锂离子蓄电池LiCoO_2正极材料的过充电行为

Overcharge behavior of cathode materials layered-LiCoO_2 for rechargeable lithium batteries

研究了不同充电终止电压(分别为4.3、4.5、4.8、5.0V)的充放电循环和不同倍率充电对钴酸锂电极性能的影响。结果表明:电池充电终止电压越高,电量转换效率越低,电极活性衰减越严重,用扫描电子显微镜法(SEM)与X射线衍射光谱法(XRD)分析说明电池性能衰退是由于LiCoO2结构变形,颗粒粉化团聚且形成惰性物质Co3O4造成的。同时,在充电终止电压为4.8V的条件下,1.5C充放电循环后,电池0.2C的充放电性能下降严重。

The influence of the charge-discharge cycles at different charging cut-off voltages （4.3, 4.5, 4.8, 5.0 V） and different charging currents on the performance of LiCoO2 electrode was investigated. The results show that the higher of charging cut-off voltage, the lower of energy conversion efficiency, the more serious deterioration of electrode activity. The analyzed results of SEM and XRD show that the electrochemical performance of the battery fades because of the structure transition of LiCoO2, particle agglomeration and the formation of inert Co3O4. After charge-discharge at 1.5 C under the condition of 4.8 V cutoff voltage, the charge-discharge performance of the battery at 0.2 C is serious deteriorated.