Aging mechanisms analysis of Graphite/LiNi0.80Co0.15Al0.05O2 lithium-ion batteries among the whole life cycle at different temperatures

Abstract

Lithium-ion batteries (LIBs) are widely used in electric vehicles, while capacity fading happens due to unwanted side reactions during cycling. Therefore, it is of great significance to study the aging mechanisms of LIBs among the whole life cycle for the use and design of LIBs. In this study, the aging experiments of Graphite/LiNi0.80Co0.15Al0.05O2 (NCA) batteries were conducted at 25°C and 45°C, the aging mechanisms were examined by differential voltage analysis method and electrochemical impedance spectroscopy analysis method, and verified by microscopic morphology observation. The results show that the loss of anode active material and lithium ions are the main degradation modes, and the lithium plating side reaction at the late aging stage is the inducement of capacity plunge both at 25°C and 45°C. But the causes of lithium plating are different, at 25 °C, the growth of solid electrolyte interphase (SEI) leads to lithium plating, while at 45 °C, the accumulation of gas leads to lithium plating.