3. A positive-electrode active material for a nonaqueous electrolyte secondary battery, the positive-electrode active material comprising:
a lithium-metal compound oxide represented by a general formula of Li1+αNixCoyMnzMtO2where 0.25≤α≤0.55, x+y+z+t=1, 0.05≤x≤0.3, 0.1≤y≤0.4, 0.55≤z≤0.8, and 0≤t≤0.1 are satisfied; and M represents one or more additive elements selected from among Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W,
wherein the positive-electrode active material precursor includes secondary particles having an average particle diameter greater than or equal to 4 μm and less than or equal to 8 μm, and
wherein the secondary particle has a particle shape including an outer shell portion and a hollow portion surrounded by the outer shell portion.
secondary particles
average particle diameter
greater than or equal to 4 μm and less than or equal to 8 μm
μm