Synthesis of rational nanostructure design of hybrid materials including uniformly growing, stable and highly porous structures have received a great deal of attention for many energy storage applications. In this study, the positive electrode of the uniform distribution of NiCo 2 O 4 nanorods anchored on carbon nanofibers has been successfully prepared by in-situ growth under the hydrothermal process. Whereas, the activated multichannel carbon nanofibers (AMCNFs) have been fabricated via electrospinning followed by alkaline activation as the negative electrode. The crystal phase, morphological structure for the proposed electrode materials were characterized by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Moreover, the electrochemical behaviors were investigated using cyclic voltammetry (CV), galvanostatic charge and discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements. Compared to the neat CNFs and the pristine NiCo 2 O 4 , the NiCo 2 O 4 @CNFs hybrid electrodes showed better electrochemical performance and achieved a high specific capacitance up to 649 F g −1 at a current density of 3 A g −1 . The optimized NiCo 2 O 4 @CNFs//AMCNFs asymmetric device achieved a high energy density of 38.5 Wh kg −1 with a power density of 1.6 kW kg −1 and possessed excellent recyclability with 93.1% capacitance retention over 6000 charging/discharging cycles. Overall, the proposed study introduces a facile strategy for the robust design of hybrid structured as effective nanomaterials based electrode for high-performance electrochemical supercapacitors.

In this work, Carbon Nanofiber mates (CNF) were fabricated by carbonization of electrospun non-conducting PolyAcryloNitrile (PAN) and PAN/PolyvinylAlcohol (PVA) nanofiber mates at 1100°C. PAN acts as a carbon source while PVA acts as a scarifying material to create porosity which leads to increase the accessible surface area. Two types of samples have been produced, carbon nanofiber mate (CNF) and Porous carbon nanofiber mate (P-CNF). The samples were first characterized by XRD, FTIR and SEM then examined as novel electrodes for supercapacitor applications. The specific capacitance (SC) results of the CNFs based on electrospun PAN mate and P-CNF based on electrospun PAN/PVA mate precursors, were 170 and 202 Fgm-1 respectively. The porous structure of P-CNF mate not only increased SC but also increased the capacitive retention and cyclic stability at discharging current density three times higher than that applied in case of CNFs. These results confirm that the tailored P-CNFs have potential for lightweight and durable flexible supercapacitor applications.

This work aims to develop and characterize a new design of free-standing interconnected carbon nanofiber electrodes for supercapacitor application. The fibers are obtained via carbonization of three components of electrospun nanofiber mats based on a polyacrylonitrile polymer (as a carbon backbone precursor), polyvinylalcohol (as a sacrificial copolymer), and 0-1.0 wt% multi-walled carbon nanotubes. Carbonizing these ternary composites results in fibers with about twice as large in surface area and one order of magnitude higher in electrical conductivity than those obtained by the carbonization of neat polyacrylonitrile and/or binary polyacrylonitrile-0-1.0 wt% carbon nanotube mats. The carbonized polyacrylonitrile-polyvinylalcohol-0.3 wt% carbon nanotube mat reveals the highest surface area and electrical conductivity and best capacitive performance. It exhibits energy and power densities of 27.8 Wh kg −1 and 110.59 kW kg −1 , respectively, and cyclic stability of 95% after 2000 charge-discharge cycles at a charging current of 1.0 Ag −1 . The nanotubes' alignment along the fiber's axis, the formation of fiber-fiber interconnected morphology with more mesopore pollution, and changes in the graphitization degree and defect features of fiber crystallites are the reasons for the observed increase in the electrical conductivity, surface area, and capacitive performance of the carbon fibers. Therefore, the new design represents a potential free-standing carbon nanofiber electrode for future electrochemical double layer capacitor (EDLC) device fabrication.