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 (rho) thus causing low volumetric capacitances (<200 F/cm(3)) of the corresponding supercapacitor. Developing a functional carbon material with large packing density while maintaining moderate gravimetric capacitance (C-g) 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 m(2)/g, nanosheet morphology, large packing density (1.64-1.69 g/cm(3)), 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/cm(3)@1.0 A/g and 200 F/cm(3)@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.

Automated summary

The study presents a strategy to enhance the volumetric performance of supercapacitors by constructing nitrogen-doped reduced graphene, which exhibits excellent rate capability, capacitance retention, and specific energy density. The developed material also shows potential for applications in sorption, catalysis, and other fields due to its rich heteroatoms.