Supercapacitive Properties Research Articles

Supercapacitor and magnetic properties of NiO and manganese-doped NiO nanoparticles synthesized by chemical precipitation method

Supercapacitor and magnetic properties of NiO and manganese-doped NiO nanoparticles synthesized by chemical precipitation method

Iron doped Gd2Zr2O7 hierarchical nanoflakes arrays as robust electrodes materials for energy storage application

The current work highlights the use of Fe doped Gd2Zr2O7 electrode materials to increase the supercapacitive properties. A hydrothermal technique is used to successfully produce pure and doped Gd2Zr2O7 (Fe = 5 %, 10 %, and 20 %) electrode material. Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) along with Brunner–Emmet–Teller (BET) testing are employed for examining the crystal structure, specific surface area, morphology, and chemical composition of investigated materials. On the other hand, Fe doping altered the crystal structure and shape of the Gd2Zr2O7 flakes like network. Additionally, the 20 % Fe doped Gd2Zr2O7 electrode material acquires great specific surface area with enhanced exposed active sites of the fabricated material on the surface. On the contrary, cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) & electrochemical impedance spectroscopy (EIS) is used for assessing electrochemical performance of the fabricated electrodes. According to the experimental results, 20 % Fe-doped Gd2Zr2O7 electrode material exhibited the best electrochemical performance, for example the specific capacitance of 2561 F g−1 at current density of 10 mV s−1 with energy density of 54 Wh kg−1 is obtained, and retention was 84 % after 30 h. Due to its high Csp as well as long durability, 20 % Fe-doped Gd2Zr2O7 electrode material is an excellent candidate for next-generation supercapacitor material.

Highly defective N-doped carbon/reduced graphene oxide composite cathode material with rapid electrons/ions dual transport channels for high energy density lithium-ion capacitor

The energy density of present Li-ion capacitors (LICs) is severely limited by the carbon-based cathode with supercapacitor properties. Herein, to address the low specific capacitance of the cathode, we prepared a structurally stable carbon composite consisting of polypyrrole-derived highly defective carbon nanotubes and highly conductive reduced graphene oxide (rGO) nanosheets, using a facile one-step hydrothermal self-assembly method. The highly defective structures serve as effective electrochemically active sites to enhance ion adsorption for high-performance capacitance characteristics. Meanwhile, the interconnected porous three-dimensional network structures constructed by one-dimensional carbon nanotubes and two-dimensional rGO nanosheets act as rapid electrons/ions dual transport channels, which synergistically promotes fast energy storage/release with abundant defect structures in the material. The carbon composite with optimized structure exhibits significantly improved specific capacitance of 160.6 F g−1 at 0.3 A g−1 and 91.0 F g−1 at a high current density of 60 A g−1 as a cathode material in half-cells pairing with lithium metal. Furthermore, the carbon composite was employed as a cathode paired with a carbon-coated FeOx (FeOx@N-3DG) anode for LIC applications, which demonstrates a superior energy density of 129.1 Wh kg−1 at a power density of 1.7 kW kg−1 and still maintains an outstanding energy density of 32.9 Wh kg−1 at an extremely high power density of 43.9 kW kg−1. The findings of this work provide an effective and rational strategy for designing high energy density LICs cathode materials.

Perspective on ultrathin layered Ni-doped MoS2 hybrid nanostructures for the enhancement of electrochemical properties in supercapacitors

