Effects of Minor Mechanical Deformation on the Lifetime and Performance of Commercial 21700 lithium-Ion Battery

Vehicular lithium-ion batteries (LIBs) may suffer from minor damage or defects owing to external mechanical abuse, such as deformation and scratches, during cycling. This study uses non-destructive testing methods to analyze the effects of minor mechanical deformation on the lifetime and performance of commercial 21700 lIBs. Firstly, incremental capacity analysis (ICA) is performed to quantify the charge/discharge performance and cycle aging behavior of LIBs under different deformations. Secondly, X-ray computed tomography (XCT) technology is utilized to qualitatively analyze the internal structure variations of LIBs caused by minor mechanical deformation. Results show that with an increase in mechanical deformation, the internal resistances of LIBs increase, charging curves move to high voltage areas, and peak points of the incremental capacity (IC) curves decrease and move to high voltage areas. Cyclic charge/discharge of LIBs with different deformations show that with an increase in cycles, the capacity and state-of-health (SOH) of mechanically deformed LIBs decrease significantly due to the changes in the internal structure of batteries. Furthermore, the tomographic images of LIBs demonstrate that the increased internal gaps within the electrodes result in the increase of internal resistance, and the mechanism for capacity loss of batteries in the cyclic is revealed.