锂离子电池低温充电容量衰减规律分析

以正极材料为LiNi0.8Co0.15Al0.05O2(NCA)的锂离子电池为实验对象,基于循环老化对照实验的结果,以容量衰减率10%为界,将低温充电的容量衰减过程分为两个阶段。分别拟合不同阶段下温度、倍率和截止电压对容量衰减速率作用的经验公式,耦合3项因子建立低温充电容量衰减规律的多应力经验模型。取若干组工况,评估该模型对容量衰减速率的预测精度。若实验条件相对参考工况仅有一个因子不同,模型的预测效果较好,估计误差小于10%。

Exploration of charge capacity degradation law of Li-ion battery at low temperature

Li-ion battery with cathode material of LiNi0.8Co0.15Al0.05O2 was used as the experimental object.Based on the results of the controlled cyclic aging trials,the capacity degradation process in the case of charging at low temperature was divided into two stages with the capacity degradation ratio of 10%.The empirical formulas for the effects of temperature,rate and cut-off voltage on the capacity degradation rate were fitted respectively at different stages.Through coupling these 3 factors,a multi-stress empirical model was established,which described the law of charge capacity degradation at low temperature.Several sets of working conditions were designed to evaluate the prediction accuracy of the model for capacity degradation rate.When the experimental condition was differed from the reference condition by only one factor,the model had a better prediction effect as estimation errors were less than 10%.