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[Display omitted] • The vacancy-defective graphene sheets are constructed successfully through polyacrylonitrile thermally mediated. • Vacancy defects on graphene sheets can enhance electrons/ions transport kinetics • The assembled aqueous zinc-ion hybrid supercapacitors exhibit a high energy density and outstanding cycling stability. The electrochemical behavior of graphene sheets in energy storage system is closely related to its electronic structures. Specifically, structural vacancy defects can expose more active sites and enhance the electrochemical performance. However, it is still a challenging problem to realize valid defect regulation on improving the reaction kinetics of electrode materials. Herein, vacancy-defective graphene sheets were constructed through the thermal mediated method via intercalation of polyacrylonitrile nanofibers. The vacancy defects were generated from the NH 3 gas resulting from polymer decomposition at gradient carbonization temperature. The obtained composites of the graphene sheets and carbon nanofibers demonstrate that the vacancy defects benefit to charge transport, allowing more electrons to pass through the interlayered structure, and enhance the adsorption capacitance during the reversible electrochemical process. In addition, the as-assembled Zn ion hybrid supercapacitors exhibit a high energy density of 129.9 Wh kg−1 and outstanding cyclic stability (99.8 % after 10,000 cycling). The confined polymer-mediated thermal modification strategy can afford abundant vacancy defective sites and exhibit promising outlook for constructing high-performance graphene-based electrode materials for Zn ion hybrid supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • PVP/ZIF-7/PAN nanofibers carbonized at 900 °C yielded flexible ZnO P /C. • A capacitance of 382.5 mF cm−2 was obtained at a current density of 1 mA cm−2. • ZnO P /C demonstrated a capacitance retention of ∼ 101 % over 10,000 cycles. • ZnO P /C delivered an energy density of 49 μWh cm−2 at a power density of 2 mW cm−2. This study investigates the carbonization of electrospun fibers derived from zeolitic imidazolate framework (ZIF)-7/polyacrylonitrile solutions containing urea or polyvinylpyrrolidone (PVP). The carbonization yields highly flexible composites comprising nitrogen-doped carbon nanofibers and ZnO. Notably, using PVP as a nitrogen source generates a composite exhibiting excellent electrochemical performance. Specifically, it delivers a high capacitance of 382.5 mF cm−2 at a current density of 1 mA cm−2. Furthermore, this composite demonstrates capacitance retentions of approximately 101 % and 80 % after 10,000 cycles and a 90° bending test, respectively. The charge-storage capability of the PVP-based ZnO P /C composite surpasses that obtained without PVP by 1.4 times. Additionally, a composite fiber mat of ZnO P /C obtained via one-step electrospinning exhibits exceptional electrical conductivity and an energy density of 49 μWh cm−2 at a power density of 2 mW cm−2. These findings highlight the potential of this material as an electrode for supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The NB-PCNF and MnO 2 /Co 3 O 4 /NB-PCNF were successfully fabricated via needleless electrospinning. • The co-doping of multiple non-metallic atoms enhances the electrochemical capability of carbon nanofibers. • The heterogeneous structure in MnO 2 /Co 3 O 4 /NB-PCNF can effectively improve the electrical conductivity. • A flexible asymmetric solid-state supercapacitor (FASS-SC) exhibits excellent electrochemical performance. Rational design of an electrode material with high flexibility and electrochemical performance is the key to wearable energy storage devices. Herein, a facile and productive needleless electrospinning method was introduced to prepare self-supported and flexible nanofibrous electrode materials for asymmetric capacitor. The MnO 2 nanoclusters and ZIF67-derived Co 3 O 4 nano-sheets were sequentially deposited on the surface of N, B-doped carbon nanofibers (hetero-junction MnO 2 /Co 3 O 4 /NB-PCNF). Attributing