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We report the microstructure, electrical and electrochemical properties of hybrid nanofibers composed of polyacrylonitrile (PAN)/lignin-derived carbon nanofibers and LaMnO3-based inorganic nanofibers for advanced applications as free-standing and binder-free electrode materials of energy storage devices. For this purpose, hybrid nanofibers are fabricated via dual-electrospinning technique and following heat-treatment at different temperatures of 700–1000 °C for simultaneous carbonization and calcination. The SEM, EDS, and XPS analyses reveal that the carbon content in the hybrid nanofibers increases with increasing the heat-treatment temperature and that La and Mn elements are dispersed uniformly over the hybrid nanofibers. The hybrid nanofibers heat-treated at 900 and 1000 °C have a high electrical conductivity of ~ 0.22 S/cm and ~ 0.35 S/cm, respectively. Accordingly, a symmetric two-electrode supercapacitor based on hybrid nanofibers heat-treated at 1000 °C is characterized to have excellent electrochemical performance such as specific capacitance of ~ 95.2 F/g at 1 A/g, power density of 667 W/kg, energy density of 17.6 Wh/kg, and capacitance retention of ~ 97% after 2000 cycles. The results denote that PAN/lignin and LaMnO3-based hybrid nanofibers can be utilized as self-supporting high-performance electrode materials for advanced energy storage devices. [ABSTRACT FROM AUTHOR]

Nickel oxide on directly grown carbon nanofibers (CNF-NiO) electrodes were fabricated and used as cathodes for hydrogen production by water electrolysis and as electrode materials for supercapacitors. Tafel polarization from the CNF-NiO electrodes showed an improvement in the hydrogen evolution reaction. This was attributed to the increment of the electrochemically active surface area, conductivity, and the synergy effects between the nickel oxide, carbon nanofibers, and nickel foam substrate. When used for supercapacitor applications, these electrodes showed a specific capacitance of ca. 776.20 ± 26 mF cm−2 at a current density 3 mA cm−2. These electrodes prepared using a facile method also exhibited a capacitance retention of 89% even after 3000 cycles with a coulombic efficiency of 89% when cycled at 20 mA cm−2. Considering the simplistic approach of the electrode preparation, the stability, and the capacitance, this method opens an avenue to try various metal oxide deposit on the directly grown CNF template. [ABSTRACT FROM AUTHOR]

In this paper, we proposed the synthesis of CoFe nanoparticles (NPs) which have been deposited on carbon nanofibers (CNFs) with a facile electrospinning route followed by thermal reduction. The performance of obtained CNF supercapacitors are improved from 51 to 190 F/g (247 mF/cm2) at 0.5 A/g with the combination of CoFe NPs and graphitized carbon layers The device possessed an energy and power density of 6.6 Wh/kg and 125 W/kg, respectively. Furthermore, the capacitance retention can still maintain about 96.6% after 10,000 cycle test and it is worth noting that the cycling stability is ultrahigh. This research proves that bimetallic nanoparticles embedded in CNFs can elucidate new insights into the development new nanofiber electrode materials for the next generation of symmetric supercapacitors. [ABSTRACT FROM AUTHOR]