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 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 lithium or sodium rechargeable battery comprising such a polymer electrolyte and / or such a positive electrode.

Description

[0001] Polymer composition for electrolyte and / or positive electrode of a rechargeable battery

[0002] The present invention relates to the field of rechargeable batteries, and more specifically to the field of rechargeable lithium or sodium batteries, notably used for the production of electric vehicles and / or the storage of intermittent solar and / or wind energy.

[0003] 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 lithium or sodium rechargeable battery comprising such a polymer electrolyte and / or such a positive electrode.

[0004] Lithium Metal Polymer (or "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 thin film wound or stacked has a thickness of around a hundred micrometers. It generally comprises at least four functional films: a negative electrode (anode) ensuring the supply of lithium ions during discharge; a positive electrode (cathode) acting as a receptacle where the lithium ions are intercalated; a solid polymer electrolyte conducting lithium ions and located between the positive electrode and the negative electrode; and a current collector connected to the positive electrode to ensure the 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) (PEO)-based polymer and at least one lithium salt; the positive electrode comprises an electrode active material, usually based on a metal oxide (such as, for example, V2O5, LiVsOs, LiCoOz, LiNiO2, LiMn204 or LiNio.5Mno.5O2) or based on a phosphate of the UMPO4 type where M represents a metal cation selected from the group Fe, Mn, Co, Ni and Ti, and a combination thereof, and optionally carbon; and the current collector is generally made of a metal foil.

[0005] The solid polymer electrolyte provides a significant safety advantage, as it avoids the use of solvents that could be dangerous in the event of overheating. Such batteries can therefore operate at high temperatures without the risk of explosion. However, commonly used polymer electrolytes, such as high-molecular-weight lithium-doped POE, have low ionic conductivity at room temperature; therefore, their operating temperature must be kept relatively high (typically between 70 and 100°C). At these temperatures, 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 deterioration of the mechanical properties.

[0006] The ionic conductivity of an electrolyte characterizes the ability of electrically charged ions to move within it. The higher it is, the more the movement of ions within it is favored. A polymer electrolyte can be considered interesting if it has an ionic conductivity of at least 10 -5S / 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 closest to 1 is desirable for an electrolyte. In solid polymer electrolytes such as lithium salt-doped POE, the fraction of the charge carried by lithium ions is low (around 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 in the thickness of the electrolyte during battery operation.This behavior generates a salt depletion at the electrode, inducing an increase in the resistance of the electrolyte and reduced power performance, and promotes the formation of lithium dendrites, causing a drop in faradic efficiency and, ultimately, short circuits.

[0007] 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 counterions are the only mobile species, have been described.

[0008] In particular, Meziane et al. (Electrochimica Acta, 2011, 57, 14-19) describes 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 produce an electrolyte membrane containing no additional lithium ions. The results obtained, however, show a relatively low ionic conductivity for temperatures below 60°C (e.g., of the order of 3.1 x 10 -6 S / cm).

[0009] Thus, the aim of the present invention is to overcome the drawbacks of the aforementioned prior art and to provide a polymer composition which has improved ionic conduction properties, a high lithium ion transport number, while guaranteeing good mechanical strength, so that it can be used as a polymer electrolyte of a rechargeable battery, and in particular of a rechargeable lithium or sodium battery.

[0010] The aim of the invention is achieved by the polymer composition which will be described below.

[0011] The inventors of the present application have in fact surprisingly discovered that it is possible to add a fluorinated non-ionic conductive polymer to a particular cationic unipolar conduction polymer associated with a plasticizer, in order to significantly improve the ionic conduction of a polymer composition.

[0012] The polymer composition

[0013] The present invention thus has as its first subject a polymer composition, characterized in that it comprises at least one polymer with cationic unipolar conduction, at least one plasticizer, and at least one fluorinated ionic non-conducting polymer, said polymer with cationic unipolar conduction 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.

[0014] By combining a cationic unipolar conduction polymer as defined above, a plasticizer, and a fluorinated non-ionic conductive polymer, a polymer composition having improved ionic conduction properties is obtained.

[0015] The cationic unipolar conduction polymer

[0016] In the invention, the term “polymer with cationic unipolar conduction” means a polymer (homopolymer or 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. Said metal cations are mobile species responsible for the ionic conduction of the polymer. In other words, the organic anionic functions are grafted onto the organic polymer chain, and / or are pendant organic anionic functions.

[0017] An organic polymer chain means a polymer chain that is free of metal and metalloid. In other words, the organic polymer chain does not contain a metal or metalloid such as silicon, or is different from a polysiloxane chain, or does not contain a Si-O bond.

[0018] An organic anionic function means 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.

[0019] The cationic unipolar conduction polymer of the invention is a polymer comprising anionic organic recurring units (organic polymer chain and organic anionic functions covalently linked to said organic chain), said anionic organic recurring units being associated (ionically) with metal cations.

[0020] The cationic unipolar conduction polymer is preferably obtained by radical polymerization, in particular using at least one 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.

[0021] The cationic unipolar conduction polymer can be:

[0022] - 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

[0023] - 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) chosen from bl) 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.

[0024] By organic monomer (b2) is meant 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.

[0025] The metal cation (of the monomer) or the metal cations (of the polymer) associated with the organic anionic functions are preferably chosen from Li cations + and Na + , and particularly preferably are Li cations + .

[0026] The monomer a) or b1), 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 chosen 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.

[0027] Examples of aromatic vinyl monomers include styrene and its derivatives.

[0028] Styrene derivatives are preferably derivatives in which the phenyl group of styrene is substituted by one or more groups chosen from methyl, ethyl, and tert-butyl groups.