to the constructed multi-pathway for redox reactions on electrode, the specific capacitance of NB-PCNF and MnO 2 /Co 3 O 4 /NB-PCNF can reach up to 204.2F/g and 141.43F/g at a small current density of 0.1 A/g, respectively. In long-term cycling tests, the electrode materials exhibited excellent cycling stability and good rate capability. The electrodes were assembled with Potassium-ion hydrogel electrolyte to form a flexible asymmetric solid-state supercapacitor (FASS-SC). FASS-SC can reach a voltage window of 1.6 V. It provided 28.2 W h/kg at an energy density of 600 W/kg and a specific capacitance retention of 94.18 % after 10,000 cycles. The FASS-SC offers new research ideas for future flexible devices and wearable technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] • ● A dual network organohydrogel based asymmetric supercapacitor exhibits temperature tolerance from −20 to 80 °C. • ● High operation voltage of 1.7 V and a high energy density of 51.1Wh kg−1 is obtained with the supercapacitor. • ● Over the repeated cycles of heating and cooling between –20 and 80 °C, 94% of the initial capacitance is retained. • ● The supercapacitor exhibits mechanical stability over bending regardless of the temperature. It is highly desirable for supercapacitors to achieve mechanical flexibility and temperature tolerance, as well as high energy density, to fully utilize their superior characteristics of high-power density and long cycle stability to realize their potential as practical wearable energy storage devices. We devise a novel strategy to fabricate a flexible asymmetric supercapacitor based on dual network organohydrogel, exhibiting high energy density and electrochemical stability over a wide temperature range spanning 100 ℃. A three-dimensional core–shell NiCo 2 O 4 @MnO 2 nanostructure is selected as the positive electrode to supply multiple ion diffusion channels through its mesoporous structure, and nano structured N-doped carbon nanofibers as the negative electrode to increase the contact area with electrolyte, and 6 M KOH based organohydrogel as electrolyte. The resulting supercapacitor exhibits high electrochemical performance including a high operation voltage of 1.7 V and high energy density of 51.1 Wh kg−1 at a power density of 850 W kg−1 and is stable over temperature changes between –20 and 80 ℃. This work demonstrates a high-performance supercapacitor designed with 3D asymmetric electrodes and a dual network organohydrogel, suitable as a practical energy storage device, requiring mechanical stability and stability against temperature change. [ABSTRACT FROM AUTHOR]

Honeycomb-like nitrogen-doped carbon/polyaniline (HNC/PANI) composite is prepared by a facile two steps method. The honeycomb-like nitrogen-doped carbon skeleton, with uniform pore sizes and three-dimensionally ordered structure, is obtained via the sacrificial template method and polyaniline is served as the N and C source during this progress. The specific surface area is 1056 m2 g−1, which is much higher than that of the disordered nitrogen-doped carbon (named NDC) and pure PANI. The subsequent polyaniline nanofibers with different concentrations are in-situ polymerization on carbon skeleton. The as-prepared HNC/PANI shows excellent performance of supercapacitors is demonstrated by the electrochemical evaluation, which specific capacitance is as high as 686 F g−1 at 1 A g−1 along with the good rate performance and superior cyclic stability (87.8% after 5000 cycles at 10 A g−1, which is superior to the NDC/PANI and pure PANI electrode). Perhaps this work offers a novel approach to improve the specific capacitance and cycle stability of supercapacitors via the ordered honeycomb-like carbon framework. Unlabelled Image • The honeycomb-like nitrogen-doped carbon/PANI composite is fabricated. • The 3D networks of the interconnected of carbon skeleton shortens the electrolyte ion diffusion paths. • The composite with 3D lawn-like structure reveals excellent electro-chemical properties. [ABSTRACT FROM AUTHOR]

