Selective lithium recovery and regeneration of LiFePO4 from spent lithium-ion batteries: An efficient and green process

With the growing retirement of lithium iron phosphate (LiFePO4) batteries, advanced recycling strategies are garnering widespread attention for resource sustainability. However, key issues such as high costs and improper disposal of hazardous waste urgently need to be addressed. Therefore, this paper proposes a systematic, green, and sustainable recycling process for spent LiFePO4 batteries. This method employs potassium pyrosulfate as a leaching agent to replace traditional inorganic acids, thereby reducing the negative environmental impact. Under optimal experimental conditions, the lithium (Li) leaching rate reaches 98.33 %, while the iron (Fe) leaching rate remains below 0.5 %, demonstrating high selectivity. The leaching process of LiFePO4 in potassium pyrosulfatehydrogen peroxide aqueous solution follows an Avrami kinetic model: lnk + nlnt =ln (-ln(1-x)) with an apparent activation energy of 18.69 kJ mol-1. This process is limited by both chemical and diffusion reactions. The recovered products, lithium carbonate and iron phosphate are utilized to synthesize regenerated LiFePO4. Compared to waste LiFePO4 and fresh LiFePO4, the regenerated LiFePO4 exhibits good electrochemical performance. Finally, an economic analysis reveals that the designed regeneration pathway possesses significant recovery value potential. This study proposes an efficient, economical, and sustainable closed-loop recycling technology for used lithium-ion batteries, facilitating resource recovery and environmental protection.