Positive electrode active material for lithium ion secondary battery, method of manufacturing positive electrode active material for lithium ion secondary battery, and lithium ion secondary battery

A method of manufacturing a positive electrode for a lithium ion secondary battery including lithium nickel manganese oxide complex particles, wherein the lithium nickel manganese complex oxide particles are composed of secondary particles formed of aggregated primary particles of a lithium nickel manganese complex oxide represented by a general formula LidNi1−a−b−cMnaMbZrcO2+α (where M is at least one element selected from Co, W, Mo, Mg, Ca, Al, Ti, Cr, and Ta, and is 0.05≤a<0.60, 0≤b<0.60, 0.00003≤c≤0.03, 0.05≤a+b+c≤0.60, 0.95≤d≤1.20, and −0.2≤α≤0.2), and wherein at least a portion of zirconium is dispersed in the primary particle, comprising:

• a step of obtaining a lithium zirconium mixture of nickel manganese complex hydroxide particles represented by a general formula Ni1−x−yMnxM′y(OH)2+β (where M′ is at least one element selected from Co, W, Mo, Mg, Ca, Al, Ti, Cr, Zr, and Ta, and is 0.05≤x≤0.60, 0≤y≤0.60, 0.05≤x+y≤0.60, and −0.1≤β≤0.4), a zirconium compound, and a lithium compound;
• and
• a step of firing a lithium nickel manganese complex oxide by firing the lithium zirconium mixture at a temperature between 850° C. and 1000° C. in an oxidizing atmosphere,
• wherein the positive electrode active material for the lithium ion secondary battery contains an amount of excessive lithium obtained by a neutralization titration method is 0.02 mass % or more and 0.09 mass % or less.