A Method of Efficiently Regenerating Waste LiFePO₄ Cathode Material after Air Firing Treatment

Waste LiFePO₄ (LFP) batteries can be harmful to the environment and lead to waste of resources if not properly disposed of. In this study, an efficient and environmentally friendly method for solid-phase recycling waste LFP cathode material (W-LFP) is proposed. Most of the impurities in the W-LFP are removed by air firing. The regenerated LFP is then obtained by adding lithium carbonate and triethanolamine for repair during heat treatment. The addition of triethanolamine converts Fe³⁺ to Fe²⁺ and also allows the formation of an N-doped modified carbon layer on the surface of the LFP particles, which improves the electrochemical properties of the regenerated material. Physical characterization and electrochemical tests are used to investigate the attenuation and regeneration mechanism of LFP. The regenerated LFP possesses a high specific discharge capacity (152.87 mAh g^-1 at 0.2 C), which is about 95.32% of the commercial LFP, and the capacity retention rate is 88.52% after 600 cycles at 1 C. It is worth noting that we do not use solvents such as acids and alkalis in the regeneration process, thus avoiding the generation of large quantities of acid and alkaline waste liquids, which is friendly to the environment. This solid-phase regeneration process offers a promising method for the future recycling of used LFP batteries because of its simplicity, environmental friendliness, and high efficiency.