低压环境下锂离子电池热失控特性研究

Thermal runaway characteristics of lithium ion batteries in low voltage environment

为了探究锂离子电池在不同环境压力下的热特性,实验通过动压变温实验舱和ISO-9705烟气分析仪作为实验条件载体,对100%SOC(荷电状态)的18650圆柱锂离子电池在不同环境压力(30、50、70、90 kPa)下进行热失控实验。结果表明,无论是常压还是低压环境下,由外部热源引起热失控都可分为三个阶段;随着环境压力的降低,电池表面中心峰值温度、热释放速率、总热释放量均降低,燃爆响应时间点延长;在30 kPa时燃爆响应时间点为515 s,比90 kPa条件下延长了348 s;90 kPa时电池热表面峰值温度为703℃,是30 kPa环境压力下的1.299倍;随着环境压力的下降,CO气体的释放量逐渐增加,CO2、CxHy的释放量逐渐减少。可见常压环境下锂离子电池表现出更高的热危害性,低压环境下表现出更大的毒危害性风险。

In order to explore the thermal characteristics of lithium-ion batteries under different environmental pressures,thermal runaway experiments of 18650 cylindrical lithium-ion batteries with 100%SOC(state of charge)under different environmental pressures(30 kPa,50 kPa,70 kPa,90 kPa)were carried out with dynamic pressure and temperature chamber and ISO-9705 flue gas analyzer.The results show that the thermal runaway caused by external heat source can be divided into three stages in either normal pressure or low pressure environment.With the decrease of the environmental pressure,the peak temperature,heat release rate and total heat release rate of the battery surface decrease,and the detonation response time point is prolonged;at 30 kPa,the explosion response time point is 515 s,which is 348 s longer than that under 90 kPa condition.The peak temperature of the thermal surface of the battery is 703℃at 90 kPa,which is 1.299 times of that under 30 kPa.With the decrease of environmental pressure,the release of CO gas increases gradually,while that of CO2 and CxHy decreases gradually.It can be seen that the lithium-ion battery in normal pressure environment has higher thermal hazard.In low-pressure environment,it will have greater risk of toxic hazard.