POSITIVE ELECTRODE ACTIVE MATERIAL FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY, AND NONAQUEOUS ELECTROLYTE SECONDARY BATTERY USING POSITIVE ELECTRODE ACTIVE MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a positive electrode active material for a nonaqueous electrolyte secondary battery with excellent cycle characteristic and high capacity, and to provide a nonaqueous electrolyte secondary battery using the positive electrode active material. SOLUTION: In a positive electrode active material for a nonaqueous electrolyte secondary battery using lithium cobalt oxide shown in a formula of LiCoO2, the lithium cobalt has a diameter of ferer of 0.1 to 4 μm in a projection figure through a SEM monitoring, and the positive electrode active material is formed of sphere or oval sphere secondary particles formed of primary particles of small crystals whose mean granular diameter is not more than 2 μm. The granular diameter of the secondary particle is from 1 to 40 μm. At least a part of the small crystals constructing the secondary particle is bonded by sintering. A tap concentration of the lithium cobalt oxide is not less than 2.2 g/cm3. The invention also provides a nonaqueous electrolyte secondary battery whose construction element is the positive electrode active material.