Microwave-assisted synthesis of functionalized graphene hydrogels for high performance supercapacitors

Abstract

The electrochemical properties of graphene-based electrode materials for supercapacitors are closely related to their structure and chemical properties. The functionalized graphene (FG) was prepared with microwave-assisted. The functionalized graphene hydrogel (FGH) was synthesized by introducing FG during the one-step hydrothermal process. The FG shows the uniform paper-like structure. Further, the FGH presents double structure of clear three dimensional (3D) networks and thin wrinkled paper-like structure. The introduction of FG can effectively prevent the accumulation between graphene sheets and the layered three-dimensional framework can accelerate ion transport and diffusion. Consequently, the proposed FGH exhibits a high specific capacitance of 340.2 F∙g−1 at the current density of 0.5 A∙g−1, which can be maintained for 82.1% even as the discharging current density increases up to 10 A∙g−1. Moreover, excellent stability is achieved for FGH with approximately 97.3% retention of the initial specific capacitance value after 20,000 cycles, measured at a high current density of 10 A∙g−1. These imply that the FGH may be a promising electrode material for high-performance supercapacitors.