| abstract |
A positive electrode active material having high fillability is obtained. An active material particle A is composed of a mixture of active material particles A and active material particles B, and the active material particles A are composed of spherical secondary particles in which primary particles are aggregated, have an average particle size of 10 to 25 μm, and a particle size distribution. (D90-d10) / MV having a value of 0.65 or less, and the active material particle B has a general formula LixM11-yM2yO2 (where M1 is Co, Ni, Mn And at least one element selected from the group consisting of transition metal elements other than M1, group 2 elements, and group 13 elements, 0.95≰x≰1.1, 0≰y≰0 .15) is a spherical lithium transition metal composite oxide particle having a hexagonal crystal structure having a layered structure represented by formula (15) and having an average particle size smaller than that of the active material particle A. [Selection figure] None |