Organic resin based high surface area and N-enriched porous carbon nanosheets for supercapacitors

Organic resins are considered as a kind of promising precursors to prepare carbon materials due to its broad resource, high char yield. Nevertheless, it is still a chanllenge on preparing of electrode materials with large specific surface area, high content of heteroatom doping, and remarkable electrochemical properties from organic resins for supercapacitors. Here we report a efficient and facile synthetic strategy to fabricate ultrahigh specific surface area and N-enriched porous carbon nanosheets (N-PCNs) using g-C3N4 as template, L-Tyrosine-based resin as carbon precursor by hydrothermal polymerization and following KOH activation process. The effects of activator ratio and activation temperature on the morphology, structure and capacitance performance of N-PCNs have been systematacially studied. The prepared N-enriched (4.13 at%) porous carbon nanosheets with ultrahigh specific surface area (3542 m2 g−1) show excellent capacitance performance. The optimized sample presents an excellent specific capacitance of 349 F g−1 at 0.5 A g−1, and can also maintain 218 F g−1 at 50 A g−1, showing an outstanding rate performance. Moreover, the symmetric flexible capacitor assembled by Agar/Na2SO4 gel electrolyte displays a relatively high energy density of 31.4 Wh kg−1 at 225 W kg−1.