Investigation on lithium-ion battery degradation induced by combined effect of current rate and operating temperature during fast charging

Operating temperature and current rate are the main parameters that induce lithium-ion battery (LIB) degradation during the fast-charging process. In this study, fast-charging degradation was investigated using a commercial 18650 Nickel-Manganese-Cobalt battery at different charging current rates (C-rates) and operating temperatures. The degradation process was evaluated using electrochemical impedance spectroscopy and incremental capacity analysis. The electrode morphology change was investigated via a multiscale post-mortem analysis. The battery degradation mechanism at different C-rates and temperatures was characterized, and the coupled effects of the C-rate and operating temperature on the battery capacity fade were determined. With increasing operating temperatures, the most significant factor influencing the battery capacity fade changed gradually from lithium plating to the growth of the solid-electrolyte interface (SEI). An experimental analysis revealed that the battery capacity fade at the higher C-rates can be alleviated to some extent by employing higher operating temperatures. In comparison, the capacity fade at lower C-rates accelerated with increasing operating temperature. The changing and position shifting of the peaks in the incremental capacity curves were analyzed. It was found in the post-mortem analysis that the fast charging degradation was embodied in the macroscopic detachment of electrode material, the microscopic cracking of electrode particle, the SEI growth, the lithium plating, and the structural change of layered material crystal. The results of this study provide insight into the development of fast-charging strategies and the design of battery management systems.