Poypyrrole/molybdenum trioxide/graphene nanoribbon ternary nanocomposite with enhanced capacitive performance as an electrode for supercapacitor

A polypyrrole/molybdenum trioxide/graphene nanoribbon (PPy/MoO₃/GNR) ternary nanocomposite was successfully synthesized via an in situ method. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses show that MoO₃ was successfully combined with the GNRs. The one-dimensional morphology was observed using field emission scanning electron microscopy and transmission electron microscopy. The electrochemical tests show that the PPy/MoO₃/GNR ternary nanocomposite exhibits the highest specific capacitance (844 F g^?1) among the investigated materials and exhibits good cycling stability for 1000 cycles. These results collectively demonstrate that the combination of each component can efficiently increase the specific capacitance and cycling stability. As such, the method reported herein represents a promising approach for fabricating supercapacitor electrode materials.     

Fabrication of novel solid-state supercapacitor using a Nafion polymer membrane with graphene oxide/multiwalled carbon nanotube/polyaniline

In the current work, the effect of aniline concentration on the polymerization process and supercapacitive behavior of graphene oxide/multiwalled carbon nanotubes/polyaniline (GMP) nanocomposites were studied. Based on the obtained results, GMP nanocomposite with 0.5 M aniline (GMP5) was selected as the optimum concentration in terms of high current density and high specific capacitance. Nafion-based ionic polymer-free metal composite (IPFMC) supercapacitor was fabricated for the GMP5 nanocomposite. Solid-state symmetric supercapacitor was made after spraying of GMP5 in. on both sides of Nafion membrane. The electrochemical properties were investigated by cyclic voltammetry (CV), galvanostatic charge–discharge (CD), and electrochemical impedance spectroscopy (EIS) techniques in 0.5 M Na₂SO₄.The specific capacitance of 383.25 F g^?1 (326 mF cm^?2) and 527.5 F g^?1 (42 mF cm^?2) was obtained for the GMP5 in solid-state supercapacitor and three-electrode cell at a scan rate of 10 mV s^?1, respectively. The maximum energy and power densities of 53.64 and 1777.4 W kg^?1 were obtained for the IPFMC-based supercapacitor.

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Graphical abstract Schematic of the solid-state supercapacitor based on the GMP5 nanocomposite

     

Design and green synthesis of 1-(4-ferrocenylbutyl)piperazine chemically grafted reduced graphene oxide for supercapacitor application

In this paper, we report the green synthesis of 1-(4-ferrocenylbutyl)piperazine chemically grafted rGO (P.Fc/rGO) as a battery-type supercapacitor electrode material. For this purpose, initially, the ability of the aqueous Damson fruit extract is investigated in the reduction reaction of graphene oxide (GO). 1-(4-ferrocenylbutyl)piperazine (P.Fc) is synthesized via nucleophilic substitution reaction of piperazine with as-synthesized 4-chlorobutylferrocene. In continue, P. Fc is incorporated to GO by ring-opening reaction of epoxide groups on the GO surface. In the next step, the modified reduction method by aqueous Damson fruit extract was used to prepare the P.Fc/rGO from P.Fc/GO. The prepared materials were characterized by various techniques including FT-IR, Uv–vis, XRD, SEM, EDX, and BET. N₂ adsorption–desorption data of P.Fc/rGO nanocomposite shows that the surface area is 37.746 m² g⁻¹. The capability of P.Fc/rGO nanocomposite for using as an energy storage electrode material in battery-type supercapacitor was examined by investigation of its electrochemical behavior by CV, EIS, and GCD measurements. The charge storage capacity of 1,102 mAh g⁻¹ is achieved at 2.5 A g⁻¹. This nanocomposite shows 89% retention of charge storage capacity after 2000 CV cycles.     

