anti-interfacial agent to prevent agglomeration is also taught as an essential condition for obtaining a free-flowing compound. However, said anti-interfacial agents are not stable in the voltage range in which the battery operates.

[0015] US 9518178 discloses the addition of thermoplastic vinylidene fluoride polymers in (per)fluoroelastomer compositions during cryogenic grinding to advantageously provide finely divided pellets that have free-flowing behavior, retain these advantageous flow properties even after long-term storage at room temperature, and achieve excellent mechanical properties in the cured compounds derived therefrom.

[0016] Therefore, there is a great need for non-conductive binders that are compatible with inorganic materials suitable for use in the manufacture of battery components, such as electrodes and solid electrolyte layers, through efficient fabrication processes. Summary of the Invention

[0017] The Applicant has now surprisingly found that amorphous (per)fluorinated polymer powders, obtainable by cryogenic grinding of amorphous (per)fluorinated polymers in the form of slabs in the presence of certain fluorinated polymers, are particularly suitable for the preparation of battery components, in particular components for solid-state batteries, since these dissolve more readily in solvents that are compatible with inorganic materials than the same polymers in slab form.

[0018] The object of the present invention is therefore to provide a binder composition [binder (B)] for use in the preparation of a component for an electrochemical device, comprising: a) micronized pellets of a (per)fluoroelastomer composition [composition (E)], composition (E) comprising at least one (per)fluoroelastomer having a weight average particle size (D50) of less than 500 μm [fluoroelastomer (A)] and at least one thermoplastic semicrystalline vinylidene fluoride polymer [polymer (F)]; b) at least one non-aqueous solvent (S) selected from the group consisting of nitrile-containing solvents, ethers, esters, thiols and thioethers, ketones, tertiary amines, and cyclic carbonate esters. The binder composition [binder (B)] is characterized by comprising:

[0019] The binder (B) is particularly suitable for use in the preparation of electrodes and solid electrolytes for secondary batteries.

[0020] Therefore, another object of the present invention is an electrode-forming composition [composition (C)] for use in the preparation of an electrode for an electrochemical device, comprising: a) at least one electrode active material (AM); b) a binder (B) as defined above; and c) optionally, at least one conductive agent The electrode-forming composition [composition (C)] is characterized by comprising:

[0021] Another object of the invention is therefore a process for producing an electrode for a secondary battery, comprising: A) providing an electrode-forming composition (C) as defined above; B) providing a metal substrate having at least one surface; C) applying the electrode-forming composition (C) provided in step A) onto at least one surface of the metal substrate provided in step B), thereby providing an assembly comprising a metal substrate coated on at least one surface with said composition (C); D) Drying the assembly provided in step C). The process includes:

[0022] In another object, the present invention provides an electrode for a secondary battery, obtainable by the process as defined above.

[0023] In another object, the present invention provides a composition (CC) suitable for preparing a composite solid electrolyte membrane, said composition comprising: i) at least one sulfide-based solid electrolyte; ii) a binder (B) as defined above; Includes.

[0024] Another object of the present invention is therefore a process for producing a composite solid electrolyte membrane for a solid-state battery, comprising: I) processing a composition (CC) as defined above to form a wet film of a solid composite electrolyte; II) drying the wet membrane provided in step (I); The process includes:

[0025] In another object, the present invention provides a composite solid electrolyte membrane obtainable by said process.

[0026] In a still further object, the present invention provides a solid-state battery comprising the composite solid electrolyte membrane and / or at least one electrode of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] In the context of the present invention, the term "weight percent" (wt%) indicates the content of a particular component in a mixture calculated as the ratio between the weight of the component and the total weight of the mixture. When referring to the total solids content (TSC) of a liquid composition, weight percent (wt%) indicates the ratio between the weights of all non-volatile components in the liquid.

[0028] The term "electrochemical cell" is hereby intended to denote an electrochemical cell comprising a positive electrode, a negative electrode and an electrolyte, wherein a single or multi-layer separator is adhered to at least one surface of one of said electrodes.

[0029] Non-limiting examples of electrochemical cells include, inter alia, batteries, preferably secondary batteries, and electric double layer capacitors.

[0030] For the purposes of the present invention, "secondary battery" is intended to denote a rechargeable battery. Non-limiting examples of secondary batteries include, in particular, alkaline or alkaline earth secondary batteries.

[0031] The composition (E) used in the binder (B) comprises finely divided pellets of a (per)fluoroelastomer composition, said composition (E) comprising at least a (per)fluoroelastomer [fluoroelastomer (A)] and at least one thermoplastic semicrystalline vinylidene fluoride polymer [polymer (F)].

[0032] For the purposes of the present invention, the term "(per)fluoroelastomer" [fluoroelastomer (A)] is intended to denote a fluoropolymer resin that serves as a base building block to obtain true elastomers, said fluoropolymer resin comprising more than 10% by weight, preferably more than 30% by weight, of repeat units deriving from at least one ethylenically unsaturated monomer containing at least one fluorine atom (hereinafter (per)fluorinated monomer) and optionally from at least one ethylenically unsaturated monomer not containing a fluorine atom (hereinafter hydrogenated monomer).

[0033] True elastomers are defined by ASTM, Special Technical Bulletin, No. 184 standard as materials which can be stretched to twice their inherent length at room temperature and which, when held under tension for 5 minutes and then released, return in the same time to within 10% of their original length.

[0034] Non-limiting examples of suitable (per)fluorinated monomers are in particular - C2 to C8 fluoro- and / or perfluoroolefins, such as tetrafluoroethylene (TFE), hexafluoropropene (HFP), pentafluoropropylene and hexafluoroisobutylene; - C2-C8 hydrogenated monofluoroolefins, such as vinyl fluoride; 1,2-difluoroethylene, vinylidene fluoride (VDF) and trifluoroethylene (TrFE); - Formula CH2=CH-R f0 (In the formula, R f0is a C1-C6 (per)fluoroalkyl or C1-C6 (per)fluorooxyalkyl having one or more ether groups; - chloro- and / or bromo- and / or iodo-C2-C6 fluoroolefins, such as chlorotrifluoroethylene (CTFE); - Formula CF2=CFOR f1 (In the formula, R f1 is C1-C6 fluoro or perfluoroalkyl, for example -CF3, -C2F5, -C3F7) fluoroalkyl vinyl ethers according to the formula: - Formula CH2=CFOR f1 (In the formula, R f1 is C1-C6 fluoro or perfluoroalkyl, for example -CF3, -C2F5, -C3F7), hydrofluoroalkyl vinyl ethers according to - Formula CF2=CFOX0 (wherein X0 is a C1-C aryl group having one or more ether groups) 12 Oxyalkyl or C1-C 12 (per)fluorooxyalkyl, for example perfluoro-2-propoxy-propyl; - Formula CF2=CFOCF2OR f2 (In the formula, R f2 is C1-C6 fluoro or perfluoroalkyl, for example -CF3, -C2F5, -C3F7 or C1-C6 (per)fluorooxyalkyl having one or more ether groups, for example -C2F5-O-CF3), fluoroalkyl-methoxy-vinyl ethers according to - Formula CF2 = CFOY0 (wherein Y0 is C1 to C 12 Alkyl or (per)fluoroalkyl or C1-C 12 Oxyalkyl or C1-C 12 (per)fluorooxyalkyl, said Y0 group containing a carboxylic or sulfonic acid group in the form of its acid, acid halide or salt; - Formula: [ka] (wherein R f3 , R f4 , R f5 , R f6 each independently is a C1-C6 fluoro or per(halo)fluoroalkyl optionally containing a fluorine atom, one or more oxygen atoms, e.g., -CF3, -C2F5, -C3F7, -OCF3, -OCF2CF2OCF3). Fluorodioxole It is.

