Preparation of Highly Conductive Graphene Hydrogels for Fabricating Supercapacitors with High Rate Capability

Graphene hydrogels prepared via hydrothermal reduction of graphene oxide dispersions (GH-Hs) were further reduced with hydrazine (Hz) or hydroiodic acid (HI) to improve their conductivities. The chemically reduced graphene hydrogels possess high conductivities of 1.3–3.2 S m^–1, which are 1 order of magnitude higher than that of a GH-H (0.3 S m^–1). The supercapacitor based on the Hz-reduced GH-H exhibited a high specific capacitance of 220 F g^–1 at 1 A g^–1, and this capacitance can be maintained for 74% as the discharging current density was increased up to 100 A g^–1. Furthermore, it showed high power density and long cycle life. The high-performances of this supercapacitor make it promising for high rate charge/discharge applications.