[0029] Examples of non-aromatic vinyl monomers include acrylate, methacrylate, acrylamide, methacrylamide, ethylene, propylene, dienes, or maleimide.

[0030] The organic monomer b2) may be a vinylidene fluoride, a phosphate, a phosphonate, an ether, a carbonate, a malonate, an amide, an acrylate, an anhydride, or an ester.

[0031] In this embodiment, the copolymer comprises, in addition to anionic organic recurring units associated with metal cations, recurring units of vinylidene fluoride, phosphate, phosphonate, ether, carbonate, malonate, amide, acrylate, anhydride, or ester.

[0032] The organic anionic function (of the monomer a) and bl)) or the organic anionic functions (of the polymer) can be chosen from sulfonate, borate, and imide functions.

[0033] The organic anionic functions are preferably imides, particularly preferably bissulfonyl imides, more particularly preferably sulfonyl(trifluoromethylsulfonyl) imides (TFSI) or sulfonyl(fluorosulfonyl) (FSI) imides, and even more particularly preferably sulfonyl(trifluoromethylsulfonyl) imides (TFSI).

[0034] According to a particularly preferred embodiment of the invention, the aromatic or non-aromatic vinyl monomer, comprising at least one organic anionic imide function covalently grafted onto said monomer and Li + as a metal cation associated with the organic anionic imide function, is chosen from the following monomers (Ia) to (Ii): The cationic unipolar conduction polymer is preferably lithium polystyrenesulfonyl(trifluoromethylsulfonyl)imide (PSTFSILi) or lithium polymethacrylatesulfonyl(trifluoromethylsulfonyl)imide (PMTFSILi).

[0035] The cationic unipolar conduction 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.

[0036] 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). The cationic unipolar conduction polymer preferably represents from 5% to 40% by mass approximately, and particularly preferably 5% to 30% by mass approximately, relative to the total mass of the polymer composition.

[0037] The cationic unipolar conduction polymer already comprises anionic functions (anionic groups derived from a lithium salt or a sodium salt directly grafted into the structure of the polymer material). The polymer composition therefore preferably does not comprise any additional or supplementary lithium or sodium salt(s), e.g. molecular lithium or sodium salts (i.e. lithium or sodium salts not grafted to a polymer material).

[0038] Fluorinated ionic non-conducting polymer

[0039] In the invention, the term “ionically non-conducting polymer” means a polymer that does not allow the conduction of lithium or sodium ions. In other words, an ionically non-conducting polymer has an ionic conductivity of less than 10 -7 S / cm, especially at working temperature.

[0040] The fluorinated ionically non-conductive polymer preferably represents from 5% to 45% by mass approximately, and particularly preferably 5% to 40% by mass approximately, relative to the total mass of the polymer composition.

[0041] The ionically non-conducting polymer is fluorinated. In other words, it is a polymer whose repeating unit is a fluorocarbon, and therefore includes several carbon-fluorine bonds.

[0042] The fluorinated ionically non-conductive polymer of the polymer composition of the invention may be chosen 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 a mixture thereof.

[0043] According to a particularly preferred embodiment of the invention, the fluorinated non-ionic conductive polymer is chosen from vinylidene fluoride (VdF) homopolymers and copolymers such as PVdF or P(VdF-HFP).

[0044] According to a more particularly preferred embodiment, the fluorinated ionic non-conducting polymer is PVdF.

[0045] The mass ratio of fluorinated ionic non-conducting polymer / cationic unipolar conducting polymer in the polymer composition preferably ranges from approximately 20 / 80 to 90 / 10, and particularly preferably from approximately 40 / 60 to 80 / 20.

[0046] The fluorinated ionic non-conducting polymer preferably has a number average molar mass (i.e. Mn) ranging from approximately 50,000 g / mol to 1,300,000 g / mol.

[0047] The plasticizer

[0048] The polymer composition comprises at least one plasticizer.

[0049] The plasticizer is a non-aqueous solvent. This allows the formation of a gelled or gel-like polymer composition.

[0050] The non-aqueous solvent or plasticizer can be chosen from:

[0051] - linear and cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), dimethylcarbonate (DMC), diethylcarbonate (DEC), or methylisopropyl carbonate (MiPC);

[0052] - fluorinated carbonates such as fluoroethylene carbonate;

[0053] - nitriles such as succinonitrile;

[0054] - lactones such as y-butyrolactone;

[0055] - liquid linear and cyclic polyethers such as dimethyl ether, polyethylene glycol dimethyl ethers (or PEGDME) such as tetraethylene glycol dimethyl ether (TEGDME), or dioxolane;

[0056] - fluorinated polyethers;

[0057] - sulfur solvents such as sulfolane or dimethyl sulfoxide;

[0058] - phosphates such as triethylphosphate or fluorophosphates; - esters such as ethyl acetate or ethyl butyrate (EB); and - a mixture thereof.

[0059] Among such solvents or plasticizers, linear and cyclic carbonates are particularly preferred.

[0060] The solvent or plasticizer preferably represents from 25% to 90% by mass approximately, particularly preferably from 35% to 90% by mass approximately, and more particularly preferably, from 65% to 90% by mass approximately, relative to the total mass of the polymer composition.

[0061] Additives in the polymer composition

[0062] The polymer composition of the invention may further comprise a reinforcing agent. This thus makes it possible to modulate the mechanical properties of the polymer composition.

[0063] Said reinforcing agent is preferably chosen from cellulose nanofibrils, and ceramic nanoparticles such as titanium oxide, aluminum oxide or silicon oxide nanoparticles.

