Influence of the Calendar Aging on the Cycle Aging of LiNiMnCoO2 lithium-Ion Batteries

An experimental and theoretical study of lithium nickel manganese cobalt oxide (NMC) cells with a long rest time under different storage temperatures is carried out. We show that the long-term storage of a cell decisively influences its cycle life, and this influence is more pronounced at the late stage of the battery cycle life. Experimental outcomes demonstrate that the cycle life drops as the storage span lengthens, and the storage under relatively low temperature helps to reduce the cycle fading. Based on the experimental data, we identify the point on the fading trajectory to separate the early-medium stage and the late stage for the cycle aging. By extending the previously proposed semi-empirical model to incorporate the two-stage fading into a single formulation, the cycling capacity loss of the stored NMC cells is predicted. An incremental capacity analysis is further performed to assess the cycle fading of the cells under various storage conditions.