Electrochemical-mechanical understanding of the accelerated degradation of lithium-ion batteries caused by mechanical stress

Mechanical damage-induced electrochemical performance degradation and associated safety risks in lithium-ion batteries (LIBs) constitute a critical scientific challenge that severely compromises their operational health and service reliability. The underlying mechanisms through which mechanical damage induces battery performance degradation and initiates cascading safety failures remain inadequately investigated. This study systematically explores the multi-physics degradation behavior and mechanism in LIBs subjected to controlled mechanical deformation. Experimental results indicate that mechanical damage accelerates the battery's performance degradation, and the capacity fade rate increases with the damage degree. The fade rate is higher under shear damage conditions for identical indentation depths compared with pure indentation conditions. Post-mortem analysis identified pronounced lithium plating phenomena specifically in shear-damaged cells. Through synergetic analysis combining electrochemical characterization, stress analysis, and damage examination to elucidate the degradation mechanism of mechanically damaged batteries. It is found that shear stress induces significant cracking of electrodes and damage inside the battery, thereby increasing the risk of lithium plating. The degradation mechanism is primarily attributed to the loss of active materials during the early cycles and the loss of lithium inventory in later cycles. The research results provide an important mechanistic insight for the healthy management and safety service of LIBs in electric vehicles.