Sustainable and facile process for Li2CO3 and Mn2O3 recovery from spent LiMn2O4 batteries via selective sulfation with waste copperas

Spent lithium-ion batteries (LIBs) are essential secondary resource, containing valuable metal elements including lithium, cobalt, nickel, manganese. Recovering valuable metals from spent LIBs is significant for achieving environmental protection and alleviating resource shortages. Herein, a sustainable and facile process for Li2CO3 and Mn2O3 recovery from spent LiMn2O4 batteries (LMO) was proposed via sulfation roasting with waste copperas. The leaching efficiencies of Li and Mn reached approximately 100 % and 82 % under the optimal conditions, and the final recovered products were Li2CO3 and Mn2O3 with high purities. The sulfation reaction between LMO and copperas was the transition from solid-solid to gas-solid reaction. During the sulfation reaction, LMO spinel structure was decomposed into MnO2 and Mn2O3 crystal structures, and the anti-fluorite structure Li2O embedded in the spinel structure was released. The Li2O was easily to be sulfated, while MnO2 was partly reduced by Fe2+ to more stable spinel structure Mn2O3. Furthermore, FeSO4 decomposed into SO2 gas, which greatly improved the sulfation reaction through permeating into the unreacted core of LMO. As a result, the spinel structure of Mn2O3 was broken, and Mn was escaped to combine with SO42- to form MnSO4. This research provided an alternative technological route for green recovery of spent LMO batteries, demonstrating high potential for broad application.