A Capacity Degradation Estimation Error Correction Method for Lithium-Ion Battery Considering the Effect of Sequential Depth of Discharge

The depth of discharge (DOD) is one of the key factors affecting the capacity degradation of lithium-ion batteries (LIBs). According to the results of battery aging tests under different DODs, a LIB capacity degradation model considering the impact of DOD can be established. However, in practical engineering, the LIB does not discharge under the discharge scenario with full DOD at one time, but discharge under the discharge scenarios with multiple sequential DODs, which leads to the sum of capacity degradation under the multiple sequential DOD discharge scenarios is higher than that under the full DOD discharge scenario. This shows that the commonly established LIB capacity degradation model considering the impact of DOD is not suitable for calculating the capacity degradation under the sequential DOD condition. Therefore, by fitting the fourth-order polynomial to the capacity degradation error generated by this process, a capacity degradation correction model of LIB considering the impact of sequential DOD is established to improve the adaptability of the LIB capacity degradation model for the sequential DOD condition, which makes the battery capacity degradation estimation more suitable for practical engineering. The results show that based on the correction model proposed in this paper, the capacity estimation degradation error can be reduced by more than 98% under the under multiple sequential DODs condition.