Core-shell structured carbon nanotubes/N-doped carbon layer nanocomposites for supercapacitor electrodes

N-Doped carbon layer–coated carbon nanotube (N-C/CNT) nanocomposites with stable core-shell structures were synthesized using a one-pot hydrothermal reaction. After high-temperature carbonization and KOH activation, the resultant N-C/CNT materials used as supercapacitor electrodes show high specific capacitance, good rate capability, and long cycle stability. The specific capacitance exhibits a high value of 322.1 F g−1 at 1 A g−1, and still maintains 200.7 F g−1, 168.7 F g−1, and 120.0 F g−1 at 5 A g−1, 10 A g−1, and 20 A g−1, respectively. During the 10,000-cycle testing at 5 A g−1, the specific capacitance was kept stable. The high performance of the supercapacitor electrodes could be attributed to the synergistic effect of the high specific surface area with fine pore structure, high electronic conductivity, and mechanical strength of CNT support and pseudocapacitance provided by doping N atoms in the carbon layer.