Over the last two decades, extensive study has been done on two-dimensional Molybdenum Sulphide (MoS2) due to its outstanding features in energy storage applications. Although MoS2 has a lot of active sulphur edges, the presence of inactive surfaces leads to limit conductivity and efficiency. Hence, in this article, we aimed to promote the additional active sites by doping various weight percentages (2%, 4%, 6%, 8% and 10%) of Nickel (Ni) into the MoS2 matrix by simple hydrothermal technique, and their doping effects were investigated with the help of Physio-chemical analyses. X-ray diffraction (XRD) pattern, Raman, and chemical composition (XPS) analyses were used to confirm the Ni incorporationin MoS2 nanosheets. Microscopic investigations demonstrated that Ni-doped MoS2 nanosheets were vertically aligned with enhanced interlayer spacing. Cyclic voltammetry, Galvanostatic charge–discharge, and electrochemical impedance spectroscopy investigations were used to characterize the electrochemical characteristics. The 6% Ni-doped MoS2 electrode material showed better CSP of 528.7 F/g @ 1 A/g and excellent electrochemical stability (85% of capacitance retention after 10,000 cycles at 5 A/g) compared to other electrode materials. Furthermore, the solid-state asymmetric supercapacitor was assembled using Ni-doped MoS2 and graphite as anode and cathode materials and analysed the electrochemical properties in the two-electrode system. To determine the impact of the Ni-atom on the MoS2 surface, first-principles computations were performed. Further, it was examined for electronic band structure, the projected density of states (PDOS) and Bader charge transfer analyses.

Electrochemical and electronic structure properties of high-performance supercapacitor based on Nd-doped ZnO nanoparticles

Recently, hybrid supercapacitors gained the interest of energy experts because of their high energy/power density and long lifespan. In this manuscript, Zn1-xNdxO (x = 0.00, 0.01, 0.03, and 0.05) nanoparticles were synthesised using the microwave assisted co-precipitation method and characterized using XRD, Raman, TEM, XAS, and electrochemical analyses.The HR-TEM images confirmed that all of the samples exhibited spherical morphologies with average particle sizes in the range of 17–20 nm. The XRD and Raman spectroscopy studies infer that crystallinity enhances with increase in the doping concentration. The Nd ions were revealed to possess a valence state of +3, while the Zn ions had a valence state of +2, confirmed from XAS analyses. The electrochemical analysis showed that 3 % Nd-doped ZnO electrode exhibited the maximum specific capacitance (SC) of 154 F/g, at a current density of 2.5 A/g and the best cycle stability when compared to the undoped and other Zn1-xNdxO samples (retaining 92 % after 1000 cycles). The specific capacitance of undoped ZnO determined at a current density of 2.5 A/g was found to be 21 F/g. The energy density and specific power of a 3 % Nd3+-doped ZnO supercapacitor were measured at 7.36 Wh/kg and 730 W/kg, respectively. The electrochemical results suggest that Nd3+-doped ZnO material would serve as an electrode material for supercapacitors application.

Introducing micropores into carbon nanoparticles synthesized via a solution plasma process by thermal treatment and their charge storage properties in supercapacitors.

Carbon materials synthesized via a solution plasma process (SPP) have recently shown great potential for various applications. However, they mainly possess a meso-macroporous structure with a lack of micropores, which limits their applications for supercapacitors. Herein, carbon nanoparticles (CNPs) were synthesized from benzene via SPP and then subjected to thermal treatment at different temperatures (400, 600, 800, and 1000 °C) in an argon environment. The CNPs exhibited an amorphous phase and were more graphitized at high treatment temperatures. A small content of tungsten carbide particles was also observed, which were encapsulated in CNPs. An increase in treatment temperature led to an increase in the specific surface area of CNPs from 184 to 260 m2 g-1 through the development of micropores, while their meso-macropore structure remained unchanged. The oxygen content of CNPs decreased from 14.72 to 1.20 atom% as the treatment temperature increased due to the degradation of oxygen functionality. The charge storage properties of CNPs were evaluated for supercapacitor applications by electrochemical measurements using a three-electrode system in 1 M H2SO4 electrolyte. The CNPs treated at low temperatures exhibited an electric double layer and pseudocapacitive behavior due to the presence of quinone groups on the carbon surface. With increasing treatment temperature, the electric double layer behavior became more dominant, while pseudocapacitive behavior was suppressed due to the quinone degradation. Regarding cycling stability, the CNPs treated at high temperatures (with a lack of oxygen functionality) were more stable than those treated at low temperatures. This work highlights a way of introducing micropores into CNPs derived from SPP via thermal treatment, which could be helpful for controlling and adjusting their pore structure for supercapacitor applications.

