A green cycle strategy for selective leach and recovery of critical metals from spent lithium-ion batteries: Experimental and new mechanistic insights.

With the global surge in lithium-ion batteries (LIBs), recycling spent LIBs has become an essential and urgent research area. In the context of global efforts to promote sustainable development, and achieve energy conservation and emission reduction, advancing recycling technologies that efficiently recover critical metals like Ni, Co, Mn, and Li is crucial. Herein, a novel and environmentally friendly simplified process for selectively extracting critical metals from the mixed electrode materials of spent LIBs is proposed for the first time. A comprehensive thermodynamic analysis of the Me-HPO-HO system was conducted to identify the thermodynamic equilibria and predict the species of each metal within the leaching system. This analysis provided a theoretical basis and experimental guidance for the selective extraction of critical metals while minimizing the dissolution of Al and Cu. The experiment results demonstrate that, under controlled conditions of 80°C, 90 min, 2.0 M HPO, 0.4 M ascorbic acid, and an L/S ratio of 10 mL/g, the extraction yields of critical metals approached 99 %. In contrast, the maximum extraction yields of Al and Cu were 20.74 % and 0.6 %, respectively. Kinetic modeling indicated that the leaching reactions for critical metals were primarily diffusion-controlled, whereas the leaching of aluminum was governed by interfacial chemical reactions. Characterization of the leachate residue revealed the formation of stable phosphate precipitates for Al and Cu, further validating the process's selectivity and feasibility. Additionally, the leachate was used as a raw material to synthesize LiNiCoMnO cathode material, achieving a comprehensive, highly efficient, and green closed-loop recycling process for spent LIBs.