Solvometallurgical recycling of spent LiNixCoyMnzO2 (NCM) cathode material using ternary choline chloride-ethylene glycol-p-toluenesulfonic acid deep eutectic solvent

Abstract

In recent years, recycling lithium-ion batteries (LIBs) has become imperative considering their growing demand will soon lead to massive disposal of spent LIBs which causes critical environmental problems. In this study, solvometallurgy using deep eutectic solvents (DESs) is used to efficiently recover valuable metals from spent LIBs. The potential of different types of DES (binary and ternary) to leach LIB samples is evaluated. Initial leaching tests demonstrate that p-toluenesulfonic acid (PTSA) -based DES results in high metal extraction at 100 °C with 10 g/L pulp density and 72 h residence time. Cyclic voltammetry indicates a high current density of PTSA, a strong leaching agent in the DES structure. A ternary DES containing choline chloride, ethylene glycol, and p-toluenesulfonic acid (ChCl-EG-PTSA) show better performance as a leachant than other DESs. The formation of hydrogen bonds between p-toluenesulfonic acid-based DES components is examined by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. This study provides a new ternary DES for solvometallurgical recycling of LIBs while considering principles for sustainable development.