Preferential and efficient extraction of lithium under the combined action of reduction of herb-medicine residue and leaching of oxalic acid

With the increasing demand for lithium resources, the efficient recovery of lithium from spent lithium-ion batteries (LIBs) has become the focus of social attention. Herein, a combined process of reduction roasting of herb-medicine residue (HMR) and oxalic acid (OA) leaching is proposed to improve the recovery efficiency of lithium. Due to the large amount of reducing gas produced by the pyrolysis of herb-medicine residue, the layered structure of LiNi_xCo_yMn_zO₂ cathode powder can be destroyed at 650℃ for 10 min, and the cathode powder is converted into Li₂CO₃, Ni, Co, MnO. Moreover, about 99.6 % of Li in the roasting residue can be selectively extracted by 0.5 mol L⁻¹ oxalic acid for 20 min. Under the combined action of HMR and OA, the extraction efficiency and kinetics of lithium are improved simultaneously. This work achieves synergistic treatment of two types of waste from the perspective of waste management for waste. Meanwhile, it provides an alternative and innovative approach for the difficult problem of low efficiency of lithium recovery from spent LIBs.