Influence of metal cations on 3D MCoMnO4 microstructures (M = Ni and Zn) for battery-type supercapacitors: A comprehensive study

Mixed transition metal oxides (MTMOs) with high conductivity and multiple metal centers are promising for energy storage. We synthesized self-assembled three-dimensional (3D) flower-like NiCoMnO4 (NCMO) and cubelike ZnCoMnO4 (ZCMO) microstructures via the hydrothermal method. These structures effectively utilize synergistic interactions among MTMOs, offering abundant electro-active sites, and enabling efficient redox reactions. The influence of the metal cation (Ni/Zn) on the physicochemical attributes of the synthesized materials was comprehensively investigated using a diverse set of analytical techniques. When assessing their electrochemical performance in the context of battery-type supercapacitors at a current density of 1 A g-1, the NCMO electrode outperformed with a significantly higher specific capacity of 170.2 mAh g-1 (612.2 C g-1) in contrast to the 145 mAh g-1 (522 C g-1) for the ZCMO electrode. Remarkably, the NCMO electrode displayed exceptional cyclic stability, preserving 91% of its capacity even when subjected to a high current density of 20 A g-1 5000 cycles. This innovative approach holds substantial potential for advancing energy storage technologies.