[0035] Examples of hydrogenated monomers are hydrogenated alpha-olefins including ethylene, propylene, 1-butene, diene monomers, styrene monomers, among others, with alpha-olefins being typically used.

[0036] The (per)fluoroelastomer (A) is an amorphous product or has a very low degree of crystallinity (heat of fusion less than 4 J / g, preferably less than 3 J / g, as measured by ASTM D3418) and a glass transition temperature (T g In most cases, the fluoroelastomer (A) advantageously has a T of less than 10° C., preferably less than 5° C., more preferably less than 0° C. g has.

[0037] The (per)fluoroelastomer (A) is preferably a fluoroelastomer.

[0038] In a preferred embodiment, the fluoroelastomer (A) is a copolymer based on VDF, the VDF being of the following class: (a) C2-C8 perfluoroolefins, such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP), hexafluoroisobutylene; (b) Hydrogen-containing C2-C8 olefins, such as vinyl fluoride (VF), trifluoroethylene (TrFE), formula CH2=CH-R f (In the formula, R fis a C1-C6 perfluoroalkyl group; (c) C2-C8 chloro- and / or bromo- and / or iodo-fluoroolefins, such as chlorotrifluoroethylene (CTFE); (d) Formula CF2=CFOR f (In the formula, R f is a C1-C6 (per)fluoroalkyl group, e.g., CF3, C2F5, C3F7), (per)fluoroalkyl vinyl ether (PAVE); (e) Formula CF2=CFOX (wherein X is a C1-C 12 (per)fluoro-oxy-alkyl vinyl ethers of ((per)fluoro)-oxyalkyl, for example perfluoro-2-propoxypropyl; (f) Formula: [ka] (wherein R f3 , R f4 , R f5 , R f6 are independently selected from C1-C6 (per)fluoroalkyl groups optionally containing a fluorine atom and one or more oxygen atoms, such as, in particular, -CF3, -C2F5, -C3F7, -OCF3, -OCF2CF2OCF3; preferably perfluorodioxols) (Per)fluorodioxole having; (g) Formula: CFX2=CX2OCF2OR'' f (In the formula, R'' f is selected from among linear or branched C1-C6 (per)fluoroalkyl containing 1-3 catenary oxygen atoms; C5-C6 cyclic (per)fluoroalkyl; and linear or branched C2-C6 (per)fluorooxyalkyl, and X2=F, H; preferably, X2 is F, and R'' f is -CF2CF3(MOVE1); -CF2CF2OCF3(MOVE2); or -CF3(MOVE3) (per)fluoro-methoxy-vinyl ether (hereinafter MOVE); (h) C2-C8 non-fluorinated olefins (Ol), such as ethylene and propylene is copolymerized with at least one comonomer selected from the group consisting of:

[0039] Optionally, the (per)fluoroelastomer (A) of the present invention has the general formula: [ka] wherein R1, R2, R3, R4, R5 and R6, which are equal or different, are H or C1-C5 alkyl; Z is a linear or branched C1-C alkyl group, which optionally contains an oxygen atom and is preferably at least partially fluorinated. 18 It is an alkylene or cycloalkylene group or a (per)fluoropolyoxyalkylene group as described for example in EP 661304 A (AUSIMONT SPA) 7 / 5 / 1995.

[0040] The bis-olefins (OF) are preferably those according to the formulae (OF-1), (OF-2) and (OF-3): (OF-1) [ka] (In the formula, j is an integer of 2 to 10, preferably 4 to 8; R1, R2, R3, and R4, which may be the same or different, are each independently H, F, or C. 1~5 alkyl or (per)fluoroalkyl groups; (OF-2) [ka] wherein each A, equal or different from each other and at each occurrence, is independently selected from F, Cl, and H; each B, equal or different from each other and at each occurrence, is independently selected from F, Cl, H, and OR B are independently selected from RB is a branched or linear alkyl group which may be partially, substantially or completely fluorinated or chlorinated; E is a divalent group having 2 to 10 carbon atoms, optionally fluorinated, which may be inserted with ether linkages; preferably, E is -(CF2) m - group, m being an integer from 3 to 5; (a preferred bis-olefin of the (OF-2) type is F2C=CF-O-(CF2)5-O-CF=CF2), (OF-3) [ka] (wherein E, A and B have the same meaning as defined above; R5, R6, R7, which are equal to or different from each other, are H, F or C. 1~5 alkyl or (per)fluoroalkyl group. is selected from the group consisting of:

[0041] Among the particular compositions of the fluoroelastomers (A) suitable for the purposes of the present invention, mention may be made of the following compositions (in mol %): (i) 35-85% vinylidene fluoride (VDF), 10-45% hexafluoropropene (HFP), 0-30% tetrafluoroethylene (TFE), 0-15% perfluoroalkyl vinyl ether (PAVE), 0-5% bis-olefin (OF); (ii) 50-80% vinylidene fluoride (VDF), 5-50% perfluoroalkyl vinyl ether (PAVE), 0-20% tetrafluoroethylene (TFE), 0-5% bis-olefin (OF); (iii) 20-30% vinylidene fluoride (VDF), 10-30% C2-C8 non-fluorinated olefins (Ol), 18-27% hexafluoropropene (HFP) and / or perfluoroalkyl vinyl ethers (PAVE), 10-30% tetrafluoroethylene (TFE), 0-5% bis-olefins (OF); (iv) Vinylidene fluoride (VDF) 35-85%, fluorovinyl ether (MOVE) 5-40%, perfluoroalkyl vinyl ether (PAVE) 0-30%, tetrafluoroethylene (TFE) 0-40%, hexafluoropropene (HFP) 0-30%, bis-olefin (OF) 0-5%.

[0042] The (per)fluoroelastomers (A) can be prepared by any known method, such as emulsion or microemulsion polymerization, suspension or microsuspension polymerization, bulk polymerization and solution polymerization.

[0043] The polymer (F) is semi-crystalline, i.e. it has at least a partially crystalline structure. Semi-crystalline thermoplastic VDF polymers generally have a heat of fusion of at least 5 J / g, preferably at least 15 J / g, more preferably at least 25 J / g, as measured by ASTM standard D3418.

[0044] Polymer (F) can be advantageously used in the preparation of finely divided pellets of composition (E) due to its combined property of being semicrystalline with an average particle size of less than 500 μm.

[0045] The calculation of the average particle size can be performed by methods known to those skilled in the art, for example according to ISO13320.

[0046] The semicrystalline thermoplastic VDF polymers used according to the invention are advantageously chosen from VDF homopolymers and copolymers of VDF with one or more fluorinated and / or hydrogenated monomers.

[0047] The term "fluorinated monomer" is intended to denote an ethylenically unsaturated monomer that contains at least one fluorine atom.

[0048] The term "hydrogenated monomer" is intended to denote an ethylenically unsaturated monomer that contains at least one hydrogen atom and that does not contain fluorine atoms.

[0049] Preferably, said polymer (F) comprises repeat units derived from VDF and repeat units derived from at least one hydrogenated monomer comprising at least one carboxylic acid end group [monomer (MA)] and / or repeat units derived from at least one fluorinated monomer different from VDF.

