Efficient Electrode Material For Supercapacitors Research Articles

Green Synthesized Carbon Quantum Dots/Cobalt Sulfide Nanocomposite as Efficient Electrode Material for Supercapacitors

In the present work, carbon quantum dots/CoS2 nanocomposite (CQDs/CoS2) was prepared through a solvent-free ball milling route followed by solvothermal treatment. The CQDs were prepared first by a green catalyst-free microwave-assisted procedure from glycerol, as a single precursor, with a quantum yield of ∼16%. Then, a ball mill–hydrothermal combination method was used to synthesize CQDs/CoS2 with edged bricklike morphology. Benefiting from advantageous features of large specific surface area (427.2 m2 g–1), unique nanostructure with high mesoporosity, and greater electronic conductivity, the as-synthesized CQDs/CoS2 nanocomposite electrode material displays a rather high specific pseudocapacitance, about 808 F g–1 at 1 A g–1 current density, a high rate capability with 83.9% capacity retention rate at 20 A g–1, and good cycling stability of 98.75% over 10 000 charge/discharge cycles at 1 A g–1. The attained results support the suitability of CQDs/CoS2 nanocomposite as a desired material for future high-performance electrochemical energy storage devices.

One-step hydrothermal synthesis of bimetallic oxides (NiO@Mn3O4) supported on rGO: A highly efficient electrode material for supercapacitors

The continuous development of novel renewable energy makes the composition electrode become more and more diversified, and the composition has been relied on the multiple chemical elements. As energy storage materials, graphene and transition metal oxides have been researched at home and abroad due to their particular advantages. NiO, Mn3O4, and reduced graphene oxide (rGO) were synthesized the NiO@Mn3O4/rGO through a simple hydrothermal method. The morphology and structure of NiO@Mn3O4/rGO is characterized by SEM, TEM, EDS, XRD and XPS. The electrochemical results (cyclic voltammetry curve, galvanostatic charge discharge and electrochemical impedance spectroscopy) confirm that NiO@Mn3O4/rGO exhibits excellent electrochemical performance. The specific capacitance of NiO@Mn3O4/rGO has a 533.97 F/g at 1 A/g. After 2000 charge and discharge cycles, it still retains a 75% capacitance at higher 10 A/g current density.

Synthesis of nickel hexacyanoferrate nanostructure on carbon cloth with predeposited nickel nanoparticles as precursor for binder-free high-performance supercapacitor electrodes

Transition metal (TM) hexacyanoferrates (TM-HCF) have been proven efficient electrode materials for supercapacitors, especially in neutral electrolyte. In this work, nickel hexacyanoferrate (Ni-HCF) with ultra-high mass-loading was synthesized on carbon cloth (CC) with nickel nanoparticles (NiNPs) as the precursor, which were in-situ converted to Ni-HCF with graphene oxide (GO) as the oxidant and NiNPs as the reductant in the presence of potassium ferricyanide. First, NiNPs were potentiostatically electrodeposited on CC. Then, the electrodeposited NiNPs was oxidized to Ni2+ by GO. The produced Ni2+ reacted immediately with potassium ferricyanide to form nanostructured nickel hexacyanoferrate. By tuning the electrodeposition time of NiNPs, the mass of the finally produced Ni-HCF can be easily adjusted. In this work, the mass-loading of Ni-HCF supported on CC reaches up to 26.4 mg cm−2. As the positive electrode, Ni-HCF/CC possesses a high areal capacity of 6.9 C cm−2 at a discharge current density of 10 mA cm−2, excellent cycling stability with 81% of its initial capacitance after 2000 continuous charge/discharge cycles, ultrahigh energy density of 36 W h kg−1 at the power density of 200 W kg−1 and nearly 100% columbic efficiency. The superior energy storage capability of Ni-HCF indicates its promising prospect as the positive electrode material of high performance supercapacitors.

Co-MoS2 nanoflower coated carbon fabric as a flexible electrode for supercapacitor

Cobalt doped MoS2 (Co-MoS2) nanoflowers have been successfully synthesized via a simple one-step hydrothermal method for supercapacitor applications. To identify the crystalline nature and morphology, the as-prepared material is characterized by XRD, SEM, and TEM measurements. The material exhibits a specific capacitance value of 86 F g−1 at a current density of 1 Ag−1 in symmetric two-electrode configuration with excellent cyclic stability of 98.5% even after 10,000 charge–discharge cycles. The results suggest the suitability of Co-MoS2 as an efficient electrode material for supercapacitors.

