Deep eutectic solvent with acidity, reducibility, and coordination capability for recycling of valuable metals from spent lithium-ion battery cathodes

The substantial increase in spent lithium-ion batteries (SLIB) has resulted in serious environmental impacts that require attention and appropriate intervention. In this study, we designed a DES composed of ethylene glycol (EG) and hydroxylamine hydrochloride (NH2OH·HCl) with appropriate acidity, remarkable reductive property and strong coordination capability for the efficient one-step leaching of cobalt ions and lithium ions from LiCoO2 (LCO). Following leaching at a modest temperature of 80 °C for 8 h, the solubility of LiCoO2 reaches an 83.3 mg g−1 (much higher than previous works), accompanied by remarkably high leaching efficiencies of up to 99.7 % for lithium and 88.0 % for recovery of cobalt. Notably, this approach significantly enhances the solubility of the LiCoO2 while upholding leaching efficiency. Importantly, this study achieves a one-step separation of lithium and cobalt, avoiding metal co-precipitation and simplifying the separation procedure. Furthermore, the residual components within the system can be reclaimed and recycled. This work provides an efficient and sustainable route for the recovery of precious metals from lithium-ion batteries, characterized by its cost-effectiveness and straightforward processing.