Patent ID: 8173301

Claim:
A positive electrode active material for a non-aqueous electrolyte secondary battery comprising a lithium-containing transition metal oxide having a closest-packed cubic structure of oxygen, wherein: said lithium-containing transition metal oxide has a composition represented by the formula (1): Li[Li p (Ni x Mn y Co z ) 1-p ]O 2 , where x, y, and z represent element contents of nickel, manganese, and cobalt, respectively, and satisfy 0.2 +y≦x≦ 0.7, 0.25 ≦y, 0.05 <z, x+y+z= 1, and 0 ≦p≦ 0.1, Ni, Mn and Co are evenly dispersed at atomic level in said lithium-containing transition metal oxide, and in a triangular phase diagram showing the element contents of nickel, manganese, and cobalt in terms of molar ratio, the composition represented by said formula (1) falls within a pentagonal region defined by five vertices satisfying (x:y:z)=(6:2:2), (5:2.5:2.5), (5:3.3:1.7), (6.36:2.73:0.091), and (6.25:2.5:1.25).