Modeling Impact Safety of Lithium-Ion Batteries in Electrified Vehicles

Lithium-ion batteries have been widely used for an energy storage system in electrified vehicles due to their high energy and power densities. Improving the safety of lithium-ion battery system is one of the top priorities in the electrified vehicle design since it is directly related to the safety of passengers. Various abuse tolerance tests have been developed to evaluate the failure conditions of lithium-ion battery cells, modules and systems. Nevertheless, these tests can be expensive and time consuming, and in some cases provide limited information on the failure mechanisms of batteries. As such, computational modeling has gained a lot of interests and played a more and more important role in evaluating the battery safety under different abuse scenarios. Here we present a multi-physics battery safety model that is able to predict coupled mechanical, thermal, electrical and electrochemical responses of automobile lithium-ion batteries under abusive conditions. In this model, the electrochemical behavior of batteries is described by a spatially distributed equivalent circuit model, where polarization and damping effects are captured by a resistance-capacitance network. During simulations, the mechanical solver predicts the onset of short circuit, and then the coupled thermal, electrical and electrochemical solver captures the evolution of temperature, voltage and current distribution after short circuit initiation. In order to make the proposed model applicable to module or pack level simulations, various element formulations and strategies have been developed to improve computational efficiency without scarifying much accuracy. Details of model set up, parameters evaluation, and case studies that demonstrate the model capabilities will be presented. Experimental validation of model prediction as well as the future development of this framework will also be discussed.