Nitrogen-doped microporous carbon coated on carbon nanotubes for high performance supercapacitors

Core-shell structure composite using carbon nanotubes as conductive core and nitrogen-doped microporous carbon as energy storage shell was synthesized by carbonization of polyaniline coated carbon nanotubes and followed by KOH activation. The optimized samples (CNTs@NC-4) possess unique core-shell structure with high specific surface area and rich heteroatoms. Consequently, the CNTs@NC-4 electrode displays a specific capacitance of 310 F g(-1) at 0.5 A g(-1), superior rate capability and good cycling durability. More interestingly, the assembled CNTs@NC-4//CNTs@NC-4 symmetric supercapacitor shows a high energy density of 18.6 Wh kg(-1), excellent rate capability and good cycling durability in 1 M Na2SO4 aqueous electrolyte.