Nonaqueous electrolyte secondary battery positive electrode active material and method for producing same, and nonaqueous electrolyte secondary battery which uses positive electrode active material

A method for manufacturing a positive electrode active material for non-aqueous electrolyte secondary batteries, the method comprising:

• a filtration and washing process (A) of washing a metal composite hydroxide with water, or with an alkali and then with water, and collecting a residual material of the metal composite hydroxide by a solid-liquid separation;
• a drying process (B) of obtaining a dried material of the metal composite hydroxide by drying the residual material;
• a mixing process (C) of forming a mixture of the dried material and a fine powder lithium compound having a maximum particle size of 10 [μm] or less;
• and
• a firing process (D) of forming a positive electrode active material for non-aqueous electrolyte secondary batteries, the positive electrode active material including a lithium-metal composite oxide as a fired body by firing the mixture, wherein
• a lithium-metal composite oxide powder is manufactured with the metal composite hydroxide containing nickel, manganese, and cobalt and the fine powder lithium compound having a maximum particle size of 10 [μm] or less as raw materials using a manufacturing process including the processes (A) to (D) in order described above,
• the lithium-metal composite oxide powder includes a secondary particle configured by aggregating primary particles containing lithium, nickel, manganese, and cobalt or includes both the primary particles and the secondary particle,
• the secondary particle has a porous internal structure,
• the lithium-metal composite oxide powder has a porosity of more than 50 to 80[%],
• a slurry has a pH of 11.5 or less at a time when a slurry concentration is 50 [g/L],
• the lithium-metal composite oxide powder contains 0.5[% by mass] of soluble lithium, and
• the lithium-metal composite oxide powder has a specific surface area of 3.0 to 4.0 [m2/g].