Polymer composition for electrolyte and / or positive electrode of a rechargeable battery

Abstract

The invention relates to a polymer composition having improved ionic conduction properties, the use of such a polymer composition for the preparation of a polymer electrolyte and / or a positive electrode for a rechargeable battery, a polymer electrolyte for a rechargeable battery comprising such a polymer composition, a positive electrode for a rechargeable battery comprising such a polymer composition, and a rechargeable lithium or sodium battery comprising such a polymer electrolyte and / or such a positive electrode. Figure to be published: Figure 1

Description

Title of the invention: Polymer composition for electrolyte and / or positive electrode of a rechargeable battery

[0001] The present invention relates to the field of rechargeable batteries, and more specifically to the field of rechargeable lithium or sodium batteries, particularly used for the production of electric vehicles and / or the storage of intermittent energies of the solar and / or wind type.

[0002] The invention relates more particularly to a polymer composition having improved ionic conduction properties, the use of such a polymer composition for the preparation of a polymer electrolyte and / or a positive electrode of a rechargeable battery, a polymer electrolyte for a rechargeable battery comprising such a polymer composition, a positive electrode for a rechargeable battery comprising such a polymer composition, and a rechargeable lithium or sodium battery comprising such a polymer electrolyte and / or such a positive electrode.

[0003] Lithium Metal Polymer (LMP®) batteries currently on the market are all-solid-state batteries generally in the form of a thin film wound several times or several stacked thin films. This wound or stacked thin film has a thickness on the order of one hundred micrometers. It generally comprises at least four functional films: a negative electrode (anode) that supplies lithium ions during discharge; a positive electrode (cathode) that acts as a receptacle where the lithium ions are intercalated; a solid polymer electrolyte that conducts lithium ions and is located between the positive and negative electrodes; and a current collector connected to the positive electrode to ensure electrical connection.The negative electrode is generally made of a metallic lithium foil or a lithium alloy; the solid polymer electrolyte is generally composed of a poly(ethylene oxide) (POE)-based polymer and at least one lithium salt; the positive electrode comprises an active electrode material, usually based on a metal oxide (such as V2O5, LiV3O8, LiCoO2, LiNiO2, LiMn2O4 or LiNio.5MnO.5O2) or on a phosphate of the LiMPO4 type where M represents a metal cation selected from the Fe, Mn, Co, Ni and Ti group, and one of their combinations, and possibly carbon; and the current collector is generally made of a metal foil.

[0004] The solid polymer electrolyte offers a significant safety advantage because it eliminates the need for potentially hazardous solvents in case of overheating. Such batteries can therefore operate at high temperatures without risk. explosion. However, commonly used polymer electrolytes such as high molecular weight POE doped with lithium salt have low ionic conductivity at room temperature, so their operating temperature must be kept relatively high (typically between 70 and 100°C). At these temperatures, however, POE becomes a viscous liquid and loses its dimensional stability. Furthermore, attempts to improve the ionic conductivity of POE by adding plasticizers have led to a deterioration of its mechanical properties.

[0005] The ionic conductivity of an electrolyte characterizes the ability of electrically charged ions to move within it. The higher the conductivity, the more the movement of ions within the electrolyte is favored. A polymer electrolyte can be considered advantageous if it has an ionic conductivity of at least 10⁵ S / cm. The transport number of an ion, denoted t, represents the fraction of the applied electric current that this ion will transport within the electrolyte; t is between 0 and 1. Since lithium ions are those involved in the chemical reactions taking place at the electrodes of a lithium metal polymer battery, a transport number t as close as possible to 1 is desirable for an electrolyte. In solid polymer electrolytes such as lithium salt-doped POE, the fraction of charge carried by lithium ions is low (on the order of 0.2), due to the strong interaction between the lithium cation and the POE chains, which limits electrical performance.A low cation transport number leads to the formation of a salt concentration gradient within the electrolyte during battery operation. This behavior generates salt depletion at the electrode, inducing an increase in electrolyte resistance and reduced power performance, and promotes the formation of lithium dendrites, resulting in a decrease in faradaic efficiency and, ultimately, short circuits.

[0006] In order to obtain t values ​​close to 1, polymers in which the anions form covalent bonds with the polymer chain, and where the lithium counter-ions are the only mobile species, have been described.

[0007] In particular, Meziane et al. (Electrochimica Acta, 2011, 57, 14-19) describe the preparation of a polystyrene bearing sulfonyl(trifluoromethylsulfonyl)imide groups by radical polymerization from sodium 4-styrene-sulfonyl(trifluoromethylsulfonyl)imide monomers. This ionic polystyrene is then used in a mixture with POE to create an electrolyte membrane containing no additional lithium ions. However, the results obtained show a relatively low ionic conductivity at temperatures below 60°C (e.g., on the order of 3.1 x 10⁶ S / cm).

[0008] Thus, the object of the present invention is to overcome the drawbacks of the aforementioned prior art and to provide a polymer composition that exhibits improved ionic conduction properties, a high lithium ion transport number, while ensuring good mechanical strength, so that it can be used as a polymer electrolyte in a rechargeable battery, and in particular in a rechargeable lithium or sodium battery.

[0009] The object of the invention is achieved by the polymer composition which will be described below.

[0010] The inventors of the present application have indeed discovered, surprisingly, that it is possible to add a fluorinated ionically non-conductive polymer to a particular cationically unipolar conducting polymer associated with a plasticizer, in order to significantly improve the ionic conductivity of a polymer composition.

[0011] The polymer composition

[0012] The present invention thus has as its first object a polymer composition, characterized in that it comprises at least one cationic unipolar conductive polymer, at least one plasticizer, and at least one fluorinated ionic non-conductive polymer, said cationic unipolar conductive polymer being a homopolymer or a copolymer comprising at least one organic polymer chain, organic anionic functions forming covalent bonds with the organic polymer chain, and metal cations associated (ionically) with the organic anionic functions.

[0013] By combining a cationic unipolar conductive polymer as defined above, a plasticizer, and a fluorinated ionically non-conductive polymer, a polymer composition with improved ionic conductivity properties is obtained.

[0014] The cationic unipolar conduction polymer

[0015] In the invention, a cationic unipolar conducting polymer is understood to be a polymer (homopolymer or copolymer) comprising at least one organic polymer chain, organic anionic groups forming covalent bonds with the organic polymer chain, and metal cations associated with the organic anionic groups. These metal cations are mobile species responsible for the ionic conduction of the polymer.

[0016] By organic polymer chain, we mean a polymer chain free of metal and metalloid. In other words, the organic polymer chain does not include a metal or metalloid such as silicon, or is different from a polysiloxane chain, or does not include a Si-O bond.

[0017] By organic anionic function, we mean an anionic function free of metal and metalloid. In other words, the organic anionic function does not include a metal or metalloid such as silicon, or does not include a Si-O bond.

[0018] The cationic unipolar conducting polymer of the invention is a polymer comprising anionic organic recurrent units (organic polymer chain and organic anionic functions covalently linked to said organic chain), said anionic organic recurrent units being associated (ionically) with metallic cations.

[0019] The cationic unipolar conducting polymer can be: - a homopolymer capable of being prepared from a) a monomer comprising at least one organic anionic function covalently grafted onto said monomer and at least one metallic cation associated with the organic anionic function; or - a copolymer capable of being prepared from a) a monomer comprising at least one organic anionic function covalently grafted onto said monomer and at least one metal cation associated with the organic anionic function, and b) at least one other monomer different from monomer a) selected from b1) monomers comprising at least one organic anionic function covalently grafted onto said monomer and at least one metal cation associated with the organic anionic function, and b2) organic monomers.