Lignin, a renewable resource, has been used as carbon precursor to prepare porous carbon nanofiber films by electrospinning with PVP as spinning agent and Mg(NO 3 ) 2 ·6H 2 O as additive. The effect of the content of Mg(NO 3 ) 2 ·6H 2 O on the morphology, microstructure, surface chemistry, specific surface area and porous structure of the lignin-based porous carbon nanofiber films (LCNFs) is investigated. Results show that with the increase of the content of Mg(NO 3 ) 2 ·6H 2 O in the spinning solution, the average diameter of fibers is decreased obviously, while specific surface area and mesoporosity are increased significantly. When mass ratio of Mg(NO 3 ) 2 ·6H 2 O/lignin is 2:1, the resultant LCNFs possessed an increased specific surface area of 1140 m 2  g −1 and a significantly improved mesoporosity of 78%, and showed hierarchical porous structure. LCNFs were cut into electrode for supercapacitors directly and were evaluated in three-electrode and two-electrode cell. With increase of Mg(NO 3 ) 2 ·6H 2 O, the capacitive performance of LCNFs turn better. When mass ratio of Mg(NO 3 ) 2 ·6H 2 O/lignin was 2:1, the specific capacitance of LCNFs reached 248 F g −1 at 0.2 A g −1 , much higher than that of sample without Mg(NO 3 ) 2 ·6H 2 O (173 F g −1 ). Moreover, LCNFs showed an outstanding rate performance (capacitance retention of 59–67% from 0.2 to 20 A g −1 ) and a good cycling stability (capacitance retention of 97% after 1000 cycles at 20 A g −1 ). [ABSTRACT FROM AUTHOR]

[Display omitted] • Functional group vitalized mesoporous carbon nanofiber for electrochemical capacitor. • Sulfur and Phosphorus co-incorporated functional group and lattice heterostructures. • Simultaneously enhanced ionic and electron transport kinetics. • Novel strategy to fabricate ultrafast electric double layer electrode. Electric double layer capacitors (EDLCs) are attracting attention as rational energy storage platforms owing to their rapid and reversible charge adsorption/desorption at the electrode interface. Despite these advantages, EDLCs still face challenges in improving their ultrafast-rate capability for realizing its tailored applicability. In this study, tailored functional group vitalization was introduced on carbon nanofibers (CNFs) using chemical interactions between poly(methyl methacrylate- co -methacrylic acid), thiourea, and phosphorus red during thermal activation of electrospun polymer fibers. The tailored functional group vitalization effects include a simultaneous introduction of sulfur and phosphorus co-incorporated heterostructures from surface to interior of the CNFs (SPD-PCNF). In the surface region, sulfur and phosphorus containing functional groups are developed, which promotes electrolyte wettability and fast ionic diffusion kinetics at the CNFs/electrolyte interface. In the interior region, sulfur (2.4 at%) and phosphorus (2.0 at%) atoms are co-doped inside the carbon lattice, which improves electrical conductivity. In both the surface and interior region, accelerated specific mesopore area (1318.9 m2/g) and proportion are developed throughout the CNFs, which accommodates increased amounts and favorable ionic transport routes for charge adsorption/desorption. With these synergistic effects on charge transfer kinetics, SPD-PCNF electrode exhibited ultrafast-rate capability (112.8 F/g at 20 A/g and 14.0 Wh/kg at 36,000 W/kg). [ABSTRACT FROM AUTHOR]

[Display omitted] • Direct laser writing carbonization and heating treatment are used to manufacture carbon fibers. • Heat treatment can increase the specific surface area of carbonized lignin fiber. • A flexible supercapacitor constructed of carbon fibers has the qualities of being light, thin, and breathable. Electrode materials significantly impact supercapacitor performance and developing high-performance electrode materials is crucial in energy storage. Commonly used laser-induced electrode materials are currently limited by severe contamination and hard-to-change intrinsic properties. This paper proposes a method for fabricating high-performance supercapacitors by laser carbonizing the lignin composite fiber membranes with heating treatment. Lignin fiber can achieve superior tensile