A cathode composition for a lithium ion battery that contains lithium having the formula (a) Li.sub.y[M.sup.1.sub.(1-b)Mn.sub.b]O.sub.2 or (b) Li.sub.y[M.sup.1.sub.(1-b)Mn.sub.b]O.sub.1.5+c where 0.ltoreq.y<1, 0