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

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 microwaveassisted. 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.