[0064] According to a particularly preferred embodiment of the invention, the polymer composition comprises (or is made up of):

[0065] - from approximately 40 to 90% by mass of plasticizer, and preferably from approximately 65 to 90% by mass of plasticizer,

[0066] - from 5 to 35% by mass approximately of fluorinated non-ionic conductive polymer, and

[0067] - from 5 to 35% by mass approximately of cationic unipolar conduction polymer.

[0068] Indeed, the mixture of fluorinated ionically non-conducting polymer and cationic unipolar conduction polymer is capable of absorbing a plasticizer, while maintaining good mechanical strength and remaining solid or quasi-solid. Furthermore, the presence of the plasticizer makes it possible to obtain a solid or quasi-solid polymer composition having improved ionic conductivity (eg conductivity of at least lxlO -5S / cm at 25°C). The polymer composition of the invention is preferably prepared by mixing the various constituents, namely the cationic unipolar conduction polymer, the plasticizer, and the fluorinated ionic non-conducting polymer. In particular, the constituents (fluorinated ionic non-conducting polymer, cationic unipolar conduction polymer, and plasticizer) are mixed in an organic solvent such as acetonitrile, advantageously with magnetic stirring. The mixing can be carried out hot, in particular at a temperature of at least 50°C, preferably at least 80°C, and more preferably at least 90°C. The resulting mixture can then be deposited on a support by coating, advantageously at room temperature (eg 18-25°C). Drying can then be carried out, in particular to remove the organic solvent.

[0069] The use of polymer composition

[0070] The second subject of the invention is the use of a polymer composition as defined in the first subject 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.

[0071] The use of a polymer composition in accordance with the present invention for the preparation of a polymer electrolyte for a rechargeable lithium battery leads to an energy storage device having excellent performance at low temperature (i.e. < 60°C, and preferably < 40°C), in particular a lithium ion transport number of the order of 1, and an ionic conductivity greater than or equal to 10 -5 S. cm -1 , preferably greater than or equal to 5xl0-5 S. cm -1 , and particularly preferably greater than or equal to 10 -4 S. cm -1, at a temperature of at most 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 speed). The use of this polymer composition also makes it possible to limit the dendritic growth of lithium, and thus to envisage rapid and safe recharges. Indeed, the problem with lithium metal battery technology is the formation of heterogeneous lithium electrodeposits (including dendrites) during recharge, which reduces cyclability and can lead to short circuits. The polymer composition in accordance with the present invention also has good mechanical strength, high thermal stability (which ensures the safety of the energy storage devices comprising them), and improved potential stability (e.g. stability up to 4.5 V vs. Li+ / Li).

[0072] The use of a polymer composition according to the present invention for the preparation of a positive electrode of a rechargeable lithium metal or sodium metal battery makes it possible to improve the ionic conductivity and thus to lower the operating temperature of the battery, and to improve its power response. Furthermore, the polymer composition improves the adhesion of the positive electrode to the current collector.

[0073] Polymer electrolyte

[0074] The third subject of the invention is a polymer electrolyte for a rechargeable battery, characterized in that it comprises a polymer composition in accordance with the first subject of the invention, or a porous separator impregnated with a polymer composition in accordance with the first subject of the invention.

[0075] The porous separator may be made of a porous, non-electronically conductive material, preferably of 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).

[0076] The polymer electrolyte is preferably in the form of a film, particularly preferably in the form of a film having a thickness ranging from about 5 to 45 μm, and more particularly preferably ranging from about 10 to 25 μm.

[0077] When the polymer electrolyte comprises (or consists of) a porous separator impregnated with a polymer composition conforming to the first object, the porous separator is preferentially coated with the polymer composition on a first face and on a second face opposite the first face.

[0078] 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, by extrusion or by pressing (cold or hot).

[0079] 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.

[0080] The positive electrode

[0081] The fourth subject of the invention is 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 subject of the invention.

[0082] The positive electrode 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.

[0083] The active material of the positive electrode

[0084] The positive electrode active material is a reversible active material of lithium or sodium ions. In other words, it can reversibly insert or de-insert lithium or sodium ions.

[0085] The positive electrode active material can be:

[0086] - a metal oxide such as, for example, vanadium oxide Ox (2 < x < 2.5), LiVsOs, LiyNii-xCOxCh (0 < x < 1; 0 < y < 1), manganese spinel LiyMni xMxC (M = Cr, Al, V, Ni, 0 < x < 0.5; 0 < y < 2), V2O5, lithium oxides such as, for example, LiCoOz, LiNiC, LiMn2O4, LiNii / 3Mni / 3Coi / 3O2 (NMC), LiNio,8Coo,i5Alo,os02 (NCA), and LiNio,5Mno,s02, - a metal phosphosilicate or phosphate, for example, LisVzCPCU or LiMPCU, where M represents a metal cation selected from the group Fe, Mn, Co, Ni and Ti, and a combination thereof, or

[0087] - a metal sulfate, for example iron sulfate FezCSCU.

[0088] The active material of the positive electrode may represent from 50 to 90% by mass approximately, and preferably from 55 to 80% by mass approximately, relative to the total mass of the positive electrode.

[0089] The agent generating electronic conductivity

[0090] The agent generating electronic conductivity may be chosen from carbon blacks, acetylene blacks, carbon fibers and nanofibers, carbon nanotubes, graphene, graphite, metal particles and fibers of at least one conductive metal such as aluminum, platinum, iron, cobalt and nickel, and one of their mixtures.

