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.