LITHIUM METAL COMPOSITE OXIDE POWDER, POSITIVE ELECTRODE ACTIVE SUBSTANCE FOR LITHIUM SECONDARY BATTERY, POSITIVE ELECTRODE FOR LITHIUM SECONDARY BATTERY, AND LITHIUM SECONDARY BATTERY

A lithium metal composite oxide powder, which comprises primary particles and secondary particles that are aggregates of the primary particles, and has an α-NaFeOtype crystal structure, wherein a half width (A) of a diffraction peak in a range of 2θ=18.7±1° in a powder X-ray diffraction measurement for the lithium metal composite oxide powder using CuKα ray is 0.135° or more and 0.165° or less, and a c-axis lattice constant of the α-NaFeOtype crystal structure is 14.178 Å or more and Å or less.