| abstract |
[Problem] To provide a positive active material which has a moderate particle diameter and has high evenness in particle diameter and a nickel composite hydroxide which is for use as a precursor for the positive active material.n[Solution] When a nickel composite hydroxide is obtained through a crystallization reaction, an aqueous solution for nucleation which contains both a metal compound at least containing nickel and an ammonium ion source is used to conduct nucleation after having been regulated so as to have a pH of 12.0-14.0 at a solution temperature of 25ºC, and thereafter the resultant aqueous solution, which is for particle growth and which contains formed nuclei, is regulated so as to have a pH that, at a solution temperature of 25ºC, is 10.5-12.0 and lower than in the nucleation step, thereby growing the particles. This particle growth is conducted in a non-oxidizing atmosphere having an oxygen concentration of 1 vol.% or lower, over a period which ranges from initiation of the particle growth step and which accounts for more than 40% of the whole period of the particle growth step. Furthermore, the stirring power per unit volume in at least the nucleation step is regulated to 0.5-4 kW/m 3 . |