挤压/冲击工况下圆柱形锂离子电池失效的影响因素分析

Analysis of Influencing Factors of Failure for Cylindrical Lithium-Ion Batteries under Compression/Impact Conditions

锂离子电池在受到挤压、冲击载荷时会发生内部短路而引发热失控,因此,研究电池失效影响因素对电池结构耐撞性设计具有重要意义。以圆柱形锂离子电池为研究对象,利用自制的平面压缩和局部压痕实验系统,研究不同挤压/冲击工况下锂离子电池的力-电-热响应,并与有限元模拟结果进行对比分析,结果表明,实验与有限元模拟结果具有较好的一致性。基于显式非线性有限元方法,研究了加载速度、压头形状和压头直径对锂离子电池失效行为和力学响应的影响。研究表明:局部压痕相较于平面压缩更容易导致锂离子电池失效;随着压头直径的减小,电池的峰值力显著降低,失效位移相应减小;失效位移随着冲击速度的增加而增大,但当冲击速度超过15 m/s时,失效位移开始减小。研究结果将对锂离子电池的耐撞性多目标优化设计和安全性评估提供一定的指导。

Lithium-ion batteries(LIBs)will cause internal short-circuits and even induce thermal runaway when they are subjected to compression and impact loadings.It is of great significance to explore the influencing factors of battery failure under different mechanical abuses for the crashworthiness design of the cells.In this paper,taking cylindrical LIBs as the research object,the force-electrical-thermal responses of the cells under different compression/impact conditions were studied by using a self-made plane compression and local indentation experimental system.The experimental results were compared with the corresponding finite element(FE)ones,and there was in good agreement with each other.Based on the explicit nonlinear FE method,the effects of loading velocity,indenter shape,and indenter diameter on the failure behaviors and mechanical responses of LIBs were also discussed.It is shown that localized indentation is more likely to induce the failure of the cells compared with plane compression.The peak force significantly decreases with the decrease of the indenter diameter,and the failure displacement also decreases correspondingly.It is noted that the failure displacement increases with the increase of the impact velocity,however,the failure displacement will decrease gradually when the impact velocity is more than 15 m/s.These results will provide some guidance for the multi-objective optimal design and safety assessment of LIBs.