Cathode coatings for Li-ion batteries

Abstract

The present invention generally relates to the field of electrical energy storage in rechargeable accumulators of the Li-ion type. More specifically, the present invention relates to a cathode coating for a fully solid-state Li-ion battery. The present invention also relates to a method for the manufacture of said coating. The present invention also relates to a cathode coated with this coating, to a method for the manufacture of such a cathode and also to a Li-ion accumulator comprising such a cathode.

Description

[Technical field]

[0001] The present invention generally relates to the field of electrical energy storage in rechargeable accumulators of the Li-ion type. More specifically, the present invention relates to a cathode coating for all-solid-state Li-ion batteries. The present invention also relates to a method for the preparation of said coating. The present invention also relates to a cathode coated with this coating, a method for producing such a cathode and also to a Li-ion accumulator comprising such a cathode. [Background technology]

[0002] Lithium batteries can be used as power sources for a variety of electronic devices, from mobile phones, laptop computers and small household electronics devices to vehicles and even large-capacity energy storage devices, and the demand for lithium batteries is constantly expanding.

[0003] Conventional lithium storage batteries generally use organic-containing liquid electrolytes that advantageously have high ionic conductivity but require additional safety devices due to the risk of liquid leakage, fire, or explosion at high temperatures.

[0004] To address the safety issues associated with liquid electrolytes, fully solid-state batteries using solid electrolytes have been developed in recent years.

[0005] An all-solid-state battery generally comprises a positive electrode, a solid electrolyte, and a negative electrode. The positive electrode includes a positive electrode active material and a solid electrolyte, and further includes an electronically conductive material and a binder. The solid electrolyte includes one or more elements from the following list: a polymer, a plasticizer, a lithium salt, an inorganic particle, and an ionic liquid. The negative electrode includes a negative electrode active material and a solid electrolyte, similar to the positive electrode, and further includes a conductive material and a binder.

[0006] However, currently there are no solid electrolytes that meet the specifications for bulk applications of solid-state batteries, due to the general difficulty in combining ionic conductivity, electrochemical stability, mechanical strength, and compatibility with anode or cathode materials for solid electrolytes.

[0007] In particular, examples may include inorganic compounds that exhibit very high ionic conductivity but electrochemical instability with respect to potentials at the anode and high potentials at the cathode. (Y. Zhu, ACS Appl. Mater. Interfaces, 2015, 7, 23685-23693) There remains a need to develop solutions that allow the cathode to be compatible with the solid electrolyte in all-solid-state Li-ion batteries. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] Y. Zhu,ACS Appl.Mater.Interfaces,2015,7,23685-23693 Summary of the Invention [Problem to be solved by the invention]

[0009] It is therefore an object of the present invention to provide a coating that can be applied directly to a Li-ion battery positive electrode and then allows for a physical separation between the solid electrolyte and the electrode active material, allowing the use of solid electrolytes that appear unstable with respect to certain active materials.

[0010] The present invention also aims to provide a method for producing said cathode coating.Finally, the present invention relates to a cathode exhibiting such a coating and to a method for producing such a cathode.

[0011] Finally, the present invention aims to provide a rechargeable Li-ion accumulator comprising such a cathode. [Means for solving the problem]

[0012] The technical solution proposed by the present invention is to provide a cathode coating that makes the cathode compatible with the solid electrolyte in an all-solid-state battery.

[0013] The present invention first provides a method for producing a a. one or more poly(vinylidene fluorides); b. a lithium salt; c. Conductive additives The present invention relates to a cathode coating consisting of

[0014] The invention also relates to a method for producing a cathode coating from an ink obtained by mixing all the constituents of the coating.

[0015] The invention also relates to a cathode for a lithium-ion battery, which cathode consists of an active material, a binder and an electrically conductive material and which presents a coating layer according to the invention.

[0016] The present invention also provides a method for producing a Li-ion battery cathode, the method comprising the steps of: providing a cathode; depositing a coating layer on said cathode. The present invention relates to a method comprising the steps of:

[0017] Another subject of the invention is a Li-ion accumulator comprising an anode, a cathode and an all-solid-state electrolyte, the cathode being as defined above.

[0018] The present invention makes it possible to overcome the drawbacks of the state of the art: the invention provides an ion-conducting coating with a homogeneous distribution of its dielectric constant.

