Recovery of valuable metals from spent lithium-ion batteries based on a green and efficient leaching system of dimethyl-β-propionic acid thiophene (DMPT)

Abstract

The recycling of spent lithium-ion batteries (LIBs) represents the terminal phase of the new energy industry chain and plays a pivotal role in resource conservation and environmental protection. Despite increasing attention, the development of green and efficient recycling strategies remains a substantial challenge. In recent years, various environmentally benign solvents—including supercritical fluids, deep eutectic solvents (DES), and ionic liquids (ILs)—have been explored to promote the sustainable recycling of LIBs. Among these, the application of biomass-derived reagents (BDRs) has emerged as a promising approach due to their renewability and low environmental impact. In this study, a novel leaching strategy employing the natural organic molecule dimethyl-β-propionic acid thiophene (DMPT) is proposed for the efficient and environmentally friendly recovery of valuable metals from spent ternary LIB cathodes. Leveraging the synergistic action of carboxyl functional groups and chloride ions inherent in the DMPT structure, leaching efficiencies of Li, Ni, Co, and Mn reached 98.7 %, 97.2 %, 97.8 %, and 98.3 %, respectively. The leaching reactions and products were systematically investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Compared with conventional hydrometallurgical processes, this DMPT-based method eliminates the need for strong acids, bases, or additional reducing agents, thus minimizing secondary pollution. The proposed approach offers a green, sustainable, and effective alternative for the recovery of critical metals from spent LIBs, and holds significant potential for future industrial application.