热电触发LFP锂离子电池热失控特性研究

Study on the thermal runaway characteristics of LFP lithium-ion batteries under overheating and overcharge

热滥用、电滥用是触发锂离子电池热失控的主要原因。本文采用加热板直接加热和恒流过充电2种方式开展了方壳磷酸铁锂(LFP)电池单体在有/无外部点火源条件下的热失控试验研究,采集了热失控进程及温度、电压等特征参数,分析了LFP电池单体的本征热失控特征及耦合外部点火源后的着火特性。结果表明,被测LFP电池在过热触发热失控后产生大量白烟,热失控最高温度仅为184℃,在外部点火源的作用下出现明火,火焰最高温度为740℃;LFP电池过充电触发热失控反应更加剧烈,热失控最高温度为450℃,未出现明火,但在外部点火源的作用下出现明火,火焰最高温度达1000℃;LFP电池未完全失控时由外部点火源点燃的火灾类型为以电解液为主的B类稳定火灾,持续加热或充电后,转变为锂离子电池热失控喷射火,火焰强度明显增强。

Thermal abuse and electrical abuse are the main reasons for triggering lithium-ion batteries into thermal runaway.In this paper,the thermal runaway experiments of LFP lithiumion batteries were carried out by overheating using a plate and constant current overcharging with or without external sparks.The thermal runaway process and characteristic parameters such as temperature and voltage were collected and analyzed,the intrinsic thermal runaway characteristics of LFP battery cells and the combustion characteristics with external ignition source were elucidated.As the result shows,the tested LFP battery produced a lot of white smoke under overheating,with maximum temperature of 184℃.The LFP battery jet flame was observed ignited by external energy,and the maximum temperature was 740℃.The thermal runaway of the LFP battery under overcharge was more severe,and the maximum temperature was 450℃,but no flame was observed.The LFP battery jet flame was observed ignited by external energy,and the maximum temperature of the flame was about 1000℃.The LFP battery fire ignited by the external ignition source was a B-type stable fire dominated by the electrolyte if it was not completely under thermal runaway.The violent jet flame was observed with the external heat or electricity adding again.