Polybenzidine-MnO2 nanocomposite on anodized graphite sheet as a novel system for high-performance supercapacitors

In this work, we report for the first time the in -situ synthesis of polybenzidine-manganese oxide (PB-MnO2) nanocomposite on anodized graphite sheet (AGS). The PB-MnO2/AGS electrode is easily fabricated through the electrochemical anodization of the graphite sheet followed by the polymerization of the benzidine monomer using KMnO4 as an oxidant and MnO2 source. The results of various instrumental analysis confirm that the PBMnO2 nanocomposite is successfully formed on the AGS without any binder. Cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques strongly prove the pseudocapacitive nature of the electrode. The PB-MnO2/AGS electrode shows a high capacitance of 950 mF cm -2 at 0.5 mA cm -2 in 1.0 M H2SO4 solution with a maximum power and energy density of 64.65 mWh cm -2 and 1.75 W cm -2. Solid-state symmetrical supercapacitor device fabricated with PB-MnO2/AGS electrode shows that this device has an excellent specific capacity of about 190.27 mF cm -2 at 0.5 mA cm -2 and maximum power and energy density of 12.375 W cm -2 and 85.625 mWh cm -2. The cyclic life of 87.22 % after 5000 GCD cycles without any ohmic drop indicates that the PB-MnO2/AGS electrode can be a promising candidate for the fabrication of high-performance supercapacitor devices in the future.