| 摘要 |
PROBLEM TO BE SOLVED: To provide outstanding crystallization property for a battery and improve its charging/discharging cycle characteristic, by specifying the amount of added cobalt in lithium-nickel complex oxide of positive electrode active material, forming a hexagonal system, and also limiting the space occupying factor of metallic ions except lithium ion in a 3a site. SOLUTION: Positive electrode active material for a secondary battery is represented by chemical formula LiCox Ni1-x O2 . Amount x of added Co is 0<x<=0.2 and it has a hexagonal system. The space occupying factor of metallic ions except lithium ion Li<+> in a 3a site, which is provided from results of the Rietveld analysis by X-ray diffraction, is less than 2%. The space occupying factor of metallic ions is usually the sum of the space occupying factors of nickel ion and cobalt ion. In the electrode which uses this positive-electrode active material, the irreversible capacity is decreased due to its outstanding stoichiometric composition. Using the positive electrode active material can increase discharging capacity and coulomb efficiency of a secondary battery. |
