NEW SOLVENT-FREE PREPARATION PROCESS FOR CATHOLYTES AND SOLID ELECTROLYTE LAYERS

Abstract

NEW SOLVENT-FREE PROCESS FOR PREPARING CATHOLYTES AND SOLID ELECTROLYTE LAYERS This application relates to solvent-free formulations based on solid sulfide electrolyte and fluoropolymer, suitable for solid electrolyte layers or electrode layers for all-solid-state batteries. Figure for abstract: None

Description

Title of the invention: NEW SOLVENT-FREE PREPARATION METHOD FOR CATHOLYTES AND SOLID ELECTROLYTE LAYERS

[0001] The present invention relates to the field of energy storage, and more specifically to accumulators, particularly of the lithium type.

[0002] The operation of lithium batteries is based on the reversible exchange of lithium ions between a positive electrode and a negative electrode, separated by a separator containing an electrolyte, with lithium being inserted into the negative electrode during charging operation.

[0003] Typically, the electrodes consist of a metal strip on which is applied an electrode formulation consisting of active material and optionally binder and conductive material.

[0004] Due to the constantly increasing need for energy and batteries, it is necessary to improve their manufacture, to facilitate their industrialization, reduce costs and improve their environmental impact.

[0005] Currently, a very significant portion of the manufacturing cost of an electrode is related to its manufacturing process. Indeed, the solvent used to prepare the ink (based on active material, optional conductive fillers, and a binder) that will be coated onto the foil to create the electrode must be evaporated. This step therefore requires the use of energy-intensive furnaces.

[0006] It is also desirable to limit the use of harmful solvents in an environmental approach.

[0007] In order to eliminate these solvents and reduce the manufacturing costs of electrodes, new so-called solvent-free processes are currently under development.

[0008] The all-solid technology is based on replacing the liquid electrolyte with a non-flammable and more thermally stable solid electrolyte, and therefore offers increased safety.

[0009] In all-solid type batteries, a solid electrolyte layer (Solid Electrolyte Layer, SEL) acts as a separator and solid electrolyte particles are present at the cathode, and possibly at the anode.

[0010] Solid sulfide electrolytes represent a preferred development route.

[0011] It is therefore desirable to make available solvent-free processes for the preparation of formulations comprising such electrolytes.

[0012] Thus, CN 105489931 describes a process for preparing formulations of solid sulfide electrolyte and PTFE, by mixing powders, grinding and compression. However, the described process presents risks of reactivity of the solid electrolyte with the environment, and results in a highly heterogeneous mixture.

[0013] It is therefore necessary to make available a more suitable and / or easily industrializable process.

[0014] The present invention thus relates to a new solvent-free route for the improved preparation of all-solid type electrochemical element formulations.

[0015] According to a first object, the present invention relates to a solvent-free method for preparing an all-solid-type electrochemical element formulation with a sulfide electrolyte, said method comprising: • The preparation of a premix comprising the mixture of • a solid sulfide electrolyte; • A fluoropolymer type binder. • Fibrillation of the resulting premix;

[0016] the premix preparation and fibrillation steps being carried out under an inert atmosphere.

[0017] The process according to the invention aims to prepare a formulation based on a solid sulfide electrolyte, adapted to an all-solid electrochemical element.

[0018] Said formulation can thus be suitable for a solid electrolyte layer (SEL), or a positive electrode layer or a negative electrode layer.

[0019] According to the invention, the process is solvent-free in that it does not use an organic or aqueous solvent, thus avoiding a drying step. By eliminating the solvent, problems related to reactivity between the solid sulfide electrolyte and solvent residues can be avoided.

[0020] The term “solid sulfide electrolyte” refers to solid sulfur-based electrolytes typically used for all-solid-state batteries.

[0021] By way of illustration, said sulfide electrolyte may be selected in particular from: • the set of phases [(Li2S)y (Li2O)t(P2S5)i_y_t](i_z)(LiX)z, with X representing one or more halogen elements; 0 <y<l; 0<z<l; 0<t< 1 • compounds having an argyrodite structure such as Li6PS5X, with X = Cl, Br, I, or Li7P3Sn; • sulfide electrolytes having the crystallographic structure equivalent to the compound LiioGeP2Si2 including for example substitutions, dopings and / or vacancies; • Li3PS4.

