High Specific Capacitance Value Research Articles

High-performance supercapacitors based on S-doped polyaniline nanotubes decorated with Ni(OH)2 nanosponge and onion-like carbons derived from used car tyres

High performance supercapacitors are designed based on hierarchical Ni(OH)2 nanosponges anchored on sulfur-enriched polyaniline (PANI) nanotubes and waste tyre-derived onion-like carbons (OLC) as counter electrode materials. The rational strategy of grafting mesoporous thin sheets of Ni(OH)2 on PANI produces unique composite nanoarchitectures that shows superior potential in supercapacitors validated by higher electrochemical stability. The designed asymmetric supercapacitor configuration with OLC as anode exhibits excellent specific capacitance of 622 F g−1 at higher current density of 2 A g−1 with an exceptional capacity retention greater than 97% achieved upon 10,000 continuous charge-discharge cycles. The asymmetric device delivers the remarkable energy and power density of 70 Wh kg−1 and 136 kW kg−1, respectively, whereas the symmetric device delivers the maximum energy density of 23 Wh kg−1 and power density of 292 kW kg−1. Further, it is demonstrated that Ni(OH)2@PANI composite-based all solid-state flexible asymmetric supercapacitor construction with OLC exhibits high specific capacitance value of 166 F g−1 at a higher current density of 5 A g−1. The prolonged cycle stability may be attributed to the synergistic effect of 3D-nanosponge-like Ni(OH)2 on PANI nanotubes surface, stabilizing the volume changes upon cycling. The OLC derived from the pyrolysis of waste-tyres offers high energy density and better rate capability.

Urchin like NiCo2O4/rGO nanocomposite for high energy asymmetric storage applications

New attractive advances in electrode preparation for supercapacitor applications with rGO based composite materials are eye-catching attention of researchers. Cobalt oxide is considered as an effective electrode for full cell fabrication due to its high specific capacitance. Cost effective solvothermal method was used to prepare pristine Co3O4 nanorods, NiCo2O4 nanorods and NiCo2O4/rGO urchin like nanocilia structure composite materials. The complete electrochemical studies were used to check the obtained product electrochemical activity. The high specific capacitance values are obtained for NiCo2O4/rGO urchin like nanocilia composite electrode material which leads to design a full cell and make use as practical applications with illuminating red, green, blue LED source. The capacitive retention of 92.28% even after 5000 cycles achieved in GCD cyclic performance at a high current density implies its excellent stability.

A new lamellar larch-based carbon material: Fabrication, electrochemical characterization and supercapacitor applications

Efficient utilization of waste wood sawdust to prepare carbon-based materials with regular morphologies and pore structures continues to be of interest, with the ultimate aim of fabricating optimized electrode materials for use in energy storage devices. This work used a process involving the liquefaction of larch wood sawdust together with in situ doping of tetraethoxysilane (TEOS) to act as a silica-based template. This allowed the fabrication of carbon materials with a uniform lamellar structure. As a result of its specific morphology and its hierarchical pore structure, this larch-based carbon demonstrated excellent electrochemical supercapacitor performance. The regular lamellar structure provided transmission channels for ions and also promoted charge storage. Remarkably, the material showed high values of specific capacitance (288 F/g), energy density (93.73 Wh/kg) and power density (850 W/kg) at a current density of 0.2 A/g in a 1 M KOH electrolyte. Good rate performance and stability (with capacitance retention exceeding 97 % after 3000 cycles) were also observed. This work demonstrates a new approach to value-added utilization of larch waste by producing a material that is an excellent candidate for manufacture of supercapacitor electrodes.

