Galvanostatic Charge Discharge Method Research Articles

Ni0.5Co0.5S nano-chains: a high-performing intercalating pseudocapacitive electrode in asymmetric supercapacitor (ASC) mode for the development of large-scale energy storage devices.

Grid-scale energy storage solutions are necessary for using renewable energy sources efficiently. A supercapattery (supercapacitor + battery) has recently been introduced as a new variety of hybrid devices that engage both capacitive and faradaic charge storage processes. Nano-chain architectures of Ni0.5Co0.5S electrode materials consisting of interconnected nano-spheres are rationally constructed by tailoring the surface structure. Nano-chains of the bimetallic sulfide Ni0.5Co0.5S are presented to have a superior charge storage capacity. The Ni0.5Co0.5S nano-chain electrode presents a capacitance of 2001.6 F g-1 at 1 mV s-1, with a specific capacity of 267 mA h g-1 (1920 F g-1) at 1 A g-1 in 4 M KOH aqueous electrolyte through the galvanostatic charge-discharge (GCD) method. The reason behind the high charge storage capacity of the materials is the predominant redox-mediated diffusion-controlled pseudocapacitive mechanism coupled with surface capacitance (electrosorption), as the surface (outer) and intercalative (inner) charges stored by the Ni0.5Co0.5S electrodes are close to 46.0% and 54.0%, respectively. Additionally, a Ni0.5Co0.5S//AC two electrode full cell operating in asymmetric supercapacitor cell (ASCs) mode in 4 M KOH electrolyte exhibits an impressive energy density equivalent to 257 W h kg-1 and a power density of 0.73 kW kg-1 at a current rate of 1 A g-1.

A simple method of fabricating activated carbon-based supercapacitor electrode sheets

Pepper shell waste is a side effect of relatively untapped pepper production. In this research, activated carbon from pepper shell waste was made using the chemical activator ZnCl2 and followed by physical activation using nitrogen gas (N2). The resulting activated carbon is then printed into supercapacitor electrode sheets by adding carbon black, PVDF, and NMP by varying the composition between activated carbon and carbon black. The performance of the fabricated electrode sheets was then tested using the Galvanostatic Charge Discharge (GCD) method. The results show that the addition of carbon black affects the specific capacitance value of the fabricated electrode sheet. The GCD results show that the sample has a specific capacitance value of 13.64 F/g.

Performance of ethanolamine-based ionic liquids as novel green electrolytes for the electrochemical energy storage applications

Supercapacitors are promising technologies for extremely effective energy storage and power management, which is a critical and major area of worldwide technological advancement. Ionic liquids (ILs) are an environmentally benign promising emerging class of versatile solvent systems. In this paper, for the first time, a new approach to the application of monoethanolamine-based ILs with anions formate, acetate, and propionate ([HEA]F, [HEA]A, and [HEA]P) as eco-friendly, affordable, and easy synthesis electrolytes are proposed for activated carbon (AC)-based supercapacitors. The ionic conductivity and the electrochemical stable potential window (ESPW) of ionic liquids were assessed. The electrochemical performance of synthesized ILs as an electrolyte in AC-based supercapacitors was compared. Electrochemical properties were performed by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV), and galvanostatic charge-discharge (GCD) methods to evaluate the electrolytic performance of ionic liquids in supercapacitors. The charge transfer resistance (Rct) and solution resistance (Rs) decreased with decreasing anion size of ILs. At a scan rate of 10 mVs−1, the prepared supercapacitors using [HEA]F, [HEA]A, and [HEA]P ionic liquids deliver specific capacitance of 114, 95, and 73 F g−1, respectively. The maximum power density 2941 W kg−1 and maximum energy density 70 Wh kg−1 were obtained for the prepared supercapacitor using [HEA]F ionic liquid. The supercapacitors prepared with [HEA]F, [HEA]A and [HEA]P electrolytes show capacitance retention of 96%, 91% and 87% after 5000 charge-discharge cycles, respectively.

