Activated nitrogen-doped porous carbon ensemble on montmorillonite for high-performance supercapacitors

An activated nitrogen-doped porous carbon ensemble on montmorillonite (MMT) was prepared through hydrothermal carbonization of glucose on MMT followed by carbonization with melamine and activation with KOH at high temperatures. The carbonaceous species was effectively guided to be heterogeneously deposited onto the surface of MMT and inserted into the interlayer spacing. The resulting N-doped carbon composite has a unique microstructure, large specific surface area (657 m2 g−1), high nitrogen content (5.5 at%), maximum specific capacitance of 223 F g−1 at a current density of 1 A g−1 and an outstanding rate capability (205 F g−1 retained at 3 A g−1) in a 6 M KOH aqueous electrolyte. Moreover, approximately 90% of the initial capacitance was retained after 8000 cycles at a current density of 1 A g−1, suggesting an excellent cycling stability.