Synthesis of three-dimensional porous reduced graphene oxide hydrogel/carbon dots for high-performance supercapacitor

A composite composed of reduced graphene oxide hydrogel/carbon dots (rGH/CDs) is prepared hydrothermally. The composite has a three-dimensional (3D) interconnected network structure and exhibits good electrical conductivity and mechanical robustness, making it ideal electrode materials in supercapacitors. The carbon dots (CDs) in the reduced graphene oxide hydrogel promotes electron transport and reduces the internal resistance and charge transfer resistance in addition to providing a large surface area. The flexible solid-state supercapacitor comprising the 130 μm thick rGH/CDs electrode delivers excellent performance including high gravimetric specific capacitance of 264 F g^{− 1} (up to 301 F g^{− 1} for a 40 μm thick electrode), areal specific capacitance of 394 mF cm^{− 2} (up to 432 F cm^{− 2} for a 200 μm thick electrode), excellent cycling stability (9.1% deterioration after 5000 cycles), larger energy density (35.3 Wh kg^{− 1}), as well as high power density (516 W kg^{− 1}). This study demonstrates the tremendous potential of rGH/CDs in high-performance flexible energy storage devices.