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

A MnO 2 @BP nanocomposite was synthesized by simultaneously reduction of KMnO 4 with Mn(CH 3 COO) 2 .4H 2 O and highly porous Black Pearls 2000 at room temperature. The specific surface area, porosity, crystalline form and conductivity of MnO 2 @BP nanocomposite were characterized by nitrogen gas adsorption measurements, scanning electron microscopy, X-ray diffraction and 4-point probe measurements, respectively. The content of MnO 2 and BP in the composite was determined by thermogravimetric analysis. Chemical mapping using Raman spectroscopy was performed to investigate the distribution of MnO 2 and BP in a composite electrode film prepared with polytetrafluoroethylene (PTFE) as binder. This composite electrode exhibits more homogeneously distributed MnO 2 particles when compared to an electrode made by physical mixing of MnO 2 , BP and PTFE (MnO 2 /BP-PTFE). Also, Raman spectroscopy data of both composite electrodes indicates a loss of electrical conductivity of BP in the case of MnO 2 @BP-PTFE. The electrochemical properties were characterized by cyclic voltammetry in aqueous 0.65 M K 2 SO 4 . The specific capacitance of MnO 2 @BP-PTFE composite electrode was 122 ± 5 F/g, which is statistically equivalent to the capacitance of MnO 2 /BP-PTFE composite electrode (129 ± 6 F/g).