N-doped hierarchical porous hollow carbon nanofibers based on PAN/PVP@SAN structure for high performance supercapacitor

Carbon nanofibers (CNFs) have been continuously studied as a high performance electrode material due to their versatility in energy storage/conversion systems. The main concern of fabricating CNFs as electrode materials is to endow pristine carbon materials with adequate pore structure and active surface functional groups. Herein, we have fabricated porous hollow carbon nanofibers (PHCNF) with high nitrogen contents (13.4%) via co-axial electrospinning and subsequent phase separation process by using poly(styrene-co-acrylonitrile) (SAN) as core and polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP) mixture as shell. Simple etching process prior to carbonization has a significant effect on making hierarchical pore structure. Moreover, hollow characteristics allow efficient heat treatment for making high crystalline structure and favorable nitrogen functional group. Such an optimized structural and surface functional properties result in a remarkable supercapacitor performance. The designed structure achieves an energy density of 4.12 Wh kg(-1) at power density of 15 kW kg(-1), and a 92.33% retention rate in 10,000 charge/discharge cycles. The results offer a new strategy for developing advanced carbon material based electrode for high performance storage devices such as supercapacitors, lithium-ion batteries, and sensors.