| abstract |
[Problem] To achieve a positive electrode active material which is suppressed in deterioration caused by repeated charging and discharging and enables stable charging and discharging, thereby enabling the achievement of higher output and longer service life of a nonaqueous electrolyte secondary battery.n[Solution] A positive electrode active material, which is composed of a layered lithium transition metal oxide represented by general formula Li a (Ni b Co c Al d Me e )O 2 (wherein Me = Mn, Mg, Ti, Ru, Zr, Nb, Mo or W; 1.00 ≤ a ≤ 1.15; 0.25 < b < 1; 0 < c ≤ 0.30; 0 ≤ d ≤ 0.05; and 0 ≤ e ≤ 0.40), is configured of secondary particles, each of which is composed of aggregated primary particles. With respect to the Li composition ratio of unreacted Li and Li produced by a decomposition reaction in the secondary particles, the variation coefficient of the Li composition ratio represented by Li/M (M = Ni + Co + Al + Me) is 30% or less. |