Faradaic-active N-doped reduced graphene as electrode for supercapacitor with high-volumetric performances

The rich porosity of carbon based materials results in low packing density (ρ) thus causing low volumetric capacitances (<200 F/cm3) of the corresponding supercapacitor. Developing a functional carbon material with large packing density while maintaining moderate gravimetric capacitance (Cg) would be an effective way to realize the enhancement of volumetric performances of carbon-based supercapacitor. Herein, we presented a strategy to get a high-volumetric supercapacitor performances by constructing a nitrogen doped reduced graphene (N-rG) via a template induced assembly and nitriding method, in which the graphene oxide (GO) was firstly assembled by induction of MgO to form the composite of GO/MgO, which was then mixed with carbon nitride and carbonized to get the final nitrogen doped reduced graphene (N-rG). The developed N-rG owns surface area of 283 m2/g, nanosheet morphology, large packing density (1.64–1.69 g/cm3), rich redox heteroatoms including nitrogen (8.2–8.9 atom%) and oxygen functionalities (4.7–20.4 atom%). Due to these features, the resultant N-rG16 fabricated with mass ratio of GO/MgO (1:6) exhibits a typical pseudocapacitive behavior, large volumetric capacitance of 272 F/cm3@1.0 A/g and 200 F/cm3@20 A/g, showing an excellent rate capability with capacitance retention of 73.5 %. The N-rG16 based symmetric supercapacitor delivers a high specific energy density of 33.6 Wh/L@1352 W/L and long cycling stability with near 99 % retention of the initial capacitance after 10,000 cycles test showing a great potential for packed energy storage devices. Moreover, the developed N-rG with rich heteroatoms may also find wide applications in many other fields such as sorption, catalysis and so on.