Chemical Mapping and Electrochemical Performance of Manganese Dioxide/Activated Carbon Based Composite Electrode for Asymmetric Electrochemical Capacitor

Abstract

A MnO2@BP nanocomposite was synthesized by simultaneously reduction of KMnO4 with Mn(CH3COO)2.4H2O and highly porous Black Pearls 2000 at room temperature. The specific surface area, porosity, crystalline form and conductivity of MnO2@BP nanocomposite were characterized by nitrogen gas adsorption measurements, scanning electron microscopy, X-ray diffraction and 4-point probe measurements, respectively. The content of MnO2 and BP in the composite was determined by thermogravimetric analysis. Chemical mapping using Raman spectroscopy was performed to investigate the distribution of MnO2 and BP in a composite electrode film prepared with polytetrafluoroethylene (PTFE) as binder. This composite electrode exhibits more homogeneously distributed MnO2 particles when compared to an electrode made by physical mixing of MnO2, BP and PTFE (MnO2/BP-PTFE). Also, Raman spectroscopy data of both composite electrodes indicates a loss of electrical conductivity of BP in the case of MnO2@BP-PTFE. The electrochemical properties were characterized by cyclic voltammetry in aqueous 0.65 M K2SO4. The specific capacitance of MnO2@BP-PTFE composite electrode was 122 ± 5 F/g, which is statistically equivalent to the capacitance of MnO2/BP-PTFE composite electrode (129 ± 6 F/g).