[0091] The agent generating electronic conductivity is preferably carbon black.

[0092] The agent generating electronic conductivity may represent from 0.1 to 10% by mass approximately, and preferably from 0.5 to 5% by mass approximately, relative to the total mass of the positive electrode.

[0093] The polymer composition

[0094] The polymer composition is a polymer composition as defined in the first subject of the invention.

[0095] The polymer composition may 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.

[0096] The positive electrode preferably does not comprise a molecular lithium or sodium salt.

[0097] The positive electrode is preferably in the form of a film whose thickness is generally of the order of 20 to a hundred micrometers.

[0098] Rechargeable lithium or sodium battery The fifth subject of the invention is a rechargeable lithium or sodium battery, characterized in that it comprises:

[0099] - a negative electrode comprising lithium metal, sodium metal, a lithium metal alloy, or a sodium metal alloy,

[0100] - a positive electrode, possibly supported by a current collector, and

[0101] - a polymer electrolyte positioned between the positive electrode and the negative electrode, characterized in that the polymer electrolyte is as defined in the third subject of the invention and / or the positive electrode is as defined in the fourth subject of the invention.

[0102] The negative electrode

[0103] The negative electrode is preferably in the form of a film whose thickness is generally of the order of 1 to a hundred micrometers.

[0104] The negative electrode may be made of metallic lithium, metallic sodium, one of the lithium alloys such as an alloy of lithium with sodium, silicon, tin, aluminum, magnesium, silver, zinc, or germanium, or one of the sodium alloys such as an alloy of sodium with lithium, silicon, tin, aluminum, magnesium, silver, zinc, or germanium.

[0105] The negative electrode is preferably made of metallic lithium or one of the lithium alloys.

[0106] The positive electrode

[0107] The positive electrode may be a positive electrode according to the fourth subject 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. The positive electrode active material and the agent generating electronic conductivity are as defined in the fourth subject of the invention.

[0108] The plasticizer

[0109] The plasticizer (or non-aqueous solvent) can be chosen from:

[0110] - linear and cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), dimethylcarbonate (DMC), diethylcarbonate (DEC), or methylisopropyl carbonate (MiPC);

[0111] - fluorinated carbonates such as fluoroethylene carbonate;

[0112] - nitriles such as succinonitrile;

[0113] - lactones such as y-butyrolactone;

[0114] - liquid linear or cyclic polyethers such as dimethyl ether, polyethylene glycol dimethyl ethers (or PEGDME) such as tetraethylene glycol dimethyl ether (TEGDME), or dioxolane;

[0115] - fluorinated polyethers;

[0116] - sulfur solvents such as sulfolane or dimethyl sulfoxide;

[0117] - phosphates such as triethylphosphate or fluorophosphates;

[0118] - esters such as ethyl acetate or ethyl butyrate (EB); and

[0119] - one of their blends.

[0120] Among such solvents or plasticizers, linear and cyclic carbonates are particularly preferred.

[0121] The plasticizer may 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.

[0122] The polymer binder

[0123] The polymer binder may be chosen from homopolymers and copolymers of ethylene; homopolymers and copolymers of propylene; homopolymers and copolymers of ethylene oxide (eg POE, copolymer of POE), methylene oxide, propylene oxide, epichlorohydrin, allylglycidyl ether, and mixtures thereof; halogenated polymers such as homopolymers and copolymers of vinyl chloride, vinylidene fluoride (PVdF), vinylidene chloride, ethylene tetrafluoride, chlorotrifluoroethylene, or mixtures thereof; non-electronically conductive polymers of anionic type 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-co-diallyldimethyl ammonium chloride) (AMAC) or mixtures thereof; polyacrylates; elastomers such as homopolymers or copolymers of ethylene, propylene, styrene, butadiene or chloroprene; cationic unipolar conduction polymers; and a mixture thereof.;

[0124] The cationic unipolar conduction polymers may be as defined in the first subject of the invention.

[0125] The polymer binder may 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.

[0126] 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 makes it possible to improve the interface: active material - polymer binder.

[0127] The carbon coating the active material preferably represents approximately 0.1 to 5% by mass, relative to the mass of active material.

[0128] The carbon layer is preferably in the form of a layer with a thickness varying from approximately 1 to 4 nm.

[0129] The positive electrode may further comprise a lithium or sodium salt, in particular when the polymer binder is other than a cationic unipolar conduction polymer. According to a particularly preferred embodiment of the invention, the positive electrode is a positive electrode in accordance with the fourth subject of the invention.

[0130] The current collector

[0131] The rechargeable battery may further comprise a current collector, connected to the positive electrode.

[0132] The current collector is usually made of a metal sheet.

[0133] The current collector is preferably a stainless steel or aluminum current collector, possibly coated with a carbon-based layer (anti-corrosion layer).

[0134] Polymer electrolyte

[0135] The polymer electrolyte may be a polymer electrolyte in accordance with the third subject of the invention or the polymer electrolyte may comprise a cationic unipolar conduction polymer; or the combination of at least one lithium salt and at least one polymer material chosen from polymer materials based on poly(ethylene oxide) (PEO), polycarbonates, and polydiesters.

[0136] The poly(ethylene oxide) (PEO)-based polymer material may be selected from a polystyrene-poly(ethylene oxide) block copolymer (PS-b-PEO), a polystyrene-poly(ethylene oxide)-polystyrene block copolymer (PS-b-PEO-b-PS), a poly(ethylene oxide-stat-propylene oxide) random copolymer (i.e., PEO-stat-PPO), a poly(ethylene oxide-stat-butylene oxide) random copolymer (i.e., PEO-stat-PBO), a poly(ethylene oxide), and a mixture thereof.