[0020] By organic monomer b2), we mean a monomer free of metal and metalloid. In other words, the organic monomer does not include a metal or metalloid such as silicon and / or is not a compound comprising Si-O bonds.

[0021] The metal cation (of the monomer) or metal cations (of the polymer) associated with the organic anionic functions are preferably chosen from Li+ and Na+ cations, and particularly preferably are Li+ cations.

[0022] The monomer a) or bl), i.e. comprising at least one organic anionic function covalently grafted onto said monomer and at least one metal cation associated with the organic anionic function, may be selected from aromatic and non-aromatic vinyl monomers, comprising at least one organic anionic function covalently grafted onto said organic monomer and at least one metal cation associated with the organic anionic function.

[0023] Styrene and its derivatives can be cited as examples of aromatic vinyl monomers.

[0024] Styrene derivatives are preferably derivatives in which the phenyl group of styrene is substituted by one or more groups selected from among the methyl, ethyl, and tert-butyl groups.

[0025] Examples of non-aromatic vinyl monomers include acrylate, methacrylate, acrylamide, methacrylamide, ethylene, propylene, dienes, or maleimide.

[0026] The organic monomer b2) can be a vinylidene fluoride, a phosphate, a phosphonate, an ether, a carbonate, a malonate, an amide, an acrylate, an anhydride, or an ester.

[0027] In this embodiment, the copolymer comprises, in addition to anionic organic recurrent units associated with metal cations, recurrent units of vinylidene fluoride, phosphate, phosphonate, ether, carbonate, malonate, amide, acrylate, anhydride, or ester.

[0028] The organic anionic function (of the monomer a) and bl)) or the organic anionic functions (of the polymer) can be chosen from among the sulfonate, borate, and imidide functions.

[0029] The organic anionic functions are preferably imidides, particularly preferably bissulfonyl imidides, more particularly preferably sulfonyl(trifluoromethylsulfonyl) imidides (TFSI) or sulfonyl(fluorosulfonyl) (FSI) imidides, and even more particularly preferably sulfonyl(trifluoromethylsulfonyl) imidides (TFSI).

[0030] According to a particularly preferred embodiment of the invention, the aromatic or non-aromatic vinyl monomer, comprising at least one organic imidide anionic function covalently grafted onto said monomer and Li+ as a metal cation associated with the organic imidide anionic function, is selected from the following monomers (La) to (Li):

[0031] [Chem.l]

[0032] The cationic unipolar conducting polymer is preferably a lithium polystyrene-sulfonyl(trifluoromethylsulfonyl)imide (PSTFSILi) or a lithium polymethacrylate sulfonyl(trifluoromethylsulfonyl)imide (PMTFSILi).

[0033] The cationic unipolar conductive polymer preferably has a number-average molar mass (i.e. Mn) ranging from approximately 10,000 g / mol to 1,000,000 g / mol, and particularly preferably ranging from approximately 50,000 g / mol to 700,000 g / mol.

[0034] In the invention, the number-average molar mass is measured by methods well known to those skilled in the art, and in particular by gel permeation chromatography (GPC).

[0035] The cationic unipolar conduction polymer preferably represents about 5% to 40% by mass, and particularly preferably about 5% to 30% by mass, relative to the total mass of the polymer composition.

[0036] The cationic unipolar conduction polymer already comprises anionic functions (anionic groups derived from a lithium or sodium salt directly grafted into the structure of the polymer material). The polymer composition therefore preferably does not include any additional lithium or sodium salt(s), e.g., molecular lithium or sodium salts (i.e., lithium or sodium salts not grafted into a polymer material).

[0037] The fluorinated ionic non-conductive polymer

[0038] In the invention, a non-ionically conductive polymer is understood to be a polymer that does not allow the conduction of lithium or sodium ions. In other words, a non-ionically conductive polymer has an ionic conductivity of less than 10⁷ S / cm, particularly at the operating temperature.

[0039] The non-conductive ionic fluorinated polymer preferably represents about 5% to 45% by mass, and particularly preferably about 5% to 40% by mass, relative to the total mass of the polymer composition.

[0040] The ionically non-conductive polymer is fluorinated. In other words, it is a polymer whose repeating unit is a fluorocarbon, and which therefore comprises several carbon-fluorine bonds.

[0041] The ionically non-conductive fluorinated polymer of the polymer composition of the invention can be selected from vinyl fluoride (VF) homopolymers and copolymers, vinylidene fluoride (VdF) homopolymers and copolymers, ethylene tetrafluoride (TFE) homopolymers and copolymers, chlorotrifluoroethylene (CTFE) homopolymers and copolymers, hexafluoropropylene (HFP) homopolymers and copolymers, and mixtures thereof.

[0042] According to a particularly preferred embodiment of the invention, the fluorinated ionically non-conductive polymer is chosen from homopolymers and copolymers of vinylidene fluoride (VdF) such as PVdF or P(VdF-HFP).

[0043] According to a more particularly preferred embodiment, the fluorinated ionically nonconductive polymer is PVdF.

[0044] The mass ratio of ionically fluorinated non-conducting polymer / cationic unipolar conducting polymer in the polymer composition preferably ranges from about 20 / 80 to about 90 / 10, and particularly preferably from about 40 / 60 to about 80 / 20.

[0045] The non-conductive ionic fluorinated polymer preferably has a number-average molar mass (i.e. Mn) ranging from approximately 50,000 g / mol to 1,300,000 g / mol.

[0046] The plasticizer

[0047] The polymer composition includes at least one plasticizer.

[0048] The plasticizer is a non-aqueous solvent. This allows the formation of a gelled polymer composition or a gel in the form of a gel.

[0049] The non-aqueous solvent or plasticizer may be chosen from: - linear and cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), or methyl-isopropyl carbonate (MiPC); - fluorinated carbonates such as fluoroethylene carbonate; - nitriles such as succinonitrile; - lactones such as y-butyrolactone; - liquid linear and cyclic polyethers such as dimethyl ether, polyethylene glycol dimethyl ethers (or PEGDME) such as tetraethylene glycol dimethyl ether (TEGDME), or dioxolane; - fluorinated polyethers; - sulfur-containing solvents such as sulfolane or dimethyl sulfoxide; - phosphates such as triethylphosphate or fluorophosphates; - esters such as ethyl acetate or ethyl butyrate (EB); and - one of their mixtures.

[0050] Among such solvents or plasticizers, linear and cyclic carbonates are particularly preferred.

[0051] The solvent or plasticizer preferably represents about 25% to 90% by mass, particularly preferably about 35% to 90% by mass, and even more particularly preferably about 65% to 90% by mass, relative to the total mass of the polymer composition.

[0052] Additives in the polymer composition

[0053] The polymer composition of the invention may further comprise a reinforcing agent. This makes it possible to modulate the mechanical properties of the polymer composition.

[0054] Said reinforcing agent is preferably chosen from cellulose nanofibrils, and ceramic nanoparticles such as titanium oxide, aluminum oxide or silicon oxide nanoparticles.

[0055] According to a particularly preferred embodiment of the invention, the polymer composition comprises (or is made up of): - approximately 40 to 90% plasticizer by mass, and preferably approximately 65 to 90% plasticizer by mass, - approximately 5 to 35% by mass of fluorinated ionic non-conducting polymer, and - approximately 5 to 35% by mass of cationic unipolar conductive polymer.

