Polyphenol\nDerived Natural Deep Eutectic Solvents\nfor High Efficiency Cathode Recycling of Li-Ion Batteries

Natural deep eutectic solvents (NADESs), derived from\nbiobased\nmaterials such as amino acids, polyphenols, sugars, and choline derivatives,\nrepresent the next generation of ionic liquid media. These solvents\noffer high solvation capacity, nontoxicity, and biocompatibility,\nmaking them ideal for various technological applications. This study\nintroduces a series of plant-derived polyphenol-based NADESs as a\ngreen and cost-effective medium for lithium-ion battery (LIB) recycling.\nNADESs were used to sequentially dissolve metal oxides from end-of-life\nLIB cathodes, such as lithium cobalt oxide (LCO) and lithium nickel\nmanganese cobalt oxide (NMC). The polyphenols in NADESs demonstrated\nexcellent metal-binding capacity and reducing properties, enabling\nhigh extraction efficiencies of ≥90% for valuable metals such\nas lithium, cobalt, nickel, and manganese. This process is energy-efficient\nand eco-friendly, offering a sustainable alternative to conventional\nhydrometallurgical techniques. To complete the recycling process,\na selective precipitation method was employed, recovering metals in\nthe form of useful chemical compounds. This approach highlights the\npotential of NADESs in addressing the challenges of LIB recycling\nwhile reducing environmental impact. Furthermore, this underscores\nthe broader applicability of plant-derived biomolecules, such as polyphenols,\nphenolics, and flavonoids, in green technological innovations.