Lithium insertion compound of high voltage used as cathodic active mass in a lithium rechargeable electrochemical generator

An insertion lithium compound is derived by substitution of dioxide of manganese lithia of spinel structure and has the formula (I) LiMn2-(x+y)(MxM'y)4 (I) x 0; y 0; X+Y 0.50 M = Ni (nickel) or Co (cobalt); and M' = Ti (titanium), Al (aluminium), Co (cobalt) or molybdenum (Mo). Independent claims are also included for: (a) fabrication of the insertion compound; (b) an electrode for a lithium rechargeable electrochemical generator containing, as the active electrochemical material, the insertion compound; and (c) a lithium based rechargeable electrochemical generator using such an electrode.