| 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 for lithium ion battery has a layer structure represented by the compositional formula: Li x (Ni y M 1-y )O z (wherein M represents Mn and Co, x denotes a number of 0.9 to 1.2, y denotes a number of 0.8 ± 0.025, and z denotes a number of 1.8 to 2.4). When a lithium ion battery using a positive electrode mix produced by the positive electrode active material, a binder, and a conductive material in a ratio by weight of 91%, 4.2%, and 4.8%, respectively, is charged to 4.3V, and then an electrolytic solution prepared by dissolving 1 M-LiPF 6 in a mixture solvent of ethylene carbonate (EC)-dimethyl carbonate (DMC) (volume ratio 1 : 1) is used based on 1.0 mg of the positive electrode mix to measure the obtained lithium ion battery by differential scanning calorimetry (DSC) performed at a temperature rise rate of 5°C/min, a difference ”T between a first exothermic peak temperature T1 (°C) and a temperature T2 at which an exothermic strength is 1/2 of the first exothermic peak strength (T2 < T1) satisfies the equation: ”T ‰¥ 13 (°C). |
