Synthesis and characterisation of polyphenol based natural deep eutectic solvents for potential recycling applications

Abstract

Natural deep eutectics solvents (NADESs) are being pursued actively for many biological as well as technological applications due to their higher thermal stability, solvation capacity and nontoxicity. Herein, we report a series of plantbased polyphenol derived deep eutectic solvents with high viscosity, thermal activity, and wide liquid temperature range. All the three NADESs are well studied by spectroscopic studies and established the possible bonding interactions between the hydrogen bonding species. Further, the application of DES as a green approach for the hydrometallurgical recycling process has been very well studied in recent years. However, the use of NADESs to leach the Li-ion battery cathode materials is rarely explored. We have proposed a green method for the leaching of valuable metals such as lithium, cobalt, manganese, and nickel from mixed spent Li-ion battery powders. Importantly, the mechanism of the leaching process has been further evaluated using spectroscopic techniques. We further highlight the prepared NADESs as an economical and environmentally friendly medium for metal recovery from spent LIBs.