A wide potential window aqueous supercapacitor based on LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript>–rGO nanocomposite

Aqueous supercapacitors based on neutral solutions have the advantages of high-ionic conductivity, being environmentally friendly, safe, and low cost. However, the operating potential window for most aqueous electrolytes is far lower than that of organic electrolytes that are commonly used in commercial supercapacitors. In this work, we report on the fabrication of a wide potential window, high-energy aqueous asymmetric supercapacitor, without sacrificing power, by using a nanostructured LiMn₂O₄/reduced graphene oxide (LMO–rGO) nanocomposite. We synthesized the uniformly distributed LMO in the LMO–rGO nanocomposite using a co-precipitation route followed by a low-temperature hydrothermal treatment. In a three-electrode cell setup, the specific capacitance of the LMO–rGO nanocomposite electrode at 1 A/g (1.2 mA/cm²) is 268.75 F/g (258 mF/cm²), which shows a dramatic improvement over the sum of the specific capacitances of pristine LMO (162.5 F/g) and pure rGO (29.94 F/g) electrodes in their relative ratios, when used alone. This finding suggests a synergistic coupling of LMO and rGO in the nanocomposite. We also assembled the LMO–rGO nanocomposite, as the positive electrode, with activated carbon, as the negative electrode, into an asymmetric cell configuration. The device shows an ultra-wide potential window of 2.0 V in a neutral aqueous Li₂SO₄ electrolyte, with a maximum energy density of 29.6 Wh/kg (which approaches the commercial lead-acid batteries), power density of up to 7408 W/kg, and an excellent cycle life (5% loss after 6000 cycles). These findings confirm that an LMO–rGO nanocomposite is a promising material to meet the demands of real world energy storage.     

Facile and scalable fabrication of graphene/polypyrrole/MnO<Subscript>x</Subscript>/Cu(OH)<Subscript>2</Subscript> composite for high-performance supercapacitors

In this study, to improve the specific capacitance of graphene-based supercapacitor, novel quadri composite of G/PPy/MnO_x/Cu(OH)₂ was synthesized by using a facile and inexpensive route. First, a two-step method consisting of thermal decomposition and in situ oxidative polymerization was employed to fabricate graphene/polypyrrole/manganese oxide composites. Second, Cu(OH)₂ nanowires were deposited on Cu foil. Afterwards, for the electrochemical measurements, composite powders were deposited on Cu(OH)₂/Cu foil substrate as working electrodes. The synthesized samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectroscopy, and Raman spectroscopy. The XRD analysis revealed the formation of PPy/graphene, Mn₃O₄/graphene, and graphene/polypyrrole/MnO_x. In addition, the presence of polypyrrole and manganese oxides was confirmed using FT-IR and Raman spectroscopies. Graphene/polypyrrole/MnO_x/Cu(OH)₂ electrode showed the best electrochemical performance and exhibited the largest specific capacitance of approximately 370 F/g at the scan rate of 10 mV/s in 6 M KOH electrolyte. In addition, other electrochemical measurements (charge–discharge, EIS and cyclical performance) of the G/Cu(OH)₂, G/PPy/Cu(OH)₂, G/Mn₃O₄/Cu(OH)₂, and G/PPy/MnO_x/Cu(OH)₂ electrodes suggested that the G/PPy/MnO_x/Cu(OH)₂ composite electrode is promising materials for supercapacitor application.     

Preparation of polypyrrole‐graft‐poly(N‐isopropylacrylamide)/silver nanocomposites from pyrrolyl‐capped macromonomer by AgNO3 and their stimuli responsibility of light emission

Pyrrolyl‐capped poly(N‐isopropylacrylamide) macromonomers (Py‐PNIPAM) were prepared through reversible addition‐fragmentation‐transfer polymerization with benzyl 1‐pyrrolylcarbodithioate as chain‐transfer agent. Polymerizations of Py‐PNIPAM with/without pyrrole using AgNO₃ as oxidizing agent and dimethylforamide as solvent resulted in graft copolymers of polypyrrole‐graft‐poly(N‐isopropylacrylamide) (PPy‐g‐PNIPAM) as well as silver nanoparticles, leading to the formation of PPy‐g‐PNIPAM/silver nanocomposites. The resulting nanocomposites were soluble in water when the content of PPy was low, and when the molar ratio of Py/Py‐PNIPAM increased to 30, the resulting products became insoluble in water. The resulting nanocomposites had special optical properties because of PPy as well as the temperature‐responsible PNIPAM. The chemical structure and composition of nanocomposite were characterized by ¹H nuclear magnetic resonance spectroscopy, gel permeation chromatograms, fourier transform infrared spectroscopy, and X‐ray diffraction. Their optical properties were characterized by UV–vis and fluorescence spectroscopy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6950–6960, 2008     

