压缩载荷作用下锂离子电池的安全性能

Abstract

摘要: 动力电池的安全性是制约电动汽车快速发展的重要因素之一。以圆柱形18650动力锂离子电池为研究对象，分别从径向和轴向对不同荷电状态的单体电池进行压缩加载实验，研究了锂离子电池在载荷作用过程中的力学响应、电压变化、温度变化以及失效破坏模式。结果表明：荷电状态、加载速度以及加载方向的不同都会对锂离子电池的安全性能产生一定的影响。电池在发生较大变形时会出现电解液泄漏和瞬间短路现象，短路后电池的温度在短时间内会急剧升高。在径向压缩实验中，当荷电状态较高、加载速度较快时，电池在发生变形后会出现爆炸喷火等剧烈的热失控现象。研究锂离子电池在受到外载荷作用时的机械完整性对汽车的安全性设计具有十分重要的意义。

The safety of power batteries is one of the important factors that restrict the rapid development of electric vehicles. In this paper, cylindrical 18650 power lithium ion batteries with different state-of-charge (SOC) were compressed in the radial and axial directions respectively to study the mechanical response, voltage change, temperature change and failure process. The results show that the safety performance of lithium-ion batteries was influenced by SOC, loading speed and loading direction. During the process of compression, electrolyte leakage and instantaneous short circuit may occur, and the temperature of the battery will be rised sharply in a short time after short circuit coming up. During the radial compression process, the phenomena of severe thermal runaway such as explosion and fire will happen for combination of higher SOC and higher loading speed. Therefore, it is important to study the mechanical integrity of lithium-ion batteries under external loads for the safety design of automobiles.