Coupled electrochemical-abuse-heat-transfer model to predict thermal runaway propagation and mitigation strategy for an EV battery module

Abstract

Safe and reliable design of lithium-ion battery packs necessitates prevention of thermal runaway and its propagation. To characterize the propagation behaviour in a battery module, a three-mode heat transfer model coupled with electrochemical and abuse-reaction-kinetics models is developed here. The efficacy of an active thermal management system in preventing damage-cascade for a standard EV module geometry (as used in Tesla) is elucidated. The model effectively captures the temperature profile, heat generation rate, and the extent of resulting decomposition of cell-components as validated against the literature. A temperature spike is applied to a cell within a standard battery module to emulate abuse driven runaway. The propagation of damage to other cells due to the temperature-spike in the triggered cell is simulated through the model as developed. A counter-intuitive non-monotonic trend (increasing first, decreasing later) is observed for the damage-severity as a function of coolant flow rate. Through a unified analysis of cumulative heat generation and heat dissipation through coolant, a mitigation strategy for runaway propagation is obtained in terms of a generalized non-dimensional parameter, Runway Mitigation Number (RMN), which predicts runaway propagation beyond a value of ~1.8 for similar module designs.