[0050] According to a preferred embodiment, said polymer (F) is (I) a repeating unit derived from VDF, and (II) Repeating units derived from at least one monomer (MA) and more preferably consisting of:

[0051] Advantageously, said monomer (MA) has the following formula: [ka] In accordance with the formula: R'1, R'2 and R'3 are hydrogen atoms, - R' OH is a C1-C5 hydrocarbon moiety containing a hydrogen atom or at least one hydroxyl group.

[0052] Non-limiting examples of said monomers (MA) are in particular acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxyethylhexyl methacrylate, hydroxyethylhexyl acrylate and mixtures thereof.

[0053] The polymer (F) (I) a repeating unit derived from VDF, and (II) Repeating units derived from at least one monomer (MA) The Applicant has surprisingly found that when the micronized pellets of composition (E) consist of

[0054] The binder (B) comprising the polymer (F) according to this preferred embodiment exhibits a low level of packing and / or compressibility of the powder, which may realize great advantages in some conditions of storage and transportation of the powder. Indeed, the high temperatures and pressures reached, for example, on the bottom of a drum containing the powder, may result in the agglomeration of the material, thereby causing the powder to lose its properties and the advantages obtained.

[0055] The low level of packing and / or compressibility of the binder powder can be suitably demonstrated by compressing the material in equipment suitable for producing tablets, simulating the pressures that may be reached upon storage of the material.

[0056] (I) a repeating unit derived from VDF, and (II) Repeating units derived from at least one monomer (MA) The binder (B), which comprises a polymer (F) consisting of: does not compact under said conditions, but remains as a free-flowing powder when the piston pressure in the apparatus is removed.

[0057] A further test that can be used to show the low level of packing and / or compressibility of the binder powder involves the passage of the material through an opening, such as a funnel. The binder (B) comprising the polymer (F) according to this preferred embodiment advantageously flows smoothly and completely through the cone of the funnel. The amount of VDF in the copolymer is preferably greater than 85 mol %, more preferably greater than 90 mol %, based on the total amount of repeat units.

[0058] The fluorinated monomer containing at least one unsaturation of ethylene type is preferably selected from the group consisting of classes (a), (b), (c), (d), (e), (f) and (g) as described above in combination with the (per)fluoroelastomer (A).

[0059] The amount of polymer (F) in the composition is comprised between 2% and 50% by weight, more preferably between 2% and 20% by weight, even more preferably between 2% and 15% by weight, relative to the total weight of (per)fluoroelastomer (A) and polymer (F).

[0060] Some of the compositions (E) used in the preparation of the binder (B) of the present invention are novel and represent further aspects of the present invention.

[0061] In another object, the present invention therefore provides micronized pellets of a composition (E) comprising at least one (per)fluoroelastomer [fluoroelastomer (A)] and at least one thermoplastic semicrystalline vinylidene fluoride polymer [polymer (F)], in which polymer (F) is present in an amount of at least 2% by weight and less than 5% by weight relative to the total weight of (per)fluoroelastomer (A) and polymer (F).

[0062] The Applicant has surprisingly found that when a binder (B) is used in the preparation of an electrode, a composition (E) comprising a polymer (F) in an amount of at least 2% by weight and less than 5% by weight is particularly suitable from the processing point of view. Indeed, due to the flow properties and fast dissolution of the powder, it is possible to prepare an electrode-forming composition whilst maintaining excellent properties in the battery.

[0063] Composition (E) can be prepared by a grinding process that can be advantageously carried out in any grinding device designed to break down solid materials into smaller pieces. Among the grinding devices suitable for the process of the invention, mention can be made of ball mills, conical mills, disk mills, hammer mills, rod mills and vibratory mills.

[0064] Generally, a comminuting device equipped with a shaft and rotating blades is preferred.

[0065] The grinding is carried out at a temperature below the glass transition temperature of the (per)fluoroelastomer (A). These conditions are required to advantageously ensure that the (per)fluoroelastomer (A) has a brittle behavior and therefore advantageously undergoes compaction without agglomeration or sticking.

[0066] Generally, grinding is carried out at a temperature at least 5° C. below, preferably at least 10° C. below, more preferably at least 20° C. below the glass transition temperature of the (per)fluoroelastomer (A).

[0067] The lower limit for the grinding temperature is not particularly critical and is selected by the person skilled in the art taking into account the availability and economics of cooling equipment. A grinding temperature comprised between -20 and -50°C is generally set.

[0068] For the purposes of the present invention, the term "micronized pellet" is intended to denote, from a geometrical point of view, a mass of material having a well-defined three-dimensional volume and shape characterized by three dimensions, generally none of said dimensions exceeding the remaining two other dimensions by more than ten times.

[0069] These micronized pellets advantageously have a free-flowing behavior at room temperature, ie the individual pellets are not closely spaced and are substantially free of sticking or clumping phenomena.

[0070] The Applicant has surprisingly observed an easy and fast dissolution of finely divided pellets of composition (E) in solvents commonly used to prepare binders for electrochemical device components, which is much faster than the dissolution of (per)fluoroelastomer (A) in the form of slabs and at the same time comparable to the dissolution of (per)fluoroelastomer powder compositions containing commonly used anti-adherents, such as calcium stearate.

[0071] The binder composition (B) of the present invention comprises a composition (E) as defined above and at least one non-aqueous solvent (S) commonly used to prepare binders for electrochemical devices. The solvent (S) is substantially free of water, the water content being preferably 100 ppm or less.

[0072] There are no specific restrictions imposed on the non-aqueous solvent (S) as long as i) the solvent is capable of dissolving the fluoroelastomer (A) and ii) the solvent is compatible with the sulfide-based solid electrolyte when the binder (B) is used to prepare the composite solid electrolyte membrane (this means that the solvent has no adverse effect on the ionic conductivity of the solid electrolyte).

[0073] The solvent (S) may suitably be selected from the group consisting of nitrile-containing solvents, ethers, esters, thiols and thioethers, ketones, tertiary amines and cyclic carbonate esters.

[0074] Suitable nitrile-containing solvents have the general formula R-CN, where R represents an alkyl group. Non-limiting examples of nitrile-containing solvents are acetonitrile, butyronitrile, valeronitrile, isobutylnitrile, and the like.

[0075] Suitable ethers have the general formula R1-O-R2, where R1 and R2 independently represent alkyl groups. Included in the ether solvents are cyclic ethers based on 3, 5 or 6 membered rings. Cyclic ethers can be substituted with alkyl groups, can have unsaturation, and can have additional functional elements in the ring, such as nitrogen or oxygen atoms. Non-limiting examples of (cyclic) ether solvents are diethyl ether, 1,2-dimethoxy ether, cyclopentyl methyl ether, dibutyl ether, anisole, tetrahydrofuran, methyltetrahydrofuran, tetrahydropyran, etc.

[0076] Suitable esters have the general formula R-COOR, where R and R independently represent alkyl groups. Non-limiting examples of ester solvents are butyl acetate, butyl butyrate, ethyl benzoate, and the like.

[0077] Suitable ketones have the general formula of R5R6CO, where R5 and R6 independently represent alkyl groups. Non-limiting examples of ketone solvents are methyl ethyl ketone, methyl isobutyl ketone, di-isobutyl ketone, acetophenone, benzophenone, and the like.