Structural adjustment on fluorinated graphene and their supercapacitive properties in KI-additive electrolyte

Structural adjustment on fluorinated graphene and their supercapacitive properties in KI-additive electrolyte

Preparation and supercapacitive performance of CuFe2O4 hollow-spherical nanoparticles

Spinel-type CuFe2O4 nanoparticles were synthesized by a solvothermal method using ethylene glycol as solvent and polyvinylpyrrolidone (PVP) as dispersant. The characterization results showed that the average diameter of the hollow-spherical CuFe2O4 was approximately 100 nm with homogeneous morphology and negligible agglomeration. CuFe2O4 was used as the active electrode material to explore its supercapacitive properties in different concentrations of KOH electrolytes. It was found that the CuFe2O4 hollow-spherical nanoparticles exhibit potential electronic performance in supercapacitor, with a specific capacitance of 368.2 F/g and capacitance stability retention of 91.0% after 2000 cycles at the current density of 5 A/g in 3 mol/L KOH electrolyte. The present findings demonstrate that the CuFe2O4 electrode materials can have important implications with practical prospects in energy storage systems.

Nitrogen-doped reduced graphene oxide-polyaniline composite materials: hydrothermal treatment, characterisation and supercapacitive properties

High-temperature treatment increased the conductivity, carrier density and mobility of N-RGO. Inclusion of PANI tailored activities from capacitive to battery-like and diffusion-controlled.

Exploring the redox characteristics of porous ZnCoS@rGO grown on nickel foam as a high-performance electrode for energy storage applications.

A supercapattery is a device that combines the properties of batteries and supercapacitors, such as power density and energy density. A binary composite (zinc cobalt sulfide) and rGO are synthesized using a simple hydrothermal method and modified Hummers' method. A notable specific capacity (Cs) of 1254 C g-1 is obtained in the ZnCoS@rGO case, which is higher than individual Cs of ZnS (975 C g-1) and CoS (400 C g-1). For the asymmetric (ASC) device (ZnCoS@rGO//PANI@AC), the PANI-doped activated carbon and ZnCoS@rGO are used as the cathode and anode respectively. A high Cm of 141 C g-1 is achieved at 1.4 A g-1. The ASC is exhibited an extraordinary energy density of 45 W h kg-1 with a power density 5000 W kg-1 at 1.4 A g-1. To check the stability of the device, the ASC device is measured for 2000 charging/discharging cycles. The device showed improved coulombic efficiency of 94%. These findings confirmed that the two-dimensional materials provide the opportunities to design battery and supercapacitor hybrid devices.

Transforming NiCo2O4 nanorods into nanoparticles using citrus lemon juice enhancing electrochemical properties for asymmetric supercapacitor and water oxidation.

Recently, the nanostructured nickel-cobalt bimetallic oxide (NiCo2O4) material with high electrochemical activity has received intensive attention. Beside this, the biomass assisted synthesis of NiCo2O4 is gaining popularity due to its advantageous features such as being low cost, simplicity, minimal use of toxic chemicals, and environment-friendly and ecofriendly nature. The electrochemical activity of spinel NiCo2O4 is associated with its mixed metal oxidation states. Therefore, much attention has been paid to the crystal quality, morphology and tunable surface chemistry of NiCo2O4 nanostructures. In this study, we have used citrus lemon juice consisting of a variety of chemical compounds having the properties of a stabilizing agent, capping agent and chelating agent. Moreover, the presence of several acidic chemical compounds in citrus lemon juice changed the pH of the growth solution and consequently we observed surface modified and structural changes that were found to be very effective for the development of energy conversion and energy storage systems. These naturally occurring compounds in citrus lemon juice played a dynamic role in transforming the nanorod morphology of NiCo2O4 into small and well-packed nanoparticles. Hence, the prepared NiCo2O4 nanostructures exhibited a new surface-oriented nanoparticle morphology, high concentration of defects on the surface (especially oxygen vacancies), sufficient ionic diffusion and reaction of electrolytic ions, enhanced electrical conductivity, and favorable reaction kinetics at the interface. The electrocatalytic properties of the NiCo2O4 nanostructures were studied in oxygen evolution reaction (OER) at a low overpotential of 250 mV for 10 mA cm-2, Tafel slope of 98 mV dec-1, and durability of 40 h. Moreover, an asymmetric supercapacitor was produced and the obtained results indicated a high specific capacitance of (Cs) of 1519.19 F g-1, and energy density of 33.08 W h kg-1 at 0.8 A g-1. The enhanced electrochemical performance could be attributed to the favorable structural changes, surface modification, and surface crystal facet exposure due to the use of citrus lemon juice. The proposed method of transformation of nanorod to nanoparticles could be used for the design of a new generation of efficient electrocatalyst materials for energy storage and conversion uses.

