放电温度对LiNi3/8Co2/8Mn3/8O2电化学性能的影响

采用X射线衍射（XRD）、X射线光电子能谱（XPS）、恒流充放电、循环伏安及交流阻抗法，研究了放电温度对LiNi3/8Co2/8Mn3/8O2的倍率特性、锂离子扩散及电荷传递的影响.结果表明， 提高放电温度可显著改善LiNi3/8Co2/8Mn3/8O2的放电容量与倍率放电性能.尽管温度升高使电荷传递活性与锂离子扩散速度都增加，但电荷传递活化能比锂离子扩散活化能大一倍多，表明电荷传递步骤是其电化学反应控制步骤.温度对其电荷传递的影响大于对锂离子扩散的影响.温度升高，电荷传递速率加快，电化学嵌入-迁出反应加速，是其放电容量与倍率放电特性显著改善的主要原因.

Effect of Cell Temperature on the Electrochemical Reaction of LiNi3/8Co2/8Mn3/8O2

The effects of cell temperature on the rate discharge capability, lithium ion diffusion rate and charge transfer activity of LiNi3/8Co2/8Mn3/8O2 were investigated by using X-ray diffractometry(XRD), X-ray photoelec-tron spectroscopy(XPS), constant-current charge-discharge test, cyclic voltammetry and electrochemical impedance spectroscopy(EIS). The experimental data show that the rate discharge capability of LiNi3/8Co2/8Mn3/8O2 is improved by increasing cell temperature. Both the charge transfer activity and the lithium ion diffusion rate in LiNi3/8Co2/8Mn3/8O2 increase at elevated temperatures. The activation energy for charge transfer is more than twice that for the lithium ion diffusion. The results indicate that the electrochemical reaction kinetics of LiNi3/8Co2/8Mn3/8O2 is mainly limited by charge transfer process. The charge transfer process is more affected by temperature than the lithium diffusion process. Improvement of the rate discharge capability of LiNi3/8Co2/8Mn3/8O2 at elevated temperatures is mainly caused by the increase of charge transfer rate in LiNi3/8Co2/8Mn3/sO2.