Low Equivalent Series Resistance Research Articles

Investigation of charge storage in admixture of dextrose derived interconnected carbon spheres and micro-sized silicon

This work reports the investigations and electrochemical properties of a material, prepared by micro-sized Si (mSi) (upto 50 μm) which were partially coated with upto ~7 μm sized carbon microspheres (CS). The mixture of mSi enwrapped with CS ([email protected]) was fabricated using a low temperature and facile hydrothermal carbonization (HTC) of dextrose. XRD and Raman study revealed an amorphous phase due to carbon/SiO2 and a highly disordered nanocrystalline graphite respectively. Also, FTIR suggested the SiO bending and symmetric stretching of linear SiOSi. The electrochemical investigation with three cell assembly of fabricated [email protected] as an electrode material for supercapacitor application exhibited a maximum specific capacitance of 278.79 F g−1 at 5 mV s−1 scan rate which is around 7 times as calculated for pristine mSi powder. In [email protected], conducting, amorphous and nano crystalline carbon combined with mSi exhibited enhanced specific capacitance and a low equivalent series resistance (ESR). mSi served as anchor and contributed to enhancing specific capacitance and providing 2 V voltage window. This work opens the possibility of designing energy materials with the waste Si and pseudocapacitive materials.

Investigation of CuxS-based electrode for one-dimensional flexible supercapacitors and its electrochemical performances

In this study, CuxS nanoplates are in-situ synthesized on the surface of copper wire (CW) as active materials (CW@CuxS) for supercapacitor electrodes, in which CW and Na2S are respectively used as copper and sulphur sources. The CW@CuxS electrode exhibits high specific capacitance up to 3.06 F cm−3, good cycling stability with nearly 80% capacitance retention after 5000 cycles, small charge transfer resistance, and low equivalent series resistance. In addition, the CW@CuxS electrode shows excellent flexibility applied to one-dimensional supercapacitors, as indicated by the relative stability of the specific capacitance in different bending states.

Electrochemical performance of aqueous electrolytes in porous carbon derived cassava peel electrode material-based for sustainable symmetrical supercapacitor

Electrolytes have been generally recognized as one of the most important components in enhancing the electrochemical performance of supercapacitors. On the other hand, aqueous electrolytes are considered prime candidates for the development of the next generation of symmetric supercapacitors due to their low-cost, environmentally friendly, high ionic conductivity, fine ionic size, and high capacitance. Herein, the symmetrical supercapacitor of the sustainable porous carbon-based electrode material was confirmed through various aqueous electrolytes consisting of neutral, basic, and acidic Na2SO4, KOH, and H2SO4. Activated carbon is obtained from high potential biomass sources of cassava peel waste. Activated carbon synthesis was performed with a comprehensive approach in order to obtain abundant pore structure, high porosity, and improved wettability through a combination of high-temperature chemical and physical activation. in addition, the electrode material is designed to resemble a solid disc without the addition of a synthetic binder. The evaluation of the disc dimensions showed high porosity in the obtained activated carbon. Furthermore, the symmetrical supercapacitor of the optimized electrode material exhibit excellent specific capacitances of 112, 150, and 183 F g-1 at 1 mV s-1 in the electrolytes Na2SO4, KOH, and H2SO4, respectively. In addition, the highest rate capability of 70% was confirmed in the H2SO4 acid electrolyte. Moreover, their coulombic efficiency can be maintained around 89% with low equivalent series resistance 0.21-0.42 ?. Therefore, the activated carbon-based supercapacitor symmetric cell device from cassava peel shows high performance for developing high-performance supercapacitor applications with guaranteed stability in aqueous electrolytes.

One-step strategy of 3D hierarchical porous carbon with self-heteroatom-doped derived bread waste for high-performance supercapacitor