[0022] Preferably, said solid sulfide electrolyte is a Li6PS5X type electrolyte, with X = Cl, Br, I.

[0023] According to the invention, the inert atmosphere refers to an atmosphere of gas inert with respect to the solid sulfide electrolyte and aims for example at an atmosphere of nitrogen (N2) or argon.

[0024] The term "electrochemical element" means an elementary electrochemical cell consisting of the assembly positive electrode / solid electrolyte layer / negative electrode, which allows the electrical energy supplied by a chemical reaction to be stored and released in the form of a current.

[0025] The chemical elements according to the invention can be adapted to different battery technologies and types of electrolytes.

[0026] The electrochemical element may be of the all-solid type, the term "solid" refers to elements with a solid electrolyte.

[0027] The term "fluoropolymer" as used herein refers to fluoropolymers whose repeating unit is a fluorocarbon, comprising multiple carbon-fluorine bonds. Examples of these fluoropolymers include polytetrafluoroethylene (PTFE) and its derivatives, particularly its copolymers such as chlorofluoroethylene, perfluoroalkoxy (PFA), polychlorotrifluoroethylene (PCTFE or PTFCE), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene or poly(ethylene-co-tetrafluoroethylene) (ETFE), tetrafluoroethylene perfluoromethyl vinyl ether (MFA), and more specifically PTFE. Preferably, these fluoropolymers are of the fibrillable type.

[0028] The term "fibrillable" refers to fluoropolymer types that are capable of fibrillating, i.e., that can form a network of fibers in the mixture with the premix under extrusion conditions. These fluoropolymer types can be of various shapes and / or grades.

[0029] The term "premix" means a preliminary composition prepared beforehand; in this case the premix comprises the mixture of powders of the solid sulfide electrolyte and the fluoropolymer.

[0030] The premix may also include additional ingredients, such as active matter, a conducting element, a co-binder, in particular depending on the nature and purpose of the formulation envisaged.

[0031] Thus, according to one embodiment, the preparation of the premix and / or the fibrillation may further include the addition of a co-binder.

[0032] The term "co-binder" refers to a material that provides the electrode with cohesion of its various components and mechanical strength on the current collector, and / or provides the electrode with a certain degree of flexibility for its implementation in cell. More specifically, the co-binder according to the invention ensures cohesion between the different constituents. The co-binder can be amorphous or semi-crystalline.

[0033] According to one embodiment, the co-binder is selected from thermoplastic polyurethane (TPU), poly(vinylidene fluoride) (PVDF) or its copolymers, cellulose and its derivatives, poly(oxyethylene) (POE), standard or modified cellulose, poly(styrene-butadiene-styrene) (SBS), poly(styrene-ethylene-butadiene-styrene) (SEBS), thermoplastic elastomers (TPE), vulcanized thermoplastics (TPV), polyamides, thermoplastic copolyesters (TPC), polystyrene-β-poly(ethylene-butylene)-β-polystyrene (SEBS), butadiene-acrylonitrile copolymers also known as "nitrile rubbers" (NBR), hydrogenated butadiene-acrylonitrile copolymers also known as "hydrogenated nitrile rubbers" (HNBR), elastomers, thermoplastics or ethylene-acrylate terpolymers.

[0034] More specifically, the co-binder is chosen from HNBR, POE, PVDF and its copolymers, cellulose and its derivatives.

[0035] The co-binder can be added at the premix preparation step and / or at the fibrillation step.

[0036] According to another embodiment, the preparation of the premix may further include the mixing of active material and optionally electronically conductive material, with the mixing of the solid sulfide electrolyte, the binder and the optional co-binder.

[0037] The premix can be prepared by simply mixing the constituents, typically in powder form, under agitation. This can notably be done with a planetary mixer.

[0038] According to one embodiment, the premix preparation step can advantageously be carried out at a temperature below 40°C.

[0039] The active electrode material can be chosen from among electrochemically active materials. It depends in particular on the type of electrode (positive or negative), the nature of the solid sulfide electrolyte and / or the type of battery considered.

[0040] Fibrillation is understood to mean a mixture under mechanical stress, aimed at fibrillating the fluoropolymer binder.

[0041] This fibrillation can typically be carried out by extrusion with an extruder, or by mixing with an internal mixer.