The preparation of polypyrrole/carboxyl functionalized multi-walled carbon nanotube@cobalthexacyanoferrate hybrid composite for high-performance supercapacitor application

Hybrid electrode materials based on nanostructured metal oxide, conductive polymer, and carbon derivative have promising properties for supercapacitors. Herein, a novel hybrid material consisting of cobalt hexacyanoferrate (CoHCF), multi-walled carbon nanotube with carboxyl functionalized (fMWCNT), and polypyrrole (PPy) was prepared as a supercapacitor element on a pencil graphite electrode (PGE) in this study. This hybrid material (PPy-CoHCF-fMWCNT) was characterized by X-Ray Diffraction (XRD), Fourier Transform-Infrared Spectroscopy (FT-IR), and Field Emission-Scanning Electron Microscope (FE-SEM) techniques and exhibited superior supercapacitive performance and long charge-discharge cycle life in an acidic medium. Supercapacitor behaviors of PPy and PPy-CoHCF-fMWCNT coated electrodes were investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) methods in a 0.5 mol L−1 H2SO4 aqueous solution. The specific capacitance (Cm) values of PPy and PPy-CoHCF-fMWCNT hybrid composite were calculated as 431.6 F g−1 and 495.0 F g−1 at a current density of 5 A g−1 under optimum coating conditions, respectively. Electrochemical tests demonstrated excellent energy storage properties with an energy density (E) of 38.67 Wh kg−1 and a power density (P) of 1.96 kW kg−1 at 5 A g−1. The stability of the charge-discharge process obtained with 4500 cycles at 10 A g−1 of the ultra-thin hybrid composite increased from 68.9 % to 79.9 % when carboxymethyl cellulose (CMC) was added to the hybrid composite structure. Moreover, we prepared a symmetrical supercapacitor to use the optimized electrodes in the energy storage application, and it managed to light the red, green, and blue light-emitting diodes (LED).

MoS2 nanobelts-carbon hybrid material for supercapacitor applications.

The MoS2 nanobelts/Carbon hybrid nanostructure was synthesized by the simple hydrothermal method. The MoS2 nanobelts were distributed in the interlayers of Lemon grass-derived carbon (LG-C), provides the active sites and avoid restacking of the sheets. The structural and morphological characterization of MoS2/LG-C and LG-C were performed by Raman spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The electrochemical measurements were studied with cyclic voltammetry, the galvanostatic charge-discharge method, and electrochemical impedance spectroscopy. The specific capacitance of MoS2/LG-C and LG-C exhibits 77.5Fg-1 and 30.1Fg-1 at a current density of 0.5Ag-1. The MoS2/LG-C-based supercapacitor provided the maximum power density and energy density of 273.2Wkg-1 and 2.1Whkg-1, respectively. Furthermore, the cyclic stability of MoS2/LG-C was tested using charging-discharging up to 3,000 cycles, confirming only a 71.6% capacitance retention at a current density of 3Ag-1. The result showed that MoS2/LG-C is a superior low-cost electrode material that delivered a high electrochemical performance for the next generation of electrochemical energy storage.

Large-scale production of 18650 cylindrical supercapacitors: Effects of separators, electrode thickness, electrolyte additives, and testing protocols

Although supercapcitors have been widely studied, large-scale 18650 cylindrical supercapacitor cells have been rarely investigated and reported. Here, we investigated the effects of polymer separators, electrode thickness, electrolyte additives, testing protocols, reproducibility, and stability of the supercapacitors at the large-scale pilot plant. The supercapacitor cells with polyethylene (PE) and Al2O3-coated PE separators are good at low and high specific currents, respectively. The Al2O3-coated PE exhibits better stability than the one with the PE separator. The supercapacitor with a thickness of 250 μm has a cell capacitance of over 120 F from 100 to 1000 mA, which is higher than that of the other cells studied in this work. Also, the cell capacitances of supercapacitors can be enhanced by having redox mediator additives. 25 mM hydroquinone and ferrocene methanol are the optimized concentrations. We also found that the cell capacitance and equivalent series resistance of the supercapacitors are sensitive to the testing protocol, for which the highest capacitance was observed using the IEC62391-1 standard method, followed by the Maxwell method and conventional galvanostatic charge discharge method without dwell time. High reproducibility and stability of the as-fabricated supercapacitors in this work may lead to the further development of practical large-scale supercapcitors in the future.

