A\nMethod of Efficiently\nRegenerating Waste LiFePO<sub>4</sub> Cathode Material after Air Firing\nTreatment

Waste LiFePO<sub>4</sub> (LFP) batteries\ncan be harmful\nto the\nenvironment and lead to waste of resources if not properly disposed\nof. In this study, an efficient and environmentally friendly method\nfor solid-phase recycling waste LFP cathode material (W-LFP) is proposed.\nMost of the impurities in the W-LFP are removed by air firing. The\nregenerated LFP is then obtained by adding lithium carbonate and triethanolamine\nfor repair during heat treatment. The addition of triethanolamine\nconverts Fe<sup>3+</sup> to Fe<sup>2+</sup> and also allows the formation\nof an N-doped modified carbon layer on the surface of the LFP particles,\nwhich improves the electrochemical properties of the regenerated material.\nPhysical characterization and electrochemical tests are used to investigate\nthe attenuation and regeneration mechanism of LFP. The regenerated\nLFP possesses a high specific discharge capacity (152.87 mAh g<sup>–1</sup> at 0.2 C), which is about 95.32% of the commercial\nLFP, and the capacity retention rate is 88.52% after 600 cycles at\n1 C. It is worth noting that we do not use solvents such as acids\nand alkalis in the regeneration process, thus avoiding the generation\nof large quantities of acid and alkaline waste liquids, which is friendly\nto the environment. This solid-phase regeneration process offers a\npromising method for the future recycling of used LFP batteries because\nof its simplicity, environmental friendliness, and high efficiency.