Efficient process for recovery of waste LiMnO cathode material: Low-temperature (NH)SO calcination mechanisms and water-leaching characteristics.

An efficient process for recycling waste LiMnO cathode material is proposed in this research. This report constitutes low-temperature (NH)SO calcination mechanisms and water-leaching characteristics of the calcined samples. A calcination temperature range of 420.65-634.12 °C is determined by analysis of the TG-DSC curve under the conditions of heating from 25 to 1000 °C, with a molar ratio of n(2Li + Mn):n(NH)SO = 1:1 in air atmosphere. The sample calcined at 600 °C for 45 min when the excess coefficient of the (NH)SO was 1.1 exhibits optimal water-leaching efficiencies of the Li and Mn elements, which are approximately 100% and 96.73%, respectively. The macro-reaction mechanism of the waste LiMnO cathode material calcined with (NH)SO is determined as the liquid-solid reaction by analysing the apparent morphologies of the calcined samples and their water-leaching residues under different calcination conditions. Moreover, the micro-reaction mechanism is investigated by analysing the phases of the calcined samples and their water-leaching residues under different calcination conditions. The free high-energy H released by the decomposition of the NH generated by the molten (NH)SO play a key role in the entire calcination process. The spinel structure of the LiMnO is broken and Li is released owing to the H bombarding the MnO bonds. Finally, the LiMnO is converted into soluble sulphate salts, such as LiMn(SO) and MnSO.