[0078] Suitably, thiols have the formula R7=SH, and thioethers have the general formula R8-S-R9, where R7, R8 and R9 are independently alkyl groups. Thioether solvents include cyclic thioethers based on 3, 5 or 6 membered rings. Cyclic thioethers can be substituted with alkyl groups, can have unsaturation, and can have additional functional elements in the ring, such as nitrogen or oxygen atoms. Non-limiting examples of thiol solvents are ethanethiol, tert-dodecyl mercaptan, thiophenol, t-butyl mercaptan, octanyl thiol, dimethyl sulfide, ethyl methyl sulfide, methyl benzyl sulfide, and the like.

[0079] Suitable tertiary amines include R 10 R 11 R 12 N, 10 , R 11 and R 12 independently represent an alkyl group). The N atom of the tertiary amine can be buried inside a 3, 5 or 6 membered ring. Non-limiting examples of tertiary amine solvents are triethylamine, dimethylbutylamine, tributylamine, cyclohexyldimethylamine, N-ethylpiperidine, etc.

[0080] In the present invention, R to R 12The alkyl group refers to "alkyl groups" that include saturated hydrocarbons having one or more carbon atoms, including straight chain alkyl groups as defined above, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, cyclic alkyl groups (or "cycloalkyl" or "alicyclic" or "carbocyclic" groups), such as cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl, branched chain alkyl groups, such as isopropyl, tert-butyl, sec-butyl, and isobutyl, and alkyl substituted alkyl groups, such as alkyl substituted cycloalkyl groups and cycloalkyl substituted alkyl groups. Additionally, the alkyl group may include functional groups, such as one or more unsaturated, ether, carbonyl, carboxyl, hydroxyl, thio, thiol, thioxy, sulfo, nitrile, nitro, nitroso, azo, amido, imide, amino, imino, or halogen.

[0081] The binder (B) may contain further co-solvents, such as cyclic, acyclic or aromatic hydrocarbons. Suitably, the co-solvents may be selected from the group consisting of heptane, toluene, xylene and mesitylene.

[0082] The binder (B) can be prepared by dissolving the composition (E) in the solvent (S) with stirring at a temperature comprised between 10 and 100°C, preferably between about 20 and 80°C.

[0083] When composition (C) is used in a process for producing an electrode or a solid electrolyte membrane, a person skilled in the art will select a proper amount of at least one solvent (S) in composition (C) according to the boiling point of said solvent (S) to achieve dissolution of composition (E) and its proper evaporation.

[0084] In one embodiment, the binder (B) is a solution of the composition (E) in the solvent (S), the composition (E) being present in the binder (B) in an amount comprised between 5 and 30% by weight, preferably between 7 and 20% by weight, the above percentages by weight referring to the total weight of the binder (B).

[0085] As is known in the art, an electrode-forming composition is a composition, typically a liquid composition, in which solid components are dissolved or dispersed in a liquid, that can be deposited onto a metal substrate and subsequently dried, thus forming an electrode, the metal substrate acting as a current collector. The electrode-forming composition typically includes at least an electroactive material and at least a binder.

[0086] The electrode-forming composition of the present invention [composition (C)] comprises finely divided pellets of a (per)fluoroelastomer composition [composition (E)] which functions as a binder.

[0087] The preparation of the electrode-forming composition then includes the preparation of a binder composition which is added along with the powdered electrode active material and, optionally, at least one conductive agent.

[0088] The electrode-forming composition of the present invention [composition (C)] is a) at least one electrode active material (AM); b) a binder (B) as defined above; and c) optionally, at least one conductive agent Includes.

[0089] For the purposes of the present invention, the term "electrode active material (AM)" is intended to denote a compound capable of incorporating or intercalating into its structure and from which alkali or alkaline earth metal ions are subsequently released during the charging and discharging phases of the electrochemical device. The electrode active material (AM) is preferably capable of incorporating or intercalating and releasing lithium ions.

[0090] The nature of the electrode active material (AM) in composition (C) depends on whether said composition is used in the manufacture of a positive electrode [electrode (AMp)] or a negative electrode [electrode (AMn)].

[0091] When forming a positive electrode (AMp) for a lithium ion secondary battery, the electrode active material (AM) may comprise a complex metal chalcogenide of 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, such as O or S. Preferred examples thereof are: - LiCoO2 (LCO), - LiNiO2, - LiNi x Co 1-x O2(0 <x<1)、 - LiMn2O4 with spinel structure, - Formula LiNi x Mn y Co z O2(NMC), especially those with x+y+z approximately 1, e.g. LiNi 0.333 Mn 0.333 Co 0.333 O2(NMC111), LiNi 0.6 Mn 0.2 Co 0.2 O2(NMC622) and LiNi 0.8 Mn 0.1 Co 0.1 Lithium Nickel Manganese Cobalt O2 (NMC811), and - General formula LiNi x Co y Al z Lithium Nickel Cobalt Aluminum Oxide (NCA) of O2 (x+y+z=1) may include.

[0092] Alternatively, when also forming a positive electrode (AMp) for a lithium ion secondary battery, the electrode active material (AM) is represented by the formula M1M2(JO4): f E 1-fwherein M1 is lithium, which may be partially replaced by another alkali metal representing less than 20% of the M1 metal, M2 is a transition metal at an oxidation level of +2 selected from Fe, Mn, Ni or mixtures thereof, which may be partially replaced by one or more further metals representing less than 35% (including 0) of the M2 metal, at an oxidation level of +1 to +5, JO4 is any oxyanion, J is P, S, V, Si, Nb, Mo or combinations thereof, E is a fluoride, hydroxide or chloride anion, and f is generally comprised between 0.75 and 1 and is the mole fraction of the JO4 oxyanion.

[0093] M1M2(JO4) as defined above f E 1-f The electroactive material is preferably phosphate-based and may have an ordered or modified olivine structure.

[0094] More preferably, the electrode active material (AM) when forming the positive electrode (AMp) has the formula Li 3-x M' y M'' 2-y (JO4)3, where 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 with another oxyanion, and J is S, V, Si, Nb, Mo or a combination thereof. Even more preferably, the electrode active material (AM) has the formula Li(Fe x Mn 1-x )PO4, where 0≦x≦1, and x is preferably 1 (i.e., lithium iron phosphate of formula LiFePO4).

[0095] When forming a negative electrode (AMn) for a lithium ion secondary battery, the electrode active material (AM) may preferably include a carbon-based material and / or a silicon-based material.

[0096] In some embodiments, the carbon-based material can be, for example, graphite, such as natural or synthetic graphite, graphene, or carbon black.

[0097] These materials may be used alone or as a mixture of two or more thereof.

[0098] The carbon-based material is preferably graphite.

[0099] The silicon-based compound may be one or more selected from the group consisting of chlorosilanes, alkoxysilanes, aminosilanes, fluoroalkylsilanes, silicon, silicon chloride, silicon carbide, and silicon oxide. More particularly, the silicon-based compound may be silicon oxide or silicon carbide.

[0100] When present in the electrode active material (AM), the at least one silicon-based compound is contained in the electrode active material (AM) in an amount in the range of 1 to 70 wt. %, preferably 1 to 50 wt. %, more preferably 1 to 30 wt. %, and even more preferably 5 to 20 wt. %, based on the total weight of the electrode active material (AM).

[0101] An optional conductive agent may be added to improve the conductivity of the resulting electrode.

