Experimental investigation on thermal runaway propagation of lithium-ion battery module under different trigger locations

The Li-ion battery (LIB) module is composed of numerous individual cells, and the locations at which thermal runaway (TR) is triggered play a crucial role in influencing thermal runaway propagation (TRP). Nevertheless, the impact of the TR trigger location on TRP within LIB modules remains inadequately understood. This work investigates the influence of the TR trigger locations location on TRP in both LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523) and LiFePO₄ (LFP) battery modules. Our findings demonstrate that relocating the trigger location from the corner to the center increases the TRP rate of the NCM523 (LFP) module from 0.365 (0.244) to 2.270 (0.685) cell/min. Additionally, the energy utilization rate of the NCM523 (LFP) module rises from 31.3 % (28.9 %) to 56.1 % (46.5 %). The ejected particulate matter from LIBs is further analyzed using scanning electron microscopy-energy dispersive spectroscopy. Finally, this paper proposes a hazard assessment model to evaluate the risks associated with LIB modules under different trigger locations. The results indicate that transitioning the trigger location from the corner to the center exacerbates the hazards associated with LIB modules. This study systematically elucidates the impact of cathode materials and trigger locations on TRP, offering definitive guidance for the safety management and design of electric vehicle modules.