[0042] "Extrusion" means a thermomechanical process in which the formulation is forced through a sleeve under the action of pressure and heat.

[0043] The extrusion step can be adapted according to several parameters, such as the mixing temperature, the type of screw profile of the extruder, the type of die of the extruder, the rotation speed and / or the length of the screws.

[0044] According to one embodiment, fibrillation can be carried out with a single- or twin-screw type extruder, preferably a co-rotating twin-screw extruder.

[0045] According to one embodiment, the screw profile used in the extruder is of the shearing type to fibrillate the fluoropolymer within the extruder. The screw profile may contain one or more mixing zones. The number of mixing zones typically depends on the number of feed zones. The position of the mixing zones in the extruder generally depends on the number of material feed zones. A mixing zone may be added after each material feed zone.

[0046] Typically, the type of screw element used to shear the material can be adapted to the type of active ingredient contained in the premix. If the active ingredient is shear-sensitive, it is preferable to use low- or medium-shear elements. If the active ingredient is not very shear-sensitive, it is possible to use low-, medium-, or high-shear elements.

[0047] The screw rotation speed is generally the same along its entire length. It is generally recommended to operate it between 100 rpm and 1000 rpm, specifically between 100 and 750 rpm. The screw rotation speed is generally adjusted according to the desired material flow rate at the extruder outlet. The lower the screw rotation speed, the lower the output flow rates. Note that low rotation speeds result in longer residence times in the extruder. In such cases, if the material inlet flow rate is high, there is a risk of clogging the extruder. With a high screw rotation speed, the output flow rates may fluctuate if the material inlet flow rates are too low.

[0048] The fibrillation step can advantageously be carried out at a temperature between 40°C and the degradation temperature of the fluoropolymer, particularly when a co-binder is present between the melting temperature of the co-binder and the melting temperature of the fluoropolymer under extrusion conditions, it being understood that the degradation and / or melting temperatures of the fluoropolymer under extrusion conditions may be reduced due to the mechanical stresses exerted. By way of illustration, for PTFE, the degradation temperature is approximately 350°C (under shear) and the melting temperature is approximately 330°C (this value may vary depending on the grade of PTFE), it being understood that, due to the stresses exerted, the extrusion temperature is preferably less than or equal to 260°C.

[0049] In the case where fibrillation is carried out by an internal mixer, the same conditions as for the extruder can be implemented.

[0050] The formulation obtained at the end of the fibrillation step is typically in the form of granules or agglomerated powder.

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[0059] According to one embodiment, the process according to the invention comprises one or more subsequent steps. Thus, said process may further comprise one or more steps of shaping the formulation into a film, and / or of depositing the film thus obtained. The shaping can typically be achieved by calendering using a heated roller calender, typically having a different roller speed, or an external roller mixer. The film thus obtained can then be deposited either on a current collector to form an electrode or on a liner in order to then adhere to a SEL in the case of an electrode formulation, or in the case of a SEL formulation deposited on a liner to then be transferred to an electrode. According to another object, the present invention also relates to a formulation that can be obtained by the process according to the invention. This can be an electrode formulation, positive or negative, or a solid electrolyte layer (SEL). Thus, according to one embodiment, when dealing with a solid electrolyte layer formulation, said formulation generally comprises, in addition to the solid sulfide electrolyte and the binder, an optional co-binder. Typically, such a formulation may include, by way of illustration (by weight): - From 70 to 99.8% solid sulfide electrolyte; From 0.1 to 30% PTFE; - From 0.1 to 14.9% co-binder. According to another object, the present invention further relates to a solid sulfide electrolyte layer comprising said formulation. According to an alternative embodiment, when the formulation is an electrode formulation, said formulation generally comprises, in addition to the solid sulfide electrolyte and the binder, an optional co-binder, active material, and optionally electronically conductive material. Thus, typically, such a formulation may comprise, by way of illustration (by weight): - From 50 to 95% active ingredient; - From 4.9 to 49.9% solid sulfide electrolyte; From 0.1 to 15% PTFE; - From 0 to 14.9% co-binder; - From 0 to 10% electronic conductor. Typically, the binder content can be adjusted to improve the homogeneity of the mixture and / or mechanical strength, particularly in the absence of a co-binder.