[0102] Examples may include carbonaceous materials such as carbon black, graphite powder, multi- or single-walled carbon nanotubes, graphene, vapor-grown carbon (nano)fibers or fibers, or metals such as nickel or aluminum, silver powder or fibers. The optional conductive agent is preferably carbon black. Carbon black is available, for example, under the brand names Super P® or Ketjenblack®.

[0103] When present, the conductive agent is different from the carbon-based materials described above.

[0104] Composition (C) is also particularly suitable for use in the preparation of an electrode for a solid-state battery further comprising at least one sulfide-based solid electrolyte. Composition (C) further comprising at least one sulfide-based solid electrolyte is hereinafter identified as composition (C1).

[0105] Thus, in a further embodiment of the present invention there is provided an electrode-forming composition (C1) suitable for use in the preparation of an electrode for a solid-state battery, said composition (C1) comprising a) at least one electrode active material (AM); b) a binder (B) as defined above; c) optionally, at least one conductive agent; and d) at least one sulfide-based solid electrolyte Includes.

[0106] As used herein, the phrase "sulfide-based solid electrolyte" refers to a Li + Refers to an inorganic solid-state material that conducts ions but is substantially electronically insulating.

[0107] In the present invention, the term "sulfide-based solid, ionically conductive inorganic particles" is not particularly limited as long as it is a solid electrolyte material that contains sulfur atoms in its molecular structure or composition.

[0108] The sulfide-based solid ionically conductive inorganic particles preferably contain Li, X (X being P, Si, Sn, Ge, Al, As or B) and S which increase the Li-ion conductivity.

[0109] The sulfide-based solid electrolyte according to the invention is more preferably - Lithium tin phosphate sulfide ("LSPS") materials, such as Li 10 SnP2S 12 ; - Lithium Phosphide ("LPS") materials, such as those of the formula (Li2S) x -(P2S5) y(wherein x+y=1 and 0≦x≦1), Li7P3S 11 , Li7PS6, Li4P2S6, Li 9.6 P3S 12 and Li3PS4 glasses, crystalline or glass-ceramics; - Doped LPS, e.g. Li2CuPS4, LiLi 1+2x Zinc 1-x PS4 (wherein 0≦x≦1), Li 3.33 Mg 0.33 P2S6 and Li 4-3x Sc x P2S6, where 0≦x≦1; - Lithium Phosphorus Sulfide Oxygen ("LPSO") material of formula LixPySzO, where 0.33≦x≦0.67, 0.07≦y≦0.2, 0.4≦z≦0.55, and 0≦w≦0.15; - X-containing lithium phosphorus sulfide materials ("LXPS"), where X is Si, Ge, Sn, As, Al, e.g. Li 10 GeP2S 12 and Li 10 SiP2S 12 ; - Lithium phosphorus sulfide oxygen containing X ("LXPSO"), where 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, e.g. Li 0.8 Sn 0.8 S2, Li4SnS4, Li 3.833 Sn 0.833 As 0.166 S4, Li3AsS4-Li4SnS4, Ge-substituted Li3AsS4; and - General formula Li 7-x P.S. 6-x X x of argyrogenite-type sulfide materials is selected from the group consisting of - Y represents at least one halogen element selected from the group of Cl, Br and I or a combination thereof; and x represents a positive number between 0.8 and 2.0, for example, the compound is devoid of sulfur, lithium or a halogen (e.g., Li 6-x PS5-xCl 1+x (wherein 0≦x≦0.5) or has an added heteroatom.

[0110] Particularly preferred sulfide solid electrolytes are LPS materials, LSPS materials and argyrogenite type sulfide materials.

[0111] Another object of the invention is therefore a process for producing an electrode for a secondary battery, comprising: A) providing an electrode-forming composition (C) as defined above; B) providing a metal substrate having at least one surface; C) applying the electrode-forming composition (C) provided in step A) onto at least one surface of the metal substrate provided in step B), thereby providing an assembly comprising a metal substrate coated on at least one surface with said composition (C); D) Drying the assembly provided in step C). The process includes:

[0112] In another object, the present invention provides an electrode for a secondary battery, obtainable by the process as defined above.

[0113] When the composition (C) used in the manufacture of the electrode is composition (C1), the invention provides an electrode for a solid-state battery, obtainable by a process such as defined above.

[0114] The binder composition (B) of the present invention is also particularly suitable for preparing composite solid electrolyte membranes when added together with at least one sulfide-based solid electrolyte.

[0115] In another object, the present invention therefore provides a composition (CC) suitable for preparing a composite solid electrolyte membrane, said composition comprising: i) at least one sulfide-based solid electrolyte; and ii) a binder (B) as defined above; Includes.

[0116] In the present invention, the term "composite solid electrolyte membrane" refers to a composite membrane having lithium ion conductivity that may be in the form of a foldable flexible membrane, and in some embodiments may have a free-standing shape without a support at room temperature.

[0117] Composition (CC) may be suitably prepared by a process comprising mixing binder (B) and a sulfide-based solid electrolyte material by any method known to the skilled artisan. In a preferred embodiment, composition (CC) is prepared by a process comprising solubilizing composition (E) in solvent (S) to provide binder (B), followed by adding sulfide-based solid electrolyte material and mixing the mixture thus obtained.

[0118] The amount of composition (E) in composition (CC) is such that a composite solid electrolyte membrane containing composition (E) is provided in an amount in the range of preferably 2 to 30% by weight, preferably 2 to 20% by weight, more preferably 2 to 15% by weight, based on the total weight of composition (E) and the sulfide-based solid electrolyte material.

[0119] When the amount of composition (E) is less than 2 wt%, the adhesion of the sulfide-based solid electrolyte material in the composite solid electrolyte membrane is insufficient, while when the amount of composition (E) is more than 30 wt%, the ionic conductivity of the composite solid electrolyte membrane is affected.

[0120] In another object, the present invention provides a process for producing a composite solid electrolyte membrane for a solid-state battery, comprising: I) processing a composition (CC) as defined above to form a wet film of a solid composite electrolyte; II) drying the wet membrane provided in step (I); This applies to processes including:

[0121] In step (I) of the process of the present invention, the composition (CC) can be deposited directly on the at least one foil of an inert flexible support or on the surface of the at least one electrode by a technique selected from casting, spray coating, rotary spray coating, roll coating, doctor blading, slot die coating, gravure coating, inkjet printing, spin coating and screen printing, brush, squeegee, foam applicator, curtain coating, vacuum coating, casting being preferred.

[0122] The wet membrane thus obtained typically has a thickness comprised between 10 μm and 400 μm, preferably between 50 μm and 400 μm.

[0123] In step (II) of the process of the invention, composition (CC) is preferably dried at a temperature comprised between 10°C and 150°C, preferably between 20°C and 120°C.

[0124] A further drying step in an oven under vacuum, preferably at a temperature comprised between 20° C. and 150° C., preferably between 30° C. and 120° C., can be suitably carried out to achieve complete solvent removal.

[0125] The person skilled in the art will select the correct duration and temperature of the drying step (II) of the process depending on the boiling point of the at least one solvent (S).

[0126] The dry film obtained in step (II) of the process typically has a thickness comprised between 10 μm and 150 μm.

[0127] The inventive process for preparing a composite solid electrolyte membrane may further comprise a further step (III) of subjecting the dried membrane provided in step (II) to a compression step, e.g. a rolling or uniaxial compression process, to reduce the porosity and increase the density of the composite solid electrolyte membrane.