[0019] In the context of the present invention, the coating makes it possible to use a positive electrode without mixing the solid electrolyte with the active material of the cathode. This is because the coating can be applied directly to a normal positive electrode having a porosity of 15% to 45%, before or after calendering. Furthermore, the coating allows a physical separation between the solid electrolyte and the active material, thus making it possible to use solid electrolytes that appear unstable for some active materials. The present invention therefore provides a positive electrode comprising a first layer of a normal positive electrode and a second layer of a cathode coating according to the present invention.

[0020] The present invention provides a coating that offers a very good compromise between ionic conductivity, electrochemical stability, high temperature stability and mechanical strength. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The invention will now be explained in more detail, without being limiting, in the following description.

[0022] According to a first aspect, the present invention provides a method for producing a composition comprising: a. one or more poly(vinylidene fluorides) (component A); b. at least one lithium salt (component B); c. at least one conductive additive (component C); The present invention relates to a cathode coating consisting of

[0023] According to various embodiments, the coating comprises the following properties when properly combined, with amounts given by weight unless otherwise specified:

[0024] Ingredient A The semi-crystalline fluoropolymers used in the present invention are polymers based on vinylidene difluoride, commonly referred to by the abbreviation PVDF.

[0025] According to one embodiment, the PVDF is a poly(vinylidene fluoride) homopolymer or a mixture of vinylidene fluoride homopolymers.

[0026] According to one embodiment, the PVDF is a poly(vinylidene fluoride) homopolymer or a copolymer of vinylidene difluoride and at least one comonomer that is compatible with vinylidene difluoride.

[0027] According to one embodiment, the PVDF is semi-crystalline.

[0028] Comonomers compatible with vinylidene difluoride can be halogenated (fluorinated, chlorinated or brominated) or non-halogenated.

[0029] Examples of suitable fluorinated comonomers are vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, trifluoropropene, in particular 3,3,3-trifluoropropene, tetrafluoropropene, in particular 2,3,3,3-tetrafluoropropene or 1,3,3,3-tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, in particular 1,1,3,3,3-pentafluoropropene or 1,2,3,3,3-pentafluoropropene, perfluoroalkyl vinyl ethers, in particular those of the general formula Rf-O-CF-CF2, where Rf is an alkyl group, preferably a C1-C4 alkyl group (preferred examples are perfluoro(propyl vinyl ether) and perfluoro(methyl vinyl ether)).

[0030] The fluorinated comonomer may contain a chlorine atom or a bromine atom. The fluorinated comonomer may be selected in particular from bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene and chlorotrifluoropropene. Chlorofluoroethylene may refer to either 1-chloro-1-fluoroethylene or 1-chloro-2-fluoroethylene. The 1-chloro-1-fluoroethylene isomer is preferred. The chlorotrifluoropropene is preferably 1-chloro-3,3,3-trifluoropropene or 2-chloro-3,3,3-trifluoropropene.

[0031] The VDF copolymer may also contain non-halogenated monomers such as ethylene and / or acrylic or methacrylic comonomers.

[0032] The fluoropolymer preferably contains at least 50 mol % vinylidene difluoride.

[0033] According to one embodiment, the PVDF is a copolymer of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) (P(VDF-HFP)), with the weight percentage of hexafluoropropylene monomer units being between 2% and 23% by weight, preferably between 4% and 15% by weight, based on the weight of the copolymer.

[0034] According to one embodiment, the PVDF is a mixture of poly(vinylidene fluoride) homopolymer and VDF-HFP copolymer.

[0035] According to one embodiment, the PVDF is a copolymer of vinylidene fluoride and tetrafluoroethylene (TFE).

[0036] According to one embodiment, the PVDF is a copolymer of vinylidene fluoride and chlorotrifluoroethylene (CTFE).

[0037] According to one embodiment, the PVDF is a VDF-TFE-HFP terpolymer. According to one embodiment, the PVDF is a VDF-TrFE-TFE terpolymer (TrFE is trifluoroethylene). In these terpolymers, the weight content of VDF is at least 10% and the comonomers are present in various proportions.

[0038] According to one embodiment, the PVDF is a mixture of two or more VDF-HFP copolymers.