A unique path to reach thermostable polypyrrole/Pd microfibers via chemical oxidative polymerization

Polypyrrole/palladium (PPy/Pd) nanocomposites, labeled by PPy/Pd-2/1-0, PPy/Pd-2/1-25, and PPy/Pd-3/1-0, are synthesized via a direct redox reaction between pyrrole monomer and PdCl₂ in the presence of sodium dodecyl sulfate (SDS) stabilizer in chloroform (CHCl₃)/acetonitrile (CH₃CN) binary organic solvents with 2:1 and 3:1 volume ratios at two temperatures involving 0 and 25 °C. A Pd-unloaded polypyrrole (PPy-2/1-0) is also synthesized similarly using iron(III) chloride (FeCl₃) oxidant for comparison purposes. The volume ratio of the solvents used as well as the temperature at which the oxidative polymerization takes place affects significantly the thermostability of the resulting nanocomposites. According to the thermogravimetric analyses, the stability order towards heat is found to be PPy/Pd-2/1-25?>?PPy/Pd-2/1-0?>?PPy/Pd-3/1-0?>?PPy-2/1-0. The nanocomposite PPy/Pd-2/1-25 shows clearly more thermostability compared to PPy/Pd-2/1-0 analog at temperatures above 400 °C. Furthermore, whereas three discrete maxima can be obviously found in the differential thermal analysis (DTA) thermogram of PPy-2/1-0 pure sample, no distinctive exothermic peak is observed in the curves of the three Pd-loaded nanocomposites.     

Preparation of polypyrrole (PPy)-derived polymer/ZrO2 nanocomposites

New polypyrrole (PPy)-derived polymer/ZrO₂ nanocomposite materials are prepared by single-step oxidative polymerization of pyrrole (Py) and/or N-methylpyrrole (mPy) in the presence of HCl-functionalized ZrO₂ nanoparticles and ammonium persulfate. The physicochemical features of the PPy–ZrO₂, poly(Py-co-mPy)–ZrO₂ and PmPy–ZrO₂ hybrids were analyzed by XPS, FTIR, XRD and UV–Vis techniques. To explore the advantages of these nanocomposites for potential applications, their thermal, conductive and electrochemical properties were investigated. The characterization reveals that a chemical bonding, based on electrostatic interactions, is established between the polymers and the ZrO₂ nanoparticles. Interestingly, it is found that the growth of polymer on the surface of Cl-functionalized ZrO₂ becomes more significant as the Py moiety (–NH– species) content in the polymer increases. The thermal stability and conductivity of the polymers increase by hybridization with the ZrO₂ nanoparticles. This is assigned to the affective interaction of the polymers with the ZrO₂ nanoparticles. Particularly, the resulting nanocomposites keep high conductivities, ranging between 0.323 and 0.929 S cm⁻¹. Finally, voltammetric characterization shows that the PPy–ZrO₂ and poly(Py-co-mPy)–ZrO₂ nanocomposites are electroactive, thus demonstrating their capability for electrochemical applications. These results highlight the great influence of the nanoparticle interface and the nature of monomer on the nanocomposite formation and properties.

     

Hollow Co9S8 from metal organic framework supported on rGO as electrode material for highly stable supercapacitors

We demonstrate a hydrothermal method to fabricate a composite of reduced graphene oxide (rGO) with hollow Co₉S₈ derived from metal organic framework (MOF), which exhibits a high specific capacitance of 575.9 F/g at 2 A/g and 92.0% capacitance retention after 9000 cycles.     

