A coupled multi-physics study on Li-ion batteries under impact loading

As lithium-ion batteries (LIBs) become more prevalent in electric vehicles (EVs), understanding their mechanical, electrical, and thermal behaviour under impact loading is crucial for crash safety. This study proposes a cost-effective numerical framework that integrates a coupled thermo-electro-chemo-mechanical model to predict the temperature distribution and mechanical failure of LIB cells under various impact conditions. The geometric data of the battery is obtained using computed tomography (CT) and scanning electron microscopy (SEM) prior to impact tests, followed by mechanical characterisation of each jellyroll layer. Four distinct impact scenarios—bending with and without electrolyte leakage, and compression causing full or partial layer delamination—are established to calibrate and validate the model for two different battery types. These scenarios are designed to encompass potential phenomena, such as shell casing damage and electrolyte leakage, which may occur during a real crash. A novel distributed Randle circuit is introduced to simulate electrolyte leakage and casing shell failure, incorporating virtual battery and virtual resistance components. The numerical model is validated through in-house experimental tests. The framework accurately predicts the temperature field, voltage drop, and mechanical delamination of LIB cells, demonstrating that the voltage drop correlates not only with separator failure but also with electrolyte leakage.