[0137] The lithium salt used in association with the poly(ethylene oxide)-based polymer material may be selected from lithium fluorate (LiFOs), lithium bis(trifluoromethanesulfonyl) imide (LiTFSI), lithium hexafluorophosphate (LiPFe), lithium fluoroborate (UBF4), lithium metaborate (UBO2), lithium perchlorate (UCIO4), lithium nitrate (LiNCh), lithium bis(fluorosulfonyl) imide (LiFSI), lithium bis(pentafluoroethylsulfonyl) imide (LiBETI), LiAsFe, UCF3SO3, LiSbFe, LiSbCl, LizTiCl, LizSeCl, U2B10Cl10, U2B12Cl12, lithium bis(oxalato)borate (LiBOB), and a mixture thereof.

[0138] The lithium salt preferably represents from 5 to 30% by mass, and even more preferably from 10 to 25% by mass, relative to the total mass of the polymer electrolyte.

[0139] The said polymer material based on poly(ethylene oxide) (PEO) can be combined with a reinforcing agent. This makes it possible to modulate the mechanical properties of the polymer material.

[0140] Said reinforcing agent is preferably chosen 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).

[0141] The cationic unipolar conduction polymer is as defined in the first subject of the invention.

[0142] According to a particularly preferred embodiment of the invention, the polymer electrolyte is a polymer electrolyte in accordance with the third subject of the invention.

[0143] The present invention is illustrated by the following exemplary embodiments, to which it is however not limited.

[0144] Brief description of the drawings

[0145] The accompanying drawings illustrate the invention.

[0146] Figure 1 shows the evolution of ionic conductivity in S. cm 1 depending on the temperature (in Kelvin -1 ) for a conventional polymer electrolyte and polymer electrolytes of the invention.

[0147] Figure 2 shows the evolution of ionic conductivity in S. cm 1 depending on the temperature (in Kelvin -1 ) for a conventional polymer electrolyte and polymer electrolytes of the invention. Figure 3 shows the evolution of the ionic conductivity in S. cm 1 depending on the temperature (in Kelvin -1 ) for a conventional polymer electrolyte and polymer electrolytes of the invention.

[0148] Figure 4 shows the evolution of ionic conductivity in S. cm 1 depending on the temperature (in Kelvin -1 ) for conventional polymer electrolytes.

[0149] Figure 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.

[0150] Figure 6 shows the capacity (in mAh / g) and the efficiency (in %) as a function of the number of cycles of a battery according to the invention.

[0151] Figure 7 shows the internal resistance Ri (in Ohm. cm 2 ) depending on the number of cycles, in discharge and in charge, of a battery according to the invention.

[0152] Figure 8 shows the capacity (in mAh / g) and the efficiency (in %) as a function of the number of cycles of a battery according to the invention.

[0153] Figure 9 shows the internal resistance Ri (in Ohm. cm 2 ) depending on the number of cycles, in discharge and in charge, of a battery according to the invention.

[0154] Figure 10 shows the evolution of ionic conductivity in S. cm 1 depending on the temperature (in Kelvin -1 ) for a conventional polymer electrolyte and a polymer electrolyte of the invention.

[0155] Examples

[0156] The raw materials used in the examples are listed below

[0157] - carbon black, Sumitomo Corp, reference “ECP-600JD”,

[0158] - Lithium Manganese Iron Phosphate (LMFP), Huayi, grade 2,

[0159] - 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,

[0160] - propylene carbonate (PC), Aldrich, anhydrous, purity 99.7%,

[0161] - triethyl phosphate (TEP), TCI, purity > 99.0%,

[0162] - PMTFSI: poly((trifluoromethane)sulfonimide lithium methacrylate), Specific Polymers, with molar mass Mn = 238,330 g / mol,

[0163] - PSTFSI: poly(styrene tri(fluoromethane) sulfonimide), molar mass Mn= 84,720g / mol,

[0164] - PMMA: poly(methyl methacrylate), Sigma-Aldrich, Mw ~ 996,000 g / mol,

[0165] - Acetonitrile, Sigma-Aldrich, anhydrous, purity 99.8%,

[0166] - lithium metal sheet, Ganfeng extruded then rolled to 72 pm,

[0167] - lithium metal electrode, Ganfeng extruded then rolled to 72 pm,

[0168] - 72 pm thick lithium metal anode, Ganfeng extruded then rolled to 72 pm,

[0169] - “EnSafe 65” collector, Armor.

[0170] Unless otherwise stated, all materials were used as received from the manufacturers.

[0171] Example 1: preparation of a polymer electrolyte EPI* not in accordance with the invention and polymer electrolytes EP2, EP3, EP4 and EP5 in accordance with the invention

[0172] Several polymer electrolytes comprising PVdF as a fluorinated ionic non-conducting polymer, PMTFSI as a cationic unipolar conducting polymer, and propylene carbonate as a plasticizer were prepared as detailed below.

[0173] The constituents (fluorinated non-ionic conducting polymer, cationic unipolar conducting 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 non-ionic conducting polymer and the cationic unipolar conducting 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 on a silicone-coated polyethylene terephthalate (PET) support to form a film which is left to dry under a hood for a few minutes, in order to evaporate the residual acetonitrile.

[0174] 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:

[0175] * not part of the invention

[0176] TABLE 1

[0177] For each of the polymer electrolytes, a lithium electrolyte lithium (LEL) cell is then manufactured by successive laminations at 75°C in dry air of a lithium sheet, a polymer electrolyte film as prepared above, and another lithium sheet.