Large-scale synthesis of 2D bismuth-enriched bismuth oxyiodides at low temperatures for high-performance supercapacitor and photocatalytic applications

Various bismuth oxyhalides materials (such as BiOX, where X = Cl, Br, F, I) are widely investigated in supercapacitors and photocatalyst fields owing to their unique morphological features and outstanding electrochemical properties. In this study, we have synthesized various bismuth-rich oxyiodides such as BiOI, Bi4O5I2, Bi5O7I, and Bi7O9I3 with two-dimensional morphologies in large scale by facile hydrothermal route. The chemical composition, surface properties, morphological features, and electrochemical properties have been systematically investigated using various advanced characterization techniques. The XRD results confirmed that the BiOI, Bi4O5I2, Bi5O7I, and Bi7O9I3 could be prepared by adjusting simply the pH values and OH− concentrations. Furthermore, the enrichment in the Bi content, the surface area, specific capacitance, and photocatalytic activity of the materials has been increased appreciably. A high specific capacitance value of 347 F g−1 is achieved for the Bi7O9I3 material, which is higher than the other bismuth-enriched oxyiodide such as BiOI, Bi4O5I2, and Bi5O7I, respectively. Moreover, compared with other bismuth oxyiodides, the Bi7O9I3 exhibited admirable photocatalytic activity toward the rhodamine B dye and 4-chlorophenol degradation under the visible light. In addition, this comprehensive study provides a new strategy in the development of highly efficient bismuth oxyhalides for constructing high-performance photocatalyst material and supercapacitor electrode for energy and environmental applications.

Tunable electrochemical activity of polyaniline salt by doping anion exchange

The exchange of mobile anion of chemically synthesized polyaniline with counter anions of electrolyte solutions is studied by using cyclic voltammetry (CV). The synthesized polyaniline (PANI) doped with sulfuric acid (H2SO4) and dodecyl benzenesulfonic acid (DBSA) is soluble in a wide range of organic solvents which makes it appealing for further processability. The exchange of dopant anions (of H2SO4 and DBSA) with a variety of counter anion has been inspected by electrochemical cycling in aqueous sodium sulfate (Na2SO4), sodium perchlorate (NaClO4), and sodium hydroxide (NaOH) solution. The CV measurements have revealed that PANI remains redox active at higher scan rate and there is exchange of dopant anion with SO42- and ClO41- of electrolytes. In NaOH solution, the emeraldine salt form of PANI is transformed into emeraldine base due to deintercalation of the anion form polymer matrix. The results indicate a significant change in electrochemical conductance and behavior of PANI in each electrolyte. Furthermore, the polymer film displayed a high specific capacitance value of 588 F/g in 1.0 M NaClO4 solution in the optimized potential window of -0.2 V to 0.9 V at 20 mV/s.

Construction of hierarchical core-shell ZnCo2O4@Ni-Co-S nanosheets with a microsphere structure on nickel foam for high-performance asymmetric supercapacitors

The hierarchical core-shell ZnCo2O4@Ni-Co-S nanosheets with microsphere structures for supercapacitors were prepared through a facile three-step method including hydrothermal reaction, subsequent annealing and electrodeposition process. The influences of deposition cycles on its structure and electrochemical performances were studied in detail. On account of a synergistic effect of the ZnCo2O4 and Ni-Co-S composite and its unique core-shell nanostructure, the as-prepared electrode reveals excellent supercapacitor properties. The ZnCo2O4@Ni-Co-S with 6 electrodeposition cycles (ZCO@NCS-6) shows high specific capacitance values of 1762.6 F g−1 at 1 A g−1, outstanding rate performance with 81.3% at 50 A g−1, and remarkable long-term stability of 18.6% capacity loss through 5000 cycles. Moreover, the asymmetric supercapacitor (ASC) device was further constructed by using of ZCO@NCS-6 and active carbon to evaluate the practical values of the fabricated composite materials. The assembled ASC device shows the maximum voltage window up to 1.7 V, high energy density of 37.1 W h kg−1 and the excellent cycling life-span (only 9.71% capacitance loss after 8000 cycles). All these results suggest that ZnCo2O4@Ni-Co-S could be the hopeful electrode materials for energy storage devices.