Synthesis and structural/electrochemical evaluation of N, S co‐doped activated porous carbon spheres as efficient electrode material for supercapacitors

AbstractMicrometer size activated porous carbon spheres doped with nitrogen and sulfur (NSAPC) are synthesized hydrothermally by using saccharose as the carbon precursor and l‐cysteine as the doping agent, followed by KOH activation. These doped porous carbon spheres possess a high specific surface area (SSA) and porosity (mainly microporous) suitable for efficient charge storage. Additionally, doping with nitrogen and sulfur significantly changes the surface chemistry. When tested as electrode material for supercapacitor, the co‐doped porous carbons outperformed the undoped carbon. NSAPC spheres show a high specific capacitance of 270 F/g at a current density of 1 A/g in 1 M H2SO4 and exhibit excellent charge‐discharge cycling stability over 5000 cycles. The enhanced electrochemical performance can be attributed to the combined effect of high specific surface area, presence of micro and mesopores along with nitrogen and sulfur heteroatoms.

MoSe2 nanoflowers as efficient electrode materials for supercapacitors

Herein, we report a facile hydrothermal synthesis of MoSe2 nanoflowers composed of several MoSe2 nanosheets for electrochemical energy storage. As an electrode material of supercapacitor, MoSe2 nanoflower exhibits high specific capacitance (95 Fg−1) and excellent cycling stability (90% after 10,000 cycles) due to their porous morphology, indicating their applicability as a potential electrode material for energy storage devices.

One-pot synthesis, characterization, and electrochemical studies of tin-nickel sulfide hybrid structures on nickel foam for supercapacitor applications

An integrated hybrid structure of SnS2Ni3S2 on nickel foam (SnS2Ni3S2@NiF) was prepared via a one-step hydrothermal route as a supercapacitor electrode. A piece of nickel foam was used as the backbone as well as the precursor for Ni3S2. During the hydrothermal process, the S species released from the thioacetamide react with the Sn ions and Ni foam and produce a SnS2Ni3S2 hybrid nanostructure at the surface of the Ni foam. The prepared material was characterized by state-of-the-art techniques and used as an electrode material for supercapacitor applications. The electrochemical performance of the as-prepared electrode was studied in a three-electrode system using a 2 M KOH aqueous solution as the electrolyte. The SnS2Ni3S2@NiF electrode exhibited a high specific capacity of 272 mAh/g at a current density of 4 mA/cm2 accompanied by a cyclic stability of 91% over 3000 charge-discharge cycles (at a current density of 20 mA/cm2). We believe that this work provides an easy and scalable strategy to prepare a highly efficient electrode material for supercapacitors.

Benzoate anions-intercalated cobalt-nickel layered hydroxide nanobelts as high-performance electrode materials for aqueous hybrid supercapacitors

Layered metal hydroxide salts (LHSs) have recently gained extensive interests as an efficient electrode material for supercapacitors (SCs). Herein, we report, for the first time ever, the synthesis of a cobalt-nickel layered hybrid organic-inorganic LHS that was intercalated with benzoate anions (B-CoNi-LHSs) and observe a high performance as electrode materials for hybrid supercapacitors (HSCs). B-CoNi-LHSs were synthesized by using a co-precipitation method, where sodium benzoate was added dropwise to cobalt and nickel salt solution, without the addition of any organic solvent or surfactant. Due to the intercalation of anions and synergistic interactions of the multi-metallic components, the B-CoNi-LHSs electrode showed a high specific capacity of 570 C g−1 (specific capacitance of 1267 F·g−1) at 1 A g−1, excellent rate performance (65% from 1 to 10 A g−1) and outstanding cycling performance (81.09% over 8000 cycles), in comparison to the mono-metallic counterparts. An HSC device, assembled by using B-CoNi-LHSs as the positive electrode and activated carbon (AC) as the negative one, exhibited a power density of 780 W kg−1 at the energy density of 31.7 Wh kg−1, and 8543 W kg−1 at 18.1 Wh kg−1. Results from this study show that the organic-inorganic hybrids of layered dual-metal hydroxides intercalated with benzoate anions may be a viable candidate as electrode materials for high-performance SCs.

