Patent ID: 7709150

Claim:
A method for preparing a positive electrode active material for a non-aqueous secondary battery comprising a step of firing a mixture of (1) at least one member selected from the group consisting of dinickel trioxide and boron compounds and (2) one or more metal compounds comprising lithium, nickel and manganese as their metal elements and a step of obtaining a compound comprising lithium, nickel and manganese and having a layered structure, wherein the compound comprising lithium, nickel and manganese and having a layered structure is a compound which is identified in X-ray diffraction as a compound represented by the composition formula Li[Ni (x-y) Li (1/3-2x/3) Mn (2/3-x/3-y) Co 2y ]O 2 , wherein 0<x≦0.5, 0≦y≦⅙ and x>y, and having a layered structure.