Intercalation cathode materials especially suited for use in high-voltage, high-energy lithium rechargeable batteries, having the formulae Li[Li(.sub.1-2x)/.sub.3M.sub.yMn(.sub.2-x)/.sub.3Ni(.sub.x-y)O.sub.2, where 0y, and M is one or more divalent cations from Ca, Cu, Mg, and Zn. A process for making such materials is also provided.