A novel method to repair and upgrade spent LFP cathode material by inherent Al impurity doping

The increasing retirement of LiFePO 4 (LFP) batteries provides a unique chance for advancing the direct regeneration of spent lithium-ion batteries (LIBs). However, the existence of Al impurities from current collectors during the pretreatment of recycling poses a challenge. In this study, we enhance the direct regeneration process of spent LFP material by utilizing Al impurities to replace some cationic sites in the olivine structure. This approach achieves simultaneous elemental compensation and valence restoration, promoting the regeneration of LFP with stable structure and enhanced Li + diffusion rate. The regenerated LFP with Al doping exhibits an initial discharge capacity of 153.9 mAh g -1 , good rate performance with capacity of 112.1 mAh g -1 at 5 C (1 C = 170 mAh g -1 ), and excellent cycling stability (96.4 % capacity retention after 200 cycles). This strategy introduces a threshold for Al impurities and offers a chance to guide the future direct regeneration of LFP materials.