Electrode Material For High-performance Supercapacitors Research Articles

Dense graphene composite hydrogels as advanced electrode materials for high-performance supercapacitors

In this work, alanine functionalized nanocellulose/graphene composite hydrogels (NCGHalas) were prepared via an easy hydrothermal reaction using alanine, GO, and nanocellulose as reactant. Thanks to this synthesis strategy, NCGHalas exhibited large bulk density, abundant heteroatom functional groups, reasonable porous structure and moderate specific surface area. Based on the above characteristics, the aqueous symmetric supercapacitors (ASSC) assembled by NCGHala25 presented high gravimetric and volumetric specific capacitance of 276.5Fg-1 and 320.8Fcm-3 at 0.3Ag-1, excellent rate performance (77.9% at 10Ag-1), and long working life of 95.4% retention after 10,000 cycles at 10Ag-1. Furthermore, the NCGHala25 based ASSC also exhibited large gravimetric and volumetric specific energy densities of 9.6Whkg-1 and 11.1WhL-1. More importantly, the flexible solid-state supercapacitors (FSSC) fabricated by NCGHala25 and PVA-KOH electrolyte delivered high specific capacitance (178.2Fg-1, 0.3Ag-1), and this value can be maintained for 74.2% even at 10Ag-1.

High-performance supercapacitor electrode materials from composite of bamboo tar pitch activated carbon and tannic acid carbon quantum dots

A novel composite electrode material comprising bamboo tar pitch-based activated carbon (BTPAC) and tannic acid-derived carbon quantum dots (TACDs) was prepared. The integration of TACDs into the composite BTPAC-60/TACD not only preserved the high conductivity characteristic of BTPAC but also enhanced its hydrophilicity, pore structure, and specific surface area. Electrochemical evaluations revealed that BTPAC-60/TACD delivers a specific capacitance of 677.7 F/g at 0.5 A/g in a three-electrode system, and 281.8 F/g at 1 A/g in a two-electrode setup. Impressively, it achieves an energy density of 56.4 Wh/kg at a power density of 600 W/kg and maintains 95.7 % of its capacitance after 10,000 cycles. This research not only capitalizes on the high-value application of bamboo tar pitch but also provides a new perspective for the development of high-performance supercapacitor electrodes.

Bimetallic MOF derived Ni[sbnd]Mn phosphide for high-performance supercapacitor electrode material

Nickel‑manganese bimetallic phosphides are prepared by phosphidization of MOF-derived bimetallic hydroxides. The bimetallic phosphides exhibit crystalline Ni2P phase, show high specific surface area, and are composed of nanosheets. When supported on carbon cloth (CC) and used as the electrode material in 4 M KOH, the (Ni0.93Mn0.07)2P-18/CC shows a specific capacitance of 851.1C g−1 at 1 A g−1 and maintains 84.87 % capacity after 5000 cycles. The origin of the high specific capacity is investigated, and electron interaction between Mn and Ni sites, the high specific surface area, and the facile ion transport leads to the high specific capacity and stability. The constructed (Ni0.93Mn0.07)2P-18//AC asymmetric supercapacitor has an energy density of 59.83 Wh kg−1 at a power density of 750 W kg−1 and a capacity retention of 95.5 % after 5000 cycles.

Synthesis of surfactant-assisted nickel ferrite nanoparticles (NFNPs@surfactant) to amplify their application as an advanced electrode material for high-performance supercapacitors.

Nickel ferrite nanoparticles (NFNPs) were synthesized in an alkaline medium (pH ∼ 11) using a wet chemical co-precipitation technique. To probe the effect of surfactants on the surface morphology, particle size and size distribution of nanoparticles; two surfactants, namely, cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulphate (SDS), were applied. The native and surfactant-assisted nickel ferrite NPs were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), dynamic light scattering (DLS) and transmission electron microscopy (TEM). The addition of surfactants (CTAB/SDS) effectively controlled the secondary growth of nickel ferrite particles and reduced their size, as examined by XRD, AFM, DLS, SEM and TEM. Characterization technique results affirmed that CTAB is a more optimistic surfactant to control the clustering, dispersion and particle size (∼22 nm) of NFNPs. To identify the impact of ferrite particle size on charge storage devices, their electrochemical properties were studied by using cyclic voltammetry (CV), galvanic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 1 M KOH electrolyte through three-electrode assembly. NiFe2O4@CTAB showed a specific capacity of 267.1 C g-1, specific capacitance of 593.6 F g-1 and energy density of 16.69 W h kg-1, which was far better than the performances of other synthesized native NFNPs and NiFe2O4@SDS having larger surface areas.

