Synthesis of nitrogen-doped electrospun carbon nanofibers with superior performance as efficient supercapacitor electrodes in alkaline solution

Abstract

Nitrogen-enriched porous carbon nanofibers were successfully prepared by using water-soluble phenolic resin/polyvinyl alcohol blend solution as precursor via electrospinning followed by carbonization and NH3 treatments. The NH3 treatment time has a significant effect on the pore structure, thermal stability as well as the surface chemistry. The as-prepared carbon materials were studied as freestanding electrodes for supercapacitor without the addition of binders and conductive additives in 6M KOH solution. The sample treated with NH3 for 3h exhibits a high specific surface area (763m2g−1), rich surface functionalities (5.26at.% nitrogen and 4.37at.% oxygen), optimized pore structure, good thermal stability and electrical conductivity. It shows the maximum specific capacitance of up to 251.2Fg−1 at 0.1Ag−1, about 25% higher than that of the sample treated with argon. Furthermore, the specific capacitance remains 193Fg−1 at 20Ag−1 with high rate capability of 77%, as well as excellent cycle stability (99% capacity retention after 2000 cycles). The outstanding performance of nitrogen-doped porous carbon nanofibers could be attributed to the synergistic effect of the proper pore size distribution, high effective surface area and certain amount of nitrogen- and oxygen-containing functional groups, resulting in both electrochemical double layer and faradaic capacitance contributions.