rGO / MnO2 / Polyterthiophene Ternary Composite: Pore Size Control, Electrochemical Supercapacitor Behavior and Equivalent Circuit Model Analysis

Abstract

In this work, a new electrode active materials including reduced graphene oxide (rGO), Manganese dioxide (MnO2) / polyterthiophene (PTTh) has been synthesized as a nanocomposite using in-situ polymerization method, microwave-assisted method for obtaining reduced graphene oxide and chemical synthesis of metal-oxide for supercapacitor devices. A ternary nanocomposites of rGO/MnO2/PTTh were characterized by the analysis of Fourier transform infrared-attenuated transmission reflectance (FTIR-ATR), Raman spectroscopy, scanning electron microscopy-energy dispersion X-ray analysis (SEM-EDX), transmission electron microscopy (TEM), thermal-gravimetric analysis (TGA-DTA), Brunauer-Emmett Teller (BET) pore analysis, Ultraviolet-visible (UV-vis) spectrophotometer, X-ray diffraction (XRD) analysis, electrochemical impedance spectroscopy (EIS), galvanostatic charge/discharge (GCD), and cyclic voltammetry (CV). The highest specific capacitance (Csp) was obtained as Csp = 908.86 F/g for rGO/MnO2/PTTh nanocomposite at 1 mV/s for [MnO2]o/[TTh]o = 1/3. Moreover, equivalent electrical circuit model of LR(QR) was chosen to interpret EIS analysis of supercapacitor device. rGO/MnO2/PTTh nanocomposite has both electrochemical double-layer capacitance and pseudocapacitance due to the fast and reversible redox processes related to the π-conjugated polymer chains.