Abstract
Lithium-ion batteries (LIBs) are typically assembled into battery packs under a preload force. Despite its significance, research on the impact of preload force on thermal runaway (TR), a critical safety concern for LIBs, remains deficient. Furthermore, few existing TR models incorporate preload force, highlighting a gap in current methodologies. In this work, a TR prediction model that integrates gas generation and mechanical responses is developed, aiming to incorporate the influence of preload force and enhance the accuracy of safety venting predictions. To validate the prediction model, TR experiments are conducted to examine the internal pressure and shell deformation of LiFePO4 (LFP) prismatic batteries under different preload forces. The experimental results reveal that an increased preload force leads to a higher internal pressure. The increase rate of internal pressure in the rapid rise stage is about 0.5 kPa/s, regardless of the preload force. Moreover, model results indicate that an excessively high preload force leads to a reduction in the opening pressure of the safety valve, due to the large stress concentration at the safety valve. Overall, this study can provide a comprehensive guide for the safety design of prismatic battery systems, advancing current standards.
Published Version
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