Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
  • H01M10/0562—Solid materials
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
  • H01M4/623—Binders being polymers fluorinated polymers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0065—Solid electrolytes

Definitions

• the present invention relates to the field of energy storage, and more precisely to accumulators, in particular of the lithium type.
• the operation of lithium accumulators is based on the reversible exchange of the lithium ion between a positive electrode and a negative electrode, separated by a separator containing an electrolyte, the lithium being inserted into the negative electrode during charging operation .
• the electrodes consist of a metal strip to which an electrode formulation consisting of active material and possibly binder and conductive material is applied.
• 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.
• a layer of solid electrolyte Solid Electrolyte Layer, SEL
• SEL Solid Electrolyte Layer
• CN 105489931 describes a process for preparing formulations of solid sulfide electrolyte and PTFE, by mixing powders, grinding and compression.
• the process described presents risks of reactivity of the solid electrolyte with the environment, and results in a highly heterogeneous mixture.
• the present invention thus relates to a new solvent-free route for the improved preparation of formulations for all-solid type electrochemical elements.
• the present invention relates to a process for preparing without solvent a formulation for an electrochemical element of all-solid type with sulphide electrolyte, said process comprising:
• a fluoropolymer type binder A fluoropolymer type binder.
• Fibrillation of the premix obtained said fibrillation being carried out by extrusion with an extruder or by mixing with an internal or planetary mixer;
• the premix preparation and fibrillation steps are carried out under an inert atmosphere.
• a process for the solvent-free preparation of a formulation for an all-solid type electrochemical element with a sulfide electrolyte comprising:
• the process according to the invention aims to prepare a formulation based on a solid sulfide electrolyte, suitable for an all-solid electrochemical element.
• Said formulation can thus be suitable for a solid electrolyte layer (Solid Electrolyte Layer, SEL), or a positive electrode layer or a negative electrode layer.
• Solid Electrolyte Layer Solid Electrolyte Layer, SEL
• SEL Solid Electrolyte Layer
• the process is solvent-free in that it does not use an organic or aqueous solvent, requiring a drying step. In the absence of solvent, problems related to the reactivity between the solid sulfide electrolyte and the solvent residues can be avoided.
• solid sulfide electrolyte refers to solid sulfur-based electrolytes typically used for all-solid-state batteries.
• said sulphide electrolyte may in particular be chosen from:
• the inert atmosphere designates an atmosphere of gas inert with respect to the solid sulphide electrolyte and refers for example to an atmosphere of nitrogen (N2) or argon.
• electrochemical element means an elementary electrochemical cell consisting of the positive electrode/solid electrolyte layer/electrode assembly. negative, allowing the electrical energy provided by a chemical reaction to be stored and released in the form of current.
• the chemical elements according to the invention can be adapted to different battery technologies and types of electrolytes.
• the electrochemical element can be of the all-solid type, the term “solid” refers to elements with a solid electrolyte.
• fluoropolymer refers to fluoropolymers whose repeat unit is a fluorocarbon, comprising multiple carbon-fluorine bonds.
• fluoropolymers mention may in particular be made of polytetrafluoroethylene (PTFE) and its derivatives, in particular its co-polymers such as chlorofluoroethylene, perfluoroalkoxy (PFA), polychlorotrifluoroethylene (PCTFE or PTFCE), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene.
• PTFE polytetrafluoroethylene
• PFA perfluoroalkoxy
• PCTFE or PTFCE polychlorotrifluoroethylene
• FEP fluorinated ethylene propylene
• fluoropolymers are of the fibrillable type.
• fibrillable we mean the types of fluoropolymers which are likely to fibrillate, that is to say which can form a network of fibers in the mixture with the pre-mix, under extrusion conditions. Fluoropolymer types can come in different shapes and/or grades.
• pre-mix is meant a preliminary composition previously prepared; in this case the pre-mixture comprises the mixture of powders of the solid sulphide electrolyte and the fluoropolymer.
• the pre-mixture may also include additional ingredients, such as active material, a conductive element, a co-binder in particular depending on the nature and purpose of the formulation envisaged.
• the preparation of the premix and/or the fibrillation may also include the addition of a co-binder.
• co-binder is meant a material making it possible to give the electrode the cohesion of the different components and its mechanical strength on the current collector, and/or to give a certain flexibility to the electrode for its implementation. in cell. More particularly, the co-binder according to the invention ensures cohesion between the different constituents.
