Ethylene glycol-inorganic solvents for the sustainable recycling of lithium-ion battery cathodes

Abstract

The dissolution process constitutes a significant barrier in the hydrometallurgical recovery of lithium-ion battery cathodes. Numerous novel solvents have been reported as alternatives to inorganic acids for reducing equipment corrosion and waste emissions; nonetheless, they remain constrained by factors such as cost, viscosity, efficiency, and environmental impact. In this work, several novel ethylene glycol-inorganic solvents (EISs) without such disadvantages were designed for the solvometallurgical recovery of LiCoO2 (LCO) and lithium nickel cobalt manganese oxides (NCMs). Also, comprehensive characterizations were carried out on detailed structures, properties, and dissolution mechanisms. The EIS of EG-AlCl3·6H2O (40 g EG was mixed with 5 g AlCl3·6H2O) completely dissolved LCO at a solid-liquid ratio of 1:50, with extremely low viscosity, simple solvent preparation, and facile dissolution. The acidity of EG in EIS was stimulated by the Lewis acid Al3+, rendering the entire dissolution process devoid of supplementary inorganic or organic acids. The recyclable nature of EIS maintained effective leaching of LCO even after three cycles. The reported EISs have high performance and environmental friendliness, illustrating the potential application in recovering high-valence metal resources.