21. A positive electrode active material for a nonaqueous electrolyte secondary battery, which is represented by the general formula (B): li1+uNixMnyCozMtO2The positive electrode active material is composed of lithium transition metal composite oxide particles having a hexagonal crystal structure and a layered structure, and in the general formula (B), -0.05. ltoreq. u.ltoreq.0.50, x + y + z + t 1, 0.3. ltoreq. x.ltoreq.0.95, 0.05. ltoreq. y.ltoreq.0.55, 0. ltoreq. z.ltoreq.0.4, 0. ltoreq. t.ltoreq.0.1, M is one or more additive elements selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W,
the positive electrode active material for a nonaqueous electrolyte secondary battery is composed of secondary particles formed by aggregating a plurality of primary particles,
the secondary particles have a central portion of a hollow structure or a hollow structure, and have at least a space portion where the primary particles are not present and an outer shell portion electrically connected to the central portion outside the central portion, and at least one inner shell portion between the space portion and the outer shell portion,
the secondary particles have an average particle diameter of 1 to 15 [ mu ] m, and the [ (d90-d 10)/average particle diameter ] as an index indicating the width of the particle size distribution is 0.7 or less.
the secondary particles
average particle diameter
1 to 15 [ mu
mu
the secondary particles
particle size distribution
0.7 or less