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The combination of multiple electrode materials and their reasonable structural design are conducive to the preparation of composite electrodes with excellent performance. In this study, based on carbon nanofibers grown with Ni(OH)2 and NiO (CHO) prepared by electrospinning, hydrothermal growth, and low-temperature carbonization, five transition metal sulfides (MnS, CoS, FeS, CuS, and NiS) were hydrothermally grown on their surfaces, exhibiting that CHO/NiS had the optimal electrochemical properties. Subsequently, the effect of hydrothermal growth time on CHO/NiS revealed that the electrochemical performance of CHO/NiS-3h was optimal, with a specific capacitance of up to 1717 F g−1 (1 A g−1), due to its multistage core–shell structure. Moreover, the diffusion-controlled process of CHO/NiS-3h dominated its charge energy storage mechanism. Finally, the asymmetric supercapacitor assembled with CHO/NiS-3h as the positive electrode demonstrated an energy density of 27.76 Wh kg−1 at a maximum power density of 4000 W kg−1, and it still maintained a power density of 800 W kg−1 at a maximum energy density of 37.97 Wh kg−1, exhibiting the potential application of multistage core–shell composite materials in high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Carbon nanofibers derived from lignocellulosic materials have become the most prevalent free-standing electrode material for supercapacitors due to their renewable and sustainable nature. This study used Arenga pinnata bunches (APB) as raw material for hemicellulose compounds to produce carbon electrodes through carbonization processes at 650 °C, 700 °C, 750 °C, and 800 °C, in the presence of flowing N2 gas. The variations in carbonization temperature resulted in carbon electrodes with surface morphology having a nanofiber structure with micro-meso pore distribution. According to the results, the carbonization temperature of 700 °C (APB-700) is the optimum temperature for producing electrode surface morphology with a combination of nanofiber, micro-and mesopore distributions, as well as specific surface area, specific capacitance, energy density, and power density of 1231.896 m2 g−1, 201.6 F g−1, 28.0 Wh kg−1, and 109.5 W kg−1, respectively, for the two electrode systems. This shows the combination of nanofibers and the distribution of micro-and mesopores produced with variations in carbonization temperature has the capacity to improve the performance of supercapacitor cells. Therefore, carbon nanofibers derived from Arenga pinnata bunches have the potential to be used as free-standing electrode materials for supercapacitors without employing doping, binder, electrospinning, and heteroatom template methods. [ABSTRACT FROM AUTHOR]

Using renewable biomass precursors to develop high-performance carbon electrodes is a promising approach for the advancement of supercapacitors. This work proposes a feasible strategy to prepare self-supporting flexible porous carbon nanofibers by electrospinning and carbonizing the mixture of cuttlefish ink, polyacrylonitrile (PAN) and polymethyl methacrylate (PMMA). The impacts of cuttlefish ink precursor on the structure, elemental composition, and capacitance properties of carbon nanofibers have been studied. Herein, the unique structural advantage of cuttlefish ink can significantly optimize the porous structure of carbon nanofibers. Due to the hierarchical porous structure, large specific surface area, hollow channels and high nitrogen content, the carbon nanofibers offer a high specific capacitance of 364.8 F g−1 at 0.5 A g−1 current density, alongside desirable rate performance and cycle life. Furthermore, the carbon nanofiber electrode performs good mechanical flexibility. The flexible solid-state supercapacitor based on this electrode exhibits 14.1 Wh kg−1 energy density at 0.4 kW kg−1 power density, and 97.8% capacitance retention after 5000 cycles. The favorable capacitive properties make this carbon nanofiber material a potential candidate for supercapacitor electrodes. [Display omitted] • Electrospun porous carbon nanofibers (CPP–CNF) were prepared from cuttlefish ink. • CPP-CNF features hierarchical pores and hollow channels. • CPP-CNF is mechanically flexible with superior capacitive performance. • The flexible supercapacitor achieves high energy density and cycling stability. [ABSTRACT FROM AUTHOR]

