2, KAIST, Daejeon, , Korea (the Republic of)
We developed a well-organized three-dimensional nitrogen-doped carbon network (NCW), composed of reduced graphene oxide(rGO)/carbon natnotube(CNT)/graphitic carbon nitride(g-C3N4) by a single-step hydrothermal process. CNT and g-C3N4 provide benefits as a conductive enhancer and a wettability enhancer, respectively, by solving the stacking problem of rGO sheets, which commonly occurs during the hydrothermal process of GO. The well-organized NCW device exhibited a very high capacitance of 338 F/g at 1 A/g in a three-electrode system, which is superior to the traditional rGO-based systems (~200 F/g). Surprisingly, almost 100% of capacitance retention was achieved for 30,000 cycles in a two electrode-system. Our symmetric NCW supercapacitor with an easy and simple fabrication method exhibited a much greater energy density, 21.5 Wh/kg at a power density of 696.5 W/kg, than that of previously reported rGO-based devices (~10 Wh/kg), which demonstrated a great potential for high-tech energy storage devices with high energy density and stability.