Nitrogen-doped carbon networks derived from the electrospun polyacrylonitrile@branched polyethylenimine nanofibers as flexible supercapacitor electrodes

Nitrogen-doped carbon nanofibers (NCNFs) are important electrode materials that have received tremendous attention in terms of their capacity to store energy. At present, it is still desirable to fabricate high-performance NCNFs for supercapacitors. Here, for the first time, polyacrylonitrile@branched polyethylenimine (PAN@bPEI) composite nanofibers are proposed as precursors to prepare freestanding NCNFs, which can then be used directly in flexible supercapacitors. The single electrode based on the resultant NCNFs with unique chemical composition exhibits electrochemical properties that are superior to those of the polyacrylonitrile-derived CNFs electrode. In addition, a quasi-solid-state symmetric supercapacitor assembled without the use of any adhesive or conductive agent also shows a comparable energy density, favorable cycling durability, and mechanical stability, indicating that bPEI is an effective nitrogen source with which to construct nitrogen-doped carbon fibers for energy storage applications.