Integrated battery–capacitor storage system: polyaniline interwoven Co-ZIF-derived hollow NiCo-LDH with enhanced electrochemical properties for hybrid supercapacitors

Schematic diagram illustrating the synthesis route for NiCo-LDH@PANI.

Supercapacitve performance of chemically exfoliated and CVD grown MoS2: A comparative study

Two-dimensional (2D) metal dichalcogenides, like molybdenum disulfide (MoS2), have been demonstrated as extremely efficient supercapacitive electrode material due to their high electrical conductivity and surface area. Herein, two different methodologies are adopted to synthesize MoS2 samples: lithium (Li) intercalated chemical exfoliation and chemical vapour deposition (CVD) techniques. The structural and morphological characterizations of the as-prepared Li intercalated and CVD grown MoS2 were done by high resolution transmission electron microscopy (HRTEM) and Scanning electron microscopy (SEM). The Raman spectra show that the Li intercalated MoS2 samples are mostly comprised of 3–4 layers whereas a monolayer signature is observed in CVD grown samples. In this study, we report a comparative study of the supercapacitive properties of chemically exfoliated and CVD grown MoS2 using an electrochemical cell arrangement. Interestingly, the cyclic voltammetry (CV) result shows higher current density in CVD grown MoS2 as compared to that of Li intercalated MoS2 samples. The observed high specific capacitance can be ascribed to a larger surface area in CVD grown MoS2 owing to a higher charge transfer facilitating the diffusion of electrolyte ions. This result shows that the CVD grown MoS2 can be used for high performance supercapacitor applications.

High Power-Density WO3-x–Grafted Corannulene-Modified graphene nanostructures for Micro-Supercapacitors

• Micro-supercapacitors (MSCs) with reduced graphene oxide (rGO) were designed. • Restocking of rGO nanosheets was prevented with corannulene Bucky-bowls. • rGO nanosheets were modified by grafted intercalation WO 3 nanoparticles. • Double-layer capacitance of rGO nanosheets was augmented with WO 3 pseudocapacitance. • High energy-density and high power-density of MSCs were achieved. The emergence of nanotechnology and development of new methods of nanoengineering novel materials have enabled to design supercapacitors, new devices filling the niche between the high energy-density electrochemical batteries and the high power-density dry capacitors. Thanks to the nanoengineering, new devices combining the unique properties of electrochemical double-layer capacitance with high storage capability of pseudocapacitance materials could became a reality. A special niche in these applications is for micro-supercapacitors, which can drive miniature sensors and implantable biodevices, requiring fast remote charging and high energy density packed in a small volume. In this work, the micro-supercapacitors were fabricated using WO 3-x nanoparticles immobilized on rGO nanosheets to increase the carbon nanoform double-layer capacitance by adding very high pseudocapacitance of WO 3-x . To improve the attachment of WO 3 to the carbon support and enhance the graphene matrix conductance, grafting of WO 3 nuclei onto the GO defect sites was employed by electrochemical processing and nanoparticle growth, followed by the electroreduction of unprotected oxidation sites of GO to form a highly-conductive reduced graphene oxide (rGO) support. Further protection of rGO nanosheets from stacking interactions was also necessary. It was achieved by modifying graphene sheets with corannulene (CORA) which is a C 20 H 10 polyaromatic hydrocarbon (PAH) molecule forming a cup (or: Bucky bowl) structure. We have found that corannulene can efficiently separate the rGO nanosheets in more hydrophobic locations of rGO where WO 3-x nanoforms are missing. The chemical structure, morphology, and electrochemical properties of hybrid materials used for designing the micro-supercapacitor devices were characterized by Raman spectroscopy (RS), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infra-red spectroscopy (FTIR), electrochemical quartz crystal nanogravimetry (EQCN), cyclic voltammetry (CV), as well as potential-pulse and current-pulse charging/discharging characteristics. The supercapacitor properties of the proposed WO 3 ,CORA/rGO devices were favorable compared with those for mono plate graphene (MPG) and laser-induced graphene (LIG) MSCs.

