车用锂电池PP隔膜机械失效导致内部微短路的机理研究

车用锂电池在工作过程中会经受机电热的耦合作用,其中机械滥用是引发锂电池内部短路的最主要风险之一,很可能导致严重的起火事故。隔膜的机械完整性是防止锂电池在机械滥用条件下发生内部短路的关键因素。通过综合的力学测试发现,不同尺寸的压头导致PP隔膜两种截然不同的变形和失效模式。最后分析了触发锂电池内部微短路的机理,并通过力学试验和理论分析提出了锂电池内部微短路下的隔膜临界位移准则。

Study on Mechanism of Internal Micro-short Circuit in EV Li-Ion Battery Caused by Mechanical Failure of PP Separator

The lithium-ion batteries for electric vehicle in the course of work will withstand the coupling of mechanical,electrical and thermal effects,in which mechanical abuse is one of the most important risks leading to the internal short circuit of lithium-ion batteries,which is likely to result in serious fire accidents.The mechanical integrity of separator is a key factor in preventing the internal short circuit of lithium-ion battery under the condition of mechanical abuse.Through comprehensive mechanical tests,it is found that different sizes of punches will lead to two distinct deformation and failure modes of PP separator.Finally,the mechanism of triggering internal micro-short circuit in lithium-ion battery is analyzed and a critical displacement criterion of separator under the internal micro-short circuit of lithium-ion battery is put forward based on mechanical tests and theoretical analysis.