Galvanostatic Charge-discharge Analysis Research Articles

Fabrication of Cu2O/CuO Nanowires by One-Step Thermal Oxidation of Flexible Copper Mesh for Supercapacitor Applications

This study focuses on the growth of Cu2O/CuO nanowires by one-step thermal oxidation using a flexible copper mesh at oxidation temperatures in the range of 300 to 600 °C in a controlled atmosphere of mixed-flow Ar and O2 gases. Thermal oxidation is one of the simplest used methods to obtain nanowires on a metal surface, offering advantages such as low production costs and the ability to produce metal oxides on a large scale without the use of hazardous chemical compounds. The growth of metal oxides on a conductive substrate, forming metal/oxide structures, has proven to be an effective method for enhancing charge-transfer efficiency. The as-synthesized Cu/Cu2O/CuO (Nw) electrodes were structurally and morphologically characterized using techniques such as XRD and SEM/EDX analysis to investigate the structure modification and morphologies of the materials. The supercapacitor properties of the as-developed Cu/Cu2O/CuO (Nw) electrodes were then examined using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) measurements, and electrochemical impedance spectroscopy (EIS). The CV curves show that the Cu/Cu2O/CuO (Nw) structure acts as a positive electrode, and, at a scan rate of 5 mV s −1, the highest capacitance values reached 26.158 mF cm−2 for the electrode oxidized at a temperature of 300 °C. The assessment of the flexibility of the electrodes was performed at various bending angles, including 0°, 45°, 90°, 135°, and 180°. The GCD analysis revealed a maximum specific capacitance of 21.198 mF cm−2 at a low power density of 0.5 mA cm−2 for the oxidation temperature of 300 °C. The cycle life assessment of the all of the as-obtained Cu/Cu2O/CuO (Nw) electrodes over 500 cycles was performed by GCD analysis, which confirmed their electrochemical stability.

Improved interfacial stability of all-solid-state batteries using cation-anion co-doped glass electrolytes

The electrochemical performance of all-solid-state batteries needs to be improved by addressing the poor stability against the lithium metal anode and the high interfacial resistance at the cathode–solid electrolyte interface. Here, metal halide-doped Li7P2S8I–type (LPSI) solid electrolytes are synthesized that improve the electrochemical performance of all-solid-state batteries. The solid electrolytes exhibit a higher ionic conductivity value of 7.77 mS cm−1 than bare LPSI solid electrolytes of 3.96 mS cm−1, at room temperature. The metal halide-doped LPSI solid electrolyte is also stable against the lithium metal anode, with a calculated critical current density value of 1 mA cm−2. The fabricated all-solid-state battery shows high electrochemical performance with 99.2% specific capacity retention after 250 cycles at a 0.5 C rate. The results of post galvanostatic charge–discharge analysis confirms that the proposed metal halide-doped LPSI solid electrolyte exhibits improved interfacial stability compared to bare LPSI solid electrolytes.

Ag2ZnSnS4 thin films elaborated by co-electrodeposition: Structural, optical and electrochemical investigations

Here, the Ag2ZnSnS4 thin film was electrodeposited on molybdenum (Mo) for the first time using an electrodeposition-sulfurization technique. By adjusting the bath concentration, XRD and Raman analyses confirmed that the tetragonal Ag2ZnSnS4 phase was well elaborated for [Zn2+] = 0.05 M. As [Zn2+] varies, UV–visible reveals a bandgap change in the range 1.35–1.50 eV, with high absorption coefficient in the magnitude of 10−4 cm−1, confirmed by the DFT calculation. Cyclic voltammetry and galvanostatic charge discharge analysis of Ag2ZnSnS4/Mo in 1 M-Na2SO4 electrolyte highlighted the pseudo-capacitor character and delivers higher specific capacitance of 450 F/g, with only a 13 % drop in specific flow capacity when the applied discharge current increases. These results strongly encourage the possible deployment of Ag2ZnSnS4 in energy conversion as well as in energy storage.

Activated Carbon Derived from Cucumber Peel for Use as a Supercapacitor Electrode Material.

