Probing Fault Features of Lithium-Ion Battery Modules under Mechanical Deformation Loading

Electric vehicle battery systems are easily deformed following bottom or side pillar collisions. There is a knowledge gap regarding the fault features of minor mechanical deformation without ISC, which can be used for early warning of mechanical deformation. In this study, the fault features of a lithium-ion battery module under different degrees of mechanical deformation were studied from the perspective of voltage consistency. The results show that the capacity of the battery module declines with an increase in indentation depth, consistent with the capacity degradation of the indented cell. During the charging and discharging processes, the voltage of the indented cell deviates to a lower value compared to the other normal cells. At the end of the discharging process, the voltage sharply declines and exhibits a significant deviation from the other normal cells. The Mean Normalization (MN) method is employed to quantitatively describe the voltage consistency. The results indicate that the MN value of the indented cell's voltage is distributed at the lowest during the charging period and sharply declines below -0.06 at the end of discharging. In the future, a fault detection method for mechanical abuse will be established based on these features.