Mixed-phase bismuth ferrite oxide (BiFeO3) nanocomposites by green approach as an efficient electrode material for supercapacitor application

The study presents bismuth ferrite nanomaterial (BiFeO3) prepared by the green method using Moringa oleifera natural extract as an anode material for supercapacitor application. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge discharge methods were employed to evaluate the electrochemical properties of the nanomaterial at the modified electrode relative to the unmodified electrode. The cyclic voltametric response revealed broad redox peaks and peak separations that clearly indicated the pseudo-capacitive characteristics derived from faradaic reactions. The EIS results indicated that the electrochemical reaction on the material electrode is kinetically and diffusionally controlled. The obtained GCE/BiFeO3 electrode has a specific capacitance of 105 F/g at 0,25 A g−1, an energy density of 90 Wh k/g, and a power density of 0,99 kW k/g. The electrochemical performance revealed an excellent electrochemical response, suggesting that BiFeO3 nanomaterial is an ideal electrode material for supercapacitance applications.Graphical abstract

Synthesis and Characterization of Eco-friendly, Biodegradable Plasticized Starch Nanocomposite using Graphene Oxide Nano-filler for Energy Storage Applications

In this study, environment-friendly, biodegradable nanocomposite has been fabricated using plasticized starch (PS) polymer and graphene oxide (GO) nanofiller. Biodegradable PS has been extracted from potatoes and a solution casting technique was used to synthesize PS/GO nanocomposite. The structural and surface morphological properties of the nanocomposite have been studied via FTIR and FESEM which demonstrate increased degree of interaction between the PS matrix and the GO nanofiller. The thermal properties of the nanocomposite showed that incorporation of GO improves the thermal stability of the nanocomposites. To study the energy storage capabilities of the PS/GO nanocomposites the electrochemical properties of the nanocomposites were as studied through cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) methods. The PS/GO nanocomposite showed improved capacitive performance with a specific capacitance of 112 F/g compared to that of pure starch (2.20 F/g) at a current density 0.1 mA/cm2. To study the effect of GO on the electrochemical properties of the nanocomposites, electrochemical impedance spectroscopy was performed and the corresponding graphs were simulated using simulation software. The incorporation of GO reduces the charge transfer resistance and thereby improve the capacitive performance. The improved electrochemical performance of the PS/GO nanocomposite can be further attributed to the large surface areas provided by the GO sheets allowing faster transport of electrolyte ions into the electrode. The result indicates that the PS/GO and nanocomposites may offer a promising route for the synthesis of bio-friendly and flexible energy storage devices.
 J. of Sci. and Tech. Res. 4(1): 145-154, 2022

Development of Modified Mesoporous Carbon from Palm oil Biomass for Energy Storage Supercapacitor Application

Energy storage system research including battery and supercapacitor devices has been studied to increase efficiency, lower their cost and improve environmental friendliness. Supercapacitor (SC) device offers high transient response and power density which suitable for many applications. The electrodes in supercapacitor device usually produced from highly porous carbon materials. In this study, the modified mesoporous carbon was produced from Palm empty fruit bunch (EFB) biomass. The production of mesoporous carbon was done using a low-temperature hydrothermal carbonization process. The mesoporous carbon from EFB biomass has shown good properties in terms of high surface area and porosity. To improve the electrical conductivity of the carbon the modification by nitrogen doping with ammonium chloride and urea was studied. The effect of different nitrogen sources on surface area and pore properties were reported. The modified mesopore carbon was tested in a symmetrical swagelok supercapacitor cell to evaluate the specific capacitance and efficiency using galvanostatic charge-discharge method. The modified mesoporous carbon with urea doped exhibits the highest specific capacitance of 121 F g-1 at current loading of 0.1 A g-1 in an aqueous 1M H2SO4 electrolyte. The modified mesoporous carbon with urea doped has lower internal resistance due to nitrogen from urea enhance the electronic conductivity of the electrodes and thus increase the supercapacitor performance.

