Patent ID: 6893776

Claim:
A positive active material for a non-aqueous electrolyte secondary battery, comprising a lithium-nickel composite oxide represented by the compositional formula Li a Ni 1−b−c Co b Mn c O 2 (in which the suffix a is not greater than 1.09, the suffix b is from not smaller than 0.05 to not greater than 0.25, and the suffix c is from not smaller than 0.2 to not greater than 0.35, and the sum of b and c is from not smaller than 0.25 to not greater than 0.55) having a hexagonal structure, wherein when subjected to X-ray diffractometry with a CuKα ray, said lithium-nickel composite oxide exhibits an intensity ratio R ((I 012 +I 006 )I 101 ) of not greater than 0.50 and not less than 0.422, R being the ratio of the sum of the diffraction peak intensity I 012 on the 012 plane and the diffraction peak intensity I 006 on the 006 plane to the diffraction peak intensity I 101 on the 101 plane, said positive active material has a mean particle diameter D 50 of from 4 μm to 25 μm and a BET specific surface area of from 0.2 to 1.5 m 2 /g.