A positive electrode for a non-aqueous lithium cell comprising a LiMn_2-xM_xO₄ spinel structure in which M is one or more metal cations with an atomic number less than 52, such that the average oxidation state of the manganese ions is equal to or greater than 3.5, and in which 0x0.15, having one or more lithium spine oxide LiM₂O₄ or lithiated spinel oxide Li_1+yM₂O₄ compounds on the surface thereof in which M are cobalt cations and in which 0y1.