The invention concerns an ionic conducting material containing an oligoether sulphate. The material comprises an ionic compound in solution in a solvating polymer. The ionic compound is a mixture of a lithium bis(trifluoromethanesulphonyl)imidide and of at least one lithium oligoether sulphate selected among lithium oligoether sulphate of formula R-[O-CH2-CH2)]n-O-SO3-Li+ (I), wherein: R is a CmH2m+1 group with 1 = m =4 and 2 = n =17, and lithium oligoether sulphate of formula Li+ O-SO2-O-CH2 [CH2-O-CH2]p-CH2-O-SO2-O- Li+ (II), wherein 3 =p =45; the overall ratio Ot/Lit is not more than 40, Ot representing the total number of atoms O supplied by the solvating polymer and by the oligoether; the LiTFSI content is such that the Ot/LiTFSI ratio is not less than 20.