• the co-binder can be amorphous or semi-crystalline.
• the co-binder is chosen from thermoplastic polyurethane (TPU), poly(vinylidene fluoride) (PVDF) or its copolymers, cellulose and its derivatives, poly(oxyethylene) (POE), standard cellulose or modified, poly(styrene-butadiene-styrene) (SBS), poly(styrene-ethylene-butadiene-styrene) (SEBS), thermoplastic elastomers (TPE), vulcanized thermoplastics (TPV), polyamides, thermoplastic copolyesters (TPC), polystyrene-b-poly(ethylene-butylene)-b-polystyrene (SEBS), butadiene-acrylonitrile copolymers also called “nitrile rubbers” (NBR), hydrogenated butadiene-acrylonitrile copolymers, also called “rubbers” hydrogenated nitrile” (HNBR), elastomers, thermoplastics
• TPU
• the co-binder is chosen from HNBR, POE, PVDF and its copolymers, cellulose and its derivatives.
• the co-binder can be added at the premix preparation stage and/or at the fibrillation stage.
• the preparation of the pre-mixture may further comprise the mixing of active material and possibly electronic conductive material, with the mixture of the solid sulphide electrolyte, the binder and the possible co-binder.
• the preparation of the premix can be carried out by simply mixing the constituents, typically in the form of powders, with stirring. It can in particular be carried out with a planetary type mixer.
• the step of preparing the premix can advantageously be carried out at a temperature below 40°C.
• the active electrode material can be chosen from 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.
• Fibrillation means a mixture under mechanical stress, aimed at fibrillizing the fluoropolymer binder. This fibrillation can typically be carried out by extrusion with an extruder, or by mixing with an internal mixer.
• extrusion we mean a thermomechanical process according to which the formulation is forced to pass through a sheath, under the action of pressure and heat.
• the extrusion stage can be adapted depending on several parameters, such as the mixing temperature, the type of extruder screw profile, the type of extruder die, the rotation speed and/or the length of screws.
• fibrillation can be carried out with a single- or twin-screw extruder, preferably co-rotating twin-screw.
• the screw profile used in the extruder is of the shearing type in order to fibrillate the fluoropolymer in the extruder.
• the screw profile may contain one or more mixing zones. The number of mixing zones typically depends on the number of introduction zones. The position of the mixing zones in the extruder generally depends on the number of material introduction zones. After each material introduction zone, a mixing zone can be added.
• the type of screw element used to shear the material can be adapted to the type of active material contained in the pre-mix. If the active material is sensitive to shear, it is preferable to favor elements with little or medium shear. If the active material is not very sensitive to shear, it is possible to use low, medium or high shear elements.
• the speed of rotation of the screw is generally the same throughout the screw. It is generally recommended to run it between 100rpm and 1000rpm, especially between 100 and 750 rpm.
• the rotation speed of the screw is generally adapted according to the desired material flow rate at the extruder outlet. The lower the screw rotation speed, the lower the output flow rates will be. Note that low rotation speeds result in longer residence times in the extruder. In such a case, if the material inlet flow rate is high, there may be a risk of clogging the extruder. In the case of a high screw rotation speed, the output flow rates may fluctuate if the incoming material flow rates are too low.
• the fibrillation step can advantageously be carried out at a temperature between 40°C and the degradation temperature of the fluoropolymer, more particularly when a co-binder is present between the melting temperature of the co-binder and the melting temperature of the fluoropolymer.
• 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 constraints exerted, the extrusion temperature is preferably less than or equal to 260°C.
• the formulation obtained at the end of the fibrillation step is typically in the form of granules or agglomerated powder.
• the method according to the invention comprises one or more subsequent steps.
• said method may further comprise one or more steps of shaping the formulation into a film, and/or deposition of the film thus obtained.
• Shaping can typically be carried out 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 with a view to subsequently adhering to an SEL in the case of an electrode formulation, or in the case of a formulation of SEL deposited on a liner to then be transferred to an electrode.
• the present invention also relates to a formulation capable of being obtained by the process according to the invention.
• It may be a positive or negative electrode formulation or a solid electrolyte layer (SEL).
• SEL solid electrolyte layer
• said formulation when it is a solid electrolyte layer formulation, said formulation generally comprises, in addition to the solid sulphide electrolyte and the binder, a possible co-binder.
