Closed-Loop Recycling of Spent LiNixCoyMn1-x-yO2 Batteries Based on Liquid-Phase Reduction-Driven Delithiation Conversion.

The recycling of spent lithium-ion batteries (LIBs) is critical to the sustainable development of the new energy industry. However, traditional recycling processes often face challenges, such as high-energy consumption, complex procedures, and excessive use of corrosive reagents. In this study, an advanced liquid-phase reduction-driven strategy is employed to selectively extract Li from spent LiNixCoyMn1-x-yO2 (NCM) batteries and regenerate the NCM cathode materials. During the delithiation process, Li+ is leached into the liquid phase from spent NCM material, while the Ni, Co, and Mn elements remain in the solid phase, with N2H4·H2O serving as the sole reagent. Under optimal reaction conditions, the Li leaching efficiency reaches 98.9%. Thermodynamic analysis and XRD results reveal that the delithiation reaction involves the transformation of spent NCM into a layered Ni-Co-Mn hydroxide (Ni/Co/Mn(OH)2). Additionally, the Li-rich leachate can be recovered as Li2CO3 products, while the Ni-, Co-, and Mn-enriched residues serve as the precursor for regenerating NCM cathode materials. The regenerated NCM exhibits a discharge-specific capacity of 183.0 mAh g-1 at 1C with a retention rate of 79.9% after 300 cycles. Overall, this work provides novel insights into the efficient closed-loop recycling of spent NCM batteries by leveraging the delithiation conversion technique.