Rapid-regroup strategy for retired batteries based on short-time dynamic voltage and electrochemical impedance spectroscopy

The disposal of retired batteries from new energy vehicles has been the subject of much attention. The process of sorting consistent cells is time-consuming when retired cells are used for regrouping. In order to solve this problem, this paper uses electrochemical impedance spectroscopy (EIS) and short-time dynamic voltage to analyze the cell consistency in retired packs. The feature parameters (FP) extracted from the EIS and short-time dynamic voltages characterize the consistency and state of health of the cells in the retired battery packs. The proposed regrouping strategy only takes about 6 min. Furthermore, the paper established a simulation to examine the effect of different factors on the regrouping of retired batteries which helps to optimize the regrouping process and understand how different factors impact the regrouping pack. Finally, it verifies through experiments that the method reduces the dispersion of cells within the pack and the risk of overcharging and over-discharging.