The Operation Dependence of C − N Fatigue for Lithium‐Ion Batteries

Abstract

AbstractLithium‐ion batteries (LIBs) fatigue in repeated service, and their cycle‐life, in resemblance to most materials subject to cyclic loading, scatters over a broad range. The dependence of critical fatigue parameters on ambient temperature and charging or discharging rate, along with the scattering nature of cycle‐life is of practical significance. Through large‐scale experimental investigations, it is shown how both temperatures and charging‐discharging rates may influence critical parameters in the C − N fatigue dependence for LIBs. The cycle‐life N of a battery subject to an average charging rate C follows C = c0 (T)Nb(D), where c0 varies with temperature T and b is a function of the discharging rate D. It is further shown that the cycle‐life of LIBs follows a lognormal distribution. The revealed cycle‐life distribution of LIBs and their fatigue law enable the construction of a probabilistic C − N model, which can be used to quantify the fatigue failure probability in LIBs. Results reported here are of compelling importance for the life‐span evaluation and safety design of large‐scale battery packing in electric vehicles and energy storage where tens of hundreds of batteries working in concert is desired.