• MnO 2 /CNF/Ag nanofabric electrodes are developed for flexible supercapacitors. • The brittle issue in the CNF electrode is greatly improved by an Ag incorporation. • The optimized MnO 2 /CNF/Ag electrode has a specific capacitance of 184 F/g at 1 A/g. • An energy density of 16.3 Wh/kg and a power density of 400 W/kg was achieved. • A capacitance retention rate of 87 % was demonstrated when subjected to bending. Flexible supercapacitors are gaining increasing popularity due to their potential in powering portable, wearable, and lightweight electronic devices. In this study, we have successfully developed a high-performance flexible electrode for quasi-solid-state supercapacitors by incorporating Ag into carbon nanofibers (CNF) through electrospinning, and growing MnO 2 as an active material on the electrode using an in-situ redox method. The Ag and MnO 2 co-decorated CNF electrode offers several advantages over conventional CNF electrodes, including an enlarged reaction area, higher charge storage capacity, and improved resistance to brittleness issues. Among all the quasi-solid-state supercapacitors tested, the MnO 2 -decorated electrode with an optimized Ag incorporation exhibited the highest specific capacitance of 184 F/g at a current density of 1 A/g, representing a remarkable 17-fold increase compared to the reference CNF electrode. Furthermore, the Ag and MnO 2 co-decorated electrode demonstrated an energy density of 16.3 Wh/kg and a power density of 400 W/kg at the same current density. Notably, the electrode exhibited excellent flexibility, with a capacitance retention rate of 87 % when subjected to bending with a curvature ranging from 5 to 1.25 cm. Our results suggest that the Ag and MnO 2 co-decorated CNF electrode holds great promise for flexible energy storage applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Summary: The design of inexpensive, binder‐free electrodes with high energy densities from naturally occurring compounds poses an interesting challenge for the construction of high‐performance supercapacitors. In particular, the synthesis of highly conductive carbon electrodes starting from miscanthus‐derived (silver grass) lignin with inorganic active sites is of interest for hybrid supercapacitors. In this work, Ni‐Mn sulfide nanograin networks are embedded on lignin‐derived carbon nanofibers (LCNFs) by electrospinning, followed by either direct vapor‐phase sulfidation or peroxidation‐induced sulfidation in an inert atmosphere. After either of the two different sulfidation processes, the direct transformation of Ni‐Mn sulfide on carbon nanofibers results in highly mechanically flexible freestanding electrodes, with a good specific capacity of 652.3 C g−1 at 1 A g−1, excellent current rate properties (73.6% capacity retention at 20 times the initial current density), and a cycling stability of 91.3% after 5000 cycles, even at the high current density of 10 A g−1. These outstanding properties are attributed to the rational design of surface‐embedded Ni‐Mn sulfide nanograins on the 3D LCNFs and the fascinating synergetic and graphitic nature of the fibrous web, which increases conductivity, influences the interfacial contact, and promotes highly electrochemically active sites on the electrode surface. Furthermore, an aqueous hybrid supercapacitor assembly of LCNFs‐NiMnS//activated carbon (AC) is demonstrated, with a maximum energy density of 52.4 W h kg−1 at a power density of 800 W kg−1, as well as 92.3% capacitance retention even after 10 000 cycles. This work not only establishes a high‐capacity anode but also provides an ideal strategy for designing flexible and conductive heterostructure network for various energy storage applications. [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]

Here, core-shell supercapacitor electrodes with high performance were prepared using electrospinning, carbonation, nitrogen-doping and chemical polymerization. The core of the electrode was a N-doped porous carbon nanofiber skeleton, its shell was a conductive polymer loaded on it. The effects of pore-forming agent content, N-doped amount, and polymerization temperature on the morphologies, structures and electrochemical performance of products in each stage were characterized, and the optimum parameters were obtained. As a freestanding electrode, the SC of core-shell composite reached 342.13 F g−1 at 1 A g−1, and its SC attenuation was only 4.6 % after 1000 cycles, indicating its good charge storage performance and cycle stability. Then a symmetric supercapacitor fabricated with the best electrode displayed an energy density of 3.10 Wh kg−1 at a power density of 50 W kg−1. Therefore, this paper proposed an effective method for developing multifunctional electrode materials of supercapacitors. [Display omitted] • A core-shell composite for high-performance supercapacitor electrode was prepared. • The core layer of the composite was the N-doped porous carbon nanofiber skeleton. • The shell layer of the composite was the polypyrrole loaded on the skeleton. • The core-shell composite electrode showed excellent electrochemical performances. • An asymmetric supercapacitor device was fabricated using the core-shell electrode. [ABSTRACT FROM AUTHOR]

