CFD study of nail penetration induced thermal runaway propagation in Lithium-Ion battery cell pack

Li-ion batteries have gained massive momentum due to their potential to hold the greatest energy density, but they suffer serious safety problems related to thermal runaway and flammability of the electrolyte components. A three-dimensional numerical modeling of Li-ion pouch cell-based battery pack is proposed in this study. The proposed three-dimensional integrated multiphysics model was validated with the experimental data, and used to investigate the impact of nail penetration depths (20 mm, 15 mm and 12.5 mm) and defect location effects on battery pack thermal runaway. The locations of the envisaged defects are at the upper, middle, lower sides of battery's lateral edge, and middle of the bottom edge. The study showed that battery pack temperature evolution due to thermal runaway is substantially affected by both internal short circuit (ISC) size and defect locations. The thermal runaway with ISCs induced at upper, middle and lower sides of battery's lateral edge have been found faster than that of ISC induced in the middle of the bottom edge. The thermal runaway inception for ISCs induced in the middle of the bottom edge lags behind 10 s when compared to thermal runaway inceptions for ISC induced at the upper, middle and lower sides of battery's lateral edge. The study also investigated the effect of convective heat transfer coefficient on suppressing the thermal runaway propagation, and a convective heat transfer coefficient of 500W/m2.K effectively suppressed thermal runaway and minimize its respective effects. The study provides insights on vulnerable sides of battery in the pack and the corresponding failure behaviors, such insights are valuable for Li-ion cell design and thermal management system design.