Battery safety is one of the top priorities in the design of electrified vehicles (EVs) since battery failure may lead to a catastrophic consequence. As such, it is critical to understand the responses of a battery system under different abuse scenarios in order to make the newly designed battery systems meet the regulation requirements. Various abuse tolerance tests have been developed to evaluate the failure conditions of lithium-ion batteries. Nevertheless, these tests can be expensive and time consuming, and in some cases provide limited information on the failure mechanisms of batteries, which is inconvenient during design iterations and optimization. On the other hand, computational modeling can predict the battery behaviors in a more efficient and cost-effective way, which becomes an important tool to evaluate battery safety. The majority of the early developed battery safety models either consider dynamic effects while focusing on mechanical response only or they consider multiple physical processes while only applying to the quasi-static loading conditions. Moreover, they are usually applied to low-energy cells, and their applications to large-format EV batteries under high-speed impact remains to be investigated. Here we present a multi-physics battery safety model that can predict coupled mechanical, thermal, electrical and electrochemical responses of automobile lithium-ion batteries under high speed impact 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. Along with the modeling effort, we also developed the method to test the impact responses of both cells and modules. These impact tests were used to calibrate the model parameters and validate the model predictions. In this talk, the multi-physics battery impact model will be introduced first, which includes model formulations in different solvers and material properties evaluation. Then the details in the set up and procedure of impact tests for pouch and prismatic cells and modules will be presented. After that, the comparison between model prediction and experimental result of the battery impact responses will be shown to demonstrate the model capabilities. At the end, the future development of battery safety modeling will be discussed.&nbsp;&nbsp;

Multi-Physics Impact Modeling and Testing of Lithium-Ion Batteries

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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