Synthesis of polyaniline-graphene oxide based ternary nanocomposite for supercapacitor application

This study focuses on the synthesis of Polyaniline (PANI), graphene oxide (GO), and their nanocomposites with metal oxides (MO) and hexagonal boron nitride (h-BN) for their application in the supercapacitor. In this study, PANI/GO, PANI/GO/TiO2, PANI/GO/MoS2 and PANI/GO/h-BN ternary nanocomposites were synthesized following a chemical oxidative polymerization method. The prepared nanocomposites were characterized by FTIR, XRD, TGA, SEM and electrochemical analysis. The electrochemical properties of the nanocomposites were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical polarization and impedance analysis. CV profile of the nanocomposite showed that incorporation of GO, MO and h-BN in the polyaniline backbone improved capacitance, energy density and power density significantly. Among the synthesized ternary nanocomposites, PANI/GO/h-BN showed highest capacitance of 946 F/g and high capacitance retention after 100 cycles of charging and discharging. Finally, a set of hybrid asymmetric supercapacitors were constructed using the synthesized nanocomposites as positive electrode and activated carbon as negative electrode. The device was assessed following the GCD method. The supercapacitor device with PANI/GO/h-BN nanocomposite as positive electrode exhibited higher specific capacitance of 351 F/g with high power density of 4500 W/kg, and it lit up a 5 mm LED for 243 min, indicating its superiority over other electrodes.

Composites containing resins and carbon nano-onions as efficient porous carbon materials for supercapacitors

Herein, we report the functionalization of carbon nano-onions (CNOs) with the hydroxyaryl group and subsequent modifications with resins: resorcinol–formaldehyde using porogenic Pluronic F-127, resorcinol–formaldehyde-melamine, benzoxazine made of bisphenol A and triethylenetetramine, and calix[4]resorcinarene-derived using F-127. Following the direct carbonization, extensive physicochemical analysis was carried out, including Fourier transform infrared, Raman and X-ray photoelectron spectroscopy, scanning and transmission electron microscopy, and adsorption–desorption of N2. The addition of CNO to the materials significantly increases the total pore volume (up to 0.932 cm3 g−1 for carbonized resorcinol–formaldehyde resin and CNO (RF-CNO-C) and 1.242 cm3 g−1 for carbonized resorcinol–formaldehyde-melamine resin and CNO (RFM-CNO-C)), with mesopores dominating. However, the synthesized materials have poorly ordered domains with some structural disturbance; the RFM-CNO-C composite shows a more ordered structure with amorphous and semi-crystalline regions. Subsequently, cyclic voltammetry and galvanostatic charge–discharge method studied the electrochemical properties of all materials. The influence of resins' compositions, CNO content, and amount of N atoms in carbonaceous skeleton on the electrochemical performance was studied. In all cases, adding CNO to the material improves its electrochemical properties. The carbon material derived from CNO, resorcinol and melamine (RFM-CNO-C) showed the highest specific capacitance of 160 F g−1 at a current density of 2 A g−1, which is stable after 3000 cycles. The RFM-CNO-C electrode retains approximately 97% of its initial capacitive efficiency. The electrochemical performance of the RFM-CNO-C electrode results from the hierarchical porosity's stability and the presence of nitrogen atoms in the skeleton. This material is an optimal solution for supercapacitor devices.

