Extraction of precious metals from used lithium-ion batteries by a natural deep eutectic solvent with synergistic effects

Abstract

As the demand for lithium-ion batteries rises, the growing quantity of waste produced from lithium-ion battery electrode materials becomes an issue of concern. We propose a novel approach for effectively extracting precious metals from cathode materials that address the problem of secondary pollution and high energy consumption that arise from the conventional wet recovery process. The method employs a natural deep eutectic solvent (NDES) composed of betaine hydrochloride (BeCl) and citric acid (CA). The leaching rates of manganese (Mn), nickel (Ni), lithium (Li), and cobalt (Co) in cathode materials may reach 99.2 %, 99.1 %, 99.8 %, and 98.8 %, respectively, due to the synergy of strong coordination ability (Cl^-) and reduction (CA) in NDES. This work avoids the use of hazardous chemicals while achieving total leaching in a short period (30 min) at a low temperature (80 °C), achieving an efficient and energy-saving aim. It reveals that NDES has a high potential for recovering precious metals from cathode materials and offers a viable, environmentally friendly method of recycling used lithium-ion batteries (LIBs).

Keywords: Betaine hydrochloride; Leaching; Natural deep-eutectic solvents; Recovery; Spent lithium-ion batteries.