Patent ID: 8137844

Claim:
A cathode active material for a lithium rechargeable battery comprising a lithium transition metal composite oxide containing Mg or Al atoms, the lithium transition metal composite oxide is obtained from a mixture of a lithium compound, a transition metal compound and a metal compound, the metal compound containing Mg or Al atoms, the metal compound is obtained from a first metal compound and a second metal compound, wherein the first metal compound is selected from a halide, a phosphate, a hydrogen phosphate, and a sulfate of Mg or Al, and the second metal compound is selected from an oxide, a hydroxide, and a carbonate of Mg or Al, wherein Mg or Al atoms are contained in a lithium transition metal oxide, said lithium transition metal oxide being represented by one of the general formulas (1) to (4): Li x CO 1-y Me y O 2 , wherein Me is a transition metal element selected from Ga, and Zn, x being a number in a range of 0.9 ≦x≦ 1.2, and y being a number in a range of 0 ≦y≦ 0.05; (1) LiFePO 4 ; (2) LiNi 0.5 Mn 1.5 O 4 ; and (3) LiMn 2 O 4 , (4) and wherein the obtained lithium transition metal composite oxide containing Mg or Al atoms contains a metal oxide of MgO or Al 2 O 3 present on or near the surface of a particle and Mg atoms or Al atoms forming a solid solution with the lithium transition metal composite oxide present inside the particle.