| abstract |
(57) [Problem] To enable a high-capacity lithium secondary battery having excellent cycle characteristics to be filled at a high density even when cathode active material particles having a large particle size are used. SOLUTION: The lithium secondary battery of the present invention includes a positive electrode active material capable of inserting and extracting lithium ions, and the positive electrode active material has a volume of a large-sized substantially spherical secondary particle in which primary particles are aggregated. The primary particles or secondary particles having a small volume ratio between the secondary particles having a large ratio and a large diameter and a substantially spherical shape are mixed with the primary particles or the secondary particles having a small volume ratio, or the primary particles or the small particles having a small volume ratio. The number ratio of the secondary particles is larger than the number ratio of the secondary particles having a large diameter and a substantially spherical shape. As a result, high-density packing becomes possible, and a decrease in the capacity retention rate can be suppressed even when charge and discharge are repeated, and a battery with improved cycle characteristics can be obtained. |