Carbon coated iron oxide (CC-IO) as high performance electrode material for supercapacitor applications

Abstract Transition metal oxides are efficient electrode materials for supercapacitors due to their high theoretical specific capacitance. However their poor electrical conductivity needs to be further improved for fast charging and discharging the supercapacitor. There is an effective approach to overcome this issue by combining the carbon based materials with metal oxides. Addition of carbon based materials into transitional metal oxides will enhance the supercapacitor performance. Herein, carbon coated iron oxide (CC-IO) was synthesized using sucrose as a soluble carbon precursor and annealed at different temperatures (1000 °C to 1300 °C). The structure of the CC-IOs was analysed by X-ray diffraction and Raman spectroscopy. Pore structures and surface chemical compositions of CC-IOs were studied using BET and X-ray photoelectron energy spectrum, respectively. Surface morphology was investigated with scanning and transmission electron microscopy. CC-IO-1300 °C showed the maximum specific capacitance of 727 Fg−1, while CC-IO-1000 °C showed the minimum capacitance of 143 Fg−1 calculated by cyclic voltammetry (CV) at a scan rate of 5 mV/sec. The improvement in the specific capacitance of CC-IOs with increasing temperature is may be due to phase change of iron oxide and improvement in the crystalline nature of carbon coated on the iron oxide surface.

Facile synthesis of activated carbon derived from Eucalyptus globulus seed as efficient electrode material for supercapacitors

In the present study, activated carbon (AC) was prepared from Eucalyptus globulus seed (EGS) by a simple hydrothermal method followed by chemical activation using potassium hydroxide as the activating agent under different carbonization temperatures. X-ray diffraction and Raman spectroscopic analysis confirmed the amorphous and turbostratic disordered nature of the carbon. FT-IR analysis of the activated carbon samples shows the presence of N and O functional groups. Brunauer-Emmett-Teller (BET) specific surface area analysis of EGS derived activated carbon at 900 °C showed the highest specific surface area of 2388.38 m2g−1 and exhibited a specific capacitance of 150 Fg−1. The appearance of small and large graphitic pores with random orientation and approximately 88.3 wt% of carbon and 11.7 wt% of oxygen were confirmed by SEM/EDX analyses. Further to understand the electrocatalytic nature of the synthesizing carbon, the material was tested as an electrode for supercapacitors. The electrochemical performance was demonstrated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance (EIS) studies. The electrochemical properties of EGS derived activated carbon demonstrate its potential application as high-performance and low-cost supercapacitor electrode material to fabricate energy storage devices.

Synthesis and characterization of rGO/Fe2O3 nanocomposite as an efficient supercapacitor electrode material

The reduced graphene oxide-Fe2O3 (rGO-Fe2O3) nanocomposites were synthesized by a facile and low-cost hydrothermal method employing rGO and Iron (III) nitrate precursors. The synthesis parameters including the reduction time and presence of reduction aid are studied. The structural and morphological studies of the nanocomposites were investigated by using Raman spectra, Fourier transform infrared spectroscopy, X-ray diffraction, and field emission scanning electron microscopy. The results indicate that Fe2O3 nanoparticles with average particle size of 25 nm are well anchored on graphene sheets and the weight percent of the nanoparticles in the nanocomposites was influenced by the reduction time. The as-synthesized nanocomposites were characterized by a three-electrode system using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge in 1 M KOH aqueous solution. The electrodes made of rGO-Fe2O3 nanocomposite synthesized by urea as reduction aid showed a high specific capacitance of 291 F g−1 at 1 A g−1 in the potential range of − 1 to 0 V. The best electrochemical performance of urea reducted rGO-Fe2O3 nanocomposites is basically attributed to the effect of Fe2O3 nanoparticles in preventing the restacking of rGO sheets.

