Abstract

As lithium metal resource supply and demand stabilize and prices decrease, the efficient recovery of valuable metals other than lithium from spent lithium-ion batteries is receiving increasing attention. Currently, challenges remain in the selective lithium recovery efficiency and the high cost of regenerating valuable metal slag after lithium extraction, particularly for spent ternary cathode materials. To address these challenges, this study introduces a closed-loop recovery process for spent ternary cathode materials, employing sulfur-assisted roasting to achieve efficient lithium extraction and high-value direct regeneration of ternary leaching residues. At moderate temperatures (500 ℃), LiNixCoyMn1-x-yO2 (NCM) materials undergo a directional transformation of lithium to Li2SO4 in synergy with sulfur and oxygen, achieving a lithium leaching extraction rate of 98.91%. Additionally, the relatively mild reaction conditions preserve the secondary spherical morphology and uniform distribution of NiCoMn-based oxide residue without introducing adverse impurities, ensuring the successful regeneration of high-value NCM cathode materials (R-NCM). The R-NCM material exhibits good discharge capacity (144.3 mA·h/g at 1 C) and relatively stable cycling performance, with a capacity retention rate of 80% after 150 cycles. This work provides a viable pathway for the efficient and environmental-friendly pyrometallurgical closed-loop recovery of spent lithium-ion batteries. The growing stream of spent LIBs would impose an enormous threat to both the natural environment and human health, owing to the presence of hazardous constituents such as heavy metals and organic compounds. Effective recycling can curb environmental and safety concerns, while simultaneously discovering opportunities for resource utilization. We propose an innovative closed-loop recycling strategy focusing on circumventing the dissolution and precipitation steps of valuable metal slag post-lithium extraction, facilitating its direct synthesis into cathode materials. This method allows for sustainable regeneration of spent LIBs through a simpler and more efficient process, resulting in lower negative environmental impact and higher economic profits.