[0039] According to one embodiment, the PVDF comprises monomer units having at least one of the following functional groups: carboxylic acid, carboxylic anhydride, carboxylic ester, epoxy (such as glycidyl), amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenol, ester, ether, siloxane, sulfonic acid, sulfuric acid, phosphoric acid or phosphonic acid. The functional groups are introduced by chemical reaction, which may be grafting or copolymerization, of a fluorinated monomer with a monomer having at least one of the functional groups and a vinyl functional group capable of copolymerizing with the fluorinated monomer, according to techniques well known to those skilled in the art.

[0040] According to one embodiment, the functional group has a carboxylic acid functionality which is a (meth)acrylic acid type group selected from acrylic acid, methacrylic acid, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxyethylhexyl (meth)acrylate.

[0041] According to one embodiment, the unit having carboxylic acid functionality further comprises a heteroatom selected from oxygen, sulfur, nitrogen and phosphorus.

[0042] According to one embodiment, the functionality is introduced by a transfer agent used during the synthesis process. The transfer agent is a polymer with a molar mass of less than or equal to 20000 g / mol, with functional groups selected from the following groups: carboxylic acid, carboxylic anhydride, carboxylic ester, epoxy (such as glycidyl), amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenol, ester, ether, siloxane, sulfonic acid, sulfuric acid, phosphoric acid or phosphonic acid. An example of this type of transfer agent is an acrylic acid oligomer.

[0043] The content of functional groups in PVDF is at least 0.01 mol %, preferably at least 0.1 mol % and at most 15 mol %, preferably at most 10 mol %.

[0044] The PVDF is preferably of high molecular weight. The term "high molecular weight" as used herein is understood to mean a PVDF having a melt viscosity of more than 100 Pa.s, preferably more than 500 Pa.s, more preferably more than 1000 Pa.s, advantageously more than 2000 Pa.s. The viscosity is measured according to standard ASTM D3825 using a capillary or parallel plate rheometer at 232°C for 100 s. -1 The shear gradient is measured at 100 nm. The two methods give similar results.

[0045] The PVDF homopolymers and VDF copolymers used in the present invention can be obtained by known polymerization methods, such as emulsion polymerization.

[0046] According to one embodiment, they are prepared by an emulsion polymerization process in the absence of fluorinated surfactants.

[0047] Polymerization of PVDF generally results in a latex having a solids content of 10% to 60% by weight, preferably 10% to 50% by weight, and a weight average particle size of less than 1 micrometer, preferably less than 1000 nm, preferably less than 800 nm and more preferably less than 600 nm. The weight average size of the particles is generally at least 10 nm, preferably at least 50 nm, and advantageously the average size is in the range of 100 to 400 nm. The polymer particles may form weak agglomerates, called secondary particles, whose weight average size is less than 5000 μm, preferably less than 1000 μm, advantageously 1 to 80 micrometers and preferably 2 to 50 micrometers. The weak agglomerates can be broken down into individual particles during formulation and application to a substrate.

[0048] According to some embodiments, the PVDF homopolymer and VDF copolymer are composed of bio-based VDF. The term "bio-based" means "obtained from biomass". This makes it possible to improve the ecological footprint of the coating. Bio-based VDF is according to the standard NF EN 16640 14 It may be characterized by a content of at least 1 atomic % of renewable carbon, i.e. carbon of natural origin derived from biological material or biomass, as determined by the content of C. The term "renewable carbon" indicates that the carbon is of natural origin and derived from biological material (or biomass), as shown below. According to some embodiments, the biocarbon content of the VDF may be greater than 5%, preferably greater than 10%, preferably greater than 25%, preferably greater than 33%, preferably greater than 50%, preferably greater than 66%, preferably greater than 75%, preferably greater than 90%, preferably greater than 95%, preferably greater than 98%, preferably greater than 99%, advantageously equal to 100%.

[0049] Component B As non-limiting examples, the lithium salt (or lithium salts) is selected from LiPF6 (lithium hexafluorophosphate), LiFSI (lithium bis(fluorosulfonyl)imide), TFSI (lithium bis(trifluoromethylsulfonyl)imide), LiTDI (lithium 2-trifluoromethyl-4,5-dicyanoimidazolate), LiPOF2, LiB(C2O4)2, LiF2B(C2O4)2, LiBF4, LiNO3, LiClO4, and mixtures of two or more of the listed salts.