Development of novel magnetic solid-phase extraction sorbent based on Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/carbon nanosphere/polypyrrole composite and their application to the enrichment of polycyclic aromatic hydrocarbons from water samples prior to GC–FID analysis

We describe a magnetic nanocomposite that consists of Fe₃O₄/carbon nanosphere/polypyrrole (Fe₃O₄/CNS/PPy). The synthesized nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. The nanocomposite was successfully applied to extract of the polycyclic aromatic hydrocarbons (PAHs) from water samples. Compared to Fe₃O₄/PPy, the Fe₃O₄/CNS/PPy nanocomposite exhibits improved properties in terms of extraction. The amount of adsorbent, salt effect, extraction time, desorption time, type, and the volume of desorption solvent were optimized. Following the desorption of the extracted analytes, the PAHs (i.e., naphthalene, 2-methylnaphthalene, 2-bromonaphthalene, fluorene, and anthracene) were quantified by gas chromatography–flame ionization detector. The PAHs can be determined in 0.05–100.00 ng mL^?1 concentration range, with limits of detection (at an S/N ratio of 3) ranging from 0.01 to 0.05 ng mL^?1. The repeatability of the method was investigated with relative standard deviations of lower than 9.9% (n = 5). Also, the recoveries from spiked real water samples were in the range of 88.9–99.0%. The results indicate that the novel material can be successfully applied for the extraction and analysis of PAHs from water samples.     

Ultrasonic-assisted synthesis of magnetite/carbon nanocomposite for electrochemical supercapacitor

Iron oxides are considered as the promising pseudocapacitive materials for high-performance supercapacitors due to their high theoretical specific capacitance, low cost, environmental benignity, and natural abundance. In this work, we study capacitive behavior of different magnetite (Fe₃O₄) nanoparticles/carbon black (CB) composites ratios. These composites are synthesized by the coprecipitation method in the presence of ultrasonic waves. The structural and morphological characteristics of the magnetite/CB composites are investigated by X-ray diffraction and scanning electron microscopy, respectively. The electrochemical performance of magnetite/CB composite electrodes is tested by cyclic voltammetry and galvanostatic charge/discharge in a Na₂SO₄ electrolyte. The results indicate that the magnetite/CB electrodes show typical pseudo-capacitive behavior in Na₂SO₄ solution. Moreover, in comparison to the pure Fe₃O₄ (37 F g^?1) and carbon black (23 F g^?1), the as-prepared 45 % magnetite/CB nanocomposite electrode shows a higher specific capacitance (300 F g^?1). Additionally, the supercapacitor device of the magnetite/CB nanocomposite exhibits excellent long cycle life along with 98.5 % specific capacitance retained after 10,000 cycle tests.     

High-performance supercapacitor based on ultralight and elastic three-dimensional carbon foam/reduced graphene/polyaniline nanocomposites

A novel supercapacitor based on ultralight and elastic three-dimensional porous melamine foam-derived macroporous carbon/reduced graphene oxide/polyaniline nanocomposites were fabricated, which showed great electrical performance and cycle performance.     

Graphene/poly(ortho-phenylenediamine) nanocomposite material for electrochemical supercapacitor

Reduced graphene oxide was synthesized by simple chemical processing of graphite. Electron microscopy investigations of synthesized graphene showed slightly folded transparent sheets with a few square micrometers dimension. Poly(ortho-phenylenediamine)/graphene/Pt electrode was electrochemically fabricated in a 2.0-M H₂SO₄ solution by means of multiple potential cycling. Due to the catalytic effect of graphene on the oxidative electropolymerization of ortho-phenylenediamine, the ortho-phenylenediamine/graphene (PoPD/GR) nanocomposite showed greatly enhanced electrical properties and excellent capacitive behavior. Electrochemical impedance spectroscopy, galvanostatic charge/discharge curves, and voltammetric investigations revealed that PoPD/GR nanocomposite represented good capacitive behavior with a specific capacitance as high as 308.3 F g^?1 at 0.1 A g^?1. It is almost three times higher than that of pure graphene (111.7 F g^?1). In addition, the nanocomposite electrode retained more than 99 % of the initial capacity after 1,500 cycles at a current density of 1 A g^?1.     