strength, stiffness, and carbonization degree under suitable heat treatment temperatures. Heat treatment at 450 °C has been proven to be the ideal temperature for supercapacitor performance. At a current density of 1 A/g, the supercapacitor can reach the highest specific capacitance of ∼391.2F/g. In addition, doping MoS 2 boosted the device's performance to a specific capacitance of ∼527.8F/g, a power density of ∼500 W/kg, and an energy density of ∼73 Wh/kg at the same current density. In addition, lignin fibers are ideal materials in electronic textiles due to their soft, thin, and breathable properties. This study provides supportive evidence and technical guidance for improving the performance of flexible wearable supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn-doped PAN nanofibers were decorated with ZIF-67. • Oriented attachment of PVP/ZIF-67 occurred on Mn-doped PAN-2MI nanofibers. • PVP/ZIF-67/Mn-fibers carbonized at 900 ℃ resulted in flexible C/Co-CoO x /Mn-CNF. • The areal capacitance of 1263 mF·cm−2 was obtained at a current density of 0.25 mA·cm−2. • The energy density of 0.18 mWh·cm−2 was obtained at a power density of 0.5 mW·cm−2. Electrodes for flexible supercapacitors were fabricated from manganese-doped carbon nanofibers (Mn-CNF) decorated with carbon-coated Co-CoO x (C/Co-CoO x) nanotubes. The Mn-doped polyacrylonitrile (PAN)–2-methylimidazole (2MI) solution was electrospun using optimized Mn concentrations and ZIF-67 was then surface loaded by wet impregnation with added polyvinylpyrrolidone (PVP). These ZIF-67 loaded Mn-fibers, when annealed, resulted in carbon-coated C/Co-CoO x nanotubes on the Mn-CNF surface. In the presence of PVP, ZIF-67 oriented attachment occurs, forming evenly dispersed CoO x particles even after high temperature annealing. XRD spectra exhibit the formation of metallic Co nanoparticles (NPs), whereas Raman spectra and XPS indicate Co particle oxidation. A carbon coating limits the oxidation of Co; thus, the particles are called C/Co-CoO x. A symmetric supercapacitor cell prepared using the CNFs decorated with C/Co-CoO x using an aqueous electrolyte has a capacitance of 1263 mF⋅cm−2 at a current density of 0.25 mA⋅cm−2 and a wide potential window of 1.4 V for the optimal case. Long-term cycling showed 110 % capacitance retention after 10,000 cycles. Moreover, bending tests and powering LEDs demonstrated the flexibility and improved charge storage of the prepared nanofiber electrodes. [ABSTRACT FROM AUTHOR]

We demonstrate the fabrication of a MnO x /carbamide carbon nanofiber (CCNF) composite consisting of MnO particles embedded in CCNFs as a highly flexible and freestanding electrode material for supercapacitors. A sacrificial polymer component, polymethylmethacrylate, included in the precursor solution, pyrolyzes during heating, resulting in pores in the fibers, some of which are filled by the MnO nanocrystals. Carbamide is added to control the size of the MnO x particles as well as to increase the carbon content of the composite and hence its conductivity. The X-ray diffraction and Raman spectra of the composite show that the MnO particles formed have low crystallinity. Transmission electron microscopy confirms that the MnO particles are distributed very uniformly over the CCNFs. Symmetric supercapacitors constructed using electrodes of this composite exhibit specific capacitances of 498 F∙g −1 at a scan rate of 10 mV∙s −1 and 271 F∙g −1 at a current density of 1 A∙g −1 . They also exhibit excellent long-term cycling performance, retaining 93% of their initial capacity after 5000 cycles of galvanostatic charging/discharging. [ABSTRACT FROM AUTHOR]