[0050] Component C The conductive additive may be an organic molecule or a mixture of organic molecules capable of swelling the fluoropolymer without dissolving it and having a dielectric constant greater than 1. According to one embodiment, component C is selected from linear or cyclic ethers, esters, lactones, nitriles, carbonates and ionic liquids.

[0051] As non-limiting examples, among the ethers, mention may be made of linear or cyclic ethers such as dimethoxyethane (DME), the methyl ethers of oligoethylene glycols of 2 to 5 oxyethylene units, dioxolane, dioxane, dibutyl ether, tetrahydrofuran, and mixtures thereof.

[0052] Among the esters, mention may be made of phosphates or sulfites, for example methyl formate, methyl acetate, methyl propionate, ethyl acetate, butyl acetate, gamma-butyrolactone or mixtures thereof.

[0053] Among the lactones, mention may in particular be made of cyclohexanone.

[0054] Among the nitriles, mention may be made, for example, of acetonitrile, pyruvonitrile, propionitrile, methoxypropionitrile, dimethylaminopropionitrile, butyronitrile, isobutyronitrile, valeronitrile, pivalonitrile, isovaleronitrile, glutaronitrile, methoxyglutaronitrile, 2-methylglutaronitrile, 3-methylglutaronitrile, adiponitrile, malononitrile and mixtures thereof.

[0055] For example, among carbonates, ethylene carbonate (EC) (CAS: 96-49-1), propylene carbonate (PC) (CAS: 108-32-7), butylene carbonate (BC) (CAS: 4437-85-8), dimethyl carbonate (DMC) (CAS: 616-38-6), diethyl carbonate (DEC) (CAS: 105-58-8), ethyl methyl carbonate (EMC) (CAS: 623-53-0), diphenyl carbonate (CAS: 102-09-0), methyl phenyl carbonate (CAS: 102-09-0), cyclic carbonates such as ethyl propyl carbonate (CAS:13509-27-8), dipropyl carbonate (DPC) (CAS:623-96-1), methyl propyl carbonate (MPC) (CAS:1333-41-1), ethyl propyl carbonate (EPC), vinylene carbonate (VC) (CAS:872-36-6), fluoroethylene carbonate (FEC) (CAS:114435-02-8), trifluoropropylene carbonate (CAS:167951-80-6) or mixtures thereof.

[0056] Among the ionic liquids, mention may in particular be made of EMIM:FSI, PYR:FSI, EMIM:TFSI, PYR:TFSI, EMIM:BOB, PYR:BOB, EMIM:TDI, PYR:TDI, EMIM:BF4 or PYR:BF4.

[0057] Composition by weight of the cathode coating according to the invention: - component A having a weight ratio of 20% to 80%, - component B having a weight ratio of 1% to 40%, -Component C having a weight ratio of 2% to 50% (However, the sum of these percentages equals 100%).

[0058] The invention also relates to a method for producing the above-mentioned cathode coating from an ink obtained by mixing all the constituents of the coating in a solvent.

[0059] The inks making it possible to prepare the coatings can be produced by any type of mixer known to those skilled in the art, such as planetary mixers, centrifuges, orbital mixers, stirrer shafts or Ultra-Turrax. The different constituents of the ink are not added in a strict order. The inks can be produced at different temperatures ranging from ambient temperature up to the boiling point of the solvent used to produce the ink. The solvents used are preferably polar solvents with a Hansen parameter greater than 2. Non-limiting examples include acetone, triethyl acetyl citrate (TEAC), gamma-butyrolactone (GBL), cyclohexanone (CHO), cyclopentanone (CPO), dibutyl phthalate (DBP), dibutyl sebacate (DBS), diethyl carbonate (DEC), diethyl phthalate (DEP), dihydrolevoglucosenone (Cyrene), dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), 1,4-dioxane, 3-heptanone, hexamethylformamide (DMF), dimethylformamide (DMSO), dimethyl ... Mention may be made of sulphoramide (HMPA), 3-hexanone, methyl ethyl ketone (MEK), N-methyl-2-pyrrolidinone (NMP), 3-octanone, 3-pentanone, propylene carbonate (PC), tetrahydrofuran (THF), tetramethylurea (TMU), triacetin, triethyl citrate (TEC), triethyl phosphate (TEP), trimethyl phosphate (TMP), N,N,N',N'-tetrabutylsuccinamide (TBSA), or a mixture of two or more of the solvents mentioned.

