空间用锂离子蓄电池循环寿命衰降机理分析

Degradation mechanism of cycling performance of space lithium ion batteries

锂离子蓄电池是一个亚稳态的体系,在循环和存储过程中由于界面副反应和材料不可逆相变的存在导致了锂离子蓄电池的界面阻抗增加和可逆比容量的损失。分析了空间用高比能锂离子蓄电池在循环中可逆比容量的损失机理,研究表明:在经过2500次循环后(2.75~4.2V,1.2C充放电),该电池可逆比容量仍然在78%以上。通过EIS、XRD等分析表明:该电池循环中的可逆比容量损失主要来自于正极材料的可逆比容量损失和界面阻抗增加,负极在循环中的可逆比容量损失不足3%,对全电池的可逆比容量损失没有贡献。

Lithium ion battery is a metastable system,and the capacity will decrease continuously as the result of side reaction,irreversible phase changing,active material loss,surface resistance increasing and active Li loss.This paper analyzed the influence factor of capacity decreasing of space lithium ion batteries.The results show that the batteries have excellent cycling performance with a capacity retention of 78%after 2 500 cycles(2.75-4.2 V,at 1.2 C charge and discharge).The analysis results of EIS and XRD indicate that the cathode's reversible capacity decreasing and surface resistance increasing are the main reasons for the reversible specific capacity decrease.The anode shows no contribution to the reversible specific capacity decrease during the cycling with a specific capacity decrease less than 3%.