Novel ternary deep eutectic solvents used for recycling lithium and cobalt from waste lithium-ion batteries

The escalating disposal of lithium-ion batteries (LIBs) poses significant environmental challenges but also offers substantial opportunities for resource recovery. In this work, we introduce a recycling strategy using a green, cost-effective ternary deep eutectic solvent (DES) composed of guanidine hydrochloride, ethylene glycol, and maleic acid. The DES can achieve >99.5 % leach efficiency of lithium (Li) and cobalt (Co) at 100 C-degrees, 9h, and L/ S=50. The kinetic study found that the chemical reaction rate at the interface was the key to controlling the leaching process. The study of leaching mechanisms found that the acidity and coordination ability of DES were the main driving forces of leaching. Co loaded in the DES phase can almost precipitate out by using oxalic acid, achieving the separation of Li and Co. After reusing three times, the maximum load of Li in the DES phase reached 4.1 mg/g. These outstanding performances, along with the avoidance of the use of hazardous chemicals and the reduction of high costs, confirmed that the DES possesses a promising prospect for sustainable, largescale application in efficiently leaching valuable metals from LiCoO2.