Nitrogen-doped sandwich-like porous carbon nanosheets for high volumetric performance supercapacitors

Nitrogen-doped sandwich-like porous carbon nanosheets (NPCG) have been prepared simply through carbonization of graphene/polyaniline hybrid materials. Due to its interconnected microporous structure, high nitrogen content (12.7 at.%), high surface area (410.4 m2 g−1) and high volumetric density (0.94 g cm−3), the obtained sample prepared at 700 °C (NPCG-700) shows both high gravimetric and volumetric capacitances of 305 F g−1 and 287 F cm−3 in 6 M KOH aqueous electrolyte, respectively. In addition, the assembled supercapacitor delivers a high energy density (16.3 Wh kg−1 and 15.3 Wh L−1) in 1 M Na2SO4 aqueous electrolyte. Importantly, 97% of the initial capacitance is maintained after 5000 cycles, suggesting excellent cycling stability.