Temperature-dependent multi-physical modeling strategy and safety optimization of lithium-ion battery under mechanical abuses

Mechanical abuse risks remain a major concern in the widespread use of lithium-ion batteries (LIBs) in electric transportation. Extreme ambient temperatures in different service environments significantly affect the mechanical properties and failure behaviors of LIBs, posing safety challenges. This study investigates the failure process of lithium-ion pouch batteries under mechanical indentation leading to internal short circuit (ISC) at both low and high temperatures using a coupled mechanical-electrical-thermal model. By incorporating a temperature-dependent, strain-based failure criterion for the separator and heat generation models, the proposed framework accurately reproduces two experimentally observed failure behaviors across different temperatures. At low temperatures, electrical failure is characterized by minor voltage drops and limited heat generation due to localized separator cracking. In contrast, at higher temperatures, extensive internal fractures result in sharp voltage drops and significant heat buildup. The indentation-induced failure mechanisms, integrating mechanical deformation and ISC characteristics, are discussed. Additionally, parametric studies on the jellyroll and shell casing reveal that optimizing the yield strength, elastic modulus, and geometric thickness enhances LIB safety under mechanical indentation. However, a balance must be maintained among failure displacement, load-bearing capacity, and ISC severity at the onset of electrical failure. This modeling strategy offers a multi-physical approach to predicting and optimizing battery safety, providing valuable insights for improving LIB design across diverse environmental conditions.