NiCoMn-LDH with core-shell heterostructures based on CoS nanotube arrays containing multiple ion diffusion channels for boosted supercapacitor applications

Nanostructure engineering and composition rationalization are crucial for materials to become candidates for high-performance supercapacitor. Herein, a novel core-shell heterostructured electrode, combining CoS hollow nanorods with NiCoMn-layered double hydroxides (LDH) ternary metal nanosheets, were prepared on carbon cloth by reasonably controlled vulcanization and electrodeposition. By optimizing electrodeposition conditions, the material's structure and properties can be fine-tuned. The enhanced capacitance of the optimized carbon cloth (CC)@CoS/NiCoMn-LDH-300 electrode (4256.0 F g−1) lies in the open space provided by CoS and the establishment of a new charge transfer channel across the interfaces of CC@CoS/NiCoMn-LDH-300 nanosheets. This is further demonstrated by Density functional theory (DFT) simulations based on OH− adsorption energy, which produces faster redox charge kinetics and significantly enhances the electrode's energy storage capacity. The hybrid supercapacitor, integrating the optimized CC@CoS/NiCoMn-LDH-300 electrode with active carbon, demonstrates the highest energy density of 86 Wh kg−1 (under the power density of 850 W kg−1) and the long cycle stability of 89.7%. This study aims to go beyond simple binary LDH by constructing a ternary LDH with a hierarchical core-shell heterostructure to provide an effective and feasible new concept for high-performance supercapacitor electrode materials via rational structure design.

A sustainable solution: Conversion of distillers' grains waste into high-performance supercapacitor electrode materials for energy storage applications

The development of cost-effective biomass-derived carbon with good electrochemical properties is crucial for advancing energy storage devices sustainably. One feasible approach to producing supercapacitor electrode materials is the conversion of heteroatom-rich biomass waste into heteroatom self-doped hierarchical porous carbons with favorable electrochemical properties. In this study, distillers' grains with abundant crude fiber and protein were utilized as precursors to prepare N, S self-doped hierarchical porous carbon, which presents a high specific surface area of 3642.87 m2 g−1. The N, S doping could improve the interfacial wettability of electrode materials and enhance the pseudocapacitive effect of the materials. In three-electrode system, the carbon delivered a high capacitance of 347 F g−1 at 1 A g−1. Symmetrical capacitors assembled with PVA/KOH gel electrolytes delivered an ultrahigh energy density of 11.29 Wh kg−1 at a power density of 250 W kg−1. This strategy provides a practical, low-cost, and renewable design approach of carbon electrode for high-performance supercapacitors.

Biodegradable Activated Carbon Material Derived from Eggplant Waste for Enhanced Supercapacitor Performance

Agricultural-waste-derived porous carbon and vegetable-waste-derived porous carbon materials have been extensively studied as electrode materials for high-performance supercapacitors due to their abundance and ability to be consistently reproduced. This paper focuses on utilizing eggplant waste, the primary by-product, as a precursor for producing porous carbon through the easy carbonization and activation process. The resultant porous carbon is then employed as an electrode material for supercapacitors. The Eggplant waste-derived porous carbon exhibits a notable surface area of 1095.4 m2 g-1. This carbon material possesses the benefits of being cost-effective and environmentally friendly while exhibiting superior electrochemical performance in comparison to materials obtained from agricultural waste. The carbon electrode made from eggplant demonstrates an energy density of 9.19 Wh Kg-1 and a power density of 2880 W Kg-1, indicating its outstanding energy storage capacity.

