Sorting and grouping optimization method for second-use batteries considering aging mechanism

With the wide application of lithium-ion batteries in electric vehicles(EVs) and battery energy storage systems(BESSs), numerous retired lithium-ion batteries have to face the problem of the disposal and reuse. However, the existing sorting method for fresh batteries takes the external characteristics such as battery capacity and internal resistance as the sorting characteristic index, which fail to guarantee high efficiency and long service life simultaneously in specific second-use application scenes. This paper proposes a novel sorting and grouping method for retired batteries considering both characteristic parameters including aging mechanism and application scenes. First, the multi-factors including capacity, internal resistance and Incremental Capacity Analysis (ICA) based aging mechanism indicator, are extracted from experiments. Second, a fuzzy clustering algorithm is utilized to sort retired batteries according to the requirement of two typical application scenes, energy storage and peak load shifting, which are characterized by high capacity and instantaneous high power charge/discharge, respectively. Finally, 80 retired LiFePO4 batteries are screened and grouped using the proposed method. The results show that the proposed sorting method can effectively select batteries considering aging mechanism to ensure good performance and consistency in both application scenes.