Patent ID: 7306779

Claim:
A process for producing a hexagonal lithium-cobalt composite oxide for a lithium secondary cell, which comprises: dry blending a cobalt oxyhydroxide powder having an average particle size of from 1 to 20 μm and a specific surface area of from 2 to 200 m 2 /g, a lithium carbonate powder having an average particle size of from 1 to 50 μm and a specific surface area of from 0.1 to 10 m 2 /g, and a powder of an oxide of metal element M having an average particle size of at most 10 μm and a specific surface area of from 1 to 100 m 2 /g; and firing a mixture of the powders at a temperature of from 850 to 1,000° C. in an oxygen-containing atmosphere, wherein the hexagonal lithium-cobalt composite oxide is represented by the formula LiCo 1-x M x O 2 , wherein x is 0.0005≦x≦0.02 and M is at least one member selected from the group consisting of Ta, Ti, Nb, Zr and Hf, and which has a half-width of the diffraction peak for (110) face at 2θ=66.5±1°, of from 0.080 to 0.180°, as measured by the X-ray diffraction using CuK α as a ray source.