[0178] For the polymer electrolyte not in accordance with the invention EPI*, the laminations are carried out at a pressure of 2 bars. For the other polymer electrolytes, EP2 to EP5, the laminations are carried out at a pressure of 5 bars.

[0179] 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.

[0180] The ionic conductivity of the polymer electrolytes EPI*, EP2, EP3, EP4, and EP5 is measured by impedance spectroscopy using a device sold under the trade name IM6EX by Zahner. The measurements are carried out with the LEL1*, LEL2, LEL3, LEL4, and LEL5 cells as prepared above, in potentiostatic mode between 100 mHz and 1 MHz for an amplitude of 10 mV at 20°C and 40°C.

[0181] Figure 1 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), EP2 (curve with solid circles connected by a wide dotted line), EP3 (curve with solid circles connected by a normal dotted line), EP4 (curve with solid circles connected by a short dotted line), and EP5 (curve with solid triangles connected by a solid line). The ionic conductivity of a polymer electrolyte is all the more important as the PVdF content used in the polymer electrolyte is high. The introduction of PVdF, as a fluorinated non-ionic conductive polymer, contributes to increasing the ionic conductivity of polymer electrolytes based on at least one cationic unipolar conduction polymer such as PMTFSI plasticized with at least one plasticizer such as propylene carbonate.

[0182] Example 2: preparation of a polymer electrolyte EP6* not in accordance with the invention and polymer electrolytes EP7, EP8, EP9 and EP10 in accordance with the invention

[0183] Several polymer electrolytes comprising PVdF as a fluorinated ionic non-conducting polymer, PSTFSI as a cationic unipolar conducting polymer, and propylene carbonate as a plasticizer were prepared as detailed below.

[0184] The constituents (fluorinated non-ionic conducting polymer, cationic unipolar conducting 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 non-ionic conducting polymer and the cationic unipolar conducting 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 on a silicone-coated polyethylene terephthalate (PET) support to form a film which is left to dry under a hood for a few minutes, in order to evaporate the residual acetonitrile.

[0185] 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:

[0186] * not part of the invention

[0187] TABLE 2

[0188] For each of the polymer electrolytes, a lithium electrolyte lithium (LEL) cell is then manufactured by successive laminations at 75°C in dry air of a lithium sheet, a polymer electrolyte film as prepared above, and another lithium sheet.

[0189] For the polymer electrolyte not in accordance with the invention EP6*, the laminations are carried out at a pressure of 2 bars. Furthermore, two layers of polymer electrolyte EP6* are used to avoid a possible short circuit. For the other polymer electrolytes, EP7 to EP10 in accordance with the invention, the laminations are carried out at a pressure of 5 bars.

[0190] 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.

[0191] The ionic conductivity of polymer electrolytes EP6*, EP7, EP8, EP9, and EP10 is measured as described in Example 1.

[0192] 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 -1) for the polymer electrolyte EP6* (curve with solid circles connected by a solid line), EP7 (curve with solid circles connected by a wide dotted line), EP8 (curve with solid circles connected by a normal dotted line), EP9 (curve with solid circles connected by a short dotted line), and EP10 (curve with solid triangles connected by a solid line). The introduction of PVdF, as a non-ionically conducting polymer, contributes to increasing the ionic conductivity of polymer electrolytes based on at least one cationic unipolar conduction polymer such as PSTFSI plasticized with at least one plasticizer such as propylene carbonate. The ionic conductivity reaches a maximum for a PVdF content of 35% by mass, relative to the total mass of the polymer electrolyte.

[0193] Example 3: preparation of a polymer electrolyte EP11* not in accordance with the invention and polymer electrolytes EP12 and EP13 in accordance with the invention

[0194] Several polymer electrolytes comprising PVdF as a fluorinated ionic non-conducting polymer, PMTFSI as a cationic unipolar conducting polymer, and triethyl phosphate (TEP) as a plasticizer were prepared as detailed below.

[0195] The constituents (fluorinated non-ionic conducting polymer, cationic unipolar conducting 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 non-ionic conducting polymer and the cationic unipolar conducting 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 on a silicone-coated polyethylene terephthalate (PET) support to form a film which is left to dry under a hood for a few minutes, in order to evaporate the residual acetonitrile.

[0196] 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:

[0197] * not part of the invention

[0198] TABLE 3

[0199] For each of the polymer electrolytes, a lithium electrolyte lithium (LEL) cell is then manufactured by successive laminations at 75°C in dry air of a lithium sheet, a polymer electrolyte film as prepared above, and another lithium sheet.

[0200] For the polymer electrolyte not in accordance with the invention EP11*, the laminations are carried out at a pressure of 2 bars and a lithium electrode is used instead of two lithium sheets. For the other polymer electrolytes, EP12 and EP13 in accordance with the invention, the laminations are carried out at a pressure of 5 bars.

[0201] The LEL11*, LEL12, and LEL13 cells comprising the polymer electrolytes EP11*, EP12, and EP13 respectively are placed in 2 bar compression systems.

[0202] The ionic conductivity of polymer electrolytes EP11*, EP12, and EP13 is measured as described in Example 1.

[0203] Figure 3 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 EP11* (curve with solid circles connected by a solid line), EP12 (start of curve with a solid square), and EP13 (curve with solid circles connected by a dotted line). The ionic conductivity of a polymer electrolyte is all the more important as the rate of PVdF used in the polymer electrolyte is high. The introduction of PVdF, as a non-ionically conducting polymer, contributes to increasing the ionic conductivity of polymer electrolytes based on at least one polymer with cationic unipolar conduction such as PMTFSI plasticized with at least one plasticizer such as triethyl phosphate.

