Research on the failure mechanism and characteristic evolution of lithium-ion battery under different operation temperatures and extrusion deformation

Lithium-ion batteries (LIBs) are essential for energy storage and electric vehicle applications due to their high energy density and long cycle life. However, safety and reliability concerns persist, particularly under varying operational conditions. This study investigates the morphology, mechanical, electrical, and thermal evolution of LiFePO₄ batteries under different temperatures, extrusion deformation, and states of charge (SOC). The primary goal was to examine the combined effects of these factors on battery performance, with a focus on improving battery management systems and safety. The results demonstrate that temperature, SOC, and deformation significantly impact the electrochemical impedance spectroscopy (EIS) of the batteries, with temperature having the most substantial effect. Notably, at low temperatures, the EIS amplitude in the mid-frequency region at −20 °C was about twice that at −10 °C, and the temperature effect diminished as the temperature exceeded 0 °C. Extrusion deformation also increased the EIS amplitude, particularly in the low-frequency region. Furthermore, deformation, SOC, and temperature significantly influenced stress–strain behavior, open-circuit voltage (OCV), and thermal performance. Internal morphological analysis revealed that severe extrusion deformation caused particle fragmentation, reduced porosity, and induced cracks in both the anode and cathode materials. These findings provide critical insights into the failure mechanisms of LIBs under complex stress conditions, which is crucial for enhancing battery safety and reliability.