The main objective of this work is to prepare a flexible supercapacitor using electrochemically synthesized pyrrole formyl pyrrole copolymer P(Py-co-FPy) coated on the carbon microfibers. Due to difficulties of working with carbon microfibers, glassy carbon was used to find out optimized conditions by varying mole ratio of pyrrole and formyl pyrrole monomers on the capacitance value. The prepared electrodes were characterized using Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FESEM), Brunauer–Emmett–Teller (BET) analysis, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Then the X-ray photoelectron spectroscopy (XPS) was used to characterize the optimized electrode. The specific capacitance is calculated using cyclic voltammetry, charge/discharge method, and impedance spectroscopy. The charge/discharge study reveals that the best specific capacitance is estimated to be 220.3 mF cm −2 for equal mole fraction of pyrrole and formyl pyrrole Py (0.1)-FP (0.1) at discharge current of 3 × 10 −4 A. This optimized electrode keeps about 92% of its capacitance value in high current of discharging. The specific capacitances calculated by all the mentioned methods are in agreement with each other. Finally, the found optimized conditions were successfully applied to produce a flexible supercapacitor on the surface of carbon microfibers. [ABSTRACT FROM AUTHOR]

[Display omitted] • All-carbon aerogels of helical carbon nanocoils (CNCs)/reduced graphene oxide (rGO)/carbon nanofibers (CNFs) are successfully synthesized. • CNCs prevent the stacking of rGO and enlarge the spaces between rGO. Moreover, the growth of CNFs improves the specific surface area and conductivity. • Our work provides new inspiration for the design of multidimensional rGO-based aerogels for energy storage electrodes. Reduced graphene oxide (rGO)-based aerogels with multidimensional structures have shown enormous potential for electrodes in supercapacitors. Currently, the interlayer stacking of rGO largely limits their capacitance performance and leads to poor structural stability. Herein, the multidimensional all-carbon aerogel of helical carbon nanocoils (CNCs)/rGO/carbon nanofibers (CNFs) has been synthesized by hydrothermal self-assembly and in-situ chemical vapor deposition (CVD). In this ternary electrode, three-dimensional (3D) CNCs serve as the inner skeleton, which facilitates the construction of 3D porous architectures and reinforces the structural stability. The intercalated CNCs prevents the stacking of rGO and effectively enlarges the spaces between rGO. Moreover, the uniform growth of one-dimensional CNFs improves the specific surface area and electrical conductivity. Due to the synergistic effect and hierarchical assembly of these components, the CNCs/rGO/CNFs electrode not only exhibits a high areal capacitance of 1581.7 mF cm−2 at 0.5 mA cm−2 in a 6 M KOH electrolyte but also shows excellent cycling durability with 108.1% capacitance retention over 30,000 cycles. This work provides inspiration and guidance for the design of multidimensional electrode materials, which has huge application potential in future energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ti 3 C 2 T x MXene/carbon nanofiber electrodes are prepared by electrospinning. • The effects of Ti 3 C 2 T x MXene sheets size on the performances were investigated. • The electrodes (SMX/C) exhibit high-rate performance (90 F/g at 300 mV/s). • The electrodes have outstanding flexibility (98% retention after 500 bending). Increasing the capacitance and rate performance of the carbon-based electrodes used in flexible supercapacitors remains a key challenge for commercial viability. To meet these requirements, free-standing Ti 3 C 2 T x MXene/carbon nanofiber (CNF) electrodes were prepared by electrospinning of polyacrylonitrile (PAN) and carbonization for application as flexible supercapacitor electrodes. The effects of Ti 3 C 2 T x MXene size on fiber formation and electrochemical performance were investigated. Ti 3 C 2 T x MXene/CNF electrodes exhibited a specific capacitance of 90 F/g at a fast scan rate of 300 mV/s, which is almost 2.3 times higher than that of a pure PAN-derived CNF (38 F/g at 300 mV/s), while showing similar capacitance values of around 120 F/g at the slow scan rate of 2 mV/s. Due to the high degree of mechanical flexibility of CNFs, MXene/CNF based flexible supercapacitors also demonstrate long-term cycling stability (98% retention after 10 K charge-discharge cycles), and outstanding flexibility in dynamic bend tests. These results suggest that the MXene/CNFs have great potential for applications in flexible and versatile electronic devices. [ABSTRACT FROM AUTHOR]