• a formulation may include for illustrative purposes (by weight):
• the present invention also targets a layer of solid sulphide electrolyte comprising said formulation.
• said formulation when the formulation is an electrode formulation, said formulation generally comprises, in addition to the solid sulphide electrolyte and the binder, a possible co-binder, active material and possibly electronic conductive material.
• a possible co-binder for illustrative purposes (by weight):
• the binder content can be adjusted to improve the homogeneity of the mixture and/or the mechanical strength, particularly in the absence of a co-binder.
• the formulation can thus be a positive electrode formulation (catholyte).
• the formulation can also be a negative electrode (anolyth) formulation, particularly when the negative electrode is based on silicon.
• the active material of the positive electrode is not particularly limited. It can be chosen from the following groups or their mixtures:
• NMC nickel-manganese-cobalt
• lamellar oxides with a high level of nickel that is to say typically those for which the molar ratio of nickel, compared 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;
• LVPF lithium vanadium fluorophosphate compounds
• LixVPC F with 0.8 ⁇ x ⁇ 1.2
• LixVi.yMyPC Fz where 0.8 ⁇ x ⁇ 1.2; 0 ⁇ y ⁇ 0.5; 0.8 ⁇ z ⁇ 1.2 and M is chosen from the group consisting of Ti, Al, Y, Cr, Cu, Mg, Mn, Fe, Co, Ni, and Zr;
• - compounds of the lithium-iron-metal-phosphate (LFMP) type in particular of formula Li x Fei- y MyPO 4 (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 ⁇ 1.2;0 ⁇ y ⁇ 0.6; - Lithium-metal-polymer (LMP) type compounds, in particular of the formula Li x Mni. y .
• LMP Lithium-metal-polymer
• NCA nickel-cobalt-aluminum
• a conductive element can also be added for positive electrode preparation. It may be selected from electronically conductive materials, such as graphite, carbon black, acetylene black, soot, graphene, carbon fibers, carbon nanotubes or a mixture thereof.
• the electrode formulations according to the invention may further comprise one or more additives chosen from lubricants such as oils or waxes or graphite.
• 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.
• the carbon additive can be comprised up to approximately 10% (by weight), in particular from 1 to 6% (weight) of the total content of the formulation.
• the present invention also targets an electrode comprising the electrode formulation according to the shaped invention.
• said electrode may consist of a conductive support used as a current collector which is coated with the shaped formulation according to the invention.
• negative electrode designates when the accumulator is discharging, the electrode operating as an anode and when the accumulator is charging, the electrode operating as a cathode, the anode being defined as the electrode where a electrochemical oxidation reaction (emission of electrons), while the cathode is the site of reduction.
• negative electrode also designates the electrode from which the electrons leave, and from which the cations (Li+) are released in discharge.
• positive electrode designates the electrode where the electrons enter, and where the cations (Li+) arrive in discharge.
• current collector is meant an element such as 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 .
• the current collector is preferably a two-dimensional conductive support such as a solid or perforated strip, based on metal.
• the current collector is typically a strip of aluminum, in particular covered with a carbon coating.
• the present invention also relates to an electrochemical element comprising at least one electrode and/or layer of solid sulphide electrolyte comprising a formulation according to the invention.
• the present invention also relates to an electrochemical module comprising the stack of at least two elements according to the invention, each element being electrically connected with one or more other element(s).
• module therefore designates here the assembly of several electrochemical elements, said assemblies being able to be in series and/or parallel.
• Another object of the invention is yet a battery comprising one or more modules according to the invention.
• battery or accumulator is meant the assembly of several modules according to the invention.
• FIG 1 Figure 1 schematically represents an all-solid electrochemical element with enlargement: the structure of the formulation of the solid electrolyte layer (SEL) consisting of solid sulfide electrolyte particles (2) dispersed within a binder fibril network (3); and 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).
• Figure 2 schematically represents an all-solid electrochemical element according to another embodiment further comprising optional elements such as an electronic conductive material (5) and a co-binder (4), by way of illustration.
• the enlargements represent respectively: the structure of the formulation of the solid electrolyte layer (SEL) consisting of solid sulphide electrolyte particles (2) and co-binder (4), dispersed within a network of binder fibrils (3); and the structure of the formulation of the positive electrode layer consisting of particles of solid sulfide electrolyte (2), conductive material (5), and particles of active material (1), dispersed within a network of binder fibrils (3).
