Synthesis of Graphene Hydrogel and Graphene Oxide/Polyaniline Composites for Asymmetric Supercapacitor

As a kind of new carbon materials, graphene has excellent performances such as superior conductivity, high specific surface area (2675 m2 g?1), and high cycle life. But graphene sheets are easily restacked by van der Waals interactions during the processes of preparation, storage, and application of them, which can loss ultrahigh specific surface area. The restacking of graphene sheets could be prevented by constructing graphene hydrogel (GH) or graphene composite. In this work, GH was prepared by a one-step hydrothermal synthesis reaction and glucose is used as a reducing agent, while graphene oxide/polyaniline (GP) composites was prepared by coating polyaniline on GO through in situ chemical polymerization of aniline. Then an asymmetric supercapacitor (GH//GP) was further assembled, where GH and GP are the positive and negative electrodes, respectively. The electrochemical properties of GH, GP, and GH//GP are studied using voltammetry and galvanostatic charge/discharge. The consequences indicate that the energy density of GH//GP reaches 5.6 W h kg?1 at power density of 226.5 W kg?1 and 3.1 W h kg?1 at energy density of 8446.2 W kg?1.