[0056] Indeed, the mixture of fluorinated ionically non-conductive polymer and cationically unipolar conductive polymer is capable of absorbing a plasticizer while maintaining good mechanical strength and remaining solid or nearly solid. Furthermore, the presence of the plasticizer makes it possible to obtain a solid or nearly solid polymer composition with improved ionic conductivity (e.g., a conductivity of at least 1 x 10⁵ S / cm at 25°C).

[0057] The use of the polymer composition

[0058] The invention has as its second object the use of a polymer composition as defined in the first object of the invention, for the preparation of a polymer electrolyte and / or a positive electrode of a rechargeable battery, preferably of a rechargeable lithium or sodium battery, particularly preferably of a lithium metal or sodium metal battery, and more particularly preferably of a lithium metal battery.

[0059] The use of a polymer composition according to the present invention for the preparation of a polymer electrolyte for a rechargeable lithium battery leads to an energy storage device exhibiting excellent low-temperature performance (i.e., < 60°C, and preferably < 40°C), in particular a lithium ion transport number on the order of 1, and an ionic conductivity greater than or equal to 10⁵ S·cm⁻¹, preferably greater than or equal to 5 × 10⁵ S·cm⁻¹, and particularly preferably greater than or equal to 10⁴ S·cm⁻¹, at a temperature of no more than 40°C. The high transport number makes it possible to limit the formation of concentration gradients in the polymer electrolyte during discharge (respectively, charging), thereby increasing power performance (respectively, charging rate).The use of this polymer composition also limits the dendritic growth of lithium, thus enabling fast and safe charging. Indeed, the problem with lithium-metal battery technology is the formation of heterogeneous lithium electrodeposits (including dendrites) during charging, which reduces cycle life and can lead to short circuits. The polymer composition according to the present invention also exhibits good mechanical strength and high thermal stability (which ensures the safety of the devices). energy storage including them), and improved potential stability (e.g. stability up to 4.5 V vs Lr7Li).

[0060] The use of a polymer composition according to the present invention for preparing a positive electrode of a rechargeable lithium metal or sodium metal battery improves ionic conductivity, thereby lowering the battery's operating temperature and improving its power response. Furthermore, the polymer composition improves the adhesion of the positive electrode to the current collector.

[0061] The polymer electrolyte

[0062] The invention has as its third object a polymer electrolyte for a rechargeable battery, characterized in that it comprises a polymer composition according to the first object of the invention, or a porous separator impregnated with a polymer composition according to the first object of the invention.

[0063] The porous separator can be made of a non-electronically conductive porous material, preferably a porous polymer material based on at least one polyolefin (e.g. polyethylene or polypropylene) or based on fibers (e.g. glass fibers or wood fibers).

[0064] The polymer electrolyte is preferably in the form of a film, particularly preferably in the form of a film having a thickness of approximately 5 to 45 pm, and more particularly preferably of approximately 10 to 25 pm.

[0065] When the polymer electrolyte comprises (or is made of) a porous separator impregnated with a polymer composition conforming to the first object, the porous separator is preferably coated with the polymer composition on a first face and on a second face opposite the first face.

[0066] The polymer electrolyte (solid or quasi-solid) can be prepared by any technique well known to those skilled in the art, such as, for example, by coating, extrusion or pressing (cold or hot).

[0067] The polymer electrolyte is preferably suitable for a rechargeable lithium or sodium battery, particularly preferably for a lithium metal or sodium metal battery, and more particularly preferably for a lithium metal battery.

[0068] The positive electrode

[0069] The invention has as its fourth object a positive electrode for a rechargeable battery, comprising a positive electrode active material, a polymer composition, and optionally an agent generating electronic conductivity, characterized in that the polymer composition is as defined in the first object of the invention.

[0070] The positive electrode is preferably suitable for a rechargeable lithium battery or sodium, particularly preferred for a lithium metal or sodium metal battery, and more particularly preferred for a lithium metal battery.

[0071] The active material of the positive electrode

[0072] The active material of the positive electrode is a reversible active material of lithium or sodium ions. In other words, it can reversibly insert or remove lithium or sodium ions.

[0073] The active material of the positive electrode can be: - a metal oxide such as, for example, a vanadium oxide VOX (2 < x < 2.5), LiV3O8, LiN12CoxO2 (0 < x < 1; 0 < y < 1), a manganese spinel LiMn12XMXO2 (M = Cr, Al, V, Ni, 0 < x < 0.5; 0 < y < 2), V2O5, lithium oxides such as, for example, LiCoO2, LiNiO2, LiMn2O4, LiN12 / 3Mn1 / 3Co1 / 3O2 (NMC), LiN12Coo2 / 3O2 (NCA), and LiN120 / 5Mn100 / 5O2, - a phosphosilicate or metal phosphate, for example Li3V2(PO4)3 or LiMPO4, where M represents a metal cation selected from the Fe, Mn, Co, Ni and Ti group, and one of their combinations, or - a metal sulfate, for example iron sulfate Fe2(SO4)3.

[0074] The active material of the positive electrode can represent approximately 50 to 90% by mass, and preferably approximately 55 to 80% by mass, relative to the total mass of the positive electrode.

[0075] The agent generating electronic conductivity

[0076] The agent generating electronic conductivity can be chosen from carbon blacks, acetylene blacks, carbon fibers and nanofibers, carbon nanotubes, graphene, graphite, metallic particles and fibers of at least one conductive metal such as aluminum, platinum, iron, cobalt and nickel, and one of their mixtures.

[0077] The agent generating electronic conductivity is preferably carbon black.

[0078] The agent generating electronic conductivity can represent from 0.1 to 10% in approximately mass, and preferably approximately 0.5 to 5% by mass, relative to the total mass of the positive electrode.

[0079] The polymer composition

[0080] The polymer composition is a polymer composition as defined in the first object of the invention.

[0081] The polymer composition can represent from 10% to 49.5% by mass approximately, and preferably from 20% to 40% by mass approximately, relative to the total mass of the positive electrode.

[0082] The positive electrode does not preferably comprise a molecular lithium or sodium salt.

[0083] The positive electrode is preferably in the form of a film whose thickness is generally on the order of 20 to one hundred micrometers.

[0084] Rechargeable lithium or sodium battery

[0085] The invention relates as a fifth object to a rechargeable lithium or sodium battery, characterized in that it comprises: - a negative electrode comprising lithium metal, sodium metal, a lithium metal alloy, or a sodium metal alloy, - a positive electrode, possibly supported by a current collector, and - a polymer electrolyte positioned between the positive electrode and the negative electrode, characterized in that the polymer electrolyte is as defined in the third object of the invention and / or the positive electrode is as defined in the fourth object of the invention.

[0086] The negative electrode

[0087] The negative electrode is preferably in the form of a film whose thickness is generally on the order of 1 to one hundred micrometers.

[0088] The negative electrode can be made of metallic lithium, metallic sodium, one of the lithium alloys such as a lithium alloy with sodium, silicon, tin, aluminium, magnesium, silver, zinc, or germanium, or one of the sodium alloys such as a sodium alloy with lithium, silicon, tin, aluminium, magnesium, silver, zinc, or germanium.

[0089] The negative electrode is preferably made of metallic lithium or one of the lithium alloys.

[0090] The positive electrode

[0091] The positive electrode may be a positive electrode according to the fourth object of the invention or the positive electrode may comprise a positive electrode active material, a polymer binder, optionally a plasticizer, and optionally an agent generating electronic conductivity.