• SiC nanofibers with various secondary nanonetworks were fabricated. • Formation mechanism of secondary nanostructure of SiC nanofiber was proposed. • Integration of developed micropores, nanosized microporous domains and suitable mesopores. • Hierachical porous structure and diameter of microporous domains were regulated. • An excellent specific capacitance of 186 F g−1 was achieved at 100 A g−1. Carbon nanofiber has been one of the promising electrode materials for supercapacitors. It is desirable but still challenging to optimize meso-/micro-pore ratio and configuration while achieving a high specific surface area in carbon nanofibers. Here, we present the design and preparation of carbon nanofiber mats with both high specific surface area and rational meso-/micropore configuration by electrospinning tetraethyl orthosilicate (TEOS)/phenolic resin (PR)/polyvinylpyrrolidone (PVP)/F127 blend solution, followed by carbothermal reduction, removal of carbon and chlorination. Silicon carbide nanofibers constructed by regulatable secondary nanostructure were achieved by adjusting TEOS content in the spinning solution, derived from which microporous carbon nanofibers with considerable mesopores (60–70% in mesoporosity), diverse secondary nanostructure (24–44 nm), and high specific surface area (1765–1890 m2 g−1) were prepared. The formation mechanism of the diverse secondary nanostructure in carbon nanofiber was proposed. The carbide-derived carbon nanofibers showed an excellent specific capacitance (316 F g−1 at 0.1 A g−1) and high-rate capability (186 F g−1 at 100 A g−1) due to the enhanced ion transportation, which was achieved by shortening micropore channels and offering convenient mesoporous channel towards microporous domains. [ABSTRACT FROM AUTHOR]

• Flexible carbon nanobelt webs with hierarchical pores and N/O groups are fabricated. • Humidity is revealed to be the key to prepare the nanobelts. • Magnesium nitrate helps to inhibit inter-nanobelt adhesions and warping of nanobelts. • Reducing warping improves the conductivity and bulk density of carbon nanobelt webs. • Face-to-face inter-belt connection triggers higher volumetric capacitance. Flexible carbon nanobelt webs (CNBWs) with a hierarchical porous structure, considerable N- and/or O-containing surface functionalities were fabricated by electrospinning of phenolic resin/PVP/magnesium nitrate (MNH) solution, followed by curing, thermal treatment and picking. The effect of spinning humidity on the morphology of cured fibers was investigated. The results showed that low humidity was required for successful spinning and collection of the nanobelts. The addition of MNH played a crucial role in inhibiting inter-nanobelt adhesions and warping of nanobelts during thermal treatment and producing hierarchical porous structure. The increase in MNH content resulted in an enhancement in the specific surface area (SSA), micropore volume, and mesoporosity of the CNBWs. The achieved CNBWs displayed the maximum SSA of 779 m2 g−1 and a mesoporosity of 82%. The reduction in the number of warping endowed the CNBWs with face-to-face inter-nanobelt connection, then brought about a significant enhancement in conductivity and packing density of the CNBWs, which ultimately improved the rate performance and volumetric capacitance. The work proposed a feasible route for improving the conductivity and volumetric capacity of electrospun carbon nanofiber webs as the electrode for supercapacitors or batteries. [ABSTRACT FROM AUTHOR]

