| 摘要 |
The present invention provides a positive electrode active material for lithium ion battery which attains a lithium ion battery having high safety. The positive electrode active material has a layer structure for a lithium ion battery, in which the positive electrode active material is represented by the following composition formula:
€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒLi x (Ni y M 1-y )O z
(wherein M represents Mn and Co, x is from 0.9 to 1.2, y is 0.8 ± 0.025, and z is from 1.8 to 2.4), and
”T = T10-T5, that is a difference between a first exothermic peak temperature T5 (°C) obtained by a differential scanning calorimetry (DSC) carried out at temperature increase rate of 5°C/min and a first exothermic peak temperature T10 (°C) obtained by a differential scanning calorimetry (DSC) carried out at temperature increase rate of 10°C/min, satisfies the condition of ”T ‰¥ 10 (°C), when a lithium ion battery using a positive electrode mixture prepared with a positive electrode active material, a binder, and a conductive material in weight ratio of 91%, 4.2%, and 4.8%, respectively is charged to 4.3 V and electrolyte liquid containing 1 M-LiPF 6 dissolved in a mixture solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) (volume ratio 1 : 1) is used per 1.0 mg of a positive electrode mixture. |
