Micro-/mesoporous carbon nanofibers embedded with ordered carbon for flexible supercapacitors

Currently carbon nanofibers are attracting myriad interest for supercapacitors due to their high specific capacitance and low cost. However, their poor electrical conductivity and microporous structure restrict their wide applications. Here, flexible micro-/mesoporous carbon nanofibers embedded with ordered carbon (MCNF) were prepared by coaxial electrospinning and subsequent corrosion. Field emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction spectroscopy and nitrogen adsorption-desorption isotherm were used to characterize their morphology, structure and specific surface area. Electrochemical tests of cyclic voltammetry and electrochemical impedance spectroscopy show that the specific capacitance of MCNF can reach 272 F g−1 at 1 A g−1, much higher than that of carbon nanofibers (216 F g−1) which is obtained by single axial electrospinning. The flexible symmetrical supercapacitor based on MCNF electrodes exhibits an excellent electrochemical performance, with a capacitance retention of 96.7% after 3000 charge-discharge cycles and a high energy density of 11.1 Wh kg−1 when the power density is 0.25 kW kg−1. More interestingly, its specific capacitance almost does not change even when it is bent to 135°. The results show that MCNF is a promising electrode material for flexible supercapacitors.