POSITIVE ELECTRODE ACTIVE MATERIAL FOR NON-AQUEOUS ELECTROLYTE SECONDARY CELL AND METHOD FOR MANUFACTURING SAME, AND NON-AQUEOUS ELECTROLYTE SECONDARY CELL

A positive electrode active material for a nonaqueous electrolyte secondary battery is disclosed which contains a lithium-nickel-manganese composite oxide containing a secondary particle formed of a plurality of flocculated primary particles and a lithium-niobium compound. The positive electrode active material is represented by General Formula (1): LiNiMnMNbO(M is at least one element selected from Co, W, Mo, V, Mg, Ca, Al, Ti, Cr, Zr, and Ta; and 0.03≤a≤0.60, 0≤b≤0.60, 0.02≤c≤0.08, a+b+c