Synthesis and characterization of WC@GNFs as an efficient supercapacitor electrode material in acidic medium

A two-step route to the preparation of graphene (G) nanoflakes (NFs), designed with tungsten carbide (WC) nanoparticles (WC@GNFs), through microwave irradiation and hydrothermal treatments. A uniform distribution of the WC nanoparticles on the graphene layers was confirmed through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. Additionally, X-ray diffraction (XRD) study demonstrated the presence of the characteristic crystal planes of tungsten carbide on those of graphene. An increase in the graphitization degree (G/1D = 4.9) of the WC@GNF nanocomposite was determined by Raman spectroscopy. These highlighted physical properties enabled the application of this nanomaterial, as a supercapacitor electrode in an H2SO4 electrolyte. The cyclic voltammetry (CV) scans indicated that the charging process was controlled by a pseudocapacitive contribution in conjunction with the electrical double-layered features. A specific capacitance, 1009.52 F/g, was estimated, at 1 mV/s, with improved retention of 106% during repeated cycles, at 20 A/g for 2000 cycles to outperform the obtained results for most relevant W-based nanomaterials. Therefore, the method of fabricating WC, proposed in this work, could be a simple method of examining the performance of a series of comparable transition metal carbides toward the technology of supercapacitors technology.

A nanocomposite consisting of cuprous oxide supported on graphitic carbon nitride nanosheets for non-enzymatic electrochemical sensing of 8-hydroxy-2'-deoxyguanosine.

Graphitic carbon nitrides supported cuprous oxide architecture isreported as an efficient electrode material for supercapacitors, especially due to itshigh charge-transfer conductivity ofthe electrochemical devices. Herein, we presentan electrochemical sensor to specifically detect 8-hydroxy-2'-deoxyguanosine (8-HDG) oxidative stress biomarker using graphitic carbon nitrides that decorate acuprous oxide cubes modified electrode. The fabricated electrochemical sensor was characterized and proved by electrochemical methods, EDX, FESEM, and amperometry (i-t). In the presence of 8-hydroxy-2'-deoxyguanosine (8-HDG), the effective interaction between graphitic carbon nitrides and 8-HDG favors the accumulation on the Cu2O/g-C3N4/GCE, which increases the electrocatalytic propertyand amperometric response. Theproposed electrochemical sensor exhibits a widelinear range for 8-HDG in 0.1M phosphate buffer (pH7.0) from 25nM to 0.91mM, and the limit of detection (LOD) is 4.5nM. The stability of theCu2O/g-C3N4/GCE is improvedwhen stored at 4°C. Therepeatability and reproducibility ofthis electrochemical sensor is good and the sensorretains its current response for 8-HDG detection also after long time storage. Themodified sensor proved high selectivity and sensitivity for 8-HDG, which made it possible to determine8-HDG in biological samples. Furthermore, the Cu2O/g-C3N4/GCE offered a favorable electron transfer between the Cu2O/g-C3N4 and theelectrode interface compared to Cu2O/GCE, g-C3N4/GCE, and unmodified GCE. Graphical abstract Electrochemical detection of oxidative stress marker based on Cu2O@g-C3N4 materials modified electrode.

Synthesis, Structure and Electrochemical Properties of Ca Doped Lanthanum Manganite Powders As Supercapacitor Electrode Material