Preparation of Positive and Negative Composite Electrode Materials for High-Performance Aqueous Asymmetric Supercapacitor by a Sequential Two-Step Reaction

Preparation of Positive and Negative Composite Electrode Materials for High-Performance Aqueous Asymmetric Supercapacitor by a Sequential Two-Step Reaction

Enzymatic synthesis of biocompatible polypyrrole with enhanced electrochemical properties for supercapacitors

This study focuses on the biocompatible and ecofriendly enzymatic synthesis of conductive polypyrrole (PPy) using mediators for supercapacitor electrode material. The work investigates the effects of various mediator systems on laccase-catalyzed oxidation of pyrrole and is confirmed through Fourier transform infrared spectroscopy (FTIR) and Ultraviolet (UV) visible spectroscopy. The x-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis has revealed that both mediators and laccase can produce crystalline and amorphous PPy with agglomeration of globular-shaped particles. The PPy-ABTS (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) demonstrates higher decomposition temperatures, indicating superior thermal stability up to 400 °C. Electrochemical studies such as cyclic voltammetry (CV), galvanometric charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) revealed that PPy-ABTS possesses good electrochemical properties. Compared to other laccase-mediated materials synthesized PPy in this study, PPy-ABTS exhibits higher specific capacitance values (242 F g−1 by CV at 10 mV s−1 and 153 F g−1 by GCD at 1 A g−1), with a capacitance retention of nearly 90 % after 10000 cycles. Cytotoxicity study shows that PPy-ABTS has an IC50 value of 528 μg ml−1 against human breast adenocarcinoma (MCF-7) cells, indicating its biocompatibility. Consequently, PPy-ABTS emerges as a promising electrode material for high-performance supercapacitors. Its unreported biocompatibility opens up possibilities for diverse biomedical applications.

Solution-processed Sb2O3: A promising electrode material for high-performance supercapacitors and electrocatalysts

Easy accessibility, wide range of redox states, affordable cost, and simple synthesis methods of metal oxides have gained a significant interest in the domains of electrochemical supercapacitors and electrocatalysts. The successive ionic layer adsorption and reaction (SILAR) chemical synthesis approach has been introduced to preparing nanocrystalline antimony oxide (Sb2O3) for both energy storage and water splitting applications. The Sb2O3 electrode demonstrates a remarkable specific capacitance of 3011 F/g at a current density of 2 A/g in a 1 M solution of potassium hydroxide (KOH). The current design of the Sb2O3//Bi2O3 (bismuth oxide) asymmetric electrochemical supercapacitor device has endowed a specific capacitance of 391 F/g, a maximum energy density of 78.2 Wh/Kg at a power density of 1000 W/Kg, and an outstanding capacitance retention of 77 % even after 5000 redox cycles. The Sb2O3 electrode demonstrates outstanding performance in the oxygen evolution process at a current density of 10 mA cm2, with an overpotential of 206 mV. The Sb2O3 as an electrocatalyst also exhibits exceptional results in the hydrogen evolution reaction with an overpotential of 124 mV/dec. Both of these electrochemical processes are distinguished by the evolution of oxygen which is capable of facilitating the process of water splitting to obtain clean energy for day by day growing population.

Mn-doped V2O5@rGO towards high-performance electrode materials for aqueous zinc-ion supercapacitors

In order to address the diverse energy storage requirements, there is an urgent need to fabricate supercapacitors with high specific capacitance, long cycle life, high power density and high energy density. Among various transition metal oxide materials, vanadium pentoxide emerges as a promising candidate for cathode materials in supercapacitors. Herein, we report an ion intercalation strategy to synthesize Mn-doped V2O5 (MnVO) and recombine it with reduced graphene oxide (rGO) to form Mn-doped V2O5@rGO (MnVO@rGO) hybrids with special hierarchical structure. During the hydrothermal process, Mn2+ gradually inserts into the layer spacing of V2O5 to form nanobelts, which could be cross-linked with graphene nanosheets to form MnVO@rGO 3D skeleton network. This unique structure enables the MnVO@rGO electrode to exhibit excellent specific capacitance of 1120 F g−1 at 0.2 A g−1. Outstanding cycling performance is demonstrated by achieving a capacity retention rate of 91.5 % after 2000 cycle. The symmetrical supercapacitor device assembled with MnVO@rGO as both positive and negative electrodes exhibits an energy density of 150.75 and 77.5 W h Kg−1 at power density of 450 and 9000 W kg−1, respectively. Moreover, DFT calculations also have been employed to account for the improved electrochemical performances of MnVO@rGO. Besides, the excellent electrochemical performances of MnVO@rGO indicate that it has broad application prospects in future energy storage devices.