Novel CoMnFeO4-MWCNT nanocomposite based on a green synthesized method for supercapacitor applications

A novel nanocomposite of CoMnFeO4-MWCNT has been synthesized via green and simple hydrothermal method and the structure characterization has been done through FT-IR, X-ray diffraction, scanning electron microscopy, EDX, and high-resolution transmission electron microscopy analysis in this research. Cyclic voltammetry and galvanostatic charge–discharge methods are picked as the strategies to compare their supercapacitor behavior. The specific capacitance of about 1310 F g−1 (at 1 A g−1) in 3 mol L−1 KOH has been recorded for CoMnFeO4-MWCNT nanocomposite when the working voltage is 1.2 V. Moreover, this nanocomposite retains 89% of its initial capacitance after 10 000 charge–discharge cycles. Also, some initial mechanistic studies are performed to achieve a deeper insight into the electrochemical behavior of the nanocomposite implying that the oxidation-reduction process of CoMnFeO4-MWCNT nanocomposite is generally quasi-reversible and diffusion-controlled. From the view of time, coat, and environment, the hydrothermal process is much more reliable and beneficial regarding higher performance.

Structural, BET and EPR properties of mixed zinc-manganese spinel ferrites nanoparticles for energy storage applications

X-ray diffraction data (XRD) validated the characteristic crystalline spinel cubic structure and a Field-emission scanning electron microscope/energy dispersive spectroscopy (FE-SEM/EDS) validated the proper stoichiometric element ratio of the prepared materials. By using X-ray photoelectron spectroscopy (XPS), the oxidation state of the elements in the prepared materials was verified. An electron paramagnetic resonance (EPR) spectrometer confirmed that Lande factor (g) values decreased as Zn2+ concentration in MnFe2O4 increased. The electrochemical (EC) characteristics of the materials were verified during production using a three electrode instrument. The EC performances confirm the EC behavior of the electrode materials. We investigated the EC properties of the electrodes using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) methods. The Mn0.85Zn0.15Fe2O4 (code as: MZF1) electrode material has a specific capacitance (Cs) of 62.96 F/g compared to Mn0.75Zn0.25Fe2O4 (code as: MZF2) and Mn0.65Zn0.35Fe2O4 (code as: MZF3) electrode at a current density (CD) of 0.5 A/g. According to recent research, electrode materials should be made with the necessary form and size for great act supercapacitor (SC) applications.

Electrochemical performance optimization of the polyaniline electrodeposited on ITO substrate.

We have elaborated polyaniline films on ITO substrate (indium tin oxide), by electrochemical process in different electrolytes (HCl, H2SO4, HNO3, and H3BO3), which allowed us to study the effect of the counter ion on electrochemical energy storage performances of polyaniline as electrode material in supercapacitors. The study of the different obtained films performances was carried out by cyclic voltammetry and galvanostatic charge-discharge method and is interpreted by the SEM technique. We found that there is a clear dependence on the specific capacitance of the counter ion. Justified by its porous structure, the PANI/ITO electrode doped with SO42- has the highest specific capacitance, 57.3 mF/cm2 at a current density of 0.2mA/cm2 and 64.8 mF/cm2 at 5mV/s. The deep analysis by Dunn's method allowed us to conclude that the faradic process dominates the energy storage in the case of PANI/ITO electrode elaborated in boric acid (99%). On the contrary, the capacitive character is the most contributory in the case of electrodes elaborated in H2SO4, HCl, and HNO3. The study at different potentials (0.80, 0.85, 0.90, 0.95, and 1.0V/SCE) from 0.2M monomer aniline showed that the deposition at 0.95V/SCE leads to higher specific capacitance (24.3 mF/cm2 at scan rate 5mV/s and 23.6 mF/cm2 at 0.2mA/cm2) with a coulombic efficiency of 94%. By varying the concentration of the monomer while keeping a potential fixed at 0.95V/SCE, we also found that the specific capacitance increases with monomeric concentration.