[0092] The active material of the positive electrode and the agent generating electronic conductivity are as defined in the fourth object of the invention.

[0093] The plasticizer

[0094] The plasticizer (or non-aqueous solvent) may be chosen from: - linear and cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), or methyl-isopropyl carbonate (MiPC); - fluorinated carbonates such as fluoroethylene carbonate; - nitriles such as succinonitrile; - lactones such as y-butyrolactone; - liquid linear or cyclic polyethers such as dimethyl ether, polyethylene glycol dimethyl ethers (or PEGDME) such as tetraethylene glycol dimethyl ether (TEGDME), or dioxolane; - fluorinated polyethers; - sulfur-containing solvents such as sulfolane or dimethyl sulfoxide; - phosphates such as triethylphosphate or fluorophosphates; - esters such as ethyl acetate or ethyl butyrate (EB); and - a mixture of them.

[0095] Among such solvents or plasticizers, linear and cyclic carbonates are particularly preferred.

[0096] The plasticizer can represent from 5 to 35% by mass approximately, and preferably from 10 to 25% by mass approximately, relative to the total mass of the positive electrode.

[0097] The polymer binder

[0098] The polymer binder can be selected from ethylene homopolymers and copolymers; propylene homopolymers and copolymers; ethylene oxide homopolymers and copolymers (e.g., POE, POE copolymer), methylene oxide, propylene oxide, epichlorohydrin, allylglycidyl ether, and mixtures thereof; halogenated polymers such as vinyl chloride homopolymers and copolymers, vinylidene fluoride (PVdF), vinylidene chloride, ethylene tetrafluoride, chlorotrifluoroethylene, or mixtures thereof; anionic non-conductive polymers such as poly(styrene sulfonate), poly(acrylic acid), poly(glutamate), alginate, pectin, gelatin, or mixtures thereof;Cationic polymers such as polyethyleneimine (PEI), polyaniline in the form of emeraldine salt (ES), quaternized poly(N-vinylimidazole), poly(acrylamide-dialyldimethyl ammonium cochloride) (AMAC) or mixtures thereof; polyacrylates; elastomers such as homopolymers or copolymers of ethylene, propylene, styrene, butadiene or chloroprene; cationic unipolar conduction polymers; and mixtures thereof.

[0099] Cationic unipolar conduction polymers can be such as defined in the first object of the invention.

[0100] The polymer binder can represent from 5 to 35% by mass approximately, and preferably from 10 to 25% by mass approximately, relative to the total mass of the positive electrode.

[0101] According to a preferred embodiment of the invention, the active material of the positive electrode is coated with a carbon layer. The presence of the carbon layer improves the interface between the active material and the polymer binder.

[0102] The carbon coating the active material preferably represents approximately 0.1 to 5% by mass, relative to the mass of the active material.

[0103] The carbon layer is preferably in the form of a layer of thickness varying from approximately 1 to 4 nm.

[0104] The positive electrode may further comprise a lithium or sodium salt, in particular when the polymer binder is different from a cationic unipolar conductive polymer.

[0105] According to a particularly preferred embodiment of the invention, the positive electrode is a positive electrode in accordance with the fourth object of the invention.

[0106] The current collector

[0107] The rechargeable battery may further include a current collector, connected to the positive electrode.

[0108] The current collector is generally made of a sheet of metal.

[0109] The current collector is preferably a stainless steel or stainless steel current collector aluminium, possibly coated with a carbon-based layer (anti-corrosion layer).

[0110] The polymer electrolyte

[0111] The polymer electrolyte may be a polymer electrolyte according to the third object of the invention or the polymer electrolyte may comprise a cationic unipolar conductive polymer; or the association of at least one lithium salt and at least one polymer material selected from poly(ethylene oxide) (POE) based polymer materials, polycarbonates, and polydiesters.

[0112] The poly(ethylene oxide) (POE) based polymer material can be selected from a polystyrene-poly(ethylene oxide) (PS-b-POE) block copolymer, a polystyrene-poly(ethylene oxide)-polystyrene (PS-b-POE-b-PS) block copolymer, a poly(ethylene oxide-stat-propylene oxide) (i.e. POE-stat-PPO) statistical copolymer, a poly(ethylene oxide-stat-butylene oxide) (i.e. POE-stat-PBO) statistical copolymer, a poly(ethylene oxide), and a mixture thereof.

[0113] The lithium salt used in association with the poly(ethylene oxide)-based polymer material can be selected from lithium fluorate (LiFO3), lithium bis(trifluoromethanesulfonyl) imidide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium fluoroborate (LiBF4), lithium metaborate (LiBO2), lithium perchlorate (LiC104), lithium nitrate (LiNO3), lithium bis(fluorosulfonyl) imidide (LiFSI), lithium bis(pentafluoroethylsulfonyl) imidide (LiBETI), LiAsF6, LiCF3SO3, LiSbF6, LiSbCl6, Li2TiCl6, Li2SeCl6, Li2B10Cl10, Li2B12Cl i2, lithium bis(oxalato)borate (LiBOB), and mixtures thereof.

[0114] The lithium salt preferably represents 5 to 30% by mass, and even more preferably 10 to 25% by mass, relative to the total mass of the polymer electrolyte.

[0115] Said poly(ethylene oxide) (POE) based polymer material can be combined with a reinforcing agent. This makes it possible to modulate the mechanical properties of the polymer material.

[0116] Said reinforcing agent is preferably selected from cellulose nanofibrils, ceramic nanoparticles such as titanium oxide, aluminum oxide or silicon oxide nanoparticles, and fluorinated polymers and copolymers such as polyvinylidene fluoride (PVdF) or vinylidene fluoride-hexafluoropropylene copolymer (PVdF-co-HFP).

[0117] The cationic unipolar conduction polymer is as defined in the first object of the invention.

[0118] According to a particularly preferred embodiment of the invention, the polymer electrolyte is a polymer electrolyte in accordance with the third object of the invention.

[0119] The present invention is illustrated by the following embodiments, to which it is not, however, limited. Brief description of the drawings

[0120] The accompanying drawings illustrate the invention.

[0121] Fig. 1 shows the evolution of the ionic conductivity in S.cm1 as a function of temperature (in Kelvin*) for a conventional polymer electrolyte and polymer electrolytes of the invention.

[0122] Figure 2 shows the evolution of the ionic conductivity in S.cm⁻¹ as a function of the temperature (in Kelvin *) for a conventional polymer electrolyte and polymer electrolytes of the invention.

[0123] Fig. 3 shows the evolution of the ionic conductivity in S.cm1 as a function of temperature (in Kelvin*) for a conventional polymer electrolyte and polymer electrolytes of the invention.

[0124] Figure 4 shows the evolution of the ionic conductivity in S.cm⁻¹ as a function of the temperature (in Kelvin *) for conventional polymer electrolytes.

[0125] Fig. 5 shows the opposite of the imaginary part of the impedance -Z” in ohms, as a function of the real part of the impedance Z' in ohms for a conventional positive electrode and for a positive electrode of the invention.

[0126] Fig. 6 shows the capacity (in mAh / g) and efficiency (in %) as a function of the number of cycles of a battery according to the invention.

[0127] Figure 7 shows the internal resistance Ri (in Ohm.cm2) as a function of the number of cycles, in discharge and charge, of a battery according to the invention.

[0128] Fig. 8 shows the capacity (in mAh / g) and efficiency (in %) as a function of the number of cycles of a battery according to the invention.

