A mild and efficient closed-loop recycling strategy for spent lithium-ion battery.

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.