基于无损检测的生命周期锂离子动力电池安全性分析

Analysis of safety performance of lithium-ion power battery during life cycle based on non-destructive testing

基于在不同条件下对车用三元锂离子动力电池的充放电循环试验,分析电池寿命衰减程度及其影响因素。利用X-ray无损检测技术,测试以不同倍率大小电流进行充放电循环前后三元锂离子动力电池的内部结构变化,并评价了电池寿命衰减和安全失效程度,为研究电池寿命衰减及安全失效提供了新的方法。在充放电循环周期过程中,随着电池容量的不断衰减,基于无损检测技术可以获得电池内部结构出现越来越明显的缺陷,说明电池的寿命衰减速度越来越大,其安全性也越来越差。以不同倍率大小电流进行充放电循环后,将不同SOH状态下内部结构的断层扫描图像进行对比,发现车用三元锂离子动力电池的内部结构发生了不同程度的变化,说明与循环前相比电池的使用寿命有不同幅度的衰减。

Based on the test of charge-discharge cycle on NCM power lithium-ion battery applied in electric vehicles under different conditions, the degree of attenuation on life of battery and influenced factors are analyzed. The internal structure of NCM power lithium-ion battery before and after charge-discharge cycle tests at different rates are tested by using X-ray non-destructive testing technology, meanwhile the degree of safety failure and decay on life of battery are evaluated. A new method to study the decline in life of battery and its safety failure is proposed. In the process of charge-discharge cycle, with the continuous decline on capacity of battery, the internal structure of the battery appears more and more obvious defects based on non-destructive testing technology, therefore it indicates the rate of attenuation on life of battery increases faster and the safety of battery gets worse. Based on the comparison on tomographic images of internal structures under different SOH states, the internal structure of the NCM power lithium-ion battery used for electric vehicles has changed on varying degrees after charge-discharge cycle tested by different ratio values of current, therefore it demonstrates that service life of battery has been greatly reduced on different levels.