Ultrasound‐assisted Synthesis of Ag‐ZnS/rGO and its Utilization in Photocatalytic Degradation of Tetracycline Under Visible Light Irradiation

Recent improvements based on heterojunction nanocomposites have opened new possibilities in photocatalysis. In this research, an ultrasound‐assisted coprecipitation method was used to fabricate silver, zinc sulfide and reduced graphene oxide (Ag‐ZnS/rGO) nanocomposite, and characterization results indicated that 3% Ag‐ZnS spherical nanoparticles are successfully embedded in rGO matrix. The potential of the Ag‐ZnS/rGO, as a visible light active photocatalyst, was assessed through optimizing degradation of Tetracycline (TC) by response surface methodology. It was found that the photocatalytic degradation of TC increased with an increase in the amount of nanocomposite and irradiation time, whereas it decreased with increasing the initial TC concentration. Under the optimal conditions (10 mg L^?1 of TC, 1.25 g L^?1 of Ag‐ZnS/rGO, at pH = 7, and irradiation duration 110 min), more than 90% of the TC was degraded. The study of the mechanism of the photocatalytic process disclosed that the synergistic role of surface plasmon resonance (SPR) induced by Ag nanoparticles and p‐type semiconductor feature of rGO leads to ZnS semiconductor stimulation in the visible light region. Eventually, a pseudo‐first order kinetics model was developed based on the proposed mechanism. The obtained results highlight the role of Ag‐ZnS/rGO nanophotocatalyst toward degradation of some antibiotics under visible light.     

PPy modified titanium foam electrode with high performance for supercapacitor

Pyrrole was polymerized on the surface of titanium foam using FeCl₃ as oxidant and the as-synthesized product could be directly used as electrode for supercapacitor. The globular polypyrrole (PPy) particles were firmly loaded on the substrate with high density. The morphology study of PPy film is observed in SEM images, the XRD, FTIR and UV–vis spectra reveal the structure and crystalline of PPy nanoparticles. The electrochemical properties of PPy modified electrode are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and cycle life techniques. The electrochemical measurements showed such a PPy–Ti electrode had a wide working potential window, a high specific capacitance of 855 F g⁻¹ and excellent cycle stability at a discharge current density of 1 A g⁻¹.     

Facile synthesis of cobalt oxide/reduced graphene oxide composites for electrochemical capacitor and sensor applications

Reduced graphene oxide sheets decorated with cobalt oxide nanoparticles (Co₃O₄/rGO) were produced using a hydrothermal method without surfactants. Both the reduction of GO and the formation of Co₃O₄ nanoparticles occurred simultaneously under this condition. At the same current density of 0.5 A g⁻¹, the Co₃O₄/rGO nanocomposites exhibited much a higher specific capacitance (545 F g⁻¹) than that of bare Co₃O₄ (100 F g⁻¹). On the other hand, for the detection of H₂O₂, the peak current of Co₃O₄/rGO was 4 times higher than that of Co₃O₄. Moreover, the resulting composite displayed a low detection limit of 0.62 μM and a high sensitivity of 28,500 μA mM⁻¹cm⁻² for the H₂O₂ sensor. These results suggest that the Co₃O₄/rGO nanocomposite is a promising material for both supercapacitor and non-enzymatic H₂O₂ sensor applications.     

Design of high-performance core-shell hollow carbon nanofiber@nickel-cobalt double hydroxide composites for supercapacitive energy storage

The supercapacitive performances of supercapacitor mainly depend on the physical nanostructure and micro-morphology of electrode materials. Here, we demonstrated the design, synthesis and electrochemical performances of core-shell hollow carbon nanofiber@nickel-cobalt-layered double hydroxide (HCNF@ Ni_0.67Co_0.33-LDH) nanocomposites with an optimized Ni/Co molar ratio of 2:1. The HCNF was used as superiorly conductive core to sustain the nanoporous silky Ni_0.67Co_0.33-LDH shell, which can efficiently provide fast transport pathways for electrons and electrolyte ions. The outstanding specific capacitance of 2486 F g^?1 at 1 A g^?1 based on galvanostatic charge-discharge curves were acquired for the highly electroactive HCNF@Ni_0.67Co_0.33-LDH. Furthermore, the HCNF@Ni_0.67Co_0.33-LDH electrode delivered a distinguished rate capability with a specific capacitance of 1890 F g^?1 even at 15 A g^?1. Notably, an asymmetric supercapacitor with HCNF@Ni_0.67Co_0.33-LDH as cathode and HCNF as anode was devised, which presented a prominent specific capacitance of 228 F g^?1, good energy density of 62.1 Wh kg^?1, and impressive cycling stability (90.6% capacitance retention after 10,000 cycles).     