The rapidly increasing energy demand due to the depletion of fossil fuels and worsening environmental pollution have led to recent research interests on clean energy sources, energy conversion, and energy-storage systems. Therefore, supercapacitors also referred as electrochemical capacitors have gained a great deal of attention in industry as well as academia compared with the batteries and fuel cells because of the significant properties such as high power density produced by fast charge/discharge rate and long cycle life. Generally, conducting polymers, carbon-based materials and metal oxides have been extensively investigated to develop the most efficient electrode material for supercapacitors. Among the metal oxides, the perovskite oxides with ABO3 crystal structure has drawn lots of interest owing to exhibiting reversible faradaic surface reactions, their high intrinsic capacity, excellent thermal stability and also low cost among pseudocapacitive materials. On the other hand, LaMnO3 perovskite is a promising material in terms of accessibility, environmental friendliness, and also its capability to store charges through intercalation and reversible faradaic surface reactions in vacancies (both oxygen and cation).Considering chemical states and type of defects are influenced by introduction of the dopant elements to main structure, in this study we have synthesized calcium doped LaMnO3 perovskites. The LaMnO3 (LMO) and La1-xCaxMnO3 (LCM-x) (x=0.1, 0.3, 0.5) nanocrystalline powders have prepared via the modified pechini method to obtain nanoparticles with high surface area, and the effect of calcium content on electrochemical properties studied with respect to pure LaMnO3. The crystalline structures of the nanopowders have characterized by X-ray diffraction (XRD, Bruker D8 Advance) and also elemental compositions of the samples have identified by X-ray fluorescence spectrometer (XRF, Bruker Tiger S8). The surface morphologies have determined with the field emission scanning electron microscopy (FE-SEM, Zeiss Ultra Plus). The Brunauer-Emmett-Teller method (BET, Micromeritics ASAP 2020) has been used for examination of the surface area. For surface electronic states of powders, X-ray photoelectron spectroscopy (XPS, Thermo K-Alpha) have performed with Al K-alpha radiation source.To evaluate the electrochemical properties of prepared samples, cyclic voltammetry (CV) and galvanostatic charge-discharge measurements (GCD) have carried out with three electrode system in 1M KOH electrolyte at the potential window of -0.1 to 1.4 V (vs RHE), and at different scan rates ranging from 2 to 100 mV. s-1. According to assessment of CV results, specific capacitance of LCM-0.3 has been found as 1114.3 F. g-1 nearly 5 times higher than that of pure LaMnO3 sample (238.1 F. g-1) at the scan rate of 2 mV. s-1. Compatible with the CV results, the LCM-0.3 sample have also performed the highest capacitance with 1499.2 F. g-1 at current density of 0.5 A. g- 1. The results have revealed that calcium doped lanthanum manganite based perovskites could be promising in the supercapacitor electrode materials area. Effect of chemical composition on structure, particle size, surface area and electrochemical performance will be discussed in detail.

Polyaniline-derived nitrogen- and oxygen-decorated hierarchical porous carbons as an efficient electrode material for supercapacitors

Polyaniline-derived oxygen- and nitrogen-decorated hierarchical porous carbons (N/O-HPC) are easily prepared by fast electrochemical polymerization combined with pyrolysis process. During the heating process, perchloric acid was decomposed to produce oxygen which could react with PANI-derived carbon to form a porous structure. The XPS results show the content of oxygen and nitrogen functional groups in the porous carbon matrix is 4.31% and 4.42%, respectively, and the BET results show that the specific surface area of the porous carbon is 1197.4 m2 g−1. The high content of oxygen and nitrogen functional groups as well as the high specific surface area is beneficial to N/O-HPC materials as supercapacitors. Typically, N/O-HPC displays a high specific capacitance of 419.8 F g−1, 179.8 F g−1, and 343.2 F g−1 at 0.2 A g−1 in 1 M H2SO4, 0.5 M K2SO4, and 6 M KOH electrolytes, respectively. Specially, the maintenance of capacitance is over 93% after 5000 cycles at 5 A g−1 in all three electrolyte solutions. The outstanding electrochemical performance of N/O-HPC can be ascribed to the introduction of nitrogen and oxygen functional groups in porous carbon matrix and the formation of special porous structure.

고성능 슈퍼 커패시터용 전극재료의 결합재가 없는 배터리 타입 나노시트로 정렬된 CuSe 나노구조의 합성

Hierarchical CuSe interconnected nanosheet arrays (NSAs)-like structures are grown on nickel foam via a facile and low-cost chemical bath deposition technique. These CuSe electrodes are used as an efficient electrode material for supercapacitor without using any binders or conducting polymer additives. The structural, composition and morphological behaviors of the CuSe electrodes are characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy methods. The CuSe NSAs provide the abundant active sites, high conductivity and rapid charge transport, which resulting the low-charge transfer resistance at the interface of electrode-electrolyte. Cyclic voltammetry and galvanostatic charge-discharge plateaus from the CuSe electrode exhibit the Faradic battery-type redox behavior, which is distinct form the profiles of carbon based materials. As a battery-type electrode, the NSAs-like CuSe nanoarchitectures exhibits the outstanding electrochemical performances with a high specific capacity (∼192.93 mA h g-1at2Ag-1) and excellent cycling life(∼95.23% at 6Ag-1over3000cycles), respectively. Therefore, with the above findings, CuSe material has remarkable application potential in supercapacitors and could be effectively applied in other energy storage technologies.

