Study on mechanical properties and failure mechanism of 18650 Lithium-ion battery using digital image correlation and acoustic emission

The safety of lithium-ion batteries (LIBs) remains the focus of engineering and scientific attention as its bending failure cannot be monitored by conventional means such as voltage and temperature due to its special failure mechanism. Therefore, it is of great significance to study the mechanical properties and failure mechanisms of LIBs during bending failure. In this paper, 18,650 LIBs are taken as the research object, and an in-situ experimental platform based on acoustic emission (AE) and three-dimensional digital image correlation (3D-DIC) methods is built to study the mechanical properties and failure mechanisms of LIBs in different states of charge (SOC) under bending loads. The results show that the bending modulus and stiffness of the battery increase with the increase of SOC. The main types of damage and the expansion process of the battery during the bending failure process are also obtained. The research results provide a theoretical basis for research on the bending failure of LIBs. Meanwhile, the experimental platform built in this article solves the failure of previous monitoring methods, including deformation and temperature during the bending failure of LIBs. In addition, this paper provides a new method for in-situ monitoring of LIBs.