NICKEL MANGANESE COBALT COMPOSITE HYDROXIDE, METHOD FOR PRODUCING NICKEL MANGANESE COBALT COMPOSITE HYDROXIDE, LITHIUM NICKEL MANGANESE COBALT COMPOSITE OXIDE, AND LITHIUM ION SECONDARY BATTERY

A nickel manganese cobalt composite hydroxide, which is a precursor of a positive electrode active material, and which is composed of secondary particles to which primary particles containing a nickel, a manganese, and a cobalt are aggregated, or composed of the primary particles and the secondary particles, wherein a sodium content contained in the nickel manganese cobalt composite hydroxide is less than 0.0005% by mass, and a void ratio of particles of the nickel manganese cobalt composite hydroxide is 20% to 50%.