5. A process for producing the Li—Ni composite oxide particles as claimed in claim 1, comprising the steps of mixing lithium compound particles and Ni—Co hydroxide particles, and calcining the resulting mixture, the Ni—Co hydroxide particles being produced by mixing an aqueous solution of a sulfuric acid salt of each metal element, an ammonia aqueous solution and a sodium hydroxide aqueous solution such that an ammonia concentration in a reaction vessel is controlled to not more than 1.4 mol/L, and a ratio of the ammonia concentration in the reaction vessel to a surplus hydroxyl group concentration in the reaction vessel is controlled to not less than 6.
ammonia
concentration
to not more than 1.4 mol/L
mol/L
ammonia
concentration
to not less than 6