To prepare a high-capacity cathode material with improved electrochemical performance for lithium rechargeable batteries, Co3(PO4)2 nanoparticles are coated on the surface of powdered Li[Co0.1Ni0.15Li0.2Mn0.55]O2, which is synthesized by a simple combustion method. The coated powder prepared under proper conditions for Co3(PO4)2 content and annealing temperature shows an optimum coating layer that consists of a Li x CoPO4 phase formed by reaction with lithium impurities during heat treatment. A sample coated with 3wt.% Co3(PO4)2 and annealed at 800°C proves to be the best in terms of specific capacity, cycle performance and rate capability. Thermal stability is also enhanced by the coating, as demonstrated a decrease in the onset temperature and/or the heat generated during thermal runaway.