[0060] According to one embodiment, the porosity of the coated cathode according to the invention is less than 10%, preferably less than 5%.

[0061] The porosity of the coated electrode (CE) is obtained according to the following calculation described in the publication by M. Cai, Nature Communications, 10, 2019, 4597:

[0062]

number

[0063]

number

[0064] The thickness of this coating may range from 0.1 to 100 μm, preferentially from 0.1 to 50 μm and more preferentially from 0.1 to 35 μm.

[0065] The present invention also relates to a cathode for an all-solid-state lithium-ion battery, the cathode being composed of an active material, a binder and an electrically conductive material, preferably composed of them and presenting a coating layer according to the invention. The cathode is deposited on a metal support. Thus, the cathode forms a first layer on the metal support.

[0066] According to one embodiment, the active material in the positive electrode is selected from the group consisting of manganese dioxide (MnO2), iron oxide, copper oxide, nickel oxide, lithium / manganese composite oxide (e.g., Li x Mn2O4 or Li x MnO2), lithium / nickel composite oxides (e.g., Li xNiO2), lithium / cobalt composite oxides (e.g., Li x CoO2), lithium / nickel / cobalt composite oxides (e.g., LiNi 1-y Co y O2), lithium / nickel / cobalt / manganese composite oxides (e.g., LiNi x Mn y Co z O2 where x + y + z = 1), lithium-rich lithium / nickel / cobalt / manganese composite oxides (e.g., Li 1+x (Ni x Mn y Co z ) 1-x O2), lithium / transition metal composite oxides, spinel-structured lithium / manganese / nickel composite oxides (e.g., Li x Mn 2-y Ni y O4), high-voltage nickel / manganese composite oxides (e.g., LiMn 1.5 Ni 0.5 - x X x O4 (X = Al, Fe, Cr, Co, Rh, Nd, other rare earth metals, and 0 < x < 0.1), vanadium oxide, S8-type sulfur, and mixtures thereof.

[0067] The electron conductive material is selected from carbon black, natural or synthetic graphite, carbon fiber, carbon nanotube, metal fiber and metal powder, and conductive metal oxides. Preferably, they are selected from carbon black, natural or synthetic graphite, carbon fiber and carbon nanotube.

[0068] The binder used to manufacture the cathode is a polymer selected from polyolefins (e.g., polyethylene or polypropylene), fluoropolymers (PVDF) that may exhibit acid functionality, polyacrylic acid (PAA), polyacrylonitrile (PAN), cellulose-based polymers, polyphenyl sulfone, polyether sulfone, phenol resin, vinyl ester resin, epoxy resin or liquid crystal polymer.

[0069] At the cathode, the coating is electrochemically stable up to 5V.

[0070] Preferably, the cathode forming the first layer comprises less than 3% by weight, advantageously less than 1% by weight, preferably less than 0.5% by weight and more preferentially less than 0.1% by weight, based on the total weight of the cathode, of a solid electrolyte, in particular free of it, the solid electrolyte being preferentially present in the coating layer according to the invention.

[0071] The present invention also provides a method for producing a Li-ion battery cathode, the method comprising the steps of: providing a cathode; depositing on said cathode a coating layer according to the invention; The present invention relates to a method comprising the steps of:

[0072] This coating can be produced by any deposition method known to those skilled in the art, such as solvent route coating, dip-pulling, centrifugal coating, spray coating or calendaring coating, etc. These deposition techniques can be carried out at different temperatures that can range from 5° C. up to 180° C.

[0073] According to one embodiment, the coating can be applied directly to a conventional cathode with a porosity of 15% to 45% before or after calendering. Moreover, this coating allows for a physical separation between the solid electrolyte and the active material, thus making it possible to use solid electrolytes that appear unstable for some active materials.

[0074] According to one embodiment, the method for producing a Li-ion battery cathode comprises, at the start of the deposition of the coating according to the invention, the following steps: mixing the active fillers, the polymeric binder and the conductive fillers by a method making it possible to obtain an electrode formulation that can be applied to a metal support; - depositing said electrode formulation on a metal substrate, - Consolidation of the electrode by thermal-mechanical treatments such as heat treatment (applying temperatures in the range of up to 50°C above the melting point of the polymer without mechanical pressure) and / or calendering. Includes.

