Numerical Modeling of the Thermal Runaway in High-Energy Lithium-Ion Battery Packs Induced by Multipoint Heating

The thermal runaway in lithium-ion batteries is a primary safety concern in energy vehicles. Herein, a numerical model based on thermal abuse ordinary and heat transfer partial differential equations and the natural convection in computational fluid dynamics for investigating the thermal propagation in battery packs is proposed. A three-dimensional geometric model of a high-energy lithium-ion battery pack comprising 18650 format cells is constructed to analyze thermal characteristics using the finite element method. A thermal abuse test is also presented to simulate the occurrence of thermal runaway in cells due to multipoint heating. In the model that does not consider natural convection, it was observed that the final cells to enter thermal runaway in the modules are A48#, B48#, C48#, and D48#. However, when natural convection is considered, these are predicted to be A45#, B45#, C45#, and D45#, respectively. The maximum differences exhibited by the two aforementioned models in terms of the time of occurrence of thermal runaway and the peak temperature are −69 s and 50 K, respectively. Thus, the coupling model at the pack level proposed in this study is expected to improve the design of battery thermal management systems