LAUSR

Due to the environmental problems of numerous metal production processes, there is a growing need for more energy-efficient approaches. Cobalt is considered a strategic element that is extracted not only from ores but also from spent Li-ion batteries. One promising new approach is ionometallurgy, i.e. extraction of metal oxides by ionic liquids (ILs). We present new investigations on the ionometallurgical processing of CoO, Co3O4 and LiCoO2 in the IL betainium bis(trifluoromethylsulfonyl)-imide, [Hbet][NTf2]. Three crystal structures of cobalt-betaine complex compounds, and combined spectroscopic and diffraction studies provide insights into the dissolution process. In addition, we present an optimized dissolution procedure for metal oxides, avoiding the previously reported decomposition of the IL. Subsequent cobalt electrodeposition is only possible from cationic complex species, highlighting the importance of a thorough understanding of the complex equilibria. We also discuss the presented method in comparison to other approaches in the recent literature.