[0075] The metal support of the electrode is generally made of aluminum for the cathode. The metal support may be surface treated and may have a conductive primer with a thickness of 5 μm or more. The support may also be a woven or non-woven fabric made of carbon fiber.

[0076] The positive electrode thus comprises a metal support on which is deposited a first layer comprising, preferably consisting of, an active material, a binder and an electrically conductive material, and a second layer deposited on the first layer, the second layer consisting of the cathode coating according to the invention.

[0077] Another subject of the invention is an all-solid-state Li-ion accumulator comprising a negative electrode, a positive electrode and an all-solid-state electrolyte, the cathode being as defined above. EXAMPLES

[0078] The following examples illustrate the scope of the invention without, however, limiting it.

[0079] Preparation of fluoropolymer (FP) solutions 14.992 g of VDF-HFP copolymer with a weight content of 23% HFP is dissolved in 85.753 g of acetone using a planetary mixer at 2000 rpm for 6 times 1 min in order to completely dissolve.

[0080] Preparation of Coating Ink I: FP / LiFSI 80 / 20 0.393 g LiFSI is dissolved in 9.683 g polymer (FP) solution. The solution is stirred for 30 min at 21° C. using a magnetic bar.

[0081] Preparation of Coating Ink II: FP / LiFSI / S1 60 / 20 / 20 0.441 g of LiFSI is dissolved in 0.449 g of tetraethylene glycol dimethyl ether (CAS 143-24-8) using a magnetic stirrer for 10 minutes at 21° C. Then 8.826 g of a 15% solution of FP in acetone is added.

[0082] Preparation of Coating Ink III: FP / LiFSI / MPCN 60 / 20 / 20 0.3986 g of LiFSI is dissolved in 0.3986 g of methoxypropionitrile (CAS 110-67-8) using a magnetic stirrer for 10 minutes at 21° C. Then 7.972 g of a 15% solution of FP in acetone is added.

[0083] Preparation of coating ink IV: FP / LiFSI / S1 40 / 30 / 30 0.528 g of LiFSI is dissolved in 0.528 g of tetraethylene glycol dimethyl ether (CAS 143-24-8) using a magnetic stirrer for 10 minutes at 21° C. Then 4.675 g of a 15% solution of FP in acetone is added.

[0084] Preparation of coating ink V: FP / LiFSI / S1 50 / 15 / 35 0.264 g of LiFSI is dissolved in 0.616 g of tetraethylene glycol dimethyl ether S1 (CAS 143-24-8) using a magnetic stirrer for 10 minutes at 21° C. Then 3.52 g of a 25% solution of FP in acetone is added.

[0085] Coating of porous NMC622 cathode with Ink I An NMC622 cathode having the following formulation NMC622 / HSV1810 / C45 97 / 1.5 / 1.5 is coated with Ink I. Before coating, the electrode has an average porosity of 44% and a surface area of ​​2.51 g / cm 3 The coating exhibits a density of 18.04 mg / cm3 after drying at ambient temperature. 2 This allows the coating to fill all the pores of the electrode. The ionic conductivity of the electrode was measured by impedance spectroscopy at 0.033 mS / cm.

[0086] Coating of porous NMC532 cathode with Ink V A commercial NMC532 cathode with a thickness of 71 μm is coated with Ink V using a bar coater. The deposited wet thickness is 200 μm. The coating is dried using heating at 35° C. The coated electrode is then calendered to reach a total thickness of 91 μm.

[0087] Output Test: A power test was performed to compare the Ink V coated electrodes with a standard electrode.

[0088] method The method consists of charging the battery at a slow C / 10 regime and discharging it at a different regime, thus measuring the capacity the battery can recover at different discharge rates.

[0089] System used : Cathode: Coated or uncoated electrode Electrolyte: 1M LiPF6 in EC / EMC 3 / 7 volume ratio Fiberglass separator Anode: Lithium metal The capacity recovered upon discharge for the two cells for the two different regimes is shown in Table 1.

[0090] [Table 1]

Claims

1. a. at least one poly(vinylidene fluoride) (PVDF) (Component A); b. at least one lithium salt (Component B); c. at least one conductive additive (Component C) comprising a cathode coating.

