Understanding of Stress‐Driven Internal Short Circuit Mechanisms in Lithium‐Ion Batteries with High SOCs

The characteristics of internal short circuits (ISC) play a critical role in determining the thermal runaway behaviors and associated hazards of lithium‐ion batteries (LIBs). However, due to safety concerns and limitations in operando characterization at high state‐of‐charges (SoCs), the fundamental understanding of stress‐driven ISCs under high SOC situations (above 30%) is still lacking. In this study, combined post‐mortem characterization and multiphysics modeling is employed to clarify the evolution of ISC modes in LIBs with high SOCs. These findings reveal that the triggered ISC mode is SOC‐dependent, with the Al current collector (Al)‐Anode coating (An) mode dominant in high SOC situations. Experimentally obtained ISC resistance for the specified ISC mode is then assigned to the corresponding ISC region in the established multiphysics model, allowing for accurate coupling of the electromechanical relationship and prediction of mechanical‐electrical‐thermal responses of the LIB. Finally, a simple yet effective approach is proposed for avoiding the Al‐An mode after battery fractures, achieved through surface notches on electrodes. Results discover novel phenomena for ISC in high SOC cells and reveal the underlying mechanisms, highlighting the importance and potential of battery structural design for developing next‐generation robust batteries.