Nonaqueous electrolyte secondary battery positive electrode active material and method for manufacturing same, and nonaqueous electrolyte secondary battery

A method for manufacturing a nonaqueous electrolyte secondary battery positive electrode active material formed of lithium-manganese-nickel complex oxide, the method comprising:

• a crystallization step of crystallizing manganese-nickel complex hydroxide from a mixed solution of manganese chloride and nickel chloride by adding the mixed solution and an alkali aqueous solution simultaneously and continuously into a reaction tank;
• a calcination step of mixing the manganese-nickel complex hydroxide obtained and a lithium compound and calcining the mixture at 800° C. or higher and 1000° C. or lower to obtain lithium-manganese-nickel complex oxide;
• and
• a recalcination step of recalcining the lithium-manganese-nickel complex oxide obtained at 500° C. or higher and 800° C. or lower for 5 hours or longer and 40 hours or shorter;
• wherein the ratio of Mn and Ni (Mn:Ni) contained in the manganese-nickel complex hydroxide is in the range of 0.8:0.2 to 0.7:0.3, and
• wherein pH for the crystallization step is maintained in a range of 10.5 or more to 12.5 or less.