Preparation of NiAl double hydroxide@polypyrrole materials for high‐performance supercapacitors

A novel NiAl double hydroxide@polypyrrole (LDH@PPy) core–shell material was designed and fabricated by a facile in situ oxidative polymerization of pyrrole (Py) monomer. The microstructure and morphology of the LDH@PPy composites were determined by X‐ray diffractometer, Fourier transform infrared (FTIR), scanning electron microscopy/transmission electron microscopy, and thermogravimetric and differential thermal, revealing that the polypyrrole (PPy) was successfully coated onto the surface of the NiAl‐LDH (LDH) core and the loading amount of PPy impacted the thickness and the dispersion of the conductive PPy shell. The electrochemical performances of the LDH@PPy composites were also evaluated by cyclic voltammogram, electrochemical impedance spectroscopy, and galvanostatic charge–discharge measurements. The results indicated that the supercapacitor performances were attributed to the synergy of unique core–shell heterostructure and each individual component, where the LDH core provided the high‐energy storage capacity and the PPy shell with networks had high electronic conductivity. These shorted the ion diffusion pathway and made electrolyte ions more easily accessible for faradic reactions to enhance the electrochemical performance of the LDH@PPy composites. It was found that the LDH@PPy composite (LDH@PPy₇) fabricated at 7 mL?L^?1 of Py monomer feed exhibiting the best electrochemical performances with high specific capacitance of 437.5 F?g^?1 at 2 A?g^?1 and excellent capacitance retention of about 91% after 1000 cycles. The work provides a simple approach for designing organic–inorganic core–shell materials with potential application in supercapacitors. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1653–1662     

A high performance solid-state asymmetric supercapacitor based on Anderson-type polyoxometalate-doped graphene aerogel

The manufacture of single-atom transition metal-doping carbon nanocomposites as electrode materials is crucial for electrochemical energy storage with high energy and power density. However, the simple strategy for preparation of such active materials with controlled structure remains a great challenge. Here, cobalt-doped carbon nanocomposites (Co-POM/rGO) were synthesized successfully by deposition of Anderson-type polyoxometalate (POM) on the surface of reduced graphene oxide (rGO) aerogel via one-pot hydrothermal treatment. The resulting Co-POM/rGO possesses three-dimensional graphene-based frameworks with hierarchical porous structure, high surface area and uniform single-atom metal doping. These intriguing features render Co-POM/rGO to be a promising electrode for applications in electrochemical energy storage. As an electrode material of a supercapacitor, Co-POM/rGO shows high-performance electrochemical energy storage (211.3 F g^?1 at 0.5 A g^?1). Furthermore, the solid-state asymmetric supercapacitor (ASC) device, using Co-POM/rGO as a positive electrode, exhibits the outstanding energy density of 37.6 Wh kg^?1 at a power density of 500 W kg^?1, and high capacitance retention of 95.2% after 5000 charge–discharge cycles. These results indicate that the proposed strategy for rational design of single-atom-metal doped carbon nanocomposites for flexible ASC devices with excellent capacitive properties.

     

Application of a novel redox-active electrolyte in MnO2-based supercapacitors

This paper reports a novel strategy for preparing redox-active electrolyte through introducing a redox-mediator(p-phenylenediamine,PPD) into KOH electrolyte for the application of ball-milled MnO 2-based supercapacitors.The morphology and compositions of ball-milled MnO 2 were characterized using scanning electron microscopy(SEM) and X-ray diffraction(XRD).The electrochemical properties of the supercapacitor were evaluated by cyclic voltammetry(CV),galvanostatic charge-discharge(GCD),and electrochemical impedance spectroscopy(EIS) techniques.The introduction of p-phenylenediamine significantly improves the performance of the supercapacitor.The electrode specific capacitance of the supercapacitor is 325.24 F g-1,increased by 6.25 folds compared with that of the unmodified system(44.87 F g-1) at the same current density,and the energy density has nearly a 10-fold increase,reaching 10.12 Wh Kg-1.In addition,the supercapacitor exhibits good cycle-life stability.