| abstract |
The positive electrode active material is represented by the general formula Li a Ni x Co y Mn z M b O 2 and satisfies 0.9<a<1.1, 0.4≤x<1.0, 0≤y<0.4, 0≤z<0.4, 0≤b <0.2, 0.9<(x+y+z+b)<1.1, the element M contains a composition selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Ga, In At least one of the group of composite oxide particles has a ratio (B/A) of the BET specific surface area (B) after the particle compression test to the BET specific surface area (A) before the particle compression test (B/A) of 1.0 or more and 3.0 or less. |