Sustainable Recovery of Metals from Spent Lithium-Ion Batteries: A Green Process

In this study, a green process with prospective environmental and economic significance has been experimentally and theoretically established for the sustainable recovery of metals from spent lithium-ion batteries (LIBs). Three leaching systems were explored for the application of different biomass as reductants. According to leaching results, H3Cit (citric acid) and tea waste and H3Cit/H2O2 systems reveal similar leaching abilities (96% Co and 98% Li; 98% Co and 99% Li, respectively), while the H3Cit/Phytolacca Americana system shows inferior leaching performance (83% Co and 96% Li) under the optimized conditions. Tentative exploration of oxidation mechanism for different biomass indicates that potential reducing substances contained in biomass can be employed as efficient reductants during leaching. Then both metal ions and waste citric acid can be simultaneously recovered by selective precipitation. About 99% Co and 93% Li could be recovered as CoC2O4·2H2O and Li3PO4, and the recycled citric acid demonstrates similar leaching capability as fresh acid according to circulatory leaching experiments. Finally, solution chemistry theory and waste stream analysis were investigated to provide theoretical foundation for the recovery process.