[0060] The formulation can thus be a positive electrode (catholyte) formulation. Alternatively, the formulation can also be a negative electrode (anolyte) formulation, particularly when the negative electrode is silicon-based.

[0061] The active material of the positive electrode is not particularly limited. It can be chosen from the following groups or mixtures thereof:

[0062] - nickel-manganese-cobalt (NMC) type compounds, in particular oxides lamellar with high nickel content, that is typically those for which the molar ratio of nickel, relative to the total of the elements nickel, manganese and cobalt, is greater than or equal to 0.6, in particular greater than or equal to 0.8;

[0063] - lithium iron phosphate (LFP) type compounds;

[0064] - lithium vanadium fluorophosphate (LVPF) compounds, in particular those of LixVPO4F formula with 0.8 <x<l,2, ou l’un de ses dérivés de formule LixVi. yMyPO4Fz où0,8<x<l,2 ; 0<y<0,5 ; 0,8<z<l,2 et M est choisi dans le groupe consistant en Ti, Al, Y, Cr, Cu, Mg, Mn, Fe, Co, Ni, et Zr ;

[0065] - lithium iron metal phosphate (LFMP) type compounds, in particular of formula LixFei yMyPO4(LFMP) where M is chosen from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo; and 0.8 <x<l,2 ; 0<y<0,6 ;

[0066] - Lithium-metal-polymer (LMP) type compounds, in particular of formula LixMni y zM'yM”zPO4 (LMP), where M' and M” are different from each other and are chosen from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo, with 0.8 <x<l,2 ; 0<y<0,6 ; 0<z<0,2 ;

[0067] - nickel-cobalt-aluminium (NCA) type compounds.

[0068] A conductive element can also be added for the preparation of the positive electrode. It can be chosen from electronically conductive materials, such as graphite, carbon black, acetylene black, soot, graphene, carbon fibers, carbon nanotubes or a mixture thereof.

[0069] According to one embodiment, the electrode formulations according to the invention may further include one or more additives selected from lubricants such as oils or waxes or graphite.

[0070] Furthermore, the formulations according to the invention may also include a carbon additive. This additive is distributed in the electrode so as to form an electronic percolating network between the active material and the current collector.

[0071] When present, the carbonaceous additive may comprise up to approximately 10% (by weight), in particular 1 to 6% (by weight) of the total content of the formulation.

[0072] According to another object, the present invention further relates to an electrode comprising the electrode formulation according to the invention in a shaped form.

[0073] According to one embodiment, said electrode may consist of a conductive support used as a current collector which is coated with the formulation according to the invention in a shaped form.

[0074] The term "negative electrode" refers to the electrode functioning as the anode when the battery is discharging, and as the cathode when the battery is charging. The anode is defined as the electrode where an electrochemical oxidation reaction (electron emission) takes place, while the cathode is the site of reduction. The term "negative electrode" also refers to the electrode from which electrons are released and from which cations (Li+) are released during discharge.

[0075] The term "positive electrode" refers to the electrode where electrons enter, and where discharged cations (Li+) arrive.

[0076] A current collector is understood to be an element such as a pad, plate, sheet or other, made of conductive material, connected to the positive or negative electrode, and ensuring the conduction of the flow of electrons between the electrode and the terminals of the battery.

[0077] The current collector is preferably a two-dimensional conductive support such as a solid or perforated metal strip.

[0078] In the case of the positive electrode, the current collector is typically an aluminium strip, in particular covered with a carbon coating.

[0079] According to another object, the present invention also relates to an electrochemical element comprising at least one electrode and / or layer of solid sulfide electrolyte comprising a formulation according to the invention.

[0080] According to another object, the present invention also relates to an electrochemical module comprising the stacking of at least two elements according to the invention, each element being electrically connected with one or more other element(s).

[0081] The term “module” therefore refers here to the assembly of several electrochemical elements, said assemblies being able to be in series and / or parallel.

[0082] Another object of the invention is yet another battery comprising one or more modules according to the invention.

[0083] The term “battery” or accumulator means the assembly of several modules according to the invention. Figures

[0084] [Fig-1] Fig. 1 schematically represents an electrochemical element. solid with widening:

[0085] the structure of the solid electrolyte layer (SEL) formulation consisting of solid sulfide electrolyte particles (2) dispersed within a network of binder fibrils (3); and

[0086] the structure of the formulation of the positive electrode layer consisting of solid sulfide electrolyte particles (2) and active material particles (1), dispersed within a network of binder fibrils (3).

