KOH-activated nitrogen doped porous carbon nanowires with superior performance in supercapacitors

Nitrogen-doped porous carbon nanowires were prepared by KOH activation of nitrogen doped carbon nanowires derived from direct carbonization of polypyrrole nanowires. The porous structure and nitrogen content were closely related to the mass ratio of KOH and carbon nanowires. The resultant nanowires demonstrated the highest specific surface area (1642 m2 g−1) and capacitance (291 F g−1 at the current density of 1 A g−1 in three-electrode systems), when the mass ratio of KOH and nitrogen doped carbon nanowires reached 2. It also exhibited the excellent high rate performance and good cycle stability (94.8% capacitance retention after 5000 cycles) in three-electrode systems. High energy density (21.9 Wh kg−1 at a current density of 0.4 A g−1 in 0-1.6 V) and good cycle stability (the capacitance retention of 98.1% over 5000 cycles) were shown in symmetric two-electrode systems. These excellent electrochemical performances could be attributed to the high surface area, unique micro/meso/macroporous structure, and optimized nitrogen content.