Biowaste conversion into activated carbon is a sustainable and inexpensive approach that relieves the pressure on its disposal. Here, we prepared micro-mesoporous activated carbons (ACs) from cucumber peels through carbonization at 600 °C followed by thermal activation at different temperatures. The ACs were tested as supercapacitors for the first time. The carbon activated at 800 °C (ACP-800) showed a high specific capacitance value of 300 F/g at a scan rate of 5 mV/s in the cyclic voltammetry and 331 F/g at the current density of 0.1 A/g in the galvanostatic charge-discharge analysis. At the current density of 1 A/g, the specific discharge capacitance was 286 F/g and retained 100% capacity after 2000 cycles. Their properties were analyzed by scanning electron microscopy, energy-dispersive X-ray analysis, porosity, thermal analysis, and Fourier-transform infrared spectroscopy. The specific surface area of this sample was calculated to be 2333 m2 g-1 using the Brunauer-Emmett-Teller method. The excellent performance of ACP-800 is mainly attributed to its hierarchical porosity, as the mesopores provide connectivity between the micropores and improve the capacitive performance. These electrochemical properties enable this carbon material prepared from cucumber peels to be a potential source for supercapacitor materials.

Flower like-novel nanocomposite of Mg(Ti0.99Sn0.01)O3 decorated on reduced graphene oxide (rGO) with high capacitive behavior as supercapacitor electrodes

In this study, ceramic materials of Mg(Ti0.99Sn0.01)O3 were synthesized and decorated on reduced graphene oxide, forming a nanocomposite of rGO/Mg(Ti0.99Sn0.01)O3 (rGO/MTS001). The successful synthesis results were confirmed by XRD, UV–vis analysis, FT-IR, and SEM-EDS. The MTS001 has a flower-like morphology from scanning electron microscopy (SEM) analysis, and the nanocomposites of rGO/MTS001 showed MTS001 particles decorated on the rGO’s surface. The electrochemical performance of rGO/MTS001 and MTS001 was investigated by determining the specific capacitance obtained in 1 M H2SO4 solution by cyclic voltammetry, followed by galvanostatic charge–discharge analysis using a three-electrode setup. The rGO/MTS001 achieved a specific capacitance of 361.97 F g‒1, compared to MTS001 (194.90 F g‒1). The capacitance retention of rGO/MTS001 nanocomposite also depicted excellent cyclic stability of 95.72% after 5000 cycles at a current density of 0.1 A g‒1. The result showed that the nanocomposite of ceramics with graphene materials has a potential for high-performance supercapacitor electrodes.

Photoluminescence and supercapacitor applications of dysprosium doped rhombohedral silver gallium oxide nanoparticles

Dy3+ doped Silver Gallium Oxide (AgGaO2) nanoparticles (NPs) (AGO:Dy3+) are effectively synthesized via a green mediated route using Aloe vera gel extract as a reducing agent, followed by calcination at 600 °C for 3 h. Powder X-ray diffraction (PXRD), Fourier transformation infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), photoluminescence (PL), and electrochemical studies were employed to confirm the synthesis, structural, luminescence, and supercapacitor properties of the NPs. The diffraction peaks of the synthesized samples possess a trigonal structure within a rhombohedral system. The surface morphology consists of a few irregular, a few hexagonal, and a few rice grain-structured NPs. The changes in the agglomeration were observed with variations in the dopant concentration. The direct energy band gap increases from 3.11 to 3.13 eV with an increase in the dopant concentration. Under 276 nm excitation, the PL spectra of AGO:Dy3+ nanophosphors reveal robust emission peaks attributed to 4F9/2→6F15/2 (480 nm) and 4F9/2→6F13/2 (565 nm). The confirmed critical distance signifies that energy transfer occurs through a multipolar interaction mechanism. The CIE chromaticity diagram illustrates the emission of yellowish green light from the phosphors. These investigations indicate the potential applications of AGO:Dy3+ nanocrystals in a light-emitting diode as a nanophosphor material. Nanocrystals in light-emitting diodes as a nanophosphor material. Thorough electrochemical investigations, encompassing cyclic voltammetry, were conducted to decipher redox reactions, electrode kinetics, and electrochemical behavior. The precise elucidation of ion transport kinetics was achieved through Electrochemical Impedance Spectroscopy (EIS), while the determination of supercapacitance values was accomplished via Galvanostatic Charge-Discharge (GCD) analysis. The supercapacitance values exhibited a remarkable range from 76.177 to 111.53 F/g, underscoring their sensitivity to dopant concentration. Consequently, the material synthesized in this groundbreaking study exhibits substantial promise for diverse applications, spanning from energy storage materials to the dynamic landscape of display technology. Electrochemical studies.

