Electrochemical Performance of MnO 2 Composite with Activated Carbon for Supercapacitor Applications

Electric vehicles/hybrid electric vehicles, next-generation personal electronics, and stationary storage have all benefited from the energy storage system (ESS) revolution. The preparation of new and especially eco-friendly electrode material is an important task in the development of modern electrochemical energy storage devices. In the present work, MnO₂ nanostructures in composite with activated carbon were synthesized via a facile hydrothermal method. X-ray Diffraction (XRD) and a Scanning Electron Microscope (SEM) were used to examine the structure, crystallite size, and morphology of the produced samples (SEM). The absence of an impurity peak in the X-ray diffraction pattern suggested that MnO₂ nanostructures formed in the tetragonal phase. The Scherrer formula was used to determine the typical size of the crystallites. The creation of nanosheets and nanorods, as seen by SEM analysis, also contributed to the improved charge storage capacity. Also, the electrochemical properties of synthesized material were studied through a three-electrode system by using KNO₃ and KOH as aqueous electrolytes. The Cyclic Voltammetry (CV) and the Galvanostatic Charge-Discharge (GCD) study showed that the KNO₃ electrolyte is more suitable as the capacitance obtained is much higher in comparison with KOH. The highest specific capacitance of 317 F/g is achieved at 1A/g current density for the KNO₃ electrolyte. Furthermore, Electrochemical Impedance Spectroscopy (EIS) confirmed that the resistance offered by KOH is higher for this composite. The research found that the synthesized material might be employed for supercapacitor applications as their electrode material.