Nanospherical Cu2O/NiO synthesized by electrochemical dealloying as efficient electrode materials for supercapacitors

In this study, Cu2O/NiO with nanosphere structure has been successfully synthesized by dealloying a copper foil coated with Zn-Cu-Ni alloy films. First, Zn-Ni films were electrodeposited on copper foil. Next, the Zn-Cu-Ni films were produced by annealing and the Cu2O/NiO was obtained after Zn-dealloying and oxidation. Due to the advantage of the tunable nanosphere structure and dealloying synthesis method, Cu2O/NiO has excellent supercapacitor properties, such as excellent cycling stability (94.5% after 5000 cycles) and high specific capacitance (2255.5 mF/cm2 in 1 mA/cm2). These data suggested that this low-cost oxide Cu2O/NiO with nanosphere morphology synthesized by dealloying method could be a promising electrode material for supercapacitors.

Enhanced Electrochemical Performance of Co2NiO4/Ti3C2Tx Structures through Coupled Synergistic Effects

AbstractIn this work, Co2NiO4/MXene (Ti3C2Tx) composites as efficient electrode materials for supercapacitors are successfully synthesized by a facile one‐pot hydrothermal route. The as‐prepared products deliver a capacitance of 719.5 F g−1 at 0.5 A g−1 and keep 83.1% of initial capacitance after 10000 cycles, revealing the remarkable electrochemical performance compared with other two single electrodes. An asymmetric supercapacitor is fabricated, which presents an energy density of 49.74 Wh kg−1 at a power density of 2752.21 W kg−1, demonstrating that the products can be potential candidates in high performance energy storage devices.

Coal derived graphene as an efficient supercapacitor electrode material

We report simple and cost effective production of water soluble graphene sheets using coal. The synthesized coal derived graphene (CDG) sheets were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), Raman, Fourier transform infrared (FTIR), ultra-violet visible (UV–vis) spectroscopy, and photoluminescence (PL) measurements. The presence of edge oxygen functionalities in CDG sheets causes to induce fluorescent properties. The nature emission peak does not change with varying the excitation wavelength. To determine its energy storage properties, cyclic voltammetry (CV), charge-discharge and electrochemical impedance spectroscopy (EIS) measurements were done in different electrolytes. The value of specific capacitance (SC) of CDG in 1 M Na2SO4 electrolyte turns out to be 277 F/g at scan rate of 5 mV/s. CDG show long cycle stability i.e., the value of SC remains at ~91% after 2000 cycles at the current density of 10 mA/g.

Supercapacitive and ORR performances of nitrogen-doped hollow carbon spheres pyrolyzed from polystyrene@polypyrrole-polyaniline

Nitrogen-doped hollow carbon spheres (NHCSs) derived from polystyrene@polypyrrole-polyaniline (PS@PPY-PANI) core-shell composite microspheres of large surface area with improved electrochemistry performances have been effectively prepared and characterized systematically. NHCSs exhibited exceptional electrochemical properties with a maximum specific capacitance of 294.9 F g−1 at a 5 mVs−1 with good cycling stability of 95% after 5000 cycles at 0.5 A g−1. It also showed enhanced oxygen reduction reaction (ORR) activity with a high onset potential of 0.83 V vs. RHE at 1600 rpm via the more favorable four-electron pathway in an alkaline medium. Enhanced electrochemical and electrocatalytic performances could arise from the hollow porous spherical structure, high surface area, and considerable pyrrolic-pyridinic nitrogen contents. Pyrolysis commences the incorporation of nitrogen units together with the high degree of graphitization which contributes exceptionally to improve the ion/charge transfers. Significantly, the synergistic effect of pyrolysis and the proper concentration of PPY-PANI improve the overall electrochemistry performances of NHCSs. The excellent cyclic stability, high specific capacitance, and exceptional ORR activity indicate its perspective as an efficient electrode material for supercapacitors and fuel cells.