Study on the preparation and performance of Cr2O3-MnOx nanocomposite material as cathode for aqueous zinc-ion batteries

Due to the advantages of environmental protection and low cost, aqueous zinc-ion batteries are widely applied in the modern energy storage system. In this study, Cr2O3-MnOx composite material was synthesized via hydrothermal method and further applied as the cathode in aqueous zinc-ion batteries. By optimizing the chromium-to-manganese ratio and the amount of urea, and optimizing the hydrothermal and calcination conditions, the composite material with the best electrochemical performance was obtained. At the current density of 50 mA/g, the maximum capacity reached 384.7 mAh/g, and the cycling stability was also good. The physical characterization of the composite material with the most stable electrochemical performance reveals that its microstructure mainly consists of nanoparticles and nanocubes. The EDS elemental distribution tests show a relatively uniform distribution of manganese, chromium, and oxygen elements. The infrared and Raman spectroscopy indicate the stretching vibrations of Cr-O and Mn-O bonds. The XPS analysis reveals that the primary valence state of Cr is trivalent, while Mn exists in + 2, + 3, and + 4 oxidation states. The quantitative fitting analysis of XRD data shows that Cr2O3 is the predominant component.