[0204] Comparative Example 4: Preparation of polymer electrolytes EP14*, EP15* and EP16* not in accordance with the invention

[0205] Several polymer electrolytes comprising PMMA instead of PVdF as the non-fluorinated ionic non-conducting polymer, PMTFSI as the cationic unipolar conducting polymer, and propylene carbonate as the plasticizer were prepared as detailed below.

[0206] The constituents (non-fluorinated ionic non-conducting polymer, cationic unipolar conduction 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-conducting polymer PMMA and the cationic unipolar conduction 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 on a silicone-coated polyethylene terephthalate (PET) support to form a film which is dried under a hood for a few minutes to evaporate the residual acetonitrile.

[0207] 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:

[0208] * not part of the invention

[0209] TABLE 4 For each of the polymer electrolytes, a lithium electrolyte lithium (LEL) cell is then manufactured by successive laminations at 75°C in dry air of a lithium sheet, a polymer electrolyte film as prepared above, and another lithium sheet.

[0210] For the polymer electrolyte not in accordance with the invention EPI*, the laminations are carried out at a pressure of 2 bars. For the other polymer electrolytes, not in accordance with the invention, EP14* to EP16*, the laminations are carried out at a pressure of 5 bars.

[0211] The LEL1*, LEL14*, LEL15*, and LEL16* cells comprising the polymer electrolytes EPI*, EP14*, EP15*, and EP16* respectively are placed in 2 bar compression systems.

[0212] The ionic conductivity of polymer electrolytes EPI*, EP14*, EP15*, and EP16* is measured as in Example 1.

[0213] Figure 4 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), EP14* (curve with empty circles connected by a wide dotted line), EP15* (curve with solid circles connected by a normal dotted line), and EP16* (curve with solid circles connected by a short dotted line). Unlike PVdF, the use of PMMA decreases the ionic conductivity of the polymer electrolyte.

[0214] Example 5: Preparation of cathodes Cl* not in accordance with the invention and C2 in accordance with the invention

[0215] Preparation of Cl* and C2 cathodes

[0216] A first cathode (positive electrode) Cl* not in accordance with the invention (i.e. without PVdF as a fluorinated non-ionic conductive 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 Armor's "EnSafe 65" to form a cathode which is calendered at 95°C to reduce porosity. A thickness of 34 μm is obtained.

[0217] A second cathode C2 according to the invention (i.e. with PVdF as a fluorinated non-ionic conducting 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 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 Armor's "EnSafe 65" to form a cathode which is calendered at 95°C to reduce porosity. A thickness of 40 μm is obtained.

[0218] Table 5 below illustrates the mass percentages of the different constituents present in the cathodes prepared according to the protocol described above:

[0219] * not part of the invention

[0220] TABLE 5

[0221] Preparation of a polymer electrolyte EP17 in accordance with the invention A polymer electrolyte EP17 in accordance with the invention comprising PVdF as a fluorinated ionic non-conducting polymer, PMTFSI as a cationic unipolar conduction polymer, and propylene carbonate as a plasticizer was prepared as follows: the constituents (fluorinated ionic non-conducting polymer, cationic unipolar conduction 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-conducting polymer and the cationic unipolar conduction 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 a first face of a 16 μm 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.

[0222] Table 6 below illustrates the mass percentages of the different constituents present in the EP17 polymer electrolyte prepared according to the protocol described above as well as its total thickness:

[0223] TABLE 6

[0224] Performance of Cl* and C2 cathodes

[0225] For each of the two cathodes Cl* and C2, a 5 cm cathode electrolyte cathode cell (CEC) 2is assembled with the polymer electrolyte EP17. The CECI and CEC2 cells with the cathodes Cl* and C2 respectively are assembled by successive rolling at 75°C and 5 bars under dry air. These cells are placed in 2 bar compression systems. An impedance spectroscopy measurement is carried out 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.

[0226] Figure 5 shows the opposite of the imaginary part Z" in ohms, as a function of the real part Z' in ohms for the cathode Cl* (curve with the dotted line), and for the cathode C2 (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 located at high frequency is 490.9% higher for the CECI cell implementing a Cl* cathode without PVDF. Since the polymer electrolyte EP17 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 PMTFSI plasticized with PC contributes to improving the ionic conductivity of the catholyte.

[0227] 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 k .cm 2 ).

[0228] * not part of the invention

[0229] TABLE 7

[0230] Example 6: preparation of a battery according to the invention

[0231] A lithium electrolyte cathode cell (LEC1) is prepared by assembling by successive rolling at 75°C and 5 bars: - a polymer electrolyte EP3' in accordance with the invention, identical to EP3 as prepared in example 1 except with regard to its thickness which is 18 μm instead of 34 μm,

[0232] - a 72 pm thick lithium metal anode, and

[0233] - a C3 cathode in accordance with the invention, then placed in a 2 bar compression system.

[0234] The LEC1 cell has a theoretical mass capacity of 5 mAh / g.

[0235] 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 min at 30 rpm. The resulting mixture is coated at room temperature at 30 mm / s on 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 pm is obtained.