The controlled fabrication of hierarchical CoS2@NiS2 core-shell nanocubes by utilizing prussian blue analogue for enhanced capacitive energy storage performance

In this project, for the first time we successfully develop an approach to fabricate a novel core-shell structure of CoPBA@Ni(OH)2, in which Ni(OH)2 nano-sheets covered on the surface of CoPBA nanocubes through in-situ etching and growing processes, furthermore, being sulfurized into its hierarchical porous structure of CoS2@NiS2. The CoS2@NiS2 composite as a high-performance surpercapacitor electrode has been demonstrated. It exhibits very high specific capacitance value of 1731.2 F g−1 at 1 A g−1, excellent rate performance of 83.5% retention at 10 A g−1 and cycle performance with 87.1% retention after 5000 cycles together with distinguished coulombic efficiency of around 100%. Kinetic analysis and electrochemical impedance spectroscopy (EIS) results reveal the related mechanism. Herein, prussian blue analogue (PBA) as central core with cubic skeleton displays some great advantages, (1) it can provide more efficient electron conduction path to reduce the resistance of composite, (2) it can effectively prevent the agglomeration of electroactive Ni(OH)2 as well as sulfurized CoS2@NiS2 composite, (3) it can reduce ion diffusion pathway with mesoporous structure and enlarged surface area, greatly improving cycle stability. Such synthetic strategy opens up a new avenue for the effective construction of core-shell structure based on PBA basement for promising supercapacitor application.

Solid polymer electrolytes from double-comb Poly(methylhydrosiloxane) based on quaternary ammonium moiety-containing crosslinking system for Li/S battery

The synthesis, characterization, and electrochemical cell performance of a double-comb poly (siloxane) solid polymer electrolyte (SPE) for Li–S battery application is reported. The SPE is designed with different degrees of chemical crosslinking via quaternary ammonium moieties. The chemical crosslinking enhanced dimensional stability and quaternization raised the dielectric constant of SPE. The SPE with 3% crosslinking ratio shows the highest Li+ ion conductivity of 6.6 × 10−4 Scm−1 at 30 °C. The electrochemical studies reveal a high specific capacity value of 1082 mAhg−1 with good capacity retention over several cycles. The SPE demonstrate excellent performance in Li–S battery even with high sulfur loading and varied electrochemical stability with good lithium plating/stripping performance.

Correlation between the Molecular Structure of Reducing Agent and pH of Graphene Oxide Dispersion on the Formation of 3D-Graphene Networks

Interactions between the reducing agent and graphene oxide (GO) has crucial importance since it affects the performance of the final three-dimensional graphene networks (3D-GNs) as a supercapacitor electrode. In this study, morphological and electrochemical properties of 3D-GNs fabricated through reducing of GO by ethylenediamine (EDA), L-ascorbic acid (AA), glucose (Glu), and citric acid (CA) reducing agents have been determined. It is observed that the pH of GO dispersion, and molecular structure and pKa of reducing agents mainly determine the porosity and electrochemical behavior of 3D-GNs. All the 3D-GNs exhibit better electrochemical performance than those of GO both in acidic and alkaline electrolytes while the EDA-(3D-GN) has the highest specific capacitance values and excellent coulombic efficiency (99) thanks to its mesoporous structures consisting of restored and enlarged the graphene sheets as well as nitrogen functionalities. The maximum energy density has been calculated as high as 41.95 Wh kg−1 in 3.0 M H2SO4 for EDA-(3D-GN) based supercapacitor device which is almost 2.3 times of GO and comparable with the Lead-acid batteries. The results put forth the great potential of the 3D-GNs as efficient electrode materials for high-performance energy storage devices.

Highly Stable Fe3O4/C Composite: A Candidate Material for All Solid-State Lithium-Ion Batteries

Fe3O4 nanoparticles synthesized by a base catalyzed method are tested in an All-Solid-State (ASLB) battery using a sulfide electrolyte. The pristine nanoparticles were morphologically characterized showing an average size of 12 nm. The evaluation of the electrochemical properties shows high specific capacity values of 506 mAhg−1 after 350 cycles at a specific current of 250 mAg−1, with very high stability and coulombic efficiency.