[0128] In a further object, the present invention provides a solid-state battery comprising a composite solid electrolyte membrane as defined above.

[0129] The solid-state battery of the present invention comprises a positive electrode and a negative electrode, and preferably, at least one of the negative electrode or the positive electrode is an electrode according to the present invention.

[0130] To the extent that the disclosures of the patents, patent applications and publications incorporated herein by reference conflict with the statements of this application to the extent that certain terms may be unclear, this statement will control.

[0131] The present invention will now be described in more detail with reference to the following examples, which are provided solely for the purpose of illustrating the present invention and are not intended to limit its scope. EXAMPLES

[0132] Materials and Methods Polymer A1 = vinylidene fluoride / hexafluoropropylene copolymer with 66.0% fluorine content; Mooney viscosity (ML1+10') = 62 MU measured at 121 °C by ASTM D1646, available in slab form, T of about -18 °C g has. Polymer A2 = vinylidene fluoride / hexafluoropropylene copolymer having 66.0% fluorine content; Mooney viscosity (ML1+10') = 40 MU measured at 121 °C by ASTM D1646, available in slab form, T of about -18 °C g has. Polymer A3 = vinylidene fluoride / tetrafluoroethylene / methyl vinyl ether copolymer having 66.0% fluorine content; Mooney viscosity (ML1+10') = 23 MU measured at 121 °C by ASTM D1646, available in slab form, T of about -32 °C g has. Polymer F1 = vinylidene fluoride / acrylic acid (0.2 wt%), MW of 512 kilodaltons, melting point (Tm2) = 160.4°C and heat of fusion of 51.5 J / g (determined by ASTM D3418) and average particle size (D50) of 3.4 μm. Polymer F2: SOLEF® 21510 VDF / HFP semi-crystalline polymer, commercially available from Solvay, having a heat of fusion of 23 J / g as measured by ASTM standard D3418 and an average particle size (D50) of 137 μm. Polymer F3: SOLEF® 6020 PVDF semi-crystalline homopolymer, commercially available from Solvay, having a heat of fusion of 50 J / g as measured by ASTM standard D3418 and an average particle size (D50) of 93 μm. Calcium stearate (hereinafter CaSt), commercially available from FACI Asian pacific PTE LTD. Butyl butyrate, commercially available from Sigma-Aldrich. Solef® 5130, a VDF / AA copolymer, is commercially available from Solvay. C-NERGY™ SUPER C65 (SC-65), commercially available from Imerys Graphite & Carbon. Active material LCO: Lithium cobalt oxide (LiCoO2), commercially available from Umicore SA.

[0133] General Procedure for the Production of Micronized Pellets Slabs of polymer A1, A2 or A3 cut into medium-sized pieces (5 mm 3The cooled slabs were then introduced into the tube of a comminuter (model 6870D from SPEX Sample Prep) in the required quantities, generally in combination with powders of polymer F1, polymer F2, polymer F3 or in combination with CaSt (comparison), at temperatures generally in the range of -20°C / -50°C. The composition ranges of the mixtures ground in the different experiments are detailed in Table 1.

[0134] [Table 1]

[0135] The resulting micronized pellets ranged from fine to powder containing agglomerates of several hundred μm and mm, which were easily broken up by manual stirring.

[0136] Dissolution kinetics test The micronized pellets of Examples 1-5 and 7 and Comparative Examples 1 and 2 were mixed with butyl butyrate at a concentration of 10% by weight.

[0137] The test started at room temperature and had a T ramp of 1°C / min until a temperature of 40°C was reached.

[0138] The normalized torque of the composition of micronized pellets in butyl butyrate was measured as a function of time. The instrument used was a Rheolab QC with a cylindrical cup and a dedicated geometry (ST24-2D / 2V / 2V-30 / 129 (sn39366) - Anton Paar.). The initial rotation speed applied was 600 RPM, which reached 800 RPM at 40°C. When the normalized torque reached a plateau (meaning that the stress to obtain a fixed rotation speed of the bob was constant), the solubility was estimated (this is due to the solubility completed at ).

[0139] For all micronized pellets containing anti-adherent agents, easy and fast dissolution of the resulting powder was observed. All five samples showed complete dissolution after approximately 25 minutes.

[0140] The solutions of Comparative Examples 1 and 2 were slightly whitish and not as transparent as the solutions of Examples 1 to 5 and 7. Furthermore, a thin deposit was observed at the bottom of the vial after standing for one week.

[0141] The dissolution times and appearances of the resulting solutions are reported in Table 2.

[0142] Comparative Example 2 A 5 g slab of Polymer A1 was mixed with butyl butyrate to give a 10 wt % composition and processed as reported above for the dissolution kinetics test.

[0143] The dissolution time of polymer A1 in the form of slabs was longer (more than twice as long) than the same polymer A1 in the form of micronized pellets (thus subjected to the grinding process at a temperature below their glass transition temperature).

[0144] The dissolution times and appearances of the resulting solutions are reported in Table 2.

[0145] Particle size distribution (PSD) The particle size distribution of the micronized pellets of Example 3 and Comparative Example 1 was measured on a Beckman Coulter LS13 320 according to ISO 13320.

[0146] Results are reported in Table 2 as the average of five measurements on approximately 0.25 cc of material (refractive index 1.4 for VDF polymer).

[0147] [Table 2]

[0148] Electrochemical Stability The electrochemical stability of the polymers used as anti-adhesive agents in the compositions of the present invention was evaluated by determining the oxidation potential by linear sweep voltammetry (LSV) of electrodes containing the anti-adhesive agents Polymer F1, Polymer F2, Polymer F3 and CaSt and conductive carbon.

[0149] Electrode generation Example E1: Anti-stick polymer F3 500 mg of polymer F3 was dissolved in 9.5 g of n-methyl-2-pyrrolidone (NMP) with magnetic stirring for 12 hours to produce a viscous solution (Solution A). 2 g of the solution was mixed with 43 mg of conductive carbon Super C65 (Imerys) in a speedmixer (flacktek) at 2000 RPM for 10 minutes to produce a homogenous black viscous ink. The ink was deposited on Al foil and knife coated with a wet thickness of 200 μm to produce an electrode (Electrode A). Electrode A was dried under a fume hood at 70° C. for 2 hours and further dried under vacuum (20 mbar) at 90° C. for 12 hours.

[0150] Example E2: Anti-stick polymer F2 1 g of polymer F2 was dissolved in 9 g of NMP with magnetic stirring for 12 hours to produce a viscous solution (Solution B). 2 g of Solution B was mixed with 86 mg of conductive carbon Super C65 (Imerys) in a speedmixer (flacktek) at 2000 RPM for 10 minutes to produce a homogenous black viscous ink. The ink was deposited on Al foil and knife coated with a wet thickness of 200 μm to produce an electrode (Electrode B). Electrode B was dried under a fume hood at 70° C. for 2 hours and further dried under vacuum (20 mbar) at 90° C. for 12 hours.

[0151] Example E3: Anti-stick polymer F1 1 g of polymer F1 was dissolved in 9 g of NMP with magnetic stirring for 12 hours to produce a viscous solution (Solution C). 2 g of Solution C was mixed with 86 mg of conductive carbon Super C65 (Imerys) in a speedmixer (flacktek) at 2000 RPM for 10 minutes to produce a homogenous black viscous ink. The ink was deposited on Al foil and knife coated with a wet thickness of 200 μm to produce an electrode (Electrode C). Electrode C was dried under a fume hood at 70° C. for 2 hours and further dried under vacuum (20 mbar) at 90° C. for 12 hours.