Investigation of surfactant assisted Fe2(MoO4)3/rGO nanocomposite for supercapacitor application

Utilizing a hydrothermal method with PEG-6000 as a surfactant material, this study presents the synthesis of Fe2(MoO4)3 nanoparticles and their nanocomposites with carbonaceous material in the form of rGO. Comprehensive fundamental characterization studies, including XRD, Raman, and FTIR, confirm the monoclinic crystal structure of Fe2(MoO4)3 and its nanocomposites. Nanorod-structured Fe2(MoO4)3/PEG/rGO exhibits a surface area of 78.571 m2/g with pore volume of 0.202 cc/g. Electrochemical analyses, employing techniques such as Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD), and Electrochemical Impedance Spectroscopy (EIS), underscore the remarkable performance of the synthesized electrodes. Notably, the Fe2(MoO4)3/PEG/rGO electrode exhibits a specific capacitance of 575.13F/g at a scan rate of 10 mV/s and demonstrates significant cyclic retention over 20,000 cycles at a current density of 20 A/g in GCD analysis. This work highlights the promising electrochemical attributes of Fe2(MoO4)3/PEG/rGO electrodes, showcasing their potential for high-performance supercapacitor applications.

Sol-gel fabricated one-dimensional LiFePO4 microstructures for carbon nanotube-based nanocomposite freestanding sheet as cathode material for Li ion batteries

Lithium Iron Phosphate (LiFePO4) microstructures have been synthesized using the sol-gel process. One-dimensional (1D) LiFePO4 microstructures were fabricated using tissue paper as a template under different temperatures to form pure phase microstructures. XRD analysis confirmed the single phase nature of orthorhombic olivine-structured LiFePO4 with Pnma space group. SEM analysis authenticated the formation of 1D LiFePO4 microstructures along with some clusters of particles. LiFePO4-multi-walled carbon nanotubes (MWCNT) freestanding sheets were prepared using a tape-casting process. Further, the electrochemical properties of LiFePO4-MWCNT freestanding sheet were analyzed through electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge analysis.

Electric field-assisted laser ablation fabrication and assembly of zinc oxide/carbon nanocomposites into hierarchical structures for supercapacitor electrodes.

One of the major challenges in the field of electrochemical energy storage device performance improvement is the development of suitable synthetic materials for electrodes that can provide high power and high energy density features combined with their long-term stability. Here, we have developed a novel two-step approach based on DC glow discharge plasma pre-treatment of a carbon cloth substrate followed by electric field-assisted laser ablation for the synthesis of ZnO/C nanocomposites in a liquid and their simultaneous assembly into hierarchically organized nanostructures onto the pre-processed carbon cloth to produce a supercapacitor electrode. To form such nanostructures, a processed carbon cloth was included in the electrical circuit as a cathode during laser ablation of zinc in water, while a zinc target served as an anode. A series of studies have been performed to explore the structure, morphology, composition and electrochemical characteristics of the synthesized ZnO/C nanocomposites. Application of the external field provided additional possibilities for tuning the particle morphology. The parameters of the obtained nanostructures were shown to depend on the direction of the applied electric field and liquid composition. SEM studies revealed a nanoflower-like morphology of the prepared nanomaterial having potential in supercapacitor applications due to a large surface area. The ZnO/C nanoflowers, deposited onto a carbon cloth substrate, were tested for energy storage by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) analysis. The results showed a pseudocapacitor behavior with a maximum specific capacitance of about 3045 F g-1 (at a scan rate of 1 mV s-1). These results demonstrate a promising storage efficiency of the synthesized ZnO/C nanocomposite as a material for supercapacitors.

