RESUMEN
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 â), 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.
RESUMEN
Given the rising lithium-ion battery retirement trend, there is a pressing need for a sustainable, cost-effective, versatile, and industrially viable positive active powder reprocessing method. The current treatment methods require significant amounts of acids, reducing agents, and other additives, resulting in increased treatment expenses and detrimental environmental consequences. This paper proposes a synergistic redox strategy, based on thermodynamic calculations of potential self-promoting reactions in mixed LFP/NCM systems, for the recovery of spent LFP and NCM batteries without the need for additional agents in a milder acidic atmosphere. In this cooperative redox strategy, the spontaneous extraction and oxidation of Fe2+ to Fe3+ took place within the acidic solution atmosphere encapsulating LFP. Simultaneously, NCM underwent further reduction, yielding Ni2+ and Fe2+, thereby enabling the proficient dissolution and segregation of lithium and transition metal ions. The leaching rate of lithium, nickel, cobalt and manganese was close to 100% when the reaction was carried out at 20 °C for 40 min. The final raw material was reprepared into a battery with a capacity of 168.8 mA h g-1 at 1C, and the cycle retention rate was 76.78% after 300 cycles. Regenerating FPO into LFP cathode material achieves closed-loop recycling of all elements and generates 12% higher profits compared to separate processes. Our method proposes a zero-additive battery recycling process and successfully explains the intrinsic redox process.
