| 摘要 |
PROBLEM TO BE SOLVED: To realize a high capacity even with a low charging voltage by using a composite oxide of lithium, copper, and titanium for the active material of a positive electrode provided together with a lithium ion conductive nonaqueous electrolyte or a negative electrode using lithium or a material capable of storing or releasing lithium as the active material. SOLUTION: In a composite oxide having a cubic crystal spinel structure expressed by formula and containing Li absorbed or desorbed into or from a crystal by a charge or a discharge, Cu ions different from Ti ions in ionic radius and valence are solved in a B site in the crystal to generate strains in the crystal, therefore the charging/discharging voltage of about 2.5 V is obtained, instead of the normal voltage of about 3 V. The composition ratio of Li in an A site is 0<a<=1 as a single spinel phase, the composition ratios of Cu and Ti in the B site are 0<b<=0.5, 1.5<=c<2, b+c=2, thereby the instability of the crystal structure and the deterioration of the cycle characteristics of a battery are resolved. This composite oxide is preferably used for a negative electrode active material, and LiCoO2, LiNiO2, or LiMn2O4 is preferably used for a positive electrode active material. |
