Selective leaching of lithium from spent lithium-ion batteries using sulfuric acid and oxalic acid

Traditional hydrometallurgical methods for recovering spent lithium-ion batteries involve acid leaching to simultaneously extract all valuable metals into the leachate. This is followed by a series of separation steps such as precipitation, extraction, and stripping to separate the individual valuable metals. These processes are time-consuming and result in high lithium loss rates due to its late recovery stage. In this study, we present a process for selectively leaching lithium through the synergistic effect of sulfuric and oxalic acids. Under optimal leaching conditions (leaching time of 1.5 h, leaching temperature of 70 °C, liquid-solid ratio of 4 mL/g, sulfuric acid: oxalic acid = 1.3:1.3), the lithium leaching efficiency reached 89.6%, with good selectivity. XRD and ICP-OES analyses showed that most of the Ni, Co, and Mn in the raw material remained as oxides and oxalates in the residue. This study offers a new approach to enriching the relevant theory for the selective preferential leaching process of lithium.