Numerical study of critical conditions for thermal runaway of lithium-ion battery pack during storage

Lithium-ion batteries (LIBs) are becoming the preferred solution for a new generation of electric vehicles and static energy storage equipment. In the process of storage and transportation of LIBs, the accumulation of large volumes of batteries is prone to self-ignite, leading to thermal runaway, resulting in serious consequences and losses. In this work, a three-dimensional model of LIBs thermal runaway is built to analyze the influence of battery positive electrode material, arrangement mode and thermal insulation plate on the self-heating ignition of battery pack. The critical ambient temperature (Ta,cr) triggering thermal runaway of battery pack is also studied. The results show that the Ta,cr of a 18,650 battery with LCO, NCM and LFP as positive electrode materials are 148 °C, 168 °C and 201 °C, respectively. The Ta,cr of the battery pack decreases with the increase of the number of cells. This work also compares the effect of arrangement modes on Ta,cr of the battery pack, which shows that the thinner the battery pack is, the higher its Ta,cr will be. Considering the effects of heat shield plate on the self-ignition behavior of battery pack, it is found that the graphite composite sheet is more suitable for battery pack storage than Al plate and aerogel layer. This work can provide guidance for improving battery safety and reducing fire risks during storage and transportation.