A reusable deep eutectic solvent for the regeneration of Li and Co metals from spent lithium-ion batteries

The prosperity of the lithium-ion battery industry has raised deep concerns about spent batteries. Recently, much attention has been focused on the development and advancement of lithium battery recycling. Deep eutectic solvents are efficient, environmentally friendly, and economical leaching solvents with great potential for the recovery of cathode materials from spent lithium-ion batteries. However, to date, deep eutectic solvents have been considered a disposable agent for lithium-ion battery recycling, resulting in organic waste after a single recycling. Here, we demonstrate a reusable deep eutectic solvent based on maleic acid (MA) and ethylene glycol (EG), designed to recycle LiCoO2 cathode materials from spent lithium-ion batteries. With a high loading capacity (59 g/L), the leaching efficiencies of Co and Li by MA:EG are 98.3 % and 98.4 % respectively. MA:EG can be refreshed by adding oxalic acid as a precipitant. Even after 4 cycles, the leaching efficiency of Co is still 90 % and the average recovery efficiency of Co products is over 96.5 %. Lithium is present in a high concentration and is also recovered in the form of oxalate. This work provides a novel and environmentally friendly recycling route that can economically and efficiently recover the valuable metals Li and Co from spent lithium-ion batteries.