Facile and efficient recycling of cathode materials of spent lithium manganate batteries

A simple scheme of selective lithium leaching by direct oxidation was proposed. The thermodynamic feasibility of this new method was verified by the E-pH diagram of the Li-Mn-H2O system. Sodium persulfate Na2S2O8 was selected as the oxidant to oxidize LiMn2O4 to MnO2, and subsequently, lithium was de-intercalated from the crystal lattice. The experimental results show that under the optimum conditions, 97% of Li is released into the solution in 120 min, while almost all the Mn remains in the leaching residue. The kinetic study results suggest that selective leaching of Li is controlled by a chemical reaction according to the Avarami model. Furthermore, XRD, XPS, and FT-IR spectroscopy were used to investigate the leaching mechanisms. The content of the LMO phase decreases gradually while the MnO2 phase increases with the lithium extraction, but the spinel structure of lithium manganate is not damaged throughout the process. Finally, a closed-loop process for recycling spent lithium manganate batteries was proposed, which is also suitable for recycling other types of spent LIBs.