Bio-waste is a promising carbon source that can be used as a basic component in renewable supercapacitors due to its abundant hierarchical pore structure potential, heteroatom self-doping capability, high surface area, as well as well-defined chemical and mechanical stability. This study converted bread bio-waste into rich 3D hierarchical porous carbon through a one-step facile strategy to be used as the main component of a supercapacitor. The porous carbon was obtained through physical activation approach at different temperatures of 750, 800, 850, and 900 °C without being combined with chemical activation. The optimized activated carbon illustrated high porosity behavior with an abundant 3D hierarchical pore structure consisting of 76.98% micropores and 23.02% mesopores and also produced a well-defined wettability of self-doping heteroatoms. Moreover, the electrochemical behavior in a symmetric supercapacitor cell showed a high specific capacitance of 202 F g−1 at 1 A g−1 with a rate capability of 73% at 10 mV s−1 in a 1 M H2SO4 electrolyte. It was also discovered that the activation temperature of 850 produced the highest energy density of 11.61 Wh kg−1 at a power density of 156.71 W kg−1 with a low equivalent series resistance of 0.11 Ω. Finally, the proof-of-concept showed that bread waste has immense potential as a 3D hierarchical porous carbon source after the synthesis through a single-stage facile approach and can be used as a major renewable electrode component for sustainable supercapacitors.

The impact of DC-bus impedance on the switching performance of low-voltage silicon power MOSFETs

Typical DC-bus stabilization for low-voltage power circuits consists primarily of ceramic capacitors due to the capacity density and low equivalent series resistance (ESR) resulting in low conduction losses. Particularly in hard-switching and hard-commutation operation, the low ESR and high equivalent series inductance (ESL) of the capacitors in the commutation path restrict the damping of the switch node voltage overshoot and introduce high-frequency ringing, reducing the voltage margin of the transistor. Therefore, this paper analyzes the impact of the DC-bus impedance and proposes a DC-bus snubber based on an RC network to form the DC-bus impedance’s characteristic, which minimizes the overshoot voltage. A comprehensive simulation using measurement-derived component models is shown, which is verified by an in-situ measurement on a test PCB. Furthermore, transient measurements using a double pulse test setup show the effectiveness of the proposed approach.

Novel macaroni‐sponge‐like pore structure biomass (Zingiber officinale Rosc. leaves)‐based electrode material for excellent energy gravimetric supercapacitor

AbstractBACKGROUNDBiomass‐based porous carbon as the basic component of electrodes has received wide interest as a renewable energy storage device with high chemical–physical stability and environmental friendliness. Therefore, novel biomass waste based on Zingiber officinale Rosc./red ginger leaves was synthesized as an electrode‐based carbon material with an abundance of unique macaroni‐sponge‐like hierarchical pore structure, as well as good chemical, physical and economic performance. Template/metal–organic framework‐free red ginger leaf‐based hierarchical porous carbon (RGPC) was prepared using a facile and zero‐residue technique as electrode material for supercapacitor application.RESULTSAdditionally, ZnCl2 impregnation with concentrations of 0.1, 0.3 and 0.5 mol L−1 was utilized for increasing the active sites between electrode and electrolyte ions through interconnecting microchannels. The combination of macaroni‐sponge‐like structure, amorphous nature, optimum specific surface area and availability of oxygen functional groups as a self‐doping heteroatom of RGPC‐0.3 greatly optimized the electrochemical performance of symmetric supercapacitor cells. The RGPC‐0.3 electrode had an ideal specific capacitance of 215.76 F g−1 with a specific energy of 29.966 Wh kg−1 and maximum specific power of 108 W kg−1 at 1 mV s−1 in a symmetric supercapacitor system. Furthermore, a relatively good coulombic efficiency of 71.01% was obtained with a low equivalent series resistance of 0.098 Ω.CONCLUSIONSThis study provides insight into the generation of unique hierarchical porous carbon as a basic component of electrodes for energy storage applications with high electrochemical performance through the utilization of waste red ginger biomass with a simple, facile and cost‐effective strategy. © 2022 Society of Chemical Industry (SCI).

Evaluating the electrocatalytic activity of flower-like Co-MOF/CNT nanocomposites for methanol oxidation in basic electrolytes.

