软包动力电池过充电热失控特征研究

研究了正极和负极分别为8系高镍三元NCM811（Li（Ni0.8Mn0.1O0.1）O2）和硅碳（SiOx/graphite）的25 Ah软包动力电池过充电触发热失控特征。结合电池材料热特性和热失控产气成分分析，揭示了绝热与非绝热环境下，电池热失控期间内部微观变化和动态产热特性。过充电触发热失控的路径为：过充电超过安全边界电压后电池内部发生副反应和内部极片微短路，引起气体和热量累积，最终电池过热达到热失控临界点。与非绝热环境相比，绝热环境下热失控触发瞬间温度高出37.5 ℃，且触发时长有不同程度的缩短（约为90～500 s）。最后对电池的安全和失效边界做出了界定。

Overcharge-induced thermal runaway characteristics of pouch cells

This paper studies the overcharge-induced thermal runaway characteristic of LiNi0.8Mn0.1O0.1O2-SiOx/graphite system 25 Ah pouch-shaped traction cells. Combined with the analysis results of the thermal characteristics of the electrode materials and gas production components during the thermal runaway process, the internal microscopic changes and dynamic heat generation characteristics of the cells during the thermal runaway triggered by overcharge in adiabatic and non-adiabatic environments was revealed. The path of overcharge triggering thermal runaway is: when overcharge causes the battery to exceed the safety margin voltage, side reaction and micro-short circuit of the pole piece occurred inside the cells, which generate gas and heat, and finally the cells overheat and reach the critical point of triggering thermal runaway. The trigger temperature of thermal runaway in adiabatic environment is 37.5 ℃ higher than that in non-adiabatic environment, and the triggering time in an adiabatic environment is shortened to varying degrees (about 90~500 s). In the end, the safety boundary and failure boundary of the cells were defined.