Hierarchical structure of graphene oxide/MnO2 electrodes for supercapacitor

A supercapacitor, also called an ultracapacitor, is a high-capacity capacitor with a capacitance value much higher than other capacitors, but with lower voltage limits, that bridges the gap between electrolytic capacitors and rechargeable batteries. To synthesize graphene oxide/polypyrrole (GO/PPy) composite, a sacrificial template is needed such as MnO2 through sacrificial template polymerization of pyrrole in the presence of GO and used for supercapacitor electrode. This GO/MnO2 composite synthesis is an intermediate step to develop GO/PPy composite. GO’s porous nanostructure offered enough potential electro-active sites for the MnO2 deposition which may further sacrificed to deposit polypyrrole. GO exhibited better electrochemical performance than the composite. The electrode performance is evaluated using aqueous electrolyte at various current densities and scan rate. The sample which was prepared is electrochemically characterized using CV, GCD and EIS. Furthermore the GO/MnO2 electrode displays good rate capability and excellent cyclic durability. GO exhibited series resistance and charge transfer resistance of 23 Ω and 20 Ω. From the specific capacitance analysis from CV and GCD as well as series resistance and charge transfer resistance from EIS of GO alone showed improved specific capacitance and high electrochemical stability. The specific capacitance of GO is exhibited 144, 204, 212 and 255 F g−1 at the current densities of 1, 2, 4 and 10 A g−1 respectively. Similarly, the composite exhibited the specific capacitance of 87, 90, 102 and 144 at the current densities of 1, 2, 4 and 10 A g−1 respectively. The prepared electrode shows good performance. So it in can be used in applications which require better flexibility.