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Flexible electrode materials play an important role in flexible portable energy storage devices. Carbon-based nanofiber has attracted numerous attentions due to its advantages on flexibility, safety, and reliability. Herein, we reported a novel and simple method to fabricate nitrogen-boron co-doped hollow porous carbon nanofiber (HPCNF) membranes as flexible supercapacitor electrodes. The higher specific surface area (413.98 m2/g) of HPCNF and the co-doping of N and B resulted in a high specific capacitance of 200.2 F/g (0.1 A/g). After 3000 cycles, NB-HPCNF still maintained high capacitance retention (104.81%). This study provides a new idea for electrochemical energy storage, which is beneficial to the deeper development of portable flexible devices. [Display omitted] • A novel and simple method was used to fabricate nitrogen-boron co-doped hollow porous carbon nanofiber membranes. • The well-developed hollow channels facilitated fast and efficient charge transport in carbon nanofibers. • A solid-state symmetric supercapacitor has good electrochemical properties and good mechanical stability. [ABSTRACT FROM AUTHOR]

Flexible supercapacitors with both high energy and high power densities are critical for flexible electronics. In this paper, hybrid flexible carbon nanofibers decorated with NiCo 2 S 4 nanoparticles are successfully prepared by combination of electrospinning, carbonization and hydrothermal treatments. The obtained hybrid carbon nanofibers display remarkable specific capacitance (527.8 F g −1 at the current density of 0.2 A g −1 and 622.5 F g −1 at 2 mV s −1 ), good rate capability (310.5 F g −1 at 4.0 A g −1 ) and excellent cycle stability (retaining 90.0% after 3000 cycles). The flexible asymmetric supercapacitors based on carbon nanofibers decorated with NiCo 2 S 4 and porous carbon nanofibers coated with activated charcoal are fabricated. The combined unique properties of each of these components enable highly flexible and mechanically strong films that can serve as electrodes directly without using any current collectors or binders. The fabricated device shows an energy density of 32.1 Wh kg −1 at power density of 67.6 W kg −1 and cycle stability retaining 88.5% after 1500 cycles at 1.0 A g −1 . Therefore, the novel flexible asymmetric device with perfect flexibility and stability can be applied as one of the most promising power supplies. [ABSTRACT FROM AUTHOR]

We demonstrate the fabrication of core-shell SnO x /carbon nanofiber (CNF) composite mats via single-nozzle one-step electrospinning for use as flexible freestanding electrodes in supercapacitors. The freestanding and flexible nature of the composites is essential for their use in lightweight, portable, and foldable electronic devices and eliminates the need for a separate current collector. We fully characterized the structural and morphological properties of the SnO x /CNF mats and optimized the SnO x to CNF precursor ratio. The optimized SnO x /CNF-based symmetric supercapacitor exhibited a capacitance of 289 F·g −1 at a scan rate of 10 mV·s −1 . Moreover, it retained more than 88% of its initial capacitance after 5000 cycles, highlighting the long-term stability of supercapacitors based on these SnO x /CNF mats. [ABSTRACT FROM AUTHOR]