[0129] Figure 9 shows the internal resistance Ri (in Ohm.cm2) as a function of the number of cycles, in discharge and charge, of a battery according to the invention.

[0130] Figure 10 shows the evolution of the ionic conductivity in S.cm⁻¹ as a function of the temperature (in Kelvin) for a conventional polymer electrolyte and a polymer electrolyte of the invention. Examples

[0131] The raw materials used in the examples are listed below: - carbon black, Sumitomo Corp, reference "ECP-600JD", - Lithium Manganese Iron Phosphate (LMFP), Huayi, grade 2, - PVDF, marketed under the reference "5130" by Solvay, with a molar mass Mw=900,000 g / mol, - PVdF-HFP, marketed under the reference "Kynarflex 2751", by the company Arkema, - Propylene carbonate (PC), Aldrich, anhydrous, purity 99.7%, - triethyl phosphate (TEP), TCI, purity > 99.0%, - PMTFSI: poly((trifluoromethane)sulfonimide lithium methacrylate), Specifies Polymers, with molar mass Mn=238,330 g / mol, - PSTFSI: poly(styrene tri(fluoromethane) sulfonimide), with a molar mass Mn = 84,720 g / mol, - PMMA: poly(methyl methacrylate), Sigma-Aldrich, Mw ~ 996,000 g / mol, - Acetonitrile, Sigma-Aldrich, anhydrous, 99.8% purity, - Lithium metal sheet, extruded from Ganfeng and then laminated to 72 µm, - Lithium metal electrode, extruded and then laminated to 72 µm, - 72 µm thick lithium metal anode, extruded and then laminated to 72 µm, - “EnSafe 65” collector, Armor.

[0132] Unless otherwise indicated, all materials were used as received from the manufacturers.

[0133] Example 1: preparation of a polymer electrolyte EPI* not according to the invention and of polymer electrolytes EP2, EP3, EP4 and EP5 according to the invention

[0134] Several polymer electrolytes comprising PVdF as a fluorinated ionic nonconductive polymer, PMTFSI as a cationic unipolar conducting polymer, and propylene carbonate as a plasticizer have been prepared in the manner detailed below.

[0135] The constituents (fluorinated ionic non-conductive polymer, cationic unipolar conductive polymer, and plasticizer) are mixed with acetonitrile (ACN) under magnetic stirring (300 rpm) at 100°C in a beaker. For 1 g of a mixture of the fluorinated ionic non-conductive polymer and the cationic unipolar conductive polymer, 1 g of plasticizer and 5 g of acetonitrile are used. After mixing, the resulting mixture is coated at 8 mm / s at temperature ambient on a silicone-coated poly(ethylene terephthalate) (PET) support to form a film which is left to dry under a fume hood for a few minutes, in order to evaporate the residual acetonitrile.

[0136] Table 1 below illustrates the mass percentages of the different constituents present in the electrolytes prepared according to the protocol described above, as well as the thicknesses:

[0137] [Tables 1] PMTFSI polymer electrolyte (% by mass) PVdF (% by mass) PC (% by mass) Film thickness obtained (nm) EP1* 50 0 50 90 EP2 30 20 50 21 EP3 25 25 50 34 EP4 20 30 50 20 EPS 15 35 50 19 * not part of the invention

[0138] For each of the polymer electrolytes, a lithium electrolyte lithium (LEL) cell is then manufactured by successive laminations at 75°C under dry air of a lithium sheet, a polymer electrolyte film as prepared above, and another lithium sheet.

[0139] For the polymer electrolyte not conforming to the invention EPI*, the rolling is carried out at a pressure of 2 bar. For the other polymer electrolytes, EP2 to EP5, the rolling is carried out at a pressure of 5 bar.

[0140] The LEL1*, LEL2, LEL3, LEL4, and LEL5 cells comprising respectively the polymer electrolytes EPI*, EP2, EP3, EP4, and EP5 are placed in 2 bar compression systems.

[0141] The ionic conductivity of the polymer electrolytes EPI*, EP2, EP3, EP4, and EP5 is measured by impedance spectroscopy using an instrument sold under the trade name IM6EX by Zahner. The measurements are carried out with the cells LEL1*, LEL2, LEL3, LEL4, and LEL5 as prepared above, in potentiostatic mode between 100 MHz and 1 MHz for an amplitude of 10 mV at 20°C and 40°C.

[0142] Fig. 1 shows the evolution of the ionic conductivity in S.cm⁻¹ as a function of temperature (measurement of the ratio 1000 / temperature, in Kelvin) for the polymer electrolyte EP1* (curve with solid circles connected by a solid line), EP2 (curve with solid circles connected by a wide dashed line), EP3 (curve with circles EP4 (curve with solid circles connected by a normal dashed line), EP5 (curve with solid triangles connected by a solid line). The ionic conductivity of a polymer electrolyte is directly proportional to the amount of PVdF used in the polymer electrolyte. The introduction of PVdF, as a fluorinated non-ionically conductive polymer, contributes to increasing the ionic conductivity of polymer electrolytes based on at least one cationic unipolar conductive polymer such as PMTFSI plasticized with at least one plasticizer such as propylene carbonate.

[0143] Example 2: preparation of a polymer electrolyte EP6* not according to the invention and of polymer electrolytes EP7, EP8, EP9 and EP10 according to the invention

[0144] Several polymer electrolytes comprising PVdF as a fluorinated ionic nonconductive polymer, PSTFSI as a cationic unipolar conducting polymer, and propylene carbonate as a plasticizer have been prepared in the manner detailed below.

[0145] The constituents (fluorinated ionic non-conductive polymer, cationic unipolar conductive polymer, and plasticizer) are mixed with acetonitrile (ACN) under magnetic stirring (300 rpm) at 100°C in a beaker. For 1 g of a mixture of the fluorinated ionic non-conductive polymer and the cationic unipolar conductive polymer, 1 g of plasticizer and 5 g of acetonitrile are used. After mixing, the resulting mixture is coated at 8 mm / s at room temperature onto a silicone-coated polyethylene terephthalate (PET) substrate to form a film, which is then dried under a fume hood for a few minutes to evaporate any residual acetonitrile.

[0146] Table 2 below illustrates the mass percentages of the different constituents present in the electrolytes prepared according to the protocol described above, as well as the thicknesses:

[0147] [Tables2] Polymer electrolyte PSTFSI (% by mass) PVdF (% by mass) PC (% by mass) Film thickness obtained (m) EP6* 50 0 50 64 EP7 35 15 50 39 EPS 25 25 50 18 EPS 15 35 50 32 EPIS 10 40 50 26 * not part of the invention

[0148] For each of the polymer electrolytes, a lithium electrolyte lithium (LEL) cell is then manufactured by successive laminations at 75°C under dry air of a lithium sheet, a polymer electrolyte film as prepared above, and another lithium sheet.

[0149] For the non-inventory polymer electrolyte EP6*, the laminations are carried out at a pressure of 2 bar. Furthermore, two layers of EP6* polymer electrolyte are used to prevent a possible short circuit. For the other polymer electrolytes, EP7 to EP10, which conform to the invention, the laminations are carried out at a pressure of 5 bar.

[0150] The LEL6*, LEL7, LEL8, LEL9, and LEL10 cells comprising respectively the polymer electrolytes EP6*, EP7, EP8, EP9, and EP10 are placed in 2 bar compression systems.

[0151] The ionic conductivity of the polymer electrolytes EP6*, EP7, EP8, EP9, and EP10 is measured as described in Example 1.

