1. A method for producing transition metal composite hydroxide particles serving as a precursor of a positive electrode active material for a nonaqueous electrolyte secondary battery by a crystallization reaction, comprising:
a nucleus-forming step of controlling an aqueous solution for nucleus formation containing at least a transition metal-containing metal compound and an ammonium ion donor so that the aqueous solution for nucleus formation has a pH of 12.0 to 14.0 at a liquid temperature of 25 ℃ and forming nuclei,
a particle growth step of controlling the aqueous solution for particle growth containing the nuclei obtained in the nucleus production step so that the pH of the aqueous solution for particle growth becomes lower than that in the nucleus production step at a liquid temperature of 25 ℃ and 10.5 to 12.0 to grow the nuclei,
the reaction environment in the initial stage of the nucleus generation step and the particle growth step is a non-oxidizing environment having an oxygen concentration of 5 vol% or less, and the reaction environment is switched from the non-oxidizing environment to an oxidizing environment having an oxygen concentration of more than 5 vol% and then from the oxidizing environment to a non-oxidizing environment having an oxygen concentration of 5 vol% or less by performing environmental control at least once in the particle growth step.
aqueous solution for nucleus formation
pH
12.0 to 14.0
aqueous solution for nucleus formation
liquid temperature
25 ℃
℃
particle growth
liquid temperature
25 ℃
particle growth
pH
10.5 to 12.0