2. The coating according to claim 1, wherein the Component A is selected from a copolymer of a poly(vinylidene fluoride) homopolymer and at least one comonomer selected from the list of vinylidene difluoride and vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropene, 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, 1,1,3,3,3-pentafluoropropene, 1,2,3,3,3-pentafluoropropene, perfluoro(propyl vinyl ether), perfluoro(methyl vinyl ether), bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoroethylene, chlorotrifluoropropene and ethylene, and mixtures thereof.

3. The coating according to claim 1, wherein the PVDF contains monomer units having at least one of the following functional groups: carboxylic acid, carboxylic anhydride, carboxylic ester, epoxy (such as glycidyl), amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenol, ester, ether, siloxane, sulfonic acid, sulfuric acid, phosphoric acid or phosphonic acid.

4. Said component B is LiPF ６ (lithium hexafluorophosphate), LiFSI (lithium bis(fluorosulfonyl)imide), TFSI (lithium bis(trifluoromethylsulfonyl)imide), LiTDI (lithium 2-trifluoromethyl-4,5-dicyanoimidazolate), LiPOF ２ , LiB(C ２ O ４ ) ２ , LiF ２ B(C ２ O ４ ) ２ , LiBF ４ , LiNO ３ , LiClO ４ and a mixture of two or more of the listed salts, the coating according to claim 1.

5. The coating according to claim 1, wherein the Component C is selected from linear or cyclic ethers, esters, lactones, nitriles, carbonates and ionic liquids.

6. The coating according to claim 1, having a thickness in the range of 0.1 to 100 μm, preferably 0.1 to 50 μm and more preferably 0.1 to 35 μm.

7. The following weight composition: - Component A in a ratio of 20% to 80%; - Component B in a ratio of 1% to 40%; - Component C in a ratio of 2% to 50% (provided that the sum of these ratios is 100%) comprising the coating according to claim 1.

8. A method for manufacturing the cathode coating according to any one of claims 1 to 7 from an ink obtained by mixing all the constituent substances of the coating in a solvent.

9. The method according to claim 8, wherein the solvent is selected from the list of acetone, triethylacetyl citrate, γ-butyrolactone, cyclohexanone, cyclopentanone, dibutyl phthalate, dibutyl sebacate, diethyl carbonate, diethyl phthalate, dihydrolevoglucosenone, dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, 3-heptanone, hexamethylphosphoramide, 3-hexanone, methyl ethyl ketone, N-methyl-2-pyrrolidinone, 3-octanone, 3-pentanone, propylene carbonate, tetrahydrofuran, tetramethylurea, triacetin, triethyl citrate, triethyl phosphate, trimethyl phosphate, N,N'-tetrabutylsuccin diamide, and mixtures thereof.

10. A cathode for an all-solid-state lithium-ion battery, the cathode comprising an active material, a binder, and a conductive material, and presenting the coating layer according to any one of claims 1 to 7.

11. The active material is selected from manganese dioxide, iron oxide, copper oxide, nickel oxide, lithium / manganese composite oxide, lithium / nickel composite oxide, lithium / cobalt composite oxide, lithium / nickel / cobalt composite oxide, lithium / nickel / cobalt / manganese composite oxide, lithium-enriched lithium / nickel / cobalt / manganese composite oxide, lithium / transition metal composite oxide, spinel-structured lithium / manganese / nickel composite oxide, high-voltage nickel / manganese composite oxide, vanadium oxide, S ８ type sulfur, and mixtures thereof, the cathode according to claim 10.

12. The cathode according to claim 10, wherein the conductive material is selected from carbon black, natural or synthetic graphite, carbon fiber, carbon nanotube, metal fiber, metal powder, and conductive metal oxide.

13. The cathode according to claim 10, wherein the binder is a polymer selected from polyolefin, fluoropolymer, fluoropolymer having acid functionality, polyacrylic acid, polyacrylonitrile, cellulose-based polymer, polyphenyl sulfone, polyether sulfone, phenolic resin, vinyl ester resin, epoxy resin, or liquid crystal polymer.

14. The cathode according to claim 10, having a porosity of less than 10%, preferably less than 5%.

15. A method for manufacturing a Li-ion battery positive electrode, the method comprising the following operations: - providing a cathode, - depositing the coating layer according to any one of claims 1 to 7 on the cathode. The method comprising.

16. An all-solid-state Li-ion battery comprising an anode, the cathode according to claim 10, and an all-solid electrolyte.