Efficient electrocatalysts, with high tolerance to methanol oxidation, good stability, and acceptable cost are the main requisites for promising direct methanol fuel cell (DMFC) electrode materials. This target can be achieved by the integration of different active materials with unique structures. In this work, a cobalt metal-organic framework (Co-MOF) flower structure was prepared by a hydrothermal method, and then a simple ultrasonication method was employed to anchor carbon nanotubes (CNTs) in between the MOF flower petals and fabricate a Co-MOF/CNT hybrid composite. Different ratios of CNTs were used in the composite preparations, namely 25, 50, and 75 wt% of the composite. The nanocomposites were entirely investigated using different characterization techniques, such as XRD, FTIR, SEM, TEM, and XPS. Comparative electrochemical measurements confirmed that due to the integration of highly conductive CNTs with the porous active fascinating structure of Co-MOF, Co-MOF/50% CNTs exhibited improved electrocatalytic activity with a current density of 35 mA cm-2 at a potential of 0.335 V and a scan rate of 50 mV s-1. The excellent electrochemical activity and stability could be due to the synergy between Co-MOF and the CNTs that conferred adequate active sites for methanol electro-oxidation and a lower equivalent series resistance, as revealed from the electrochemical impedance spectroscopy study. This study opens a new avenue to decrease the utilization of platinum and increase the methanol oxidation activity using low-cost catalysts.

Application of GO anchored mediator in a polymer electrolyte membrane for high-rate solid-state supercapacitors

We synthesized a novel polymer electrolyte membrane by combining poly (vinylidene fluoride) (PVDF) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) with graphene oxide (GO) nanosheets and a lithium salt of tungstosilicic acid (Li4SiW12O40, hereafter, referred to SiWLi). The impact of the addition of GO/SiWLi on the microstructure and morphology of the membrane were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). We found that adding the GO/SiWLi to the PVDF/LiTFSI polymer electrolyte membrane significantly reduced the pore size. Furthermore, the addition of the GO/SiWLi resulted in not only an increase of the ionic conductivity from 0.87 × 10−2 to 3.12 × 10−2 S cm−1 but also an increase in the lithium-ion transference number from 0.52 to 0.87. The polymer electrolyte membranes with and without GO/SiWLi were utilized to fabricate solid-state supercapacitors. The supercapacitors fabricated with the membrane containing GO/SiWLi displayed 37.2% lower equivalent series resistance and 88.2% greater specific capacitance than those fabricated using the membrane without GO/SiWLi at 200 mV s−1.

Direct laser-assisted fabrication of turbostratic graphene electrodes: Comparing symmetric and zinc-ion hybrid supercapacitors

Lasers offer a versatile means towards the single-step, binder-free synthesis of three-dimensional graphene-like porous networks, providing an enticing alternative over energy intensive, multi-step traditional synthesis protocols creating unwanted waste streams. Here, we report on a novel laser-assisted method for the one-step preparation of the electrode component, not solely the active material, based on the simultaneous synthesis of turbostratic graphene-like structures on a carbon precursor and its transfer/deposition on the selected current collector. The performance of the graphene-based electrodes was electrochemically evaluated for both electric double layer capacitor (EDLC) and zinc-ion hybrid capacitor (ZIC) configurations. The performance of the EDLC devices was found to be superior to that of the current state-of-the-art devices prepared by laser-grown graphene. The ZIC exhibited higher areal energy density than the symmetric devices by one order of magnitude. The devices showed very low equivalent series resistance, good rate performance and high long-term cycling stability. Notably, the EDLC with the KOH electrolyte demonstrated an unexpected ∼20% increase in capacitance during the stability test of 10,000 cycles. This result was attributed to the substantial increase of oxygen content of the graphene electrodes, which act as sites for redox activity.

Preparation and Characterization of Reduced Graphene Oxide-Incorporated ZnO Nanorods for Supercapacitor Application

This study’s objective is to prepare and characterize a ZnO-rGO composite for use in supercapacitors. The hydrothermal method was used to successfully prepare ZnO and ZnO-rGO. Characterization of the prepared materials was carried out using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and ultraviolet-visible (UV–Vis) spectrometers. The electrochemical properties of the ZnO and ZnO-rGO electrodes were examined using cyclic voltammetry (CV) and impedance spectroscopy. The specific capacitance of the ZnO-rGO composite electrode in 1[Formula: see text]M NaOH as an electrolyte was 293.37[Formula: see text]F/g at the scan rate of 5[Formula: see text]mV/s. As a result of the low equivalent series resistance and improved ion diffusion produced by ZnO and rGO working together, the ZnO-rGO nanoparticles electrode has a higher super capacitance. The result achieved a higher energy density of 39.93[Formula: see text]Wh/kg and a power density of 54.45[Formula: see text]kW/kg. These findings demonstrated the significance of rGO-based composites in the development of high-performance energy storage systems as well as their enormous potential for improvement.

