Insights into the electrochemical performance of manganese dioxide coated metallic foils as potential electrodes for supercapacitors

Abstract Manganese dioxide (MnO 2 ) is a promising electrode material for supercapacitors due to its high theoretical specific capacitance. In this study, MnO 2 particles were synthesized using a simple hydrothermal method and subsequently coated onto silver, nickel, and aluminum foils via dip coating. The structural, morphological, and functional properties of the resulting MnO 2 nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT–IR). Electrochemical impedance spectroscopy (EIS), galvanostatic charge–discharge (GCD), and cyclic voltammetry (CV) were employed to investigate the electrochemical performance of the coated metallic foils. The results demonstrated that MnO 2 /Ag foils exhibited the highest specific capacitance of 198 F g –1 at a scan rate of 0.25 A g −1 , accompanied by excellent cycle stability (89% capacitance retention). This performance surpassed that of MnO 2 /Ni and MnO 2 /Al foils, which exhibited maximum specific capacitances of 150 and 101 F g −1 , respectively. Additionally, MnO 2 /Ag foils displayed the highest charge storage capacity, as evidenced by EIS analysis, reaching 4000 Ω, nearly double that of MnO 2 /Ni and MnO 2 /Al foils. These findings highlight the potential of cost-effective and high-performance MnO 2 /Ag foils for widespread applications in energy storage devices such as electrochemical capacitors. Graphical Abstract