High-Selective Lithium Extraction from Spent LiFePO4 by Battery Roasting-Water Leaching Method

In this study, a roasting-water leaching green process for highly selective lithium extraction from the cathode material of spent lithium iron phosphate (LiFePO4) battery was proposed. Using spent LiFePO4 as raw material and sodium bisulfate (NaHSO4) as an additive, the best roasting parameters were determined as follows: molar ratio of LiFePO4/NaHSO4 1:1.25, roasting temperature 400°C and roasting time 5 h. Under this condition, using pure water as a leaching agent, with leaching efficiency of 99.08% for Li and 0.12% for Fe, achieved the goal of high-selective leaching of Li. The study of the roasting mechanism shows that H and Li have similar external electron arrangements and coordination environments. Under the influence of temperature, the reactivity of the solid is improved, and the thermal, chemical reaction is initiated at the nanometer scale, resulting in the local rearrangement of particles, resulting in the reaction of LiFePO4 and NaHSO4 to generate LiNaSO4, which is helpful for subsequent leaching. This study can provide a process reference for high-selective recovery of Li in spent LiFePO4 batteries.