One-step electrochemical preparation of sulfonated graphene/polypyrrole composite and its application to supercapacitor

A sulfonated graphene/polypyrrole (s-G/PPy) composite was successfully prepared by a method of one-step electrodeposition using water soluble sulfonated graphene (s-G) and polypyrrole as the starting materials. The morphology, structure and thermal stability of s-G/PPy were characterized using transmission electron microscope, scanning electron microscope, thermogravimetric analysis, and Raman spectroscopy. The electrochemical performance of s-G/PPy is evaluated with galvanostatic charge/discharge, cyclic voltammetry and electrochemical impedance spectroscopy in 1 mol L−1 KCl. The composite exhibits high specific capacitance and good cycling stability. The specific capacitance of s-G/PPy is as high as 310 F g−1 at a current density of 0.3 A g−1 and retains 71% after 1500 cycles at a scan rate of 50 mV s−1. The equivalent series resistance of s-G/PPy film is only 0.6 Ω. In addition, a s-G/PPy//s-G/PPy symmetric supercapacitor was also fabricated and in which the s-G/PPy showed specific capacitance still up to 253 F g−1.