Patent ID: 8623551

Claim:
A positive electrode active material for a lithium ion battery represented by; Compositional formula: Li x Ni 1−y M y O 2+α wherein M is one or more selected from Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Ge, Al, Bi, Sn, Mg, Ca, B, and Zr, 0.9≦x≦1.1, 0<y≦0.7, and 0.05≦α≦0.2, which contains primary particles and has a tap density of 1.3 to 2.6 g/cm 3 , wherein the average particle size of the primary particles is 0.3 to 3.0 μm and the specific surface area is 0.3 to 2.3 m 2 /g, the positive electrode active material having, in a particle size distribution graph (x-axis: particle size, y-axis: relative particle weight), a maximum point in a particle size of 1 μm or more and a difference between the particle size in the maximum point and a median diameter (D50) of 1.5 μm or less.