A multiphysics understanding of internal short circuit mechanisms in lithium-ion batteries upon mechanical stress abuse

Lithium-ion batteries (LIBs) have played an increasingly dominant role in the current mobile society. Due to the risky safety testing procedure, ultra-rigorous demands of the testing facility, and complicated multiphysics nature of the safety issues, the lack of high-fidelity models to describe the safety behaviors of lithium-ion batteries upon abusive loading has significantly deferred the further application of LIBs. Herein, by assistance from the ex-situ observation using the X-ray Computed Tomography scanning technique and postmortem characterization of the battery samples, we reveal the formation process of various internal short circuit (ISC) modes upon abusive loading guiding our modeling. Strain-based and ISC mode-dependent criteria are first developed to establish the mechanical-electrical coupling relationship. Particularly, we establish a fully multiphysics-coupled model capable of identifying various ISC modes and describing the entire evolution process of the battery from the initial deformation to the final thermal runaway (TR) of the LIBs. The multiphysics model demonstrates a promising generalization in various SOC and loading situations. Finally, the multiphysics model is applied for 100% SOC of the LIB to reveal the evolution mechanism of deformation-different ISC modes-TR. Results highlight the power of computational modeling to understand the underlying mechanism of safety issues in energy storage systems in a broader context.