A review on characterization of supercapacitors and its efficiency analysis for different charging methods and applications

AbstractThe dependence on renewable energy to solve the major energy issues related to global warming and shortage of energy resources is increasing drastically. This has led to high level awareness of proper energy storage and management. In this regard, supercapacitors have evolved as an efficient energy storage solution and hence successfully employed in several applications. This is attributed to its high‐power density, superior performance, and extended maintenance‐free lifetime. Also, it is known for low equivalent series resistance, that means, only a small amount of energy is lost while its charging/discharging even at high current. As a result, it has developed a lot of inquisitiveness among the research community of recent past for further exploration of different aspects of supercapacitors, ranging from material science, modeling and characterizations, engineering applications, and so forth. This review article aims at putting forth an exclusive study of their characterization of supercapacitor for different charging methods and applications. Further, the prime focus is given to the efficiency estimation of supercapacitors which is very essential as it denotes the amount of energy loss or the utilizable state of charge. The analysis has been carried out based on different charging methods and applications, which is essential for improving overall system reliability and performance. The purpose is to organize all important research carried out in this domain till date and to stimulate further insights for effective energy storage and management.

Synthesis and electrochemical characterization of polyaniline doped cadmium oxide (PANI-CdO) nanocomposites for supercapacitor applications

High-performance nanoscale supercapacitor (SC) electrode materials of polyaniline (PANI) and polyaniline cadmium oxide (PANI-CdO) composites are fabricated using In-situ chemical polymerization route. The structural parameters, crystallite size, and lattice strain of the prepared samples are estimated by X-ray diffraction analysis. The CdO stretching peak in PANI-CdO nanocomposite's FTIR spectra confirms the interaction of CdO with PANI. SEM analysis exposing a random dispersion of CdO nanoparticles in PANI matrix and showing the cluster of indefinitely shaped fibrous flaky architectures. The cyclic voltammetry (CV) results show a higher specific capacitance of 866 F g−1 for PANI-5%CdO composite as compared to Pure PANI 222 F g−1 and Pristine CdO 35.2 F g−1 at 5 mV s−1 scan rate. Galvanostatic charge-discharge (GCD) results also show a higher specific capacitance value of 906.8 F g−1 for PANI-5%CdO composite at 9.26 A g−1 current density revealing a maximum energy density and power density of 9.04 Wh kg−1 and 1510 W kg−1 respectively. The frequency response behavior of PANI-CdO nanocomposites (EIS spectra) reveals (Warburg) diffusive resistance of the electrolyte into the interior of the electrode and ion diffusion into the electrode surface. The higher capacitance and lower ESR (equivalent series resistance) value of PANI-CdO nanocomposite refer to the formation of a more ordered structure and rapid ion diffusion that can develop enhanced surface-dependent electrochemical properties and recommend this material to be a promising potential candidate for practical supercapacitor electrode preparation.

In-situ polymerized polyacrylamide/magnesium phosphate cement electrolyte for structural supercapacitor

Organic/inorganic composite electrolytes can effectively avoid contradictory relationship between ionic conductivity and mechanical properties as well as poor interfacial contact of electrode/solid electrolyte. However, direct mixing of organic/inorganic materials leads to low dosage and poor dispersion of polymers owing to macromolecular chains. Herein, we firstly prepare polyacrylamide/magnesium phosphate cement (PAM/MPC) electrolytes via in-situ polymerization during cement hydration. The weight average molecular weight of polymerized PAM in MPC paste is around 1500 with high concentrated degree of molecular weight distribution. As the dosage of acrylamide (AM) increases to 40 %, polymerized PAM completely interpenetrates into MPC matrix. The composite electrolyte possesses the optimum multifunctionality with ionic conductivity of 54 mS cm−1 and compressive strength of 30.2 MPa, corresponding structural supercapacitor (SSC) can obtain high specific capacitance of 32.0 F g−1 and energy density of 4.4 Wh kg−1. With the lowest equivalent series resistance, the resulted SSC with 10 % AM exhibits the best energy storage properties with energy density of 5.4 Wh kg−1 and power density of 1600 W kg−1. Hopefully, SSC via in-suit polymerization in MPC paste can be integrated with solar panels to generate and store energy in building structures.