[0152] Comparative Example E1: Anti-sticking CaSt Since it was not possible to obtain a film with CaSt, it was embedded in a stable binder (Solef® 5130). The three-component electrode was made of CaSt-C65-Solef® 5130 in a 4-3-3 ratio.

[0153] 500mg of Solef® 5130 was dissolved in 9.5g of NMP with magnetic stirring for 12 hours to produce a viscous solution (Solution D). 2g of Solution A + 100mg of Super C65 + 130mg of CaSt were mixed in a speed mixer at 2000RPM for 20 minutes to produce a homogenous black viscous ink. The ink was deposited on Al foil and knife coated with a wet thickness of 200μm to produce an electrode (Electrode D). Electrode D was dried under a fume hood at 70°C for 2 hours and further dried under vacuum (20mbar) at 70°C for 12 hours.

[0154] To verify the inertness of the polymer binder used in Comparative Example E1, a carbon Solef® 5130 electrode was prepared. 2 g of solution D was mixed with 43 mg of conductive carbon Super C65 (Imerys) in a speedmixer (flacktek) at 2000 RPM for 10 minutes to produce a homogenous black viscous ink. The ink was deposited on Al foil and knife coated with a wet thickness of 200 μm to produce an electrode (Electrode E). Electrode E was dried under a fume hood at 70° C. for 2 hours and further dried under vacuum (20 mbar) at 90° C. for 12 hours.

[0155] The electrodes were assembled into a cell using lithium metal as the counter and reference electrodes and 1M LiPF6 in ethylene carbonate / dimethyl carbonate (1 / 1 volume %) as the electrolyte. After a rest period of 5 hours to allow wetting of the electrodes by the electrolyte, linear sweep voltammetry (LSV) was performed. During LSV, the potential was gradually increased and the current required to increase the potential was monitored. The increase in current corresponds to the occurrence of the oxidation reaction.

[0156] Evaluation of oxidation potential: Cell Creation In an argon-filled glove box, 18 mm diameter disks were punched from any of electrodes A through E as described above. Lithium cells were assembled with each disk of electrodes A through E using a lithium metal disk (18 mm diameter) and 70 μl of LiPF in EC-DMC (1-1 volume) as the reference / counter electrodes.

[0157] Test conditions Each cell was placed in a controlled temperature chamber at 20° C. and left undisturbed for at least 5 hours to allow the electrolyte to wet the electrodes. After 5 hours, LSV measurements were started under the following conditions: Starting potential: open circuit potential Final potential: 6.5 V vs. reference (Li counter electrode) Speed: 0.1mV / s.

[0158] The LSV profiles of all electrodes A-C and D (compared to electrode E) are very similar and show the following: - current increase starting at 3.8 V vs Li; this signal is caused by the passivation of the Al current collector; - The current is stable for all of the tested electrodes from 4.65 to 5.2 V, which corresponds to the onset of decomposition of the conductive carbon super C65 and the liquid electrolyte. For comparative example E1, an additional decomposition peak is observed at 4.6 to 4.7 V, which corresponds to the oxidation of the Ca stearate anti-adherent agent. Thus, Ca stearate, in contrast to the semi-crystalline fluorinated polymer, may have a detrimental effect on the stability and performance of the battery.

[0159] Preparation of the positive electrode Binder Composition A 10 wt % solution of polymer A1 (binder 1) in the form of a slab manually cut into small pieces and finely divided pellets of the elastomer composition of Example 3 (containing polymer A1) (binder 2) in butyl butyrate was prepared in a glass flask with stirring at room temperature. The solution viscosity was measured.

[0160] Preparation of slurry Formulations containing 2 wt% binder, 2 wt% SC65 and 96 wt% LCO with a total solids content of 80% were prepared with both Binder 1 (Slurry 1) and Binder 2 (Slurry 2). The slurries were prepared using a Speedymixer polymer container.

[0161] viscosity The slurry rheology was measured with a rheometer "Rheolab QC" from Anton Paar. The rheological profiles of the slurries obtained starting with binder 1 and binder 2 were comparable, with a slightly higher viscosity for the slurry containing binder 2.

[0162] Casting and drying Slurry 1 and Slurry 2 were cast onto an Al current collector (15 μm thick, not etched, only cleaned with acetone).

[0163] The height of the coating knife is selected to reach the target loading (30mg / cm2). A wet thickness of 200-300um is used. The speed of the coating machine is 30mm / s.

[0164] The cast was transferred to an oven (preheated at 90° C.): 25' at 90° C. under dynamic vacuum (N2 atmosphere) of approximately 500-600 mbar, followed by 25' under static vacuum and 3' in dynamic vacuum again at 600 mbar.

[0165] Electrode 1 was obtained from slurry 1 and electrode 2 was obtained from slurry 2.

[0166] Pull-off adhesive To evaluate the adhesive properties of the positive electrodes 1 and 2 produced by the above procedure, a pull-off test was performed. The test consisted in measuring the force required to peel the electrode coating from the aluminum current collector. During the test, a cylindrical pin was used to apply a compressive force perpendicular to the electrode. Afterwards, the pin (with double-sided adhesive tape at the end) was retracted and the force required to remove the electrode coating from the collector was measured.

[0167] The results of the test are comparable for electrode 1 and electrode 2, with no differences in the two cases. The positive electrode containing the micronized pellets of composition (E) according to the invention does not show a decrease in adhesion compared to the positive electrode prepared by using fluoroelastomer in the form of slabs without treatment and without anti-sticking additive, while at the same time realizing the advantage of faster solubility in the preparation of the binder. The results are summarized in Table 4.

[0168] [Table 3]

Claims

1. A binder composition [binder (B)] for use in the preparation of components for an electrochemical device, a) micronized pellets of a (per)fluoroelastomer composition [composition (E)], the composition (E) comprising at least one (per)fluoroelastomer [fluoroelastomer (A)] having a weight average particle size (D50) of less than 500 μm and at least one thermoplastic semi-crystalline vinylidene fluoride polymer [polymer (F)] by the method reported herein, micronized pellets; b) at least one non-aqueous solvent (S) selected from the group consisting of nitrile-containing solvents, ethers, esters, thiols and thioethers, ketones, tertiary amines and cyclic carbonate esters A binder composition [binder (B)] characterized by comprising.

