圆柱型磷酸铁锂电池针刺热失控实验研究

摘要

Internal short circuit would be triggered when lithium ion batteries in nail penetration, it will generating massive heat and smokes and may cause thermal runaway damage. In this paper, the internal structure and thermogenesis mechanism of cylindrical LiFePO4 battery after nail penetration are analyzed. An experimental platform for nail penetration test is established, Φ5 mm tungsten steel needle is used to penetrate the battery at initial ambient temperature 20 ℃. The battery thermal runaway process, battery voltage changes, battery surface temperature changes and so on are investigated. According to the experimental results, the following conclusions are obtained: (1) Intensity of thermal runaway about cylindrical LiFePO4 batteries during nail penetration is random. (2) The battery voltage would drop to 0 V after battery penetrated, and will drop more rapidly if the battery sprays smoke and explodes. (3) The temperature of the battery will rise rapidly after nail penetration, and it will rise faster and higher as the battery belches smoke or explodes. The damage of nail penetration to the lithium iron battery is devastating and causes thermal runaway. Therefore, the battery structure should be designed to prevent nail penetration and provide extra protection.%锂离子电池在发生针刺之后会造成内部短路, 进而产生大量热量和浓烟以至引发热失控.本文通过模拟实验剖析圆柱型磷酸铁锂电池针刺后的内部结构, 结合理论分析探究针刺热失控产热机理.以自行设计搭建的磷酸铁锂电池针刺热失控实验平台为基础, 在初始20℃室温下采用Φ5 mm的钨钢针刺穿电池, 观测电池的热失控发展情况以及电池电压、表面温升变化规律.根据实验结果得到以下结论:①针刺对圆柱型磷酸铁锂电池造成的热失控剧烈情况带有随机性;②电池电压在针刺后下降至0V, 若破坏过程中电池内部热反应气体泄漏甚至发生爆炸则电压下降更迅速;③电池温度在被刺破后迅速上升, 其温升趋势总体随破坏程度增加而加快.综合来看, 针刺对磷酸铁锂电池的损坏是不可逆且通常会并发热失控, 因此建议在设计电池结构时应当充分考虑防针刺及对电池进行额外保护.