| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary cell which has a stable crystal structure of an active material, and has a high safety without burst ignition in nailing test. SOLUTION: In a lithium ion cell equipped with a positive electrode 4 including an active material, a negative electrode 6, and a nonaqueous electrolyte, the active material includes a compound oxide having a composition which is expressed in a chemical formula: Lix(Ni1-yTay)(O2-zXz). Here, X is at least one kind of halogens selected from a group of F, Cl, Br and I, and mole ratios x, y and z are given as 0.02<=x<=1.3, 0.005<=y<=0.5, and 0.01<=z<=0.5. |