• The δ-MnO 2 @Fe-CNFs with various morphology were fabricated by varying pH and Fe ratio. • The δ-MnO 2 @Fe-CNF-5% at pH = 2 shows tubular structure with uniform MnO 2 nanosheet assembly. • The δ-MnO 2 @Fe-CNF-5% has excellent supercapacitor performance. • The δ-MnO 2 @Fe-CNF-5% achieves a high salt adsorption of 20 mg/g in CDI device. • The δ-MnO 2 @Fe-CNF-5% has high stability, superior to δ-MnO 2 @CNF. Birnessite-type MnO 2 (δ-MnO 2) nanosheet assembly with various structures were achieved by redox reaction of KMnO 4 under acidic condition with Fe regulation on Fe-doping carbon nanofibers (Fe-CNFs). The Fe-CNFs with various Fe contents were conveniently obtained by carbonization of the electrospun ferric acetylacetonate-polyacrylonitrile (AAI-PAN) fiber with various AAI ratios. X-ray diffraction and transmission electron microscopy demonstrated the formation of δ-MnO 2 on the Fe-CNFs. pHs of KMnO 4 solution and Fe content in the fiber affected the morphology of δ-MnO 2. At pH = 2, the uniform δ-MnO 2 nanosheet assembly was transferred into a tubular structure by adjusting Fe content in the Fe-CNFs template (AAI = 5%, mass ratio). The obtained δ-MnO 2 @Fe-CNF-5% exhibited the highest aspect ratio, large surface area and best charge-transfer behavior. The δ-MnO 2 @Fe-CNF-5% electrode delivered a specific capacitance of 210 F/g (0.3 A/g) and a superior cycling stability with 94% capacitance retention in 4500 cycles. The δ-MnO 2 @Fe-CNF-5%, as a negative electrode presented an excellent performance both in supercapacitor with high energy density (20 Wh/kg) and in capacitive deionization cell with the salt adsorption capacity of 20 mg/g. The unique nanostructure and excellent electrochemical performance render the δ-MnO 2 @Fe-CNF-5% composite as a much promising material for charge storage and deionization applications. [ABSTRACT FROM AUTHOR]

• NPCNFs/PANI with Integrated architecture has been well designed. • 3D continuous and conductive network can reduce internal resistance effectively. • Large surface areas and hierarchical porosity decrease the ion diffusion length. • The all-solid-state flexible device exhibits desirable electrochemical properties. Electrode materials with rationally designed architecture are crucial to achieve high-performance supercapacitors. However, there is still a great challenge for integrating the features of large accessible surface areas, fast electron/ion transport kinetics and favorable mechanical flexibility within a single electrode. Herein, we propose a facile approach to fabricate high-performance freestanding carbon-based electrode of polyaniline modified nitrogen-doped hierarchical porous carbon nanofibers, which effectively combine the merits of highly conductive electrospun carbon nanofibers with hierarchical porous structure, suitable nitrogen content as well as pseudocapacitive materials. Benefiting from the well-designed architecture, the as-assembled symmetric all-solid-state flexible device exhibits a high specific capacitance of 260 F g−1 at 0.5 A g−1 and high rate capability with a capacitance retention of 60% at 16 A g−1. Furthermore, the device also displays a desirable energy density of 8.9 Wh kg−1 with power density of 0.27 kW kg−1 and excellent cycling stability with 80.1% capacitance retention after 10,000 charge-discharge cycles at 2 A g−1. Eventually, the as-designed composite electrodes open up new avenues for facile construction of high-performance supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

Making full use of the high water-holding capability of bacterial cellulose, a highly N/S dual-doped carbon fibers (NSCF) with interconnected three dimensional structure is prepared by an absorption-swelling strategy. Supercapacitor electrode fabricated from this material delivers a high specific capacitance of 202 F g−1, which is two times higher than that of the pristine un-doped one at current density of 1.0 A g−1. This dual-doped NSCF shows good wettability, fast ion-transportation and desirable electrical conductivity, which are indispensable characters of an electrode material in building the supercapacitor with desired high power performances. Three-dimensional nanofibrous NSCFs with a high N/S doping content (6.90 at.% for N and 1.02 at.% for S) were obtained via an absorption-swelling strategy and subsequent heat treatment. Unlabelled Image • N/S co-doped carbon nanofibers (NSCF) was prepared by a concise and eco-friendly way. • NSCF shows superiorities in wettability, ion-transport and electrical conductivity. • N/S dual-doping is proved to improve the capacitance behaviors. [ABSTRACT FROM AUTHOR]