文献类型：期刊文献

中文题名：LiFePO4涂层厚度对锂离子电池电化学性能的影响

英文题名：Effects of LiFePO4 coating thickness on electrochemical performance of lithium-ion batteries

作者：施柳柳[1];陈怡沁[1];周静红[1];周兴贵[1]

机构：[1]华东理工大学化工学院

年份：2019

卷号：38

期号：5

起止页码：52

中文期刊名：电子元件与材料

外文期刊名：Electronic Components And Materials

收录：CSTPCD;;北大核心:【北大核心2017】；CSCD:【CSCD_E2019_2020】；

基金：国家自然科学基金资助项目(21676082)

语种：中文

中文关键词：锂离子电池;磷酸铁锂;涂层厚度;电化学性能;表观扩散系数

外文关键词：lithium-ion battery;LiFePO4;coating thickness;electrochemical performance;diffusion rate

摘要：以LiFePO4为正极材料制备不同电极涂层厚度的扣式半电池,利用恒电流充放电、循环伏安、交流阻抗等测试手段对电池电化学性能进行了测试,探讨了涂层厚度对电池充放电性能、循环性能、阻抗等的影响,并结合阻抗谱图拟合分析Li+在极片内的扩散速率,揭示了涂层厚度影响电化学性能的作用机制。研究结果表明:涂层厚度增加,一方面使得锂离子的传递距离加长,另一方面在同等压实压力作用下得到的涂层孔隙率有所增加,造成实际传质路径减小,因此存在最佳厚度以实现最优电化学性能。在实验研究范围内,当涂覆湿膜厚度为120μm时,锂离子表观扩散系数达1.76×10^-12cm^2/s,表现出最优的电化学性能,1C的充放电倍率下,首次放电比容量可达145.8mAh/g。
Half coin cells were prepared by coating a variety of thickness of LiFePO4 as the cathode material. The electrochemical performance of the battery was characterized by galvanostatic charge / discharge, cyclic voltammetry and AC impedance. The effects of coating thickness on charge and discharge, cycle performance and impedance of Li -ion batteries were investigated. The diffusion rate of Li+ in the pole piece was then analyzed by impedance spectrum to reveal how the coating thickness affect the electrochemical performance. The results show that thicker coating, on the one hand, increases the migration distance of lithium ions, and on the other hand, also shorten the effective mass transfer path due to the increased porosity of the coating layer, which is compacted under the same pressure. Thus, there exists an optimal thickness of coating layer which achieves best electrochemical performance. The optimal coating thickness of the electrode is determined to be 120 μm in this work with a specific capacity of 145. 8 mAh / g at 1C rate and the apparent lithium-ion diffusion coefficient of 1. 76×10^-12 cm^2 / s. These results could provide fundamental understanding for the rational design of electrode.