[0087] [Fig.2] Fig.2 schematically represents an electrochemical element solid according to another embodiment further comprising optional elements such as an electronically conductive material (5) and a co-binder (4), by way of illustration. Thus, the enlargements represent respectively:

[0088] the structure of the solid electrolyte layer (SEL) formulation consisting of solid sulfide electrolyte particles (2) and co-binder (4), dispersed within a network of binder fibrils (3); and

[0089] the structure of the formulation of the positive electrode layer consisting of solid sulfide electrolyte particles (2), conductive material (5), and active material particles (1), dispersed within a network of binder fibrils (3).

[0090] By way of illustration, Figures 1 and 2 have been shown with PTFE as a binder and carbon additive as a conductive material.

[0091] It is understood that the presence of electronic conductor in the cathode and of coliant in the SEL is not mandatory.

[0092] The void areas between the different components represent residual porosity. It should also be noted that the thicknesses of the different layers, namely the thickness of the negative electrode, the SEL, or the positive electrode, are purely indicative.

[0093] Examples

[0094] Example 1: Fabrication of a positive electrode

[0095] The active ingredient, binder, sulfide-type solid electrolyte, and optionally the electronic conductor and co-binder are pre-mixed in a planetary mixer to ensure homogeneous distribution of the different materials. The various materials may be introduced into this mixer either all at once or in several stages. In the latter case, the different materials may be introduced in a specific order. It should be noted that graphite, carbon black, and graphene present a greater risk of reactivity with the solid electrolyte than other electronic conductors.

[0096] By way of illustration, the following compositions were produced:

[0097] Positive electrode formulation:

[0098] NMC811 (75%), binder: PTFE (5%); argyrodite type sulfide electrolyte (20%);

[0099] electronic conductor carbon fibers (3%), PTFE (3%); argyrodite (20%) and NMC811 74%

[0100] Formulation of SEL:

[0101] 97% solid electrolyte and 3% PTFE;

[0102] 94% solid electrolyte, 3% PTFE and 3% co-binder.

[0103] In a first configuration: the premix is ​​kept in this planetary mixer and is heated to a high temperature (between 40°C and 150°C, preferably between 60 and 130°C) for the fibrillation of the PTFE. The texture of the recovered material can depend on the level of PTFE fibrillation but also on the formulation (presence or absence of co-binder and the particle size of the different components).

[0104] In a second alternative configuration: once the premix has been prepared, it can then be introduced into an extruder (preferably a twin-screw extruder) or an internal mixer to fibrillate the binder (PTFE). This extruder is heated to a temperature between 40°C and 270°C. The temperature depends on the presence or absence of a co-binder and, if present, also on its chemical nature. If there is no co-binder in the premix, it can optionally be introduced into the extruder using a separate dosing unit. The screw profile is chosen according to the desired level of PTFE fibrillation and the presence or absence of a co-binder in the formulation. The screw rotation speed is also adjusted according to these two criteria.

[0105] It should be noted that this extruder and the planetary mixer are both used in a suitable inert environment (nitrogen atmosphere) for the use of a solid sulfide-type electrolyte, whether or not it is subjected to thermo-mechanical stress. The material recovered from the extruder is then either in the form of agglomerated powder or in the form of granules.

[0106] Regardless of the configuration chosen, the material is then reworked or not before being introduced into a heated roller calender. This calender (composed of a minimum of 2 rollers) has rollers rotating at the same or different speeds. One or more electrode films are then produced. These are either deposited directly onto a current collector or a transfer material or recovered as self-supporting film(s).

[0107] Example 2: Fabrication of a solid electrolyte layer

[0108] The solid electrolyte of type, the binder and the possible co-binder are pre-mixed using a planetary mixer in order to properly disperse the different components.

[0109] In a first configuration: the premix is ​​kept in this planetary mixer and is heated to a high temperature (between 40°C and 150°C, preferably between 60 and 130°C) for the fibrillation of the PTFE. The texture of the recovered material depends on the level of PTFE fibrillation but also on the formulation (presence or absence of co-binder and the particle size of the different components).