Puffed millet derived bi-functional carbon nitride nano-sheets as efficient photocatalyst and high performance supercapacitor electrode material

The graphitic carbon nitride has been synthesized by eco-friendly method using millet seeds. The thermal puffing effect had turned millet into puffed millet and formed adjacent nanosheets nanostructure. High surface area of g-CN was achieved by using KOH through activation process and nanosheets are in the range of 150–250 nm. CV measurement demonstrated that it has capacitance of 250F/g with high stability and cyclic retention (92.2 %) which are crucial for supercapacitors. The degradation of methyl orange exhibited good photocatalytic performance (efficiency >90 %). This depicts that both “puffing effect” and chemical activation process could change biomaterials into functional materials for practical application.

Designing reduced graphene oxide decorated Ni doped δ-MnO2 nanocomposites for supercapacitor applications

Reduced Graphene Oxide (rGO) decorated δ-MnO2 and Ni-doped δ-MnO2 samples have been synthesized by a microwave-assisted co-precipitation technique which is low cost, simple and fast reaction method. The structural and morphological properties of synthesized samples have been characterized using x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). XRD result indicates that all samples have monoclinic crystal structure with δ phase of MnO2. The morphologies of MnO2 transformed into perforated porous nanoflakes with Ni doping and rGO composition in MnO2. AFM images confirmed that surface roughness for 3 % Ni-doped MnO2 samples is higher due to the chemical adsorption of samples. Raman spectroscopy results show the presence of vibrational and Raman active modes of MnO2.X-ray photoelectronic spectroscopy revealed the presence of mixed valencies of Mn such as Mn2+, Mn3+, and Mn4+ in prepared nanocomposites while Ni shows 2+ valency. The specific capacitance (Cs) of pure δ -MnO2 samples were 68 Fg-1 and rGO decorated 3 % Ni-doped MnO2 composition 694 Fg-1 at 10 mVs−1 respectively. EIS data of the rGO decorated Ni-doped MnO2 composition samples confirm that the porous nanoflake-shaped rGO decorated 3 % Ni-doped MnO2 composite sample has a low resistance value among all samples. These results reveal that rGO-decorated 3 % Ni-doped MnO2 nanoflakes should be a promising material for designing and fabricating the electrode material for high-performance supercapacitors.

Ligand regulation and capacitive properties of nickel based pyrazole trinuclear copper cluster organic framework

Traditional metal organic framework (MOF) hinders its application as high-performance electrode materials for supercapacitors due to the limited electron transfer efficiency and conjugation of its ligand molecules. Therefore, in this article, highly electrochemical active pyrazole trincore-copper cluster derivatives as the core unit were covalently assembled by Schiff base reaction with organic linkers of different structures to obtain a series of structurally different electroactive ligands. It was found that ligands with multiactive metal chelation site structure with polydentate carboxylate linker and aromatic extension showed high coordination ability and high degree of conjugation. The nickel-based MOF synthesized with this novel electroactive ligand exhibited a high specific capacitance of 1804 Fg−1 at a current density of 1 Ag−1. At a power density of 747.25 W kg−1, the maximum energy density of the assembled asymmetric supercapacitor assembled with Cu-PyAc-Am2Ac-Ni is 58.95 Wh kg−1 with cycling stability of 88.95 % after 5000 charges and discharges. This means that Cu-PyAc-Am2Ac-Ni is a promising electrode material for supercapacitors.

A High-Performance Supercapacitor Based on Hierarchical Template-Free Ni/SnO2 Nanostructures via Hydrothermal Method.

Novel flake-like Ni1-xSnxO2 particles were successfully prepared by template-free hydrothermal synthesis. The prepared samples were investigated for their properties by different characterization techniques. Scanning micrographs showed that the obtained particles consisted of nanoflakes. The X-ray diffraction results of the Ni1-xSnxO2 revealed the formation of mixed-phase Ni/SnO2 having the typical tetragonal structure of SnO2, and the cubic structure of Ni in a nanocrystalline nature. The doping with Ni had a certain influence on the host's lattice structure of SnO2 at different doping concentrations. Confirmation of the functional groups and the elements in the nanomaterials was accomplished using FTIR and EDS analyses. The electrochemical performance analysis of the prepