Synthesis of sulfonated graphene/carbon nanotubes/manganese dioxide composite with high electrochemical properties

Combining MnO2 with conductive carbon materials is an efficient approach to improve the electrical conductivity of MnO2-based electrodes, which could greatly improve the electrochemical performance of supercapacitors. Here, a ternary composite consisting of sulfonated graphene, carbon nanotubes, and manganese dioxide (SG/CNTs/MnO2) has been successfully fabricated by a facile yet efficient method. The electrochemical properties are evaluated by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. The results show a prominent improvement of electrochemical performance of MnO2-based electrodes. For instance, the specific capacitance of SG/CNTs/MnO2 composite is 336.4Fg(-1) at the current density of 0.5Ag(-1), which is much higher than pure MnO2 (77.1Fg(-1)) and binary SG/MnO2 (213.0Fg(-1)). Moreover, SG/CNTs/MnO2 composite shows good cycling stability with 91.3% capacitance retention after 10,000cycles at a current density of 5Ag(-1).