Utilization of Coal Fly-Ash derived Silicon (Si) as Capacity Enhancer of Li-Ion Batteries Anode Material

The increasing demand for energy has caused a rise in coal usage, resulting in high fly ash generation. The high SiO2, Al2O3, and Fe2O3 content in fly ashes (FAs) allow them to be processed in electrical energy storage technology, such as lithium-ion-based secondary batteries. The research aims to develop silicon from FAs for Li-ion battery applications. The fabrication of silicon materials employed in this study are (i) extraction of SiO2 from FA, (ii) gelation of SiO2, (iii) magnesiothermic reduction of SiO2 to Si under N2 flow, (iv) purification of silicon, (v) the solid-state composite fabrication of Si/C. The as-prepared Si was characterized. XRD test showed the presence of silicon phase and minor impurities in Mg. SEM analysis of the Si showed that the material has a polymorph shape with a rough surface of micron-sized secondary particles. EDX test showed the presence of impurities in the form of O and Mg atoms; meanwhile, the EDX mapping confirmed the dominant distribution of Si in the sample. Galvanostatic charge-discharge analysis of a battery with 5%Si/C anode and LiNi0.8Co0.1Mn0.1O2 or NCM811 cathode resulted in a specific charge and discharge capacity of 600 mAh/g and 473.6 mAh/g, respectively, which is greater than the graphite theoretical capacity of 372 mAh/g.

Morphology regulation of conductive metal-organic frameworks in situ grown on graphene oxide for high-performance supercapacitors.

In this work, nickel-catecholate (Ni-CAT) nanorods were in situ compounded on graphene oxide (GO) to form a composite Ni-CAT@GO (NCG) with a special "blanket-shape" structure, which was used as an electrode material for supercapacitors. The morphology of Ni-CATs in situ grown on GO was modulated by introducing various contents of GO. With increasing GO, the length of nanorods of Ni-CATs is obviously shortened, and the charge transfer resistance of NCG is significantly reduced as the GO content is relatively low while it increases with further addition of GO, because excessive GO in NCG results in smaller crystal sizes accompanied by smaller stacking pores. Both the over-long Ni-CAT nanorods and the smaller stacking pores can restrict the accessible surface areas for the electrolyte. Optimal nanorod sizes are crucial to achieve good electrochemical performance for electrode materials. Galvanostatic charge-discharge analysis of NCG electrodes shows that their capacity initially increases and then decreases with the addition of more and more GO, and Ni-CAT@GO-0.5 (NCG0.5) with minimal charge transfer resistance exhibits the best electrochemical performance. The results demonstrate that the NCG0.5 electrode with optimal morphology possesses an excellent capacitance of 563.8 F g-1 at 0.5 A g-1 and a good rate performance of 61.9% at 10 A g-1, indicating that Ni-CAT@GO is a new type of promising electrode material for supercapacitors based on conductive metal-organic frameworks.

Nano-graphitic crystallites effect on the improved K-ion intercalation properties of Kigelia Africana fruit-derived hard carbon for potassium-ion batteries

The development of intermittent renewable energy storage technology is essential for building a sustainable, low-carbon society. Potassium-ion (K-ion) batteries are being extensively explored as alternate energy storage devices due to their closest redox potential and similarities to Lithium (Li) and Sodium (Na) batteries. Identifying alternate carbonaceous materials is, therefore, crucial to overcome the shortcomings of graphite. In this context, hard carbon derived from cellulose-rich Kigelia Africana fruit (KAP) was pyrolyzed at 1000 °C and 1100 °C and characterized using various techniques. The employed facile direct carbonization retains the inherent oxygen atoms (6.6 %). It restricts the growth of graphitic crystallites in the ab plane, thereby reducing the d-spacing revealed by X-ray Diffraction (XRD) and Raman Spectral analysis. The enhanced K-ion storage through insertion, as corroborated by Cyclic Voltammetry (CV) through the increased kinetics at the low potential < 0.5 V vs K/K+. The Galvanostatic Charge-Discharge (GCD) analysis further substantiates the role of graphitic nanocrystallites combined with the adsorption of O-atoms through the improved rate capability of KAP-1100 (110 mAh/g at 200 mA/g). On the other hand, KAP-1000 provides 10 mAh/g at 200 mA/g, which is almost ten times lower. Galvanostatic Intermittent Titration Technique (GITT) and Electrochemical Impedance Spectroscopy (EIS) analysis further prove the efficient diffusion coefficient (1.5 × 10-8 cm2/s) of K-ions in the hard carbon and low charge transfer resistance (Rct). This study reveals the effect of local structure and the inherently available heteroatom for developing better anodes for K-ion batteries.