[0110] In a second configuration: once the pre-mixing has been carried out, it is then introduced into an extruder (preferably twin-screw) or an internal mixer in order to to fibrillate the binder (PTFE). This extruder is heated to a temperature between 40°C and 270°C. The temperature depends on the presence and, if present, the chemical nature of a co-binder. If the premix does not contain a co-binder, it can be added to the extruder using a separate dosing unit. The screw profile is selected based on the desired level of PTFE fibrillation and the presence or absence of a co-binder in the formulation. The screw rotation speed is also adjusted according to these two criteria.

[0111] It should be noted that this extruder and the planetary mixer are both used in an inert environment (nitrogen atmosphere) suitable for the use of a solid sulfide-type electrolyte, whether or not it is subjected to thermo-mechanical stress. The material recovered from the extruder is then either in the form of agglomerated powder or in the form of granules.

[0112] Regardless of the configuration chosen, the material is then reworked or not before being introduced into a heated roller calender. This calender (composed of a minimum of 2 rollers) has rollers rotating at the same or different speeds. One or more solid electrolyte film layers are then produced. These are either deposited directly onto a positive electrode (itself or not on a current collector) or onto a negative electrode (itself or not on a current collector) or onto a transfer material (liner type) or recovered as a self-supporting film.

Claims

Demands

1. A solvent-free process for preparing an all-solid type electrochemical element formulation with a sulfide electrolyte, said process comprising: • The preparation of a premix comprising a mixture of • a solid sulfide electrolyte; • A fluoropolymer type binder; the premix preparation step being carried out at a temperature below 40°C; • The fibrillation of the resulting premix; The premix preparation and fibrillation steps being carried out under an inert atmosphere, and wherein the fibrillation step is carried out by extrusion using an extruder or by mixing using an internal or planetary mixer.

2. A method according to claim 1 wherein the preparation of the premix and / or fibrillation further comprises the addition of a co-binder to the mixture.

3. A process according to claim 1 or 2, wherein the preparation of the premix further comprises the mixing of active material and optionally of electronically conductive material, with the mixing of the electrolyte, binder and optional co-binder.

4. A process according to any one of the preceding claims wherein said solid sulfide electrolyte is a Li6PS5X type electrolyte, with X = Cl, Br, I.

5. A process according to any one of the preceding claims wherein the fluoropolymer binder is selected from polytetrafluoroethylene (PTFE) and its co-polymers, such as chlorofluoroethylene, perfluoroalkoxy (PFA), polychlorotrifluoroethylene (PCTFE or PTFCE), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene or poly(ethylene-co-tetrafluoroethylene) (ETFE), tetrafluoroethylene perfluoromethyl vinyl ether (MFA).

6. A process according to any one of the preceding claims, wherein the fluoropolymer is PTFE.

7. The method according to claim 2 wherein the co-binder is selected from thermoplastic polyurethane (TPU), poly(vinylidene fluoride) (PVDF) or its copolymers, cellulose and its derivatives, poly(oxyethylene) (POE), standard or modified cellulose, poly(styrene-butadiene-styrene) (SBS), poly(styrene-ethylene-butadiene-styrene) (SEBS), thermoplastic elastomers (TPE), vulcanized thermoplastics (TPV), polyamides, thermoplastic copolyesters (TPC), polystyrene-β-poly(ethylene-butylene)-β-polystyrene (SEBS), butadiene-acrylonitrile copolymers also known as "nitrile rubbers" (NBR), hydrogenated butadiene-acrylonitrile copolymers also known as "hydrogenated nitrile rubbers" (HNBR), elastomers, thermoplastics or ethylene-acrylate terpolymers.

8. A process according to any one of the preceding claims wherein the fibrillation step is carried out at a temperature between 40°C and the degradation temperature of the fluoropolymer.

9. A method according to any one of the preceding claims, further comprising the steps of forming into a film, and depositing the film thus obtained.

10. Formulation for any solid electrochemical element with sulfide electrolyte such that it is a solid sulfide electrolyte formulation, and such that it comprises (by weight): - From 70 to 99.8% solid sulfide electrolyte; From 0.1 to 30% PTFE; - From 0.1 to 14.9% co-binder selected from the group consisting of PVDF, POE, HNBR and modified cellulose.

11. Electrochemical element comprising at least one electrode and / or the solid sulfide electrolyte layer comprising the formulation according to claim 10.

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