In view of the current problem that MOFs (Metal-organic frameworks)-based carbon as electrode materials for supercapacitors have poor conductivity and single component. We design porous hybrid carbon nanofibers (C-ZIF-67 @PAN@ZIF-8) derived from 1D core-shell MOFs. They can combine the advantages of 1D carbon materials (high conductivity) with hybrid carbon materials (multiple components) showing excellent electrochemical performance. The specific capacitance can reach 320.8 F g−1 at a current density of 1 A g−1, which is higher than C-ZIF-8 (180.8 F g−1) and C-ZIF-8 @PAN (273.7 F g−1) in a three-electrode system. In addition, symmetrical supercapacitors are assembled with C-ZIF-67 @PAN@ZIF-8, which can provide very stable performance and almost no capacitance decay after 10,000 cycles at a current density of 5 A g−1. The supercapacitors also can offer a high energy density of 8.0 wh kg−1 at a power density of 250 w kg−1. [Display omitted] • A new and highly efficient design of 1D porous hybrid carbon materials are demonstrated. • The 1D porous hybrid carbon materials can combine the advantages of 1D carbon materials with 0D hybrid carbon materials. • 1D porous hybrid carbon materials show excellent electrochemical performance for supercapacitors. [ABSTRACT FROM AUTHOR]

In this work, the in-situ formation of MnMoO 4 nanoparticles and simultaneous encapsulation within the porous carbon nanofiber (CNF) matrix through electrospinning-carbonization-thermal annealing processes were carried out. The results of various spectroscopic and morphological analyses confirmed the successful formation of rectangular-shaped MnMoO 4 nanorods within the CNF matrix. The MnMoO 4 @CNF hybrid yielded a maximum specific capacitance of 389.7 F/g at 0.1 A/g, which is 3-folds more than that of CNF (123.4 F/g). The MnMoO 4 @CNF symmetric cell with an aqueous KOH electrolyte possessed a maximum energy density of 54.12 Wh/kg at a power density of 10 W/kg. The excellent capacitive performances of as-prepared MnMoO 4 @CNF nanofibers could be ascribed to their high specific surface area (229.35 m2/g) with wide mesoporous distribution (3–13 nm) and enhanced reactivity of the nano-sized MnMoO 4 nanoparticles. The hybrid electrode demonstrated excellent cyclic stability with capacitance retention of 92.1% after 5000 cycles, suggesting restricted extrication of metal oxide from the CNF matrix during the charge-discharge process. A flexible solid-state asymmetric supercapacitor was assembled by using MnMoO 4 @CNF hybrid mat as a positive electrode and activated carbon cloth as a negative electrode. The polymer gel electrolyte (PVA + KOH) was used as electrolyte-cum-separator. The as-prepared MnMoO 4 @CNF//AC cell yielded a highest energy density of 37.46 Wh/kg and an equivalent power density of 278 W/kg. The present investigation could open new horizons in developing next-generation flexible solid-state supercapacitors for wearable electronics. [Display omitted] [ABSTRACT FROM AUTHOR]

Highly porous carbon electrodes for supercapacitors with high energy storage performance were prepared by using a new precursor blend of aromatic polyimide (PI) and polyvinylidene fluoride (PVDF). Supercapacitor electrodes were prepared through the electrospinning and thermal treatment of the precursor blends of aromatic PI and PVDF. Microstructures of the carbonized PI/PVDF nanofibers were studied using Raman spectroscopy. Nitrogen adsorption/desorption measurements confirmed their high surface area and porosity, which is critical for supercapacitor performance. Energy storage performance was investigated and carbonized PI/PVDF showed a high specific capacitance of 283 F/g at 10 mV/s (37% higher than that of PI) and an energy density of 11.3 Wh/kg at 0.5 A/g (27% higher than that of PI) with high cycling stability. [ABSTRACT FROM AUTHOR]

