Positive electrode active material for lithium secondary battery, positive electrode, and secondary battery

Abstract

Provided is a positive electrode active material which is useful for a lithium secondary battery having a battery resistance lower than that of the conventional positive electrode active material below freezing point. The positive electrode active material for a lithium secondary battery contains at least one element selected from a group consisting of nickel, cobalt and manganese, the positive electrode active material having a layered structure and satisfying all of the following requirements (1) to (3): (1) a primary particle size is 0.1 μm to 1 μm and a secondary particle size is 1 μm to 10 μm; (2) in an X-ray powder diffraction measurement using CuKα radiation, a crystallite size in the peak within 2θ=18.7±1° is 100 Å to 1200 Å and a crystallite size in the peak within 2θ=44.6±1° is 100 Å to 700 Å; and (3) in a pore distribution obtained by a mercury intrusion method, a pore peak exists in a range where the pore size is 10 nm to 200 nm and a pore volume in the said range is 0.01 cm/g to 0.05 cm/g.