Nitrogen-doped porous carbon nanosheets for high-performance supercapacitors

Two-dimensional (2D) porous carbon nanosheets have received widespread attention in supercapacitor because of their high specific surface area, high aspect ratio and short ion diffusion distance. Here, we develop a novel strategy to prepare 2D porous nitrogen-doped carbon nanosheets (NCS) using MgAl-LDH as the template by electrostatic self-assembly with anionic polyacrylamide, then followed carbonization and KOH activation. The optimized NCS-700 samples possess high specific surface area, hierarchical porous sheet-like structure and rich N (3.15 at%) and O (9.58 at%) functional groups. As an electrode material, the NCS-700 samples exhibit a high specific capacitance of 356 F g−1 at 0.5 A g−1 and superior rate characteristic (228 F g−11 at 30 A g−1), as well as long lifespan. Moreover, the assembled NCS-700//NCS-700 symmetrical supercapacitor shows a high energy density of 29.0 Wh kg−1 and outstanding cycling stability in 1 M Na2SO4 aqueous electrolyte. Therefore, the above results show that this work provides a new method for the synthesis of porous carbon sheets for high performance supercapacitor.