Recyclable Conjugated Polyelectrolyte Hydrogels for Pseudocapacitor Fabrication.

In alignment with widespread interest in carbon neutralization and sustainable practices, we disclose that conjugated polyelectrolyte (CPE) hydrogels are a type of recyclable, electrochemically stable, and environmentally friendly pseudocapacitive material for energy storage applications. By leveraging ionic-electronic coupling in a relatively fluid medium, one finds that hydrogels prepared using a fresh batch of an anionic CPE, namely, Pris-CPE-K, exhibit a specific capacitance of 32.6 ± 6.6 F g-1 in 2 M NaCl and are capable of 80% (26.1 ± 6.5 F g-1) capacitance retention after 100,000 galvanostatic charge-discharge (GCD) cycles at a current density (J) of 10 A g-1. We note that equilibration under a constant potential prior to GCD analysis leads to the K+ counterions in the CPE exchanging with Na+ and, thus, the relevant active material Pris-CPE-Na. It is possible to remove the CPE material from the electrochemical cell via extraction with water and to carry out a simple purification through dialysis to produce a recycled material, namely Re-CPE-Na. The recycling workup has no significant detrimental impact on the electrochemical performance. Specifically, Re-CPE-Na hydrogels display an initial specific capacitance of 26.3 ± 1.2 F g-1 (at 10 A g-1) and retain 77% of the capacitance after a subsequent 100,000 GCD cycles. Characterization by NMR, FTIR, and Raman spectroscopies, together with XPS and GPC measurements, revealed no change in the structure of the backbone or side chains. However, rheological measurements gave evidence of a slight loss in G' and G''. Overall, that CPE hydrogels display recyclability argues in favor of considering them as a novel materials platform for energy storage applications within an economically viable circular recycling strategy.

Fabrication of niobium selenide-based rGO hybrid nanoparticles by hydrothermal method for supercapacitor applications

The innovative development of electrode materials and their application through compositing offers promising opportunities for advancing the efficiency of future energy storage devices (ESDs), particularly in high-efficiency supercapacitors (SCs). In this study, we examine the synthesis of electrode combinations consisting of NbSe2 (niobium diselenide) and reduced graphene oxide (rGO) for applications in supercapacitors. The successful integration of rGO and NbSe2 was confirmed by Raman analysis, which identifies characteristic peaks associated with both materials. The thermal stability of the electrode material was explained using thermogravimetric analysis (TGA). The electrochemical investigations reveal that the NbSe2/rGO composite illustrates improved electrochemical performance. The excellent specific capacitance (Csp) of 1512.15 F g−1, power density (Pd = 275.5 W kg−1) and energy density (Ed = 63.76 Wh Kg−1) at 1 A g−1 observed in galvanostatic charge-discharge (GCD) analysis. Furthermore, the long duration of cycling exhibits a notable level of stability (6000th) as observed by using the chronoamperometry technique. The NbSe2/rGO composite exhibits remarkable electrochemical performance and notable structural characteristics, making it a desirable candidate for application in supercapacitors (SCs).

Novel bio-waste of Cinnamomum Verum leaves-derived carbon coin cylinder-like as sustainable electrode material for symmetrical supercapacitor

