Reduced graphene oxide paper based nanocomposite materials for flexible supercapacitors

Abstract

In this article, a light-weight and highly flexible supercapacitor based on cellulose fibers and reduced graphene oxide (rGO) nanocomposites electrode is designed and assembled. The reduced graphene oxide (rGO) paper was prepared from natural graphite by a modified Hummer's method, with hydroiodic acid (HI) as a reducing agent. The as-prepared rGO, which was characterized by Raman spectroscopy, XRD, TEM and SEM, was assembled into the supercapacitor. XRD and Raman spectroscopy results confirm the oxidation of graphite and reduction of graphite oxide (GO) to reduced graphene oxide (rGO) sheets. The double-layer capacitive behavior of the supercapacitor is studied by cyclic voltammetry techniques in aqueous (6 M KOH) and non aqueous room temperature ionic liquid (RTIL) electrolytes, respectively. The ionic liquid enables a larger operating voltage range of 0.0–2 V compared to 0.0–1 V in aqueous medium. The specific capacitance of the supercapacitor has been determined to be 255 F g⁻¹ at a scan rate of 10 mV s⁻¹ in an aqueous medium. In an non aqueous medium, the graphene based supercapacitor exhibits specific capacitance values of 78 F g⁻¹ at a scan rate of 10 mV s⁻¹. The supercapacitor devices exhibit excellent long cycle life, with only a 10% decrease in specific capacitance after 5000 cycles.