Effect of Mo-Doped Strontium Cobaltite on Graphene Nanosheets for Creating a Superior Electrode in Supercapacitor Applications

By employing the sol-gel process and “Mo-doped strontium cobaltite,” such as SrCo0.9 Mo0.1O3−δ (SCM), which has a lot of oxygen vacancies creating a charge storage material. However, a simple hydrothermal approach was used to make a cell SCM@GQDs and “Graphene Quantum Dots (GQDs).” The produced SCM@GQDs with increased conductivity have been found to be a promising electrode material for achieving larger energy densities. Through the use of the galvanostatic charge-discharge method for three electrode cells with 6.0 M potassium hydroxide as the electrolyte, the electro-chemical performance of the SCM@GQDs was examined. Due to enhanced conductivity and quicker ion diffusion between working electrodes and electrolyte, the produced electrode material for super-capacitor has a specific capacitance that is higher than GQDs at 0.65 A g−1. These outcomes demonstrate an excellent properties of SCM@GQDs material in the energy storage applications in the specific area of supercapacitors.

Structural and Electrochemical Properties of Li2O-V2O5-B2O3-Bi2O3 Glass and Glass-Ceramic Cathodes for Lithium-Ion Batteries.

In this study, 20Li2O-60V2O5-(20 - x)B2O3-xBi2O3 (x = 5, 7.5, 10 mol%) glass materials have been prepared by the melt-quenching method, and the structure and morphology of the glass materials have been characterized by XRD, FTIR, Raman, and FE-SEM. The results show that the disordered network of the glass is mainly composed of structural motifs, such as VO4, BO3, BiO3, and BiO6. The electrochemical properties of the glass cathode material have been investigated by the galvanostatic charge-discharge method and cyclic voltammetry, and the results show that with the increases of Bi2O3 molar content, the amount of the VO4 group increases, and the network structure of the glass becomes more stable. To further enhance the electrochemical properties, glass-ceramic materials have been obtained by heat treatment, and the effect of the heat treatment temperature on the structure and electrochemical properties of the glass has been studied. The results show that the initial discharge capacity of the glass-ceramic cathode obtained by heat treatment at 280 °C at a current density of 50 mA·g-1 is 333.4 mAh·g-1. In addition, after several cycles of charging and discharging at a high current density of 1000 mA·g-1 and then 10 cycles at 50 mA·g-1, its discharge capacity remains at approximately 300 mAh·g-1 with a capacity retention rate of approximately 90.0%. The results indicate that a proper heat treatment temperature is crucial to improving the electrochemical properties of glass materials. This study provides an approach for the development of new glass cathode materials for lithium-ion batteries.

Activation of nipah fruit coir-derived carbon material with KOH and NH3 for supercapacitor cell applications

Chemical impregnation is a simple and low-cost activated carbon activation method that can engineer the electrochemical properties of supercapacitor cell electrodes. The carbon material was derived from nipah fruit coir biomass by optimizing chemical activator reagents (without activating agents, KOH, NH3). The carbon material derived from nipah fruit coir is synthesized through of pre-carbonization, chemical activation, carbonization-activation physics in an integrated manner. The carbonization process uses N2 gas flow at a temperature of 600℃ with a flow rate of 1.5 l/min and a heating rate of 3ºC/min, as well as physical activation using CO2 gas at a temperature of 800°C with a flow rate of 1 l/min and a heating rate of 10ºC/min. Electrochemical properties were analyzed using Cyclic Voltametry (CV) and Galvanostatic Charge-Discharge (GCD) methods. The symmetrical supercapacitor based on SBN electrode material has an optimum specific capacitance of 224 Fg-1 at a scan rate of 1mV/s in an aqueous electrolyte (H2SO4 1M) operated at a potential of 1V. These results provide a clear, simple and easy synthesis strategy for the large-scale conversion of sustainable waste biomass into activated carbon materials for energy storage and conversion applications.