• SEL solid electrolyte layer
• the positive electrode layer consisting of particles of solid sulfide electrolyte (2), conductive material (5), and particles of active material (1), dispersed within a network of binder fibrils (3).
• Figures 1 and 2 have been shown with PTFE as binder and carbon additive as conductive material.
• 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.
• Example 1 Making a positive electrode
• the active material, the binder, the solid sulfide-type electrolyte, and possibly the electronic conductor and the co-binder are pre-mixed in a planetary type mixer in order to distribute the different materials evenly.
• the introduction of the different materials into this mixer can be done either in one go or in several. In the latter case, the different subjects can follow an order of introduction. Note that graphite, carbon black and graphene present a greater risk of reactivity with the solid electrolyte than other electronic conductors.
• compositions were produced:
• NMC81 1 (75%), binder: PTFE (5%); argyrodite type sulfide electrolyte (20%); electronic conductor carbon fiber (3%), PTFE (3%); argyrodite (20%) and NMC81 1 74% SALT formulation:
• the pre-mixture is kept in this planetary mixer and is brought to high temperature (between 40°C and 150°C, preferably between 60 and 130°C) for the fibrillation of the PTFE.
• high temperature between 40°C and 150°C, preferably between 60 and 130°C
• the texture of the recovered material may depend on the level of fibrillation of the PTFE but also on the formulation (presence or not of co-binder and the particle size of the different components).
• the pre-mixture once the pre-mixture has been made, it can then be introduced into an extruder (preferably twin-screw) or an internal mixer in order 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 it is present, also on its chemical nature. In the case of an absence of co-binder in the pre-mixture, it can possibly be introduced into the extruder using a separate doser.
• the profile of the screws is chosen according to the level of fibrillation of the PTFE desired and depending on the presence or absence of a co-binder in the formulation. The rotation speed of the screws is also adjusted according to these two criteria.
• this extruder as well as the planetary mixer are both used in an inert environment (nitrogen atmosphere) suitable for the use of a solid sulfide-type electrolyte exposed or not 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.
• the material is then reworked or not before being introduced into a heated roller calender.
• This calender (composed of at least 2 rollers) presenting rollers rotating at the same or different speed.
• One or more electrode films is/are then produced. These are either deposited directly on a current collector or transfer material or recovered as self-supported film(s).
• Example 2 Production of a solid electrolyte layer
• the solid electrolyte, the binder as well as the possible co-binder are pre-mixed using a planetary mixer in order to correctly disperse the different components.
• the pre-mixture is kept in this planetary mixer and is brought to high temperature (between 40°C and 150°C, preferably between 60 and 130°C) for the fibrillation of the PTFE.
• high temperature between 40°C and 150°C, preferably between 60 and 130°C
• the texture of the recovered material depends on the level of fibrillation of the PTFE but also on the formulation (presence or not of co-binder and the particle size of the different components).
• the pre-mixture is then introduced into an extruder (preferably twin-screw) or an internal mixer in order 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 it is present, also on its chemical nature. In the case of an absence of co-binder in the pre-mixture, it can possibly be introduced into the extruder using a separate doser.
• the profile of the screws is chosen according to the level of fibrillation of the PTFE desired and depending on the presence or absence of a co-binder in the formulation. The rotation speed of the screws is also adjusted according to these two criteria.
• this extruder as well as the planetary mixer are both used in an inert environment (nitrogen atmosphere) suitable for the use of a solid electrolyte of sulphide type exposed or not 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.
• the material is then reworked or not before being introduced into a heated roller calender.
• This calender (composed of at least 2 rollers) presenting rollers rotating at the same or different speed.
• One or more solid electrolyte layer films is/are then produced. This (these) is/(are) either deposited directly on a positive electrode (itself being or not on a current collector) or on a negative electrode (itself being or not on a current collector). current) or on a transfer material (liner type) is recovered as a self-supported film.

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• 2022
  • 2022-12-16 FR FR2213679A patent/FR3143860B1/fr active Active
• 2023
  • 2023-12-15 EP EP23833098.9A patent/EP4635003A1/de active Pending
  • 2023-12-15 WO PCT/EP2023/086158 patent/WO2024126826A1/fr not_active Ceased

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