Carbon nanofibers from electrospun polymer nanofibers have received considerable attention. However, most of the carbon nanofibers with a surface area above 1000 m2/g were reported to have a supercapacitor electrode capacitance far below 350 F g−1. Herein, we report a novel carbon nanofibrous material that has a supercapacitor electrode capacitance as high as 394 F g−1 (1.0 A g−1). We used a polymer blend of polyacrylonitrile (PAN) and novolac (NOC) as materials, to electrospin them into precursor nanofibers and subsequently carbonize the nanofibers into carbon nanofibers. The carbon nanofibers prepared had a specific surface area as high as 1468 m2 g−1 with a meso-micro pores (average pore size 2.2 nm) predominated porous structure. The carbon nanofiber electrodes after 10,000 cycles of charging and discharging at 1.0 A g−1 maintained the capacitance almost unchanged. At the optimal condition, the supercapacitor device made of the electrodes had an energy density as high as 13.6 Wh∙kg−1 (at 0.5 kW kg−1). The high capacitance value comes from the carbon nanofibers with a large surface area and a unique porous structure. The high inter-fiber interconnection contributes to high capacitance. This super-high surface area carbon may be useful for the development of high-performance supercapacitors and other energy devices. Image 1 • Carbon nanofibers are prepared from electrospun polyacrylonitrile/novolac. • They contain micro-mese pores with a surface area as high as 1468 m2 g−1. • Electrodes made from the carbon nanofibers show a capacitance of 394 F g−1. • High capacitance originates from the unique structure and large surface area. [ABSTRACT FROM AUTHOR]

Porous carbon nanofibers (CNFs) with high energy storage performance were fabricated with a single precursor polymer, 6FDA-TFMB, without the use of any pore-generating materials. 6FDA-TFMB was synthesized, electrospun, and thermally treated to produce binder-free CNF electrodes for electrochemical double-layer capacitors (EDLCs). Highly porous CNFs with a surface area of 2213 m2 g−1 were prepared by steam-activation. CNFs derived from 6FDA-TFMB showed rectangular cyclic voltammograms with a specific capacitance of 292.3 F g−1 at 10 mV s−1. It was also seen that CNFs exhibit a maximum energy density of 13.1 Wh kg−1 at 0.5 A g−1 and power density of 1.7 kW kg−1 at 5 A g−1, which is significantly higher than those from the common precursor polymer, polyacrylonitrile (PAN). [ABSTRACT FROM AUTHOR]

Tailoring the chemical structures of a precursor polymer for carbon nanofibers (CNFs) produced by thermal treatment of electrospun nanofibers was studied to prepare the electrodes for electrochemical double layer capacitors (EDLCs). To improve energy storage performance of CNF electrodes, 6FDA-durene nanofibers were crosslinked by a vapor crosslinking method, and subsequently carbonized. Chemical modification via crosslinking was confirmed by FTIR spectra while the conversion of crosslinked 6FDA-durene into carbon was done by Raman spectroscopy. Electrochemical performance of these CNF electrodes was evaluated by assembling coin cells, and the CNFs derived from crosslinked 6FDA-durene nanofibers showed higher specific capacitances, energy densities and cycling stability than those from non-crosslinked ones. It was also shown that CNFs prepared using 1 min crosslinking exhibit the highest energy storage performances, a specific capacitance of 301 F g−1 (at 10 mV s−1), and the maximum energy density of 11.1 Wh kg−1 (at 0.5 A g−1) and power density of 1.8 kW kg−1 (at 6 A g−1). Surface area and porosity of CNFs, which is critical for the performance of EDLC electrodes, were studied by nitrogen adsorption/desorption measurements, and it was clearly seen that surface crosslinking of precursor polymers improved surface properties of the resultant CNFs. [ABSTRACT FROM AUTHOR]