NiO nanoplates for energy storage application: Role of electrolyte concentration on the energy storage property

Here in, synthesis of NiO nanoplates by employing a mixed solvent system under solvothermal method followed by calcining the obtained product nickel hydroxide in air is reported. Diffraction, microscopic, and spectroscopic results confirmed the formation of NiO phase. The as synthesized NiO nanoplates are tested as a robust material for energy storage applications. The effect of electrolyte concentration on the capacitive behavior of NiO is studied thoroughly. The outcome from the electrochemical analysis reveals that NiO nanoplates have a high specific capacity value of 108.4 C g−1 (270 F g−1) in 6 M KOH electrolyte and the value decreases to 85.0 C g−1 (212.5 F g−1) and 78.2 C g−1 (195.5 F g−1) for 4 M, and 2 M KOH electrolyte, respectively. The resistance values also decreased with increase in the KOH concentration. The better electrochemical performance depicted by the 6 M KOH electrolyte is mainly ascribed to the availability of plenty of OH− ions in the electrolyte solution, which helped in the proper wettability of the sample so that the OH− ions can participate to higher extent during the electrochemical redox reactions, due to which the observed charge storage capacity is more in higher electrolyte concentration and vice-versa. Thus, the results suggest the usefulness of this material for energy storage applications.

Specific capacitance and impedance of electrodeposited polyaniline, polypyrrole and polyaniline/polypyrrole composite films

The aim of this work was to prepare polyaniline, polypyrrole and polyaniline/polypyrrole composite films using electrodeposition techniques. Films were examined using a Fourier transform infrared spectrometer, which confirmed the formation of the single polymers and their composite. Morphological analysis was carried out using a scanning electron microscope and showed the flat and highly compact deposit of polypyrrole/polyaniline composites, whose morphological characteristics varied from those of the single polymers, which had porous deposits. Electrochemical properties of the materials were evaluated using cyclic voltammetry and electrochemical impedance spectroscopy techniques. Impedance values showed that polyaniline had the best charge transfer and the polyaniline/polypyrrole composite had the highest specific capacitance value, which was 530.96 F/g. This result indicates that the electrodeposited films can find application for electrode in capacitive deionization systems.

Functionalization of textile cotton fabric with reduced graphene oxide/MnO2/polyaniline based electrode for supercapacitor

In this work, a new cotton electrode has been synthesized by coating ternary materials of reduced graphene oxide (rGO), manganese dioxide (MnO2), and polyaniline (PANi) on textile cotton fabric. First, Graphene oxide was deposited on cotton fibers by a simple ‘dip and dry’ method and chemically reduced into rGO/cotton fabric. MnO2 nanoparticles were accumulated on rGO/cotton fabric by in situ chemical deposition method. PANi layer was coated on rGO/MnO2/cotton fabric by in situ oxidative polymerization technique. A thin PANi coating layer acts as a protective layer on rGO/MnO2/cotton fabric to restrain MnO2 nanoparticles and rGO from dissolution in H2SO4 acidic electrolyte. The specific surface area of cotton electrode was measured using the Brenauer-Emmett-Teller (BET) method. The cyclic voltammetry (CV) results show that the cotton electrode has good capacitive behavior. The ternary cotton electrode exhibits high specific capacitance values of 888 F g−1 and 252 F g−1 at a discharge current density of 1 A g−1 and 25 A g−1 in 1 M H2SO4 electrolyte solution. The high areal specific capacitance of 444 Fcm−2 was achieved for as-fabricated electrode. Also, the cotton electrode retains around 70% of specific capacitance after 3000 cycles at charge-discharge current density of 15 A g−1. The slow decrease in specific capacitance is observed with increased discharge current density which proves its excellent rate capability. These results of rGO/MnO2/PANi/cotton fabric electrode show that this can be an excellent electrode for supercapacitor in energy storage devices.