Hydrogen bond stabilized β-Ni(OH)x–SO4 interlaminar materials for highly active supercapacitors

Porous β-Ni(OH)x–SO4 interlaminar material has been prepared with an expanded interplane spacing and in-plane porous channels, which exhibits advanced supercapacitor property with a high specific capacity of 212.5 mA h g−1 at 3 A g−1.

Electrochemical analysis of asymmetric supercapacitors based on BiCoO3@g-C3N4 nanocomposites.

Supercapacitors are gaining popularity these days because of their good cycle stability, superior specific capacitance, high power density, and energy density. Herein, we report the synthesis of bismuth cobalt oxide (BiCoO3) combined with graphitic carbon nitride (g-C3N4) by the hydrothermal method. The BiCoO3@g-C3N4 nanocomposite was well characterized using XRD, FE-SEM, FT-IR, and DRS-UV techniques. The supercapacitor properties of the BiCoO3@g-C3N4 nanocomposite were then studied using cyclic voltammetry, galvanic charging-discharging, and impedance spectroscopy techniques. Due to the synergistic effect, BiCoO3@g-C3N4 showed a high specific capacitance value of 341 F g-1 at a current density of 1 A g-1 and excellent retention of specific capacitance (98.82%) after 1000 cycles and a high power density of 1125 W kg-1. Using the impedance spectroscopy technique, the charge transfer resistance of BiCoO3, g-C3N4, and BiCoO3@g-C3N4 was measured. BiCoO3@g-C3N4 showed a low charge transfer resistance compared with BiCoO3 and g-C3N4. The asymmetric supercapacitor (ASC) device was prepared using activated carbon (negative side) and BiCoO3@g-C3N4 (positive side) electrodes. It showed a specific capacitance of 129 F g-1 at 1 A g-1, power density 2800 W kg-1 and energy density 35 W h kg-1. Finally, we conclude that, due to the high specific capacitance, good cycle retention, fast redox activity, and low charge transfer resistance BiCoO3@g-C3N4 is a good electrode material for energy storage applications.

Hybrid high performance supercapacitor based on zeolitic imidazolate frameworks-67-derived nano-structure NiCo2S4

In this work, NiCo2S4, nickel-cobalt layered double hydroxides (NiCo-LDH) and CoS2 electrodes are successfully prepared by using ZIF-67 as the precursor, the results show that NiCo-LDH and NiCo2S4 are nano-flower-like structures and CoS2 exhibits a nano-cage structure. The electrochemical properties of the hybrid supercapacitor assembled with NiCo2S4 and activated carbon (AC) as electrodes were tested. As the positive electrode of NiCo2S4//AC hybrid supercapacitor, the NiCo2S4 electrode has the largest specific capacity of 2934 mAh g−1 at a current density of 1 A g−1. The NiCo2S4//AC capacitor generates the highest energy density of 38.8 Wh kg−1 when the power density is 993.0 W kg−1 and has a nice cycling performance with a capacity retention rate of 81.2% after 10,000 cycles at 5 A g−1.