[0236] Table 8 below illustrates the mass percentages of the different constituents present in the C3 cathode prepared according to the protocol described above:

[0237] TABLE 8 Cycling at 40°C was carried out (a 3-hour break is marked when the cell is placed in the oven) according to the following protocol:

[0238] - an activation of lOh first takes place by applying a voltage of 3.3V vs Li / Li + ;

[0239] - LEC1 performs a first C / 10 charge with a cut-off voltage of 4.2V vs Li / Li + ;

[0240] - the voltage of 4.2V vs Li / Li + is maintained for 1h30, and a D / 10 discharge follows with a cut-off voltage of 2.5V vs Li / Li + ;

[0241] - following this first cycle, the battery cycles according to a C / 10 - D / 5 regime. The cut-off voltages for charging and discharging remain respectively 4.2V vs Li / Li + and 2.5V vs Li / Li+ Each charge is punctuated by a voltage of 4.2V vs Li / Li + imposed for 1h30;

[0242] - after 40 cycles, the applied regime becomes C / 4 - D / 2.

[0243] The cell, after 358 cycles, has a discharge capacity of 123 mAh / g and an efficiency of 99.8%.

[0244] Figure 6 shows the capacity of the LEC1 cell (in mAh / g) as a function of the number of cycles (curve with solid diamonds), and the efficiency of the LEC1 cell (in %) as a function of the number of cycles (curve with solid squares).

[0245] Figure 7 shows the internal resistance Ri of the LEC1 cell (in Ohm. cm 2 ) as a function of the number of cycles, in discharge (curve with solid diamonds) and in charge (curve with solid squares).

[0246] Example 7: preparation of a battery according to the invention

[0247] A lithium electrolyte cathode cell (LEC2) is prepared by assembling by successive rolling at 75°C and 5 bars:

[0248] - the polymer electrolyte EP17 as prepared in example 5 in accordance with the invention,

[0249] - a 72 μm thick lithium metal anode, and - a C3 cathode as prepared in Example 6 in accordance with the invention, then placed in a 2 bar compression system.

[0250] The LEC2 cell has a theoretical mass capacity of 6 mAh / g.

[0251] Table 9 below illustrates the mass percentages of the different constituents present in the C3 cathode prepared according to the protocol described above:

[0252] TABLE 9

[0253] A cycling protocol identical to that described in example 6 was carried out except that the applied regime becomes C / 4 - D / 2 at the end of the 7 ème cycle instead of 40 ème cycle.

[0254] The cell, after 260 cycles, has a discharge capacity of 123 mAh / g and an efficiency equal to 100%.

[0255] Figure 8 shows the capacity of the LEC2 cell (in mAh / g) as a function of the number of cycles (curve with solid diamonds), and the efficiency of the LEC2 cell (in %) as a function of the number of cycles (curve with solid squares).

[0256] Figure 9 shows the internal resistance Ri of the LEC2 cell (in Ohm. cm 2 ) as a function of the number of discharge cycles (curve with solid diamonds) and charge cycles (curve with solid squares). Example 8: preparation of an EP18 polymer electrolyte in accordance with the invention

[0257] A polymer electrolyte comprising PVdF-HFP as a fluorinated ionic non-conducting polymer, PMTFSI as a cationic unipolar conducting polymer, and propylene carbonate as a plasticizer was prepared as detailed below.

[0258] The constituents (fluorinated non-ionic conducting polymer, cationic unipolar conducting 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 non-ionic conducting polymer and the cationic unipolar conducting 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 on a silicone-coated polyethylene terephthalate (PET) support to form a film which is left to dry under a hood for a few minutes, in order to evaporate the residual acetonitrile.

[0259] 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:

[0260] TABLE 10

[0261] The polymer electrolyte EP18 was compared to the polymer electrolyte EPI* not in accordance with the invention prepared in example 1 (i.e. free of fluorinated non-ionic conductive polymer).

[0262] Two lithium electrolyte (LEL) cells are then manufactured by successive laminations at 75°C in dry air of a lithium sheet, a polymer electrolyte film, and another lithium sheet. For the polymer electrolyte not in accordance with the EPI* invention, the laminations are carried out at a pressure of 2 bars. For the polymer electrolyte in accordance with the EP18 invention, the lamination is carried out at a pressure of 5 bars.

[0263] The LEL1* and LEL18 cells comprising the polymer electrolytes EPI* and EP18 respectively are placed in 2 bar compression systems.

[0264] The ionic conductivity of the polymer electrolytes EPI* and EP18 is measured as described in Example 1.

[0265] 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 EP18 (curve with solid circles connected by a dotted line). The ionic conductivity of a polymer electrolyte is improved in the presence of PVdF-HFP as a fluorinated non-ionic conductive polymer.

Claims

Claims 1. Polymer composition, characterized in that it comprises at least one cationic unipolar conduction polymer, at least one plasticizer, and at least one fluorinated ionic non-conducting polymer, said cationic unipolar conduction 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.

2. Polymer composition according to claim 1, characterized in that the cationic unipolar conduction 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) chosen from bl) 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.

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

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

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

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

7. Polymer composition according to any one of the preceding claims, characterized in that the fluorinated non-ionic conductive polymer is chosen 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 a mixture thereof.

8. Polymer composition according to any one of the preceding claims, characterized in that the plasticizer is chosen from linear and cyclic carbonates; fluorinated carbonates; nitriles; lactones; liquid linear and cyclic polyethers; fluorinated polyethers; sulfur-containing solvents; phosphates; esters; and one of their mixtures.

9. 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.

10. 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.

11. Polymer electrolyte for a rechargeable battery, characterized in that it comprises a polymer composition as defined in any one of claims 1 to 9, or a porous separator impregnated with a polymer composition as defined in any one of claims 1 to 9.

12. 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 any one of claims 1 to 9.

13. 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 11 and / or the positive electrode is as defined in claim 12.

Images