[0152] Figure 2 shows the evolution of ionic conductivity in S·cm⁻¹ as a function of temperature (measurement of the ratio 1000 / temperature, in Kelvin) for the polymer electrolyte EP6* (curve with solid circles connected by a solid line), EP7 (curve with solid circles connected by a wide dashed line), EP8 (curve with solid circles connected by a normal dashed line), EP9 (curve with solid circles connected by a short dashed line), and EP10 (curve with solid triangles connected by a solid line). The introduction of PVdF, as a non-ionically conductive polymer, contributes to increasing the ionic conductivity of polymer electrolytes based on at least one cationically unipolar conducting polymer such as PSTFSI plasticized with at least one plasticizer such as propylene carbonate. Ionic conductivity reaches a maximum for a PVdF content of 35% by mass, relative to the total mass of the polymer electrolyte.

[0153] Example 3: preparation of a polymer electrolyte EP11* not according to the invention and of polymer electrolytes EP12 and EP13 according to the invention

[0154] Several polymer electrolytes comprising PVdF as a fluorinated ionic nonconducting polymer, PMTFSI as a cationic unipolar conducting polymer, and triethyl phosphate (TEP) as a plasticizer have been prepared in the manner detailed below.

[0155] The constituents (fluorinated ionic non-conductive polymer, cationic unipolar conductive polymer, and plasticizer) are mixed with acetonitrile (ACN) under magnetic stirring (300 rpm) at 100°C in a beaker. For 1 g of a mixture of the fluorinated ionic non-conductive polymer and the cationic unipolar conductive polymer, 1 g of plasticizer and 5 g of acetonitrile are used. After mixing, the resulting mixture is coated at 8 mm / s at temperature ambient on a silicone-coated poly(ethylene terephthalate) (PET) support to form a film which is left to dry under a fume hood for a few minutes, in order to evaporate the residual acetonitrile.

[0156] Table 3 below illustrates the mass percentages of the different constituents present in the electrolytes prepared according to the protocol described above, as well as the thicknesses:

[0157] [Tables3] PMTFSI polymer electrolyte (% by mass) PVdF (% by mass) TEP (% by mass) Film thickness obtained (µm) EP11* 50 0 50 52 EP12 35 15 50 23 EP13 25 25 50 22 * not part of the invention

[0158] For each of the polymer electrolytes, a lithium electrolyte lithium (LEL) cell is then manufactured by successive laminations at 75°C under dry air of a lithium sheet, a polymer electrolyte film as prepared above, and another lithium sheet.

[0159] For the polymer electrolyte not conforming to the invention, EP1*, the laminations are carried out at a pressure of 2 bar and a lithium electrode is used instead of two lithium sheets. For the other polymer electrolytes, EP12 and EP13, conforming to the invention, the laminations are carried out at a pressure of 5 bar.

[0160] The LEL11*, LEL12, and LEL13 cells comprising respectively the polymer electrolytes EPI 1*, EP12, and EP13 are placed in 2 bar compression systems.

[0161] The ionic conductivity of the polymer electrolytes EPI 1*, EP12, and EP13 is measured as described in Example 1.

[0162] Figure 3 shows the evolution of the ionic conductivity in S·cm⁻¹ as a function of temperature (measurement of the ratio 1000 / temperature, in Kelvin) for the polymer electrolyte EPI 1* (curve with solid circles connected by a solid line), EPI2 (beginning of the curve with a solid square), and EP13 (curve with solid circles connected by a dashed line). The ionic conductivity of a polymer electrolyte is higher when the proportion of PVdF used in the polymer electrolyte is higher. The introduction of PVdF, as a non-ionically conductive polymer, contributes to increasing the ionic conductivity of polymer electrolytes based on at least one cationically unipolar conducting polymer such as PMTFSI plasticized with minus a plasticizer such as triethyl phosphate.

[0163] Comparative Example 4: Preparation of EP14*, EP15* and EP16* polymer electrolytes not in accordance with the invention

[0164] Several polymer electrolytes comprising PMMA instead of PVdF as a non-fluorinated ionic non-conducting polymer, PMTFSI as a cationic unipolar conducting polymer, and propylene carbonate as a plasticizer have been prepared in the manner detailed below.

[0165] The constituents (non-fluorinated ionic non-conductive polymer, cationic unipolar conductive polymer, and plasticizer) are mixed with acetonitrile (ACN) under magnetic stirring (300 rpm) at 100°C in a beaker. For 1 g of a mixture of the non-fluorinated ionic non-conductive PMMA polymer and the cationic unipolar conductive polymer, 1 g of plasticizer and 5 g of acetonitrile are used. After mixing, the resulting mixture is coated at 8 mm / s at room temperature onto a silicone-coated polyethylene terephthalate (PET) substrate to form a film, which is then dried under a fume hood for a few minutes to evaporate any residual acetonitrile.

[0166] Table 4 below illustrates the mass percentages of the different constituents present in the electrolytes prepared according to the protocol described above, as well as the thicknesses:

[0167] [Tables4] Polymer electrolyte PMTFSI (% by mass) PMMA (% by mass) PC (% by mass) Film thickness obtained (m) EPI* 50 0 50 90 EP14* 35 15 50 30 EPI 5* 25 25 50 23 EP16* 15 35 50 26 * not part of the invention

[0168] For each of the polymer electrolytes, a lithium electrolyte lithium (LEL) cell is then manufactured by successive laminations at 75°C under dry air of a lithium sheet, a polymer electrolyte film as prepared above, and another lithium sheet.

[0169] For the polymer electrolyte not conforming to the invention EPI*, the rolling is carried out at a pressure of 2 bar. For the other polymer electrolytes, not conforming to the invention, EP14* to EP16*, the rolling is carried out at a pressure of 5 bar.

[0170] The cells LEL1*, LEL14*, LEL15*, and LEL16* comprising respectively the EPI*, EP14*, EP15*, and EP16* polymer electrolytes are placed in 2 bar compression systems.

[0171] The ionic conductivity of the polymer electrolytes EPI*, EP14*, EP15*, and EP16* is measured as in Example 1.

[0172] Figure 4 shows the evolution of the ionic conductivity in S·cm⁻¹ as a function of temperature (measurement of the ratio 1000 / temperature, in Kelvin) for the polymer electrolyte EPI* (curve with solid circles connected by a solid line), EPI4* (curve with open circles connected by a wide dashed line), EP15* (curve with solid circles connected by a normal dashed line), and EPI6* (curve with solid circles connected by a short dashed line). Unlike PVdF, the use of PMMA decreases the ionic conductivity of the polymer electrolyte.

[0173] Example 5: Preparation of cathodes Cl* not according to the invention and C2 according to the invention

[0174] Preparation of Cl* and C2 cathodes

[0175] A first cathode (positive electrode) Cl* not according to the invention (i.e., without PVdF as a fluorinated ionically nonconductive polymer) in the form of a film was prepared as follows: 1.32 g of propylene carbonate (PC), 1.32 g of PMTFSI, and 12 g of ACN are mixed in a beaker under magnetic stirring at 300 rpm and 100°C. Then, 4.2 g of lithium manganese iron phosphate (LMFP) and 0.17 g of carbon black (KB) are added when a homogeneous result is obtained. The resulting mixture is then ground using a ball mill for 8 min at 30 rpm. The resulting mixture is coated at room temperature at 30 mm / s onto a collector known as "EnSafe 65" from Armor to form a cathode, which is then calendered at 95°C to reduce porosity. A thickness of 34 µm is achieved.

