Polyphenol Derived Natural Deep Eutectic Solvents for High Efficiency Cathode Recycling of Li-Ion Batteries

Natural deep eutectic solvents (NADESs), derived from biobased materials such as amino acids, polyphenols, sugars, and choline derivatives, represent the next generation of ionic liquid media. These solvents offer high solvation capacity, nontoxicity, and biocompatibility, making them ideal for various technological applications. This study introduces a series of plant-derived polyphenol-based NADESs as a green and cost-effective medium for lithium-ion battery (LIB) recycling. NADESs were used to sequentially dissolve metal oxides from end-of-life LIB cathodes, such as lithium cobalt oxide (LCO) and lithium nickel manganese cobalt oxide (NMC). The polyphenols in NADESs demonstrated excellent metal-binding capacity and reducing properties, enabling high extraction efficiencies of ≥90% for valuable metals such as lithium, cobalt, nickel, and manganese. This process is energy-efficient and eco-friendly, offering a sustainable alternative to conventional hydrometallurgical techniques. To complete the recycling process, a selective precipitation method was employed, recovering metals in the form of useful chemical compounds. This approach highlights the potential of NADESs in addressing the challenges of LIB recycling while reducing environmental impact. Furthermore, this underscores the broader applicability of plant-derived biomolecules, such as polyphenols, phenolics, and flavonoids, in green technological innovations.