Carbon material sourced from bio-organic waste is a promising electrode material exploration for the development of sustainable supercapacitor devices. Interestingly, their relatively environmentally benign sources and unlimited availability are the right choices to be developed as energy conversion systems and energy storage applications. Here, a novel high-potential bio-waste has been studied as a carbon source for electrode materials for symmetrical supercapacitor applications. Biomass materials were selected from Cinnamomum Verum leaves waste which was given a series of measurable and systematically structured treatments. Carbon precursor was synthesized with a simple strategy through a one/two-step activation ratio in an integrated pyrolysis system. Their chemical impregnation focused on H3PO4, ZnCl2, and H3PO4+ZnCl2 solutions. The renewal of the study was also highlighted in the design of a solid coin-like carbon cylinder material without additive binder. The solid carbon material that has been obtained has been evaluated for all dimensions including mass, thickness, diameter, and volume. In addition, the density of the coins that have been generated through density calculations is also reviewed. The density of the coin’s carbon shows a value of 0.98 g cm−3 with an average standard deviation of 0.08. The electrochemical properties of carbon electrode materials were studied through cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) analysis. In the two-system configuration, the optimized electrode exhibits a specific capacitance of 162.83 F g−1 at 1 A g−1 and 101 F g−1 at 10 A g−1. Furthermore, their performance is relatively high at a coulombic efficiency of around 76.23% with a capability rate of 63.11%. Moreover, the resulting energy density is 17.18 Wh kg−1 at a maximum power density of 125 W kg−1. Therefore, this study offers a new strategy to obtain carbon solid coin-like from bio-organic sources of Cinnamon Verum leaves as a high-quality electrode material to improve the performance of symmetric energy storage devices.

Identified potential of mangosteen peel agricultural waste as electrodes component of a supercapacitor: a study of electrochemical behaviour

Renewable porous carbon from lignocellulose material as the basic material for supercapacitors is of great interest to researchers because of its high application potential while solving environmental problems. Biomass-based lignocellulose components are the main choice because of the extraordinary impact on the carbon structure they get. Here, the identification of the potential of lignocellulose biomass from mangosteen cultivars as source material for electrode materials for supercapacitors has been studied on their electrochemical behaviour. The electro-physico-chemical features are reviewed in detail through cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) analysis at different ranges of scan rates and current densities. The obtained electrode was prepared by adding 10% polyvinyl alcohol binder to 0.7 gr carbon powder. The supercapacitor cell design is prepared in a symmetrical shape bounded by an organic separator. In general, the electrochemical properties of the electrode materials that have been obtained confirm the normal electrical double-layer capacitor features with an indication of the presence of apparent capacitance. The highest specific capacitance was 153.31 at 1 A g−1. Furthermore, the energy output was recorded of 1.67 Wh kg−1. These results confirm that an electrochemical study of mangosteen peel-based carbon materials has been successfully carried out for supercapacitor energy storage applications.

β-Cyclodextrin-Stabilized CuO/MXene Nanocomposite as an Electrode Material for High-Performance Supercapacitors.

Supercapacitors are the best energy storage systems due to their high power density, quick charge/discharge rate, and long-term reliability. In this study, β-cyclodextrin-stabilized CuO nanoparticles (CuO@βCD NPs) were synthesized through a simple reduction method and anchored on the surface of MXene nanosheets in three different proportions (1:1, 4:1, and 1:4) to obtain CuO@βCD/MXene nanocomposites through the wet-impregnation method. The formation of CuO@βCD NPs and their physicochemical characteristics were verified by XRD, XPS, FE-SEM, and HR-TEM analysis. The actual focus is on the evaluation of the electrochemical performances of CuO@βCD, MXene, and CuO@βCD/MXene nanocomposites for supercapacitor applications. The cyclic voltammetry and galvanostatic charge-discharge analysis revealed the pseudocapacitance and an improved specific capacitance of 1693.43 F g-1 at 0.90 A g-1 for the CuO@βCD/MXene (1:1) nanocomposite. The electrochemical impedance analysis displays superior electrical conductivity with a low charge transfer resistance value on incorporating CuO@βCD between the MXene layers. Furthermore, the CuO@βCD/MXene (1:1) nanocomposite exhibited improved long-term cycling stability by retaining 86% of its initial specific capacitance even after the 10,000th cycle at the current density of 4.54 A g-1. Based on the electrochemical performance, the CuO@βCD/MXene (1:1) nanocomposite proves its suitability as an electrode material for supercapacitor application with long-term cycling stability and rate capability.

