Positive active material, positive pole piece, battery and electric device

The invention relates to a positive active material, a positive pole piece, a battery and an electric device. The positive electrode active material comprises lithium-containing phosphate in component, the positive electrode active material comprises secondary particles in morphology, and the volume average particle size Dv50 of the secondary particles is 0.5-25 [mu] m; primary particles forming the secondary particles, the average particle diameter of which is 0.2 [mu] m to 2 [mu] m; in the positive electrode active material, the proportion X of the number of particles with the particle size distribution being more than 3 microns is more than or equal to 10%, and the proportion Y of the number of particles with the particle size distribution being more than 5 microns is more than or equal to 5%.