Nitrogen and sulfur co-doped porous carbon fibers film for flexible symmetric all-solid-state supercapacitors

Flexible supercapacitors have drawn tremendous attention resulting from the rapid development of wearable electronic devices. Herein, we develop an effective and facile two-step approach to prepare high content nitrogen, sulfur co-doped porous carbon nanofibers film as electrodes of flexible supercapacitors. Benefiting from the high specific surface area and rich nitrogen/sulfur content, nitrogen and sulfur co-doped porous carbon fibers film (N, S co-doped PCFF) electrodes exhibit a high mass specific capacitance of 307.8 F g−1, and the capacitance retains 98% of initial capacitance after 5000 cycles in a three-electrode system. The as-assembled flexible supercapacitor devices with polyvinyl alcohol/KOH gel electrolyte demonstrate a highest mass specific capacitance of single electrode of 183.9 F g-1 at the scan rate of 2 mV s-1, which is better than that of other heteroatom doping carbon materials. In addition, the energy density reaches as high as 16.35 Wh kg−1 with the power density of 147 W kg−1 and retains as 5.34 Wh kg−1 with higher power density of 2402 W kg−1. Furthermore, the flexible devices show good cycling stability, superior flexibility and stable electrochemical performance.