Synthesis of pH-moderated cobalt molybdate with bifunctional (photo catalyst and graphene-based supercapacitor) application

The present manuscript deals with one photosynthesis of cobalt molybdate for multifunctional application as supercapacitor and photo catalyst. The cobalt molybdate is synthesized by various concentration of urea as precursor. Nanostructured transition metal has been synthesized by hydrothermal method from spent catalyst leach liquor. Different physico-chemical characterization techniques are obtained to illustrate the nanomaterials followed by X-ray diffraction, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and nitrogen adsorption–desorption isotherm for surface area analysis. Nanorod cobalt molybdate is proved as efficient photocatalyst for Rhodamine B dye under visible light irradiation, which possess a high degradation rate of 98% after 15 min. Electrochemically active cobalt molybdate shows high specific capacitance value of maximum specific capacitance of 175.34 F g-1at three-electrode system and 74.2 F g−1at two-electrode system. It also revealed excellent rate capability and superior cycling stability with long cycle life (92.7% retention in specific capacitance after 5000 cycles) along with high energy and power densities.

Homogeneous MnO2@TiO2 core-shell nanostructure for high performance supercapacitor and Li-ion battery applications

In this work, MnO2 layered TiO2 core-shell nanostructure is prepared by a two-step method. The prepared homogeneous MnO2 layered TiO2 core-shell architecture characterized by various physiochemical techniques. The crystalline nature and other structural details of the synthesized core-shell architecture obtained from powder X-ray diffraction (XRD) technique. The formation of core-shell architecture confirmed by field emission electron microscopy (FE-SEM) technique and the elemental analysis carried out using energy-dispersive X-ray spectroscopy (EDS) analysis. The electrochemical behavior of the prepared MnO2 layered TiO2 core-shell architecture studied using cyclic voltammetry (CV), charge-discharge, and electrochemical impedance techniques in 1 M Li2SO4 aqueous electrolyte. The prepared MnO2 layered TiO2 core-shell architecture shows high specific capacitance and energy density value of 564 F g−1 and 38.39 Wh kg−1, respectively, at the applied current density of 2 A g−1. Further, the resistive and capacitive nature of the synthesized electrode material studied from Nyquist and bode diagrams within the frequency range of from 10 mHz to 100 kHz. Finally, a MnO2 layered TiO2 nanorods/activated carbon asymmetric supercapacitor device fabricated and its lithium-ion storage capacity evaluated at different applied current densities. With these outstanding electrochemical performances, prepared MnO2@TiO2 core-shell nanostructure holds good potential to develop high-performance electrochemical energy storage devices.

Polyaniline-cobalt oxide nano shrubs based electrodes for supercapacitors with enhanced electrochemical performance

The present work focuses on the design and development of highly oriented well aligned nano shrubs of polyaniline decorated Co3O4 (COP) and demonstration as an efficient electrode for the fabrication of supercapacitors. Morphological results suggest that COPs are composed of PANI nano shrubs grown from the pores of Co3O4 to form a three-dimensional nanostructure. Further, supercapacitor with the configurations of [(indium tin oxide)ITO-COP/1 M Na2SO4/COP-ITO] was fabricated and its performance evaluated leading to high specific capacitance value (1151 F g−1 @ 3 A g−1), high rate performance of 70% at the current density ranging from 3 to 20 A g−1, and excellent cycling stability (92% after 5000 cycles @ 10 A g−1). The excellent performance of this hybrid nanocomposite is attributed to well aligned self-assembled structural advantage of COP and the synergistic effects of cobalt oxide and polyaniline which is responsible for the substantial reduction in the charge transfer resistance as revealed by electrochemical impedance spectroscopy. All these results suggest that the developed strategy can be used for the development of efficient hybrid conductive nanocomposite based electrode material for other combinations of transition metal oxide-conductive polymer based supercapacitors.

