Hydrometallurgical recovery of metals from spent lithium-ion batteries with ionic liquids and deep eutectic solvents

The widespread adoption of lithium -ion batteries (LIBs) in modern electric vehicles has successfully addressed the issues of limited oil and gas resources, as well as environmental degradation. This development is crucial for achieving "carbon neutrality " and reduce "carbon peaking ". Proper disposal of used LIBs is vital for effective resource management and avoiding pollution and potential hazards associated with toxic substances. Moreover, a significant weight fraction of LIBs is constituted by so-called critical raw materials (CRMs), presenting a high supply risk and price variability. Over the past few years, considerable progress has been made in developing processes for the safe treatment and material recovery from spent LIBs, besides the recovery of CRMs. Among them, hydrometallurgical recycling of LIBs components employing affordable and eco-friendly ionic liquids (ILs) and deep eutectic solvents (DESs) has gained significant attention for their potentially superior selectivity, low energy consumption, and environmental impact. Such liquids present various advantages over traditional organic solvents employed in liquid separations in terms of volatility, safety, chemical and thermal stability, recyclability, and selectivity. This review provides an overview of the most recent advances in the application of ILs and DESs to recover CRMs from LIBs.