Abstract:  To meet the requirements of crashworthiness design of electric vehicle power battery packs， the failure mechanism of lithium-ion batteries was studied under different mechanical abuse conditions. Based on local indentation and plane compression loading tests on three different capacity NCR18650 cylindrical lithium-ion batteries， the force-electric-thermal responses of lithium-ion batteries were analyzed and the cross-section failure modes of the compressed battery samples were given. Then the effects of loading types and battery capacity on the failure mechanism of cylindrical batteries were discussed. The results show that internal short circuit and external short circuit failure modes of batteries may be caused by local indentation and plane compression， respectively. With the increase of battery capacity， the bearing performances of the batteries may reduce， which leads to the failure displacements decrease. Loading types and rated capacity also have an effect on the surface temperature changes of the batteries. The maximum surface temperature of the batteries after the local indentation is higher， and the surface temperature changes of the medium-capacity batteries are relatively smooth. 

Key words: lithium-ion battery, battery capacity, compression loading, force-electric-thermal response, failure mechanism

摘要： 为满足电动汽车动力电池组耐撞性设计的要求，对不同机械滥用工况下锂离子电池单体的失效机理进行了试验研究。通过对三种不同容量的NCR18650圆柱形锂离子电池进行局部压痕和平面压缩加载试验，研究了锂离子电池样本的力-电-热响应，给出了失效电池样本的横截面破坏形式，具体讨论了加载形式和电池容量对锂离子电池失效的影响。研究结果表明，局部压痕和平面压缩将导致电池分别出现内短路和外短路两种触发失效模式。随着额定容量的提高，电池的承载能力降低，从而导致失效位移减小。机械加载形式和额定容量亦对电池表面温度变化有重要影响，局部压痕失效后电池达到的最高表面温度较高，中等容量电池的表面温度变化相对平稳。

关键词: 锂离子电池, 电池容量, 挤压载荷, 力-电-热响应, 失效机理