Azure B microspheres/nitrogen-doped reduced graphene oxide: Non-covalent interactions based crosslinking fabrication for high-performance supercapacitors

Organic molecules with conjugated π-bonds are promising electrode materials for supercapacitors due to their outstanding redox reversibility and structural stability. Yet they are limited for applications in supercapacitors on account of poor conductivity and inferior cyclability. In this work, a series of azure B/nitrogen-doped reduced graphene oxide (AB/N-rGO) composites are prepared via hydrothermal process and following freeze-drying. As expected, non-covalent bonds between N-rGO and AB allow them to link together and form three-dimensional porous structure, exhibiting enhanced specific capacitance and cycle life. The supercapacitive properties of AB/N-rGO composites are optimized by controlling mass ratio of graphene oxide and AB raw materials. The prepared AB/N-rGO-5 electrode exhibits optimal specific capacitance of 371 F g − 1 at 1 A g − 1 and excellent cyclic stability (94% capacitance retention after 10,000 cycles) in 1.0 M H2SO4 electrolyte. Besides, the as-assembled asymmetric supercapacitor constructed with AB/N-rGO-5 cathode and WO3 anode not only displays wide voltage window (1.55 V) and high energy density of 25.0 Wh kg−1 at power density of 387.9 W kg−1, but also exhibits prominent cyclic stability (81% capacity retention after 10,000 cycles). This work offers ideas for applications of more electroactive molecules with excellent capacitive properties in supercapacitors.

A new strategy for the preparation of multi-walled carbon nanotubes/NiMoO4 nanostructures for high-performance asymmetric supercapacitors

Over the past decade, boosting the electrical conductivity of nickel molybdate materials has been established to improve their supercapacitive performance. Nevertheless, it is significant to investigate a different approach from economic efficiency and operation time perspectives. Herein, we first prepare NiMoO4 nanoparticles using a simple ball-milling technique and then serve them in two different multi-walled carbon nanotubes (MWCNTs)/NiMoO4 composites fabricated using simple blending and ball-milling. The ball-milled nanocomposite delivers outstanding supercapacitive properties because of its good surface area, outstanding conductivity, fast kinetics, and many active sites. Its specific capacitance reached 727.2 F g−1 at 1 A g−1 and 709.8 at 10 mV sec−1, and cycling stability was measured to be 86.8 % after 2000 cycles at a current density of 20 A g−1, surpassing the other two samples. An asymmetric device based on ball-milled composite nanostructure resulted in a high specific energy of 40.9 Wh kg−1, a remarkable specific power of 918.5 W kg−1, an appealing rate performance of 73.6 % at 50 A g−1 current density, and a superb cycling durability of 85.4 %. As a result, combining storage attributes of NiMoO4 and MWCNTs with the ball-milling route provides a new strategy to enhance the electrochemical properties of nickel molybdate.

Probing the supercapacitive properties of hydrothermal routed MWCNTs@Cd0.98MoO4:Eu3+0.02 nanoparticles

In the present study, cadmium molybdate (CdMoO4) nanoparticles are synthesized successfully by most adoptable hydrothermal method. To improve the supercapacitive properties of sole CdMoO4, optimized quantity of Eu3+ is doped in the material, and improved capacitance is obtained. The prepared material is figured out by various characteristic techniques such as XRD, FTIR, RAMAN, ICP, FESEM, TEM, BET, XPS and EDX analysis. The electrochemical analysis of the prepared material is obtained by CV, GCD and EIS techniques. High specific capacitance of 601 F g−1 was obtained from Cd0.98MoO4:Eu3+0.02 at 1 A g−1 which was higher from CdMoO4 (343 g−1 at 1 A g−1). Further, the specific capacitance of doped material was improved by adding the small amount of MWCNTs. The high specific capacitance of 1011 F g−1 was obtained at the current density of 1 A g−1 from the MWCNTs@Cd0.98MoO4:Eu3+0.02 composite. In addition, MWCNTs@Cd0.98MoO4:Eu3+0.02//AC device is fabricated, and high energy density of 25.2 W h kg−1 at power density of 362.5 W kg−1 was obtained using the current density of 0.5 A g−1. Furthermore, LEDs, toy motor fan and kitchen timer are also powered by series connected two MWCNTs@Cd0.98MoO4:Eu3+0.02//AC device.