A facile synthesis of hydroxyl functionalized graphene oxide as an electrode material for energy storage devices

In this case, a facile synthesis of alcohol functionalized graphene oxide (GO) material has been made using water soluble, non-toxic, biocompatible tris buffer (TB) and diethenolamine (DEA). This functional material was characterized by various techniques such as, XRD, TEM, XPS, Raman, TGA and Cyclic voltametry (CV). The molecular level grafting of amines to graphene has been occurred due to the functionalization of alcohol by the enlargement of interlayer spacing and specific surface area. The synthesized material shows high specific capacitance value of 372 and 252 F g−1 at a current density of 1 A g−1 in 6% KOH solution.

Fabrication of ZIF-67 Derived Co3S4-WS2 Heterostructures for All-Solid-State Symmetrical Supercapacitors

Development and modification of the existing material for renewable energy area is gaining its significance however a long way to get commercialization. Transition metal dichalcogenides (TMDs) are gaining interest rapidly in the field of supercapacitors due to their 2D layered morphology, however loses interest for long cyclic stability. Herein we employed hollow Co3S4 microspheres using nitrogen rich ZIF-67 as a precursor. Furthermore, these hollow Co3S4 microspheres are insitu modified by covering with WS2 nanostructures to enhance its energy density. The obtained Co3S4/WS2 composite when employed as an electrode, delivers the specific capacitance of 412.7 F/g at the current density of 1 A/g. Furthermore, the Co3S4/WS2 composite electrodes are used to fabricate an all solid-state symmetrical supercapacitor device, exhibiting a wide potential window of 2 V. The assembled device delivers a very high energy density of 70.7 Wh/kg along with a high-power density of 10.2 kW/kg. The excellent electrochemical performance with 92 % capacity retention proves its potential toward the practical application. The high value of specific capacitance and splendid cycle stability is attributed to the synergy of high surface area ZIF-67 derived Co3S4 microsphere with 2D networked WS2 material.

A-site cation-ordered double perovskite PrBaCo2O5+δ oxide as an anion-inserted pseudocapacitor electrode with outstanding stability

As anionic insertion pseudopotential electrode, perovskite oxides have attracted more and more attention due to their high electrical conductivity and oxygen vacancy concentration. In this study, double perovskite PrBaCo2O5+δ (PBCO) oxide was synthesized by simple sol-gel method. Phase composition, porous structure and surface chemistry were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) curves were used to explore the electrochemical performance. The tests show that the PBCO electrodes exhibit good capacitance performance with the high specific capacity value of 428.2 C g−1 at 1 mV s−1. Furthermore, the capacitance retention still achieves 93% after 2000 cycles, showing excellent cycling stability. This paper analyzes the capacitance behavior of PBCO electrodes, and demonstrates the insertion mechanism that oxygen vacancies are filled by oxygen ions. All these prove that PrBaCo2O5+δ has potential applications in supercapacitors.

Synergistic Cobalt Sulfide/Eggshell Membrane Carbon Electrode.

The preparation of green, facile, and cost-effective energy storage materials remains a big challenge. In this paper, a cobalt sulfide/porous carbon (Co4S3/PC) composite electrode is facilely prepared using the natural eggshell membrane (ESM) as a basal substrate. Under hydrothermal conditions, Co4S3 is grown on the ESM to form Co4S3/ESM and carbonized to form Co4S3/PC. The as-synthesized Co4S3/PC composite is used as an electrode material. The carbide from the ESM shows a porous structure and high specific surface area, which provides large space for Co4S3 attaching and ion migrating. Co4S3/PC shows much higher specific capacitance values than the sum of Co4S3 and PC electrodes, indicating a significant synergistic effect. More importantly, the Co4S3 is a typical faradic material, which exchanges Faraday charge with an electrolyte and subsequently transmits an electron to the whole electrode due to the high conductivity of the carbonized ESM. Such a synergistic effect offers the as-synthesized Co4S3/PC electrode a significant improvement in performance over both the ESM-derived carbon and the original Co4S3. Besides, the Co4S3/PC electrode shows a wide potential window, low resistance, and high specific capacitance. After 1000 cycles, the electrode retains a high cycling capacity. This study provides a novel insight for high-performance biomass-derived carbon preparation for pseudocapacitors and other electrochemical devices.