A Lithium-ion Battery Capacity Degradation Correction Method for Off-Design Cycling Conditions

The depth of discharge (DoD) is one of the key factors affecting the capacity degradation of lithium-ion batteries (LIBs). However, the empirical models of capacity degradation based on DoD are generally deduced from the datasets in fixed cycling conditions and may have inconsistent characteristics for those off-design cycling conditions, for example, the sum of degradation in small DoDs may be overestimated and be even larger than viewing the small DoDs as a whole. To resolve this issue, this paper proposes a LIB capacity degradation error correction model (CDECM) for the widely used polynomial and exponential LIB empirical aging models (EAMs), so as to improve their adaptability to off-design conditions, such as irregular discontinuous discharging scenarios. The results show that, the proposed method can greatly reduce the capacity degradation estimation error in different DoD conditions, and therefore brings a consistent performance under cycling condition variations.