2. The fluoroelastomer (A) is a copolymer based on vinylidene fluoride (VDF), and VDF is of the following classes: (a) C ２ - C ８ perfluoroolefins such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP), hexafluoroisobutylene; (b) hydrogen-containing C ２ - C ８ olefins such as vinyl fluoride (VF), trifluoroethylene (TrFE), the formula CH ２ = CH - R ｆ (wherein R ｆ is a C １ - C ６ perfluoroalkyl group) perfluoroalkyl ethylene; (c) C ２ - C ８ chloro, and / or bromo, and / or iodo-fluoroolefins such as chlorotrifluoroethylene (CTFE); (d) the formula CF ２ = CFOR ｆ (wherein R ｆ is C １~C ６ (Per)fluoroalkyl group, such as CF ３ , C ２ F ５ , C ３ F ７ ), of (per)fluoroalkyl vinyl ether (PAVE); (e) formula CF ２ =CFOX (wherein X is a C containing a catenary oxygen atom １ ~C １２ ((Per)fluoro)-oxyalkyl, such as perfluoro-2-propoxypropyl group), of (per)fluoro-oxy-alkyl vinyl ether; (f) formula: [Chemical formula 1] (wherein R ｆ３ , R ｆ４ , R ｆ５ , R ｆ６ are each independently a C containing a fluorine atom and one or more oxygen atoms optionally １ ~C ６ (Per)fluoroalkyl group, such as especially -CF ３ , -C ２ F ５ , -C ３ F ７ , -OCF ３ , -OCF ２ CF ２ OCF ３ ; preferably independently selected from perfluorodioxoles) having (per)fluorodioxole; (g) formula: CFX ２ =CX ２ OCF ２ OR’’ ｆ (wherein R’’ ｆ is a linear or branched C containing 1 to 3 catenary oxygen atoms １ ~C ６ (Per)fluoroalkyl; C ５ ~C ６ cyclic (per)fluoroalkyl; and linear or branched C ２ ~C ６Selected from (per)fluorooxyalkyl and X ２ = F, H; preferably, X ２ is F, and R'' ｆ is -CF ２ CF ３ (MOVE1); -CF ２ CF ２ OCF ３ (MOVE2); or -CF ３ (MOVE3)), having a (per)fluoro-methoxy-vinyl ether (hereinafter MOVE); (h)C ２ ~C ８ a non-fluorinated olefin (Ol), such as ethylene and propylene The binder (B) according to claim 1, copolymerized with at least one comonomer selected from the group consisting of

3. The polymer (F) is selected from a VDF homopolymer and a copolymer of VDF having one or more fluorinated monomers and / or hydrogenated monomers, the binder (B) according to claim 1 or 2.

4. The polymer (F) is (I) a repeating unit derived from VDF, and (II) a repeating unit derived from at least one hydrogenated monomer [monomer (MA)] containing at least one carboxylic acid terminal group The binder (B) according to claim 1 or 2, comprising, more preferably consisting of,

5. The amount of the polymer (F) in the composition is 2% to 50% by weight, more preferably 2% to 20% by weight, even more preferably 2% to 15% by weight, based on the total weight of the (per)fluoroelastomer (A) and the polymer (F), the binder (B) according to claim 1 or 2.

6. A micronized pellet of the composition (E), comprising at least one (per) fluoroelastomer [fluoroelastomer (A)] and at least one thermoplastic vinylidene fluoride polymer [polymer (F)], wherein the polymer (F) in the composition (E) is present in an amount of at least 2% by weight and less than 5% by weight based on the total weight of the (per) fluoroelastomer (A) and the polymer (F), the micronized pellet.

7. An electrode forming composition [composition (C)] for use in the preparation of an electrode for an electrochemical device, a) at least one electrode active material (AM); b) the binder (B) according to claim 1 or 2; and c) optionally, at least one conductive agent characterized by comprising an electrode forming composition [composition (C)].

8. d) at least one sulfide-based solid electrolyte further comprising the electrode forming composition (C) according to claim 7.

9. A process for manufacturing an electrode for a secondary battery, A) providing the electrode forming composition (C) according to claim 7; B) providing a metal substrate having at least one surface; C) applying the electrode forming composition (C) provided in step A) onto the at least one surface of the metal substrate provided in step B), thereby providing an assembly comprising a metal substrate coated with the composition (C) on the at least one surface; D) drying the assembly provided in step C) comprising a process.

10. An electrode for a secondary battery obtainable by the process according to claim 9.

11. A composition (CC) suitable for preparing a composite solid electrolyte membrane, i) at least one sulfide-based solid electrolyte; ii) the binder (B) according to claim 1 or 2 A composition (CC) comprising.

12. The sulfide-based solid electrolyte is - Lithium tin phosphorus sulfide ("LSP S") material, such as Li １０ SnP ２ S １２ ; - Lithium phosphorus sulfide ("LPS") material, such as the formula (Li ２ S) ｘ -(P ２ S ５ ) ｙ (where x + y = 1 and 0 ≤ x ≤ 1), Li ７ P ３ S １１ 、Li ７ PS ６ 、Li ４ P ２ S ６ 、Li ９．６ P ３ S １２ And Li ３ PS ４ Of glass, crystalline or glass-ceramic; - Doped LPS, such as Li ２ CuPS ４ 、LiLi １＋２ｘ Zn １－ｘ PS ４ (where 0 ≤ x ≤ 1), Li ３．３３ Mg ０．３３ P ２ S ６ And Li ４－３ｘ Sc ｘ P ２ S ６ (where 0 ≤ x ≤ 1); - Lithium phosphorus sulfide oxygen ("LPSO") material of the formula LixP ySzO (where 0.33 ≤ x ≤ 0.67, 0.07 ≤ y ≤ 0.2, 0.4 ≤ z ≤ 0.55, 0 ≤ w ≤ 0.15); - A lithium phosphorus sulfide material containing X (the "LXPS") (where X is Si, Ge, Sn, As, Al), for example Li １０ GeP ２ S １２ and Li １０ SiP ２ S １２ ; - A lithium phosphorus sulfide oxygen containing X (the "LXPSO") (where X is Si, Ge, Sn, As, Al); - A lithium silicon sulfide (the "LSS") material; - A lithium boron sulfide material, for example Li ３ BS ３ and Li ２ S - B ２ S ３ - LiI; - A lithium tin sulfide material and a lithium arsenide material, for example Li ０．８ Sn ０．８ S ２ , Li ４ SnS ４ , Li ３．８３３ Sn ０．８３３ As ０．１６６ S ４ , Li ３ AsS ４ - Li ４ SnS ４ , Ge substituted Li ３ AsS ４ ; and - A sulfide material of the argyrodite type of general formula Li ７－ｘ PS ６－ｘ X ｘ selected from the group consisting of - Y represents at least one halogen element selected from the group of Cl, Br and I or combinations thereof; and x represents a positive number from 0.8 to 2.0, the composition (CC) according to claim 11.

13. A process for manufacturing a composite solid electrolyte membrane for a solid battery, comprising I) processing the composition (CC) according to claim 11 to form a wet membrane of a solid composite electrolyte; II) forming a dry composite electrolyte membrane from the wet membrane; and II) drying the wet film provided in step (I); A process comprising.

14. A composite solid electrolyte membrane for a solid battery, obtainable by the process according to claim 13.

15. A process for manufacturing a composite solid electrolyte membrane for a solid battery, comprising: I) A composition (CC) suitable for preparing a composite solid electrolyte membrane, i) A sulfide-based solid electrolyte; ii) The binder (B) according to claim 1 or 2 processing a composition (CC) comprising to form a wet film of a solid composite electrolyte; and II) drying the wet film provided in step (I); A process for manufacturing a composite solid electrolyte membrane for a solid battery and / or an electrode for a secondary battery, obtainable by a process comprising: A) An electrode-forming composition [composition (C)] for use in the preparation of an electrode for an electrochemical device, a) at least one electrode active material (AM); b) The binder (B) according to claim 1 or 2; and c) Optionally, at least one conductive agent providing an electrode-forming composition [composition (C)] characterized by comprising; B) providing a metal substrate having at least one surface; C) applying the electrode-forming composition (C) provided in step A) onto the at least one surface of the metal substrate provided in step B), thereby providing an assembly comprising a metal substrate coated with the composition (C) on the at least one surface; D) drying the assembly provided in step C); A solid battery including an electrode for a secondary battery, which can be obtained by a process including

Images