Abstract: The invention relates to an electrochemical cell comprising: —at least one anode comprising metallic lithium or a lithium alloy or at least one anode comprising a current collector at least partially covered with metallic lithium deposited after at least one charge of the cell, the cell not containing metallic lithium at the time of its manufacture, —at least one cathode, - a liquid or gelled electrolyte composition comprising: a) a solvent comprising: i) either a mixture of 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFMP) and/or 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFMFP), ethylene monofluorocarbonate (F1EC) and 2,2,2-trifluoroethyl methyl carbonate (F3EMC), ii) or a mixture of 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFMP) and/or 1,1,1,3,3,3-hexafluo-ro-2-(fluoromethoxy)propane (HFMFP), ethylene monofluorocarbonate (F1EC) and 2,2,2-trifluoroethyl acetate (F3EA), b) at least one salt whose cation is the lithium cation, c) lithium difluorophosphate LiPO2F2 in an amount representing from 0.

Abstract: Disclosed is an electrolyte composition comprising: a) a solvent comprising: i) either a mixture of 1,1,1,3,3,3-hexaflu-oro-2-methoxypropane (HFMP) or of 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFMFP), of monofluoroethylene carbonate (F1EC) and of 2,2,2-trifluoroethyl methyl carbonate (F3EMC), ii) or a mixture of 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFMP) or of 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFMFP), of monofluoroethylene carbonate (F1EC) and of 2,2,2-trifluoroethyl acetate (F3EA), b) at least one lithium salt, the cation of which is the cation of an alkali metal.

Abstract: A gel-type electrolyte comprising a matrix which is a poly(vinylidene fluoride-co-hexafluoropropylene) polymer in which is embedded a liquid mixture comprising at least one lithium salt and a solvent comprising at least one linear carbonate, the poly(vinylidene fluoride-co-hexafluoropropylene) polymer matrix representing 5 to 95% by weight in relation to the weight of the gel-type electrolyte and the liquid mixture representing 95 to 5% by weight in relation to the weight of the gel-type electrolyte. This electrolyte exhibits increased stability with respect to oxidation and reduction.

Abstract: An electrolyte composition for a lithium-ion electrochemical element, comprising: —at least one lithium tetrafluoride or hexafluoride salt, —the salts of lithium bis(fluorosulfonyl)imide LiFSI, —vinylene carbonate, —ethylene sulfate, —at least one organic solvent chosen from the group consisting of cyclic or linear carbonates, cyclic or linear esters, cyclic or linear ethers and a mixture of same. The use of this composition in a lithium-ion electrochemical element increases the service life of the element, in particular under low and high temperature cycling conditions.

Abstract: An electrolyte composition for a lithium-ion electrochemical cell, comprising: at least one tetrafluorinated or hexafluorinated lithium salt, lithium bis(fluorosulfonyl)imide LiFSI salt, vinylene carbonate, ethylene sulfate, lithium difluorophosphate, at least one organic solvent selected from the group consisting of cyclic or carbonates, cyclic or linear esters, cyclic or linear ethers and a mixture thereof, the ratio of the mass of ethylene sulfate to the mass of vinylene carbonate before addition to the solvent being strictly less than 1, the mass percentage of lithium bis(fluorosulfonyl)imidide representing less than 1% of the mass of the group consisting of said at least one tetrafluorinated or hexafluorinated lithium salt, the lithium bis(fluorosulfonyl)imidide salt and said at least one organic solvent. The use of this composition in a lithium-ion electrochemical cell increases the life of the cell, especially under low- and high-temperature cycling conditions.