Electrochemical Deposition of Multicomponent Mixed Metal Oxides on rGO/Ni Foam for All-Solid-State Asymmetric Supercapacitor Device: Mn, Co, and Ni Oxides with Ag Doping

In this study, an asymmetric supercapacitor (ASSC) device is assembled by the deposition and annealing of silver-doped mixed metal oxides on reduced graphene oxide (rGO)/Ni foam and activated carbon (AC) on Ni foam as positive and negative electrodes, respectively. The best performing Ag:MnCoNiO active material is synthesized on rGO/Ni foam using chronopotentiometry combined with heat treatment. The XRD study clearly confirms the crystalline nature of the electrode with MnCo2O4 and MnNi2O4 phases. FT-IR and XPS studies revealed the formation of Ag:MnCoNiO/rGO on Ni foam. SEM images show a thin-film layer of fabricated material on the surface of rGO/Ni foam. The supercapacitor properties were tested in two- and three-electrode configurations, with cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) experiments in a 6 M KOH aqueous electrolyte. In the three-electrode configuration, reversible faradic reactions can be observed in a potential range of 0.0 and +0.6 V vs. Hg/HgSO4. In the two-electrode device configuration, the system exhibits a maximum energy density of 45.5 Wh kg(-1) and provides a maximum power density of 4.5 kW kg(-1). The results showed that the doping of Ag in a MnCoNiO electrode shows promising properties, achieved by a very simple fabrication process. The results showcase the synergistic effects achieved by mixed multiple-component metal oxides, leading to improved supercapacitive properties.