Facile synthesis of CoCo2O4/rGO spinel nanoarray as a robust electrode for energy storage devices

• Graphene based CoCo 2 O 4 nanostructure array was developed through hydrothermal route. • The electrochemical activity of CoCo 2 O 4 /rGO was performed for supercapacitor application. • The fabricated electrode CoCo 2 O 4 /rGO exhibited the specific capacitance of 1352.2 F g -1 with high energy density (E d ) of 75.96 Wh Kg -1 at low current density of 2 A g -1 . • The enhanced CoCo 2 O 4 /rGO was ascribed to the synergistic effect, diverse morphology and larger surface area. Pseudocapacitor electrodes made of spinel oxide nanomaterial is considered as a better solution to overcome the current energy crisis. In this work, CoCo 2 O 4 is fabricated and then combined with reduced graphene oxide (rGO) through clean hydrothermal method. The microscopic and spectroscopic tools were employed to examine the properties of the fabricated electrode material. The electrochemical activity of the material was determined by using polarization curves (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge methods (GCD) and chronoamperometry (CA). The electrochemical results revealed that the addition of rGO into CoCo 2 O 4 electrode, increases the discharge duration, improves its specific capacitance, and its extensive stability. The electrochemical results of CoCo 2 O 4 /rGO display the specific capacitance (Csp) of 1352.2 Fg -1 , energy density (E d ) of 75.96 Wh Kg -1 and power density (P d ) of 636 W Kg -1 at low current density of 2 Ag -1 . The nanocomposite exhibited the capacitance retaining of 98.22% over 2000 cycles and stable for 40 h. Though, the capacitive activity of fabricated electrode was further improved with change in electronic and structural arrangement, alteration in the morphology, or incorporation of other metal or non-metals.

A simple solution combustion method for the synthesis of V2O5 nanostructures for supercapacitor applications

The enhanced power density, long term cycling stability, and fast rate of operation, makes supercapacitors as desirable energy storage devices. Though metal oxides play a significant part in energy storage systems, Vanadium oxides have piqued the interest of electrochemists due to their multi-valency, potential window, unique layer structure, affordability, and plentiful availability. Vanadium pentoxide typically has relatively low specific capacitance due to its weak electrical conductivity and ionic diffusivity. However, these properties can be enhanced by encasing vanadium pentoxide in metal or carbonaceous materials, reducing it to the nanoscale, or changing its shape. On the other hand, the synthetic strategies are mostly essential in raising a compound's specific capacitance. Here, we report the synthesis of vanadium pentoxide nanoparticles using a cost effective solution combustion method. The synthesized material was characterized by X-ray diffraction analysis, UV-Vis Spectroscopy, FT-IR Spectroscopy, Scanning Electron Microscopy, Cyclic voltammetry, Galvanostatic Charge-discharge, and Electrochemical Impedance Spectroscopy. The crystallite size of obtained nanoparticles is 28 nm. The specific capacitance of Vanadium pentoxide nanoparticles is 310 F/g and is calculated at 1 A/g using Galvanostatic Charge-discharge method. The obtained specific capacitance is higher than the existing reports on V2O5 nanoparticles.

FeS2/SRGO nanocomposite: Synthesis, characterization and comprehensive study of supercapacitor behavior in different electrolytes

In this study, fine FeS2 nanoparticles were synthesized using novel, easy and efficient methods. Graphene oxide was reduced and sulfur-doped in one step by a new simple chemical method and used to prepare the (pyrite- sulfur doped reduced graphene oxide) FeS2-SRGO nanocomposite. The prepared samples were characterized and approved by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning- electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) mapping, transmission electron microscopy (TEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The FeS2-SRGO nanocomposite was coated on a carbon paste electrode substrate and the electrochemical capacitive behavior of the electrode was studied by CV and galvanostatic charge-discharge (GCD) method in different electrolytes including 6 M KOH, 1 M H2SO4, 1 M Na2SO4, 1 M NaCl, 1 M NaNO3, 1 M KCl, 3 M NaOH. Experimental results and specific capacitance calculations showed that the electrode in 1 M H2SO4 electrolyte with a specific capacity of 277 F g−1 has the best supercapacitor performance. The capacity retention is about 90 % of the initial capacity even after 200 charge and discharge cycles.