Reduction of Output Impedance of Buck Converter with Genetic Algorithm

This paper introduces a technique to reduce the output impedance in the PWM buck converters with voltage-mode control (VMC) without requiring low Equivalent Series Resistance (ESR) output capacitors. Proposed technique uses the infinity norm ( ) to convert the problem into an optimization problem. Obtained optimization problem is solved with the aid of Genetic Algorithm (GA). The proposed technique is applied to a sample buck converter operating in Continuous Conduction Mode (CCM). Simulink simulation is used to test the suggested method. Simulation results showed a considerable decrease in the low frequency region of output impedance. Such a decrease in output impedance is very desired for low voltage high current loads like computer CPU’s.

Hierarchical porous carbon foam electrodes fabricated from waste polyurethane elastomer template for electric double-layer capacitors

Plastic waste has become a major global environmental concern. The utilization of solid waste-derived porous carbon for energy storage has received widespread attention in recent times. Herein, we report the comparison of electrochemical performance of porous carbon foams (CFs) produced from waste polyurethane (PU) elastomer templates via two different activation pathways. Electric double-layer capacitors (EDLCs) fabricated from the carbon foam exhibited a gravimetric capacitance of 74.4 F/g at 0.1 A/g. High packing density due to the presence of carbon spheres in the hierarchical structure offered excellent volumetric capacitance of 134.7 F/cm3 at 0.1 A/g. Besides, the CF-based EDLCs exhibited Coulombic efficiency close to 100% and showed stable cyclic performance for 5000 charge–discharge cycles with good capacitance retention of 97.7% at 3 A/g. Low equivalent series resistance (1.05 Ω) and charge transfer resistance (0.23 Ω) due to the extensive presence of hydroxyl functional groups contributed to attaining high power (48.89 kW/kg). Based on the preferred properties such as high specific surface area, hierarchical pore structure, surface functionalities, low metallic impurities, high conductivity and desirable capacitive behaviour, the CF prepared from waste PU elastomers have shown potential to be adopted as electrodes in EDLCs.

Activated carbon and its hybrid composites with manganese (IV) oxide as effectual electrode materials for high performance supercapacitor

Waste wood-dust of Dalbergia sisoo (Sisau) is presented, as a novel, low-cost, renewable, and sustainable source of agro-waste for the production of a highly porous activated carbon electrodes (Ds-electrodes) for supercapacitor. Ds-electrode was initially tested as supercapacitor electrode, which showed a lesser specific capacitance of 104.4 Fg −1 . Therefore, hybrid-composite-electrodes (HCEs) were fabricated by adopting the nanostructured “manganese IV oxide (MnO 2 )-activated carbon (Ds) composite” in various ratios as the core electrode materials. The HCEs was prepared via a simple facile mechanical mixing method and polyvinylidine fluoride (PVDF) polymeric solution was used as the electrode material binder. The experimental results showed that the 1:1 Ds: MnO 2 composite displayed highest specific capacitance of 300.2 Fg −1 , capacity retention of 96.3 % after 1000 cycles, 16.3 WhKg −1 of specific energy density at power density of 148.2 WKg −1 and low equivalent series resistance (ESR) value of 0.41 Ω at equivalent (1:1, Ds:MnO 2 ) loading of MnO 2 to Ds. It is clear that the equivalent (1:1) concentration of MnO 2 has improved the capacitive performance of the composite via pseudocapacitance charge storage mechanism as well as the enhancement on the specific surface area of the electrode. However, further increasing of the MnO 2 content (1:2, Ds:MnO 2 ) in the electrode was found to distort the capacitive performances and deteriorate the specific surface area of the electrode, mainly due to the aggregation of the MnO 2 particles within the composite.

Three-dimensional network of poly(3,4-ethylenedioxythiophene)/nanocrystalline cellulose/cobalt oxide for supercapacitor

A ternary composite film comprising poly(3,4-ethylenedioxythiophene) (PEDOT) and nanocrystalline cellulose (NCC) integrated with cobalt oxide (Co3O4) was fabricated through facile electrodeposition. The formation of the ternary hybrid was confirmed via Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray diffraction (XRD). Field emission scanning electron microscopy (FESEM) revealed a formation of a three-dimensional porous network after the integration of Co3O4 that allowed a very high degree of utilization of active sites. The specific capacitance of ternary composite was 200.7 F/g which was greater than PEDOT (42.0 F/g and PEDOT/NCC (101.1 F/g). The ternary composite also showed excellent specific capacitance retention of 84.3% after 2000 cycles. The lower equivalent series resistance (ESR) of the ternary composite compared to PEDOT/NCC and PEDOT demonstrated its good conductivity as well as its relatively low charge transfer resistance (Rct), implying its potential candidacy as electrode material for supercapacitors.

