Mechanical abuse and safety in sodium-ion batteries

Abstract

Sodium-ion batteries (SIBs) are emerging as promising alternatives to lithium-ion batteries (LIBs) because of their low cost and abundant resources. However, their safety and reliability under mechanical abusive loading remain unclear, posing a barrier to further commercialization. In this study, we investigate the mechanical–electrochemical–thermal behavior and underlying mechanisms of SIBs through ball indentation tests. Meanwhile, we develop a multiphysics coupling computational framework—encompassing a 3D mechanical model, a 3D thermal model, an electrochemical model, and an internal short circuit (ISC) model—to gain deeper insights into the internal processes of SIBs. Using this framework, we comprehensively analyze the effects of ball size, battery aspect ratio, and ball loading position, and compare the safety of SIBs and LIBs. Experimental results show that, during ISC, the battery temperature gradually increases, reaching only about 35 °C due to the extremely rapid voltage drop and relatively lower capacity. Parametric studies reveal that using a larger steel ball or a smaller battery aspect ratio delays the ISC trigger and lowers the ISC temperature. Moreover, the computational model demonstrates that SIBs exhibit a slightly later ISC trigger and significantly lower ISC temperatures. Overall, this study lays a solid foundation for understanding SIB behavior and mechanisms under mechanical abuse and provides valuable guidance for designing safer next-generation sustainable batteries.