[0176] A second cathode C2 according to the invention (i.e., with PVdF as the fluorinated ionic nonconductive polymer) in the form of a film was prepared as follows: 1.32 g of propylene carbonate (PC), 0.79 g of PMTFSI, 0.53 g of PVdF, and 18 g of ACN were mixed in a beaker under magnetic stirring at 300 rpm and 100°C. Then, 4.2 g of lithium manganese iron phosphate (LMFP) and 0.17 g of carbon black (KB) were added when a homogeneous result was obtained. The resulting mixture was then ground using a ball mill for 8 min at 30 rpm. The resulting mixture is coated at room temperature at 30 mm / s onto a collector known as "EnSafe 65" from Armor to form a cathode, which is then calendered at 95°C to reduce porosity. A thickness of 40 µm is achieved.

[0177] Table 5 below illustrates the mass percentages of the different constituents present in the cathodes prepared according to the protocol described above:

[0178] [Tables5] Constituents Cl* C2 LMFP (mass %) 60 60 KB (mass %) 2.4 2.4 PMTFSI (mass %) 18.8 11.3 PVdF (mass %) 0 7.5 PC (mass %) 18.8 18.8 * not part of the invention

[0179] Preparation of a polymer electrolyte EP17 according to the invention

[0180] A polymer electrolyte EP17 according to the invention, comprising PVdF as a fluorinated ionic nonconductive polymer, PMTFSI as a cationic unipolar conductive polymer, and propylene carbonate as a plasticizer, was prepared as follows: the constituents (fluorinated ionic nonconductive polymer, cationic unipolar conductive polymer, and plasticizer) are mixed with acetonitrile (ACN) under magnetic stirring (300 rpm) at 100°C in a beaker. For 1 g of a mixture of the fluorinated ionic nonconductive polymer and the cationic unipolar conductive polymer, 1 g of plasticizer and 5 g of acetonitrile are used. After mixing, a first coating of the resulting mixture is carried out at 8 mm / s at room temperature on one face of a 16 pm thick porous polypropylene separator to form a film which is left to dry under a hood for a few minutes, in order to evaporate the residual acetonitrile.The second face of the porous separator is then coated with the resulting mixture under the same conditions as for the first coating.

[0181] Table 6 below illustrates the mass percentages of the different constituents present in the EPI7 polymer electrolyte prepared according to the protocol described above, as well as its total thickness:

[0182] [Tableauxô] Electre iyte polymer PMTFSI (% by mass) PVdF (% by mass) PC (% by mass) Film thickness obtained (m) EP17 25 25 50 38

[0183] Performance of cathodes Cl* and C2

[0184] For each of the two cathodes Cl* and C2, a 5 cm² cathode-electrolyte-cathode (CEC) cell is assembled with the EP17 polymer electrolyte. The CECI and CEC2 cells, with the Cl* and C2 cathodes respectively, are assembled by successive rolling at 75°C and 5 bar under dry air. These cells are placed in 2 bar compression systems.

[0185] An impedance spectroscopy measurement is performed on each of these two cells. The ionic conductivity of the electrolytes is measured by impedance spectroscopy. The measurements are carried out in potentiostatic mode between 100 mHz and 1 MHz for an amplitude of 10 mV at 40°C.

[0186] Figure 5 shows the inverse of the imaginary part Z'' in ohms, as a function of the real part Z' in ohms for the Cl* cathode (curve with the dashed line), and for the C2 cathode (curve with the solid line). In Figure 5, the first semicircle obtained at high frequency (HF) is attributed to the polymer electrolyte + catholyte contribution, and the second semicircle to the cathode / collector interfaces. The impedance of the polymer electrolyte + catholyte contribution at high frequency is 490.9% greater for the CECI cell implementing a Cl* cathode without PVDF. Since the EP17 polymer electrolyte is the same for both CECI and CEC2 cells, it is possible to conclude that the use of PVDF in a cathode based on LMFP and PC-plasticized PMTFSI contributes to improving the ionic conductivity of the catholyte.

[0187] Table 7 below lists for each cathode Cl* and C2, the characteristic frequency of the high frequency contribution (in KHz) and the impedance of the high frequency contribution (in kQ.cm2).

[0188] [Tables7] Cathode Characteristic frequency of the high-frequency contribution (in kHz) Impedance of the HF contribution (in kΩ.cm²) Cl* 53.3 4.32 C2 131.4 0.88 * not part of the invention

[0189] Example 6: preparation of a battery according to the invention

[0190] A lithium electrolyte cathode cell (LEC1) is prepared by assembling by successive rolling at 75°C and 5 bars: - a polymer electrolyte EP3' according to the invention, identical to EP3 as prepared in Example 1 except with regard to its thickness, which is 18 pm instead of 34 pm, - a 72 µm thick lithium metal anode, and - a C3 cathode according to the invention, then placed in a 2-bar compression system. The LEC1 cell has a theoretical mass capacity of 5 mAh / g.

[0191] The C3 cathode according to the invention, in the form of a film, was previously prepared as follows: 1.32 g of propylene carbonate (PC), 1.06 g of PMTFSI, 0.26 g of PVdF, and 15 g of ACN are mixed in a beaker under magnetic stirring at 300 rpm and 100°C. Then, 4.2 g of lithium manganese iron phosphate (LMFP) and 0.17 g of carbon black (KB) are added when a homogeneous result is obtained. The resulting mixture is then ground using a ball mill for 8 minutes at 30 rpm. The resulting mixture is coated at room temperature at 30 mm / s onto a collector known as "EnSafe 65" from Armor to form a cathode, which is calendered at 95°C to reduce porosity. A thickness of 37 µm is obtained.

[0192] Table 8 below illustrates the mass percentages of the different constituents present in the C3 cathode prepared according to the protocol described above:

[0193] [Tables8] Constituents C3 LMFP (mass %) 60 KB (mass %) 2.4 PMTFSI (mass %) 15.04 PVdF (mass %) 3.76 PC (mass %) 18.8

[0194] A 40°C cycle was carried out (a 3-hour pause is noted when the cell is placed in an oven) according to the following protocol: - an activation of lOh first occurs by applying a voltage of 3.3V vs Li / Li 4- • 9 - LEC1 performs a first charge C / 10 with a cutoff voltage of 4.2V vs Li / Li+; - the voltage of 4.2V vs Li / Li+ is maintained for 1h30, followed by a discharge D / 10 with a cutoff voltage of 2.5V vs Li / Li+; - Following this first cycle, the battery cycles according to a C / 10 - D / 5 regime. The cutoff voltages during charging and discharging remain at 4.2V vs Li / Li+ respectively. and 2.5V vs Li / Li+. Each charge is punctuated by a voltage of 4.2V vs Li / Li+ imposed for 1h30; - after 40 cycles, the applied regime becomes C / 4 - D / 2.

[0195] The cell, after 358 cycles, has a discharge capacity of 123 mAh / g and an efficiency of 99.8%.

[0196] Fig. 6 shows the capacity of the LEC1 cell (in mAh / g) as a function of the number of cycles (curve with filled diamonds), and the efficiency of the LEC1 cell (in %) as a function of the number of cycles (curve with filled squares).

[0197] Fig. 7 shows the internal resistance Ri of the LEC1 cell (in Ohm.cm2) as a function of the number of cycles, in discharge (curve with solid diamonds) and in charge (curve with solid squares).