Polyaniline wrapped carbon nanotube/exfoliated MoS2 nanosheet composite as a promising electrode for high power supercapacitors

Polyaniline (PANI) wrapped, carbon nanotube (CNT)/and exfoliated MoS2 composite (PANI/CNT/e-MoS2) based electrodes are developed for applications as high-quality supercapacitor electrodes by a facile and effective in-situ oxidative polymerization method. Exfoliation of single/bilayer MoS2 nanosheets via electrochemical method and incorporation of CNT in PANI/e-MoS2 composite are confirmed by scanning and transmission electron microscopy techniques. Electrochemical properties of PANI/CNT/e-MoS2 electrode are evaluated by cyclic voltammetry and galvanostatic charge-discharge techniques. The incorporation of CNT in PANI/e-MoS2 composite provides maximum utilization of PANI nanowires to achieve maximum capacitance. Composite electrode based on PANI/CNT/e-MoS2 shows high specific capacitance of 532 F g−1 at a current density of 1 A g−1 as well as good rate capability from 1 A g−1 to 10 A g−1. Symmetric supercapacitor assembled using PANI/CNT/e-MoS2 composite electrode exhibits good cycling stability and 80% capacity retention after 4000 cycles and gives energy density of 11.8 Wh kg−1 and power density of 3785 W kg−1. Furthermore, electrochemical impedance spectroscopy (EIS) analysis ensures much lower equivalent series resistance of the PANI/CNT/e-MoS2 electrode. Besides, CNT acts as active electrode material in PANI/CNT/e-MoS2 composite and also provides more active sites for insertion and extraction of ions. This electrode design provides a facile and promising approach for improving the electrochemical performance of PANI based electrodes.

A High-Loop-Gain Low-Dropout Regulator with Adaptive Positive Feedback Compensation Handling 1-A Load Current

Low-dropout regulators, which have the capabilities of handling large output current and obtaining a superior transient response, are receiving increasing attention. This paper presents a high-output-current low-dropout regulator with high loop gain. An adaptive positive feedback compensation method is presented. It guarantees stability under full load conditions and achieves high loop gain. Without relying on an external zero, a ceramic capacitor with low equivalent series resistance can be employed, resulting in the minimized output voltage variation during the load transient response. In addition, the load regulation and line regulation are both small. An impedance adapting stage is inserted between the error amplifier and power transistor. It is suitable for low-supply voltage applications and drives the power transistor quickly. The simulation results indicate that the proposed LDO can supply a 1000 mA load current with a 200 mV dropout voltage. The load regulation and line regulations are 0.089 μV/mA and 0.562 m V/V, respectively. The power supply rejection is above 75 dB at 1 kHz under the full range of the output current.

Carbon nanofibers derived from cellulose via molten-salt method as supercapacitor electrode

Carbon nanofibers (CNFs) have been paid much attention as supercapacitor electrode due to outstanding chemical stability, high electron transfer rate and large specific surface area. However, the preparation process of CNFs is always stalemated in electrospinning, heat stabilization and carbonization. The problems of solvent pollution in the electrospinning process, complex process and high energy consumption in conventional carbonization process can't be solved. Herein, CNFs have been innovatively prepared from nanofibrillated cellulose by the molten-salt method (NaCl/NaOH). Molten salt penetrates between the fibers, separates and activates the fibers. The obtained carbon nanofibers remain developed branching structures and have a large specific surface area (899 m2 g−1). The electrical properties are tested in a symmetrical two-electrode system. The specific capacitance is 150 F g−1 at the current density of 1 A g−1. Low equivalent series resistance (1.13 Ω) indicates that it has high electrode conductivity. This study has taken into account energy conservation, environmental protection, recyclability and simplified preparation process, which has a very far-reaching significance for the industrial production of CNFs.