Patent ID: 8920687

Claim:
A cathode active material for nonaqueous electrolyte rechargeable batteries comprising single crystal grains; and secondary particles each composed of a plurality of primary particles, said cathode active material being represented by the following formula: Li x Co 1−y M y O 2+z wherein M stands for one or more elements selected from the group consisting of Na, Mg, Ca, Y, rare earth elements, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Ni, Cu, Ag, Zn, B, Al, Ga, C, Si, Sn, N, P, S, F, and Cl, with Ti and/or Mg being essential; x is 0.9≦x≦1.1, y is 0<y≦0.1, and z is −0.1≦z≦0.1, said cathode active material having a specific surface area of not less than 0.20 m 2 /g and less than 0.50 m 2 /g, wherein average number A represented by formula (1) is not less than 2 and not more than 10: A =( m+p )/( m+s ) (1) wherein m is the number of single crystal grains, p is the number of primary particles composing the secondary particles, and s is the number of secondary particles, wherein the particle diameter of said secondary particles is not smaller than 1 μm and not larger than 70 μm.