Enhancing pseudocapacitive energy storage system performance with electrodeposited CuSx and CoSx biphasic transitional metal sulfide (TMS) based nanostructured electrode on nickel foam

This study investigated the pseudocapacitive energy storage system of biphasic CuSx and CoSx electrodeposited on nickel foam (NF). XRD, FESEM, and EDX show the formation of nano-flower-shaped biphasic layer on NF. The biphasic electrode shows higher areal specific capacitance (Csp) than the single-layered NF/CuSx and NF/CoSx electrodes. The Csp of the NF/CuSx/CoSx drops by 42 % as the scan rate (ϑ) rises from 5 mV s−1 to 20 mV s−1. Electrode polarization and reduced ion migration occurring with rapid scan rates are responsible for this decrement. Galvanostatic charge-discharge (GCD) analysis showed that Csp declined from 11.42 to 9.63 F cm−2, and the retained Csp was 84 % as the current density shifted from 4 to 8 mA cm−2. The energy density of 0.30 mWh.cm−2 and power density of 1.57 mW cm−2 imply significant energy storage capability of the electrode. The kinetic analysis indicates that 78 % of the capacitance is diffusion-controlled process in the NF/CuSx/CoSx electrode. The b-value of around 0.7 suggests that the pseudocapacitance mostly originates from diffusion-controlled processes. The poor cyclic stability of NF/CuSx/CoSx was demonstrated by only upholding 61 % of its original Csp after 500 cycles. However, the higher coulombic efficiency indicates that a greater proportion of the electrical charge is stored in the supercapacitor. The study explores the biphasic design of copper and cobalt sulphide-based electrodes as potential pseudocapacitive energy storage system applications such as supercapacitors and supercapatteries.

Synthesis and characterization of zinc aluminate electrodes for supercapacitor applications

We report, for the first time, the thorough electrochemical characterization of zinc aluminate spinel. Four different stoichiometric composition of zinc aluminate (ZnAl1.5O3.25, ZnAl2O4, ZnAl2.87O5.30, and ZnAl4O7) were prepared by solution combustion method. The obtained powders after calcination at 1000 °C were characterized through scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDX) and x-ray diffraction to analyze the morphology, elemental composition and structure, respectively, of the zinc aluminate compositions. The electrodes were prepared by coating slurry of zinc aluminate, carbon black and polyvinylidene fluoride on nickel foam in a ratio of 8:1:1. The electrochemical characterization was carried out by cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS). ZnAl1.5O3.25 exhibited the highest specific capacity of 546 C/g at 1 mV/s and 336 C/g at 1 A/g, as appraised by CV and GCD analysis, respectively. EIS test revealed that ZnAl1.5O3.25 had the modest impedance value. The energy density value for ZnAl1.5O3.25 sample was 16.79 Wh/kg at 1 A/g with a power density of 179.9 W/kg. The as developed electrodes showed predominantly pseudo-capacitive charge storage mechanism.

Enhancing EDLC applications with [BMIM]BF4-integrated cellulose gel electrolyte for sustainable energy storage

Researchers worldwide have extensively carried out the fabrication of supercapacitors using ionic liquid-based gel electrolytes. Gel polymer electrolytes (GPEs) are an excellent alternative electrolyte due to their high ionic conductivity and lack of safety issues associated with solid and liquid polymer electrolytes. This work highlights the performance of a GPE composed of 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM]BF4 mixed with ammonium nitrate (NH4NO3) as the charge carrier, entrapped in methylcellulose (MC) for its application as an electrolyte in supercapacitors. The results of the Fourier transform infrared spectroscopy (FTIR) study are in good agreement with the literature, confirming the interaction between the materials observed through the shifting of the hydroxyl band. Moreover, the addition of [BMIM]BF4 successfully reduced the degree of crystallinity and crystallite size, thus enhancing the amorphous region of the electrolytes, as observed in the X-ray diffraction (XRD) diffractogram. The sample with 10 wt% [BMIM]BF4 (IL10) exhibits the highest ambient conductivity of (2.44 ± 0.36) × 10−2 S cm−1. The obtained ionic transference number (tion) of 0.98 confirms that ions are the dominant charge carriers. Considering its electrochemically stability up to 2.6 V within a potential range of 3.0 V, the IL10 electrolyte was chosen as a separator for application in an electric double-layer capacitor (EDLC). The EDLC is characterized via cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) analysis.