[0198] Example 7: preparation of a battery according to the invention

[0199] A lithium electrolyte cathode (LEC2) cell is prepared by assembling successively rolled components at 75°C and 5 bar: - the EP17 polymer electrolyte as prepared in Example 5 according to the invention, - a 72 µm thick lithium metal anode, and - a cathode C3 as prepared in example 6 according to the invention, then placed in a 2-bar compression system. The LEC2 cell has a theoretical mass capacity of 6 mAh / g.

[0200] Table 9 below illustrates the mass percentages of the different constituents present in the cathode C3 prepared according to the protocol described above:

[0201] [Tables9] Constituents C3 LMFP (mass %) 60 KB (mass %) 2.4 PMTFSI (mass %) 15.04 PVdF (mass %) 3.76 PC (mass %) 18.8

[0202] A cycling protocol identical to that described in example 6 was carried out, with the difference that the applied regime becomes C / 4 - D / 2 at the end of the 7th cycle instead of the 40th cycle.

[0203] The cell, after 260 cycles, exhibits a discharge capacity of 123 mAh / g and a yield equal to 100%.

[0204] Fig. 8 shows the capacity of the LEC2 cell (in mAh / g) as a function of the number of cycles (curve with filled diamonds), and the efficiency of the LEC2 cell (in %) as a function of the number of cycles (curve with filled squares).

[0205] Fig. 9 shows the internal resistance Ri of the LEC2 cell (in Ohm.cm2) as a function of the number of cycles in discharge (curve with solid diamonds) and in charge (curve with solid squares).

[0206] Example 8: preparation of an EP18 polymer electrolyte according to the invention

[0207] A polymer electrolyte comprising PVdF-HFP as a fluorinated ionically nonconductive polymer, PMTFSI as a cationically unipolar conducting polymer, and propylene carbonate as a plasticizer was prepared in the manner detailed below.

[0208] The constituents (fluorinated ionic non-conductive polymer, cationic unipolar conductive polymer, and plasticizer) are mixed with acetonitrile (ACN) under magnetic stirring (300 rpm) at 100°C in a beaker. For 1 g of a mixture of the fluorinated ionic non-conductive polymer and the cationic unipolar conductive polymer, 1 g of plasticizer and 5 g of acetonitrile are used. After mixing, the resulting mixture is coated at 8 mm / s at room temperature onto a silicone-coated polyethylene terephthalate (PET) substrate to form a film, which is then dried under a fume hood for a few minutes to evaporate any residual acetonitrile.

[0209] Table 10 below illustrates the mass percentages of the different constituents present in the electrolyte prepared according to the protocol described above, as well as its thickness:

[0210] [TableauxlO] Electrophoretic PMTFSI (% by mass) PVdF-HFP (% by mass) PC (% by mass) Thickness of the film obtained (m) EP18 25 25 50 33

[0211] The EP18 polymer electrolyte was compared to the non-inventory EPI* polymer electrolyte prepared in Example 1 (i.e., free of fluorinated ionically non-conductive polymer).

[0212] Two lithium electrolyte lithium (LEL) cells are then manufactured by successive laminations at 75°C under dry air of a lithium sheet, a polymer electrolyte film, and another lithium sheet.

[0213] For the polymer electrolyte not conforming to the EPI* invention, the laminations are made at a pressure of 2 bars. For the polymer electrolyte according to the invention EPI8, the rolling is carried out at a pressure of 5 bars.

[0214] The LEL1* and LEL18 cells comprising the EPI* and EPI8 polymer electrolytes respectively are placed in 2 bar compression systems.

[0215] The ionic conductivity of the polymer electrolytes EPI* and EPI8 is measured as described in Example 1.

[0216] Figure 10 shows the evolution of ionic conductivity in S.cm⁻¹ as a function of temperature (measurement of the ratio 1000 / temperature, in Kelvin⁻¹) for the polymer electrolyte EPI* (curve with solid circles connected by a solid line) and EPI8 (curve with solid circles connected by a dashed line). The ionic conductivity of a polymer electrolyte is improved in the presence of PVdF-HFP as a fluorinated ionically nonconductive polymer.

Claims

Demands

1. Polymer composition, characterized in that it comprises at least one cationic unipolar conductive polymer, at least one plasticizer, and at least one fluorinated ionic non-conductive polymer, said cationic unipolar conductive polymer being a homopolymer or a copolymer comprising at least one organic polymer chain, organic anionic functions forming covalent bonds with the organic polymer chain, and metal cations associated with the organic anionic functions, and in that the cationic unipolar conductive polymer is: - a homopolymer capable of being prepared from a) a monomer comprising at least one organic anionic function covalently grafted onto said monomer and at least one metal cation associated with the organic anionic function;or - a copolymer capable of being prepared from a) a monomer comprising at least one organic anionic function covalently grafted onto said monomer and at least one metal cation associated with the organic anionic function, and b) at least one monomer different from monomer a) selected from b1) monomers comprising at least one organic anionic function covalently grafted onto said monomer and at least one metal cation associated with the organic anionic function, and b2) organic monomers.;

2. Polymer composition according to claim 1, characterized in that the metal cation(s) associated with the organic anionic functions are chosen from the Li+ and Na+ cations.

3. Polymer composition according to any one of the preceding claims, characterized in that the organic anionic function(s) are bissulfonyl imidides.

4. Polymer composition according to any one of the preceding claims, characterized in that the cationic unipolar conductive polymer represents from 5% to 40% by mass, relative to the total mass of the polymer composition.

5. Polymer composition according to any one of the preceding claims, characterized in that the fluorinated ionically non-conductive polymer represents from 5% to 45% by mass, relative to the total mass of the polymer composition.

6. A polymer composition according to any one of the preceding claims, characterized in that the ionically nonconductive fluorinated polymer is selected from vinyl fluoride (VF) homopolymers and copolymers, vinylidene fluoride (VdF) homopolymers and copolymers, ethylene tetrafluoride (TFE) homopolymers and copolymers, chlorotrifluoroethylene (CTFE) homopolymers and copolymers, hexafluoropropylene (HFP) homopolymers and copolymers, and mixtures thereof.

7. Polymer composition according to any one of the preceding claims, characterized in that the plasticizer is selected from linear and cyclic carbonates; fluorinated carbonates; nitriles; lactones; liquid linear and cyclic polyethers; fluorinated polyethers; sulfur solvents; phosphates; esters; and a mixture thereof.

8. Polymer composition according to any one of the preceding claims, characterized in that the plasticizer represents from 25% to 90% by mass, relative to the total mass of the polymer composition.

9. Use of a polymer composition as defined in any one of the preceding claims, for the preparation of a polymer electrolyte and / or a positive electrode of a rechargeable battery.

10. Polymer electrolyte for a rechargeable battery, characterized in that it comprises a polymer composition as defined in any one of claims 1 to 8, or a porous separator impregnated with a polymer composition as defined in any one of claims 1 to 8.

11. Positive electrode for a rechargeable battery comprising a positive electrode active material, a polymer composition, and optionally an agent generating electronic conductivity, characterized in that the polymer composition is as defined in any one of claims 1 to 8.

12. A rechargeable lithium or sodium battery, characterized in that it comprises: - a negative electrode comprising lithium metal, sodium metal, a lithium metal alloy, or a sodium metal alloy, - a positive electrode, optionally supported by a current collector, and - a polymer electrolyte positioned between the positive electrode and the negative electrode, characterized in that the polymer electrolyte is as defined in claim 10 and / or the positive electrode is as defined in claim 11.

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