| abstract |
This invention provides a positive electrode active substance for lithium secondary battery that exhibits high volume capacity density and high safety and is excellent in uniform coating capability, charge-discharge cyclic durability and low-temperature characteristics, in particular, a process for producing lithium cobalt composite oxide of the general formula LipCoxMyOzFa in which M is a transition metal element other than Co, aluminum or an alkaline earth metal element; 0.9≤p≤1.1; 0.980≤x≤ 1.000; 0≤y≤0.02; 1.9≤z≤2.1; x+y=1; 0≤a≤0.02), comprising firing a mixture of cobalt source and lithium source optionally together with source of element M mentioned above and fluorine source in an oxy atmosphere at 800 to 1050 DEG C, in which as the cobalt source, use is made of cobalt hydroxide of 5 to 50 m<SP>2</SP>/g specific surface area and 1.0 to 2.5 g/cm<SP>3</SP> press density having such a structure that secondary particles are formed by coagulation of primary particles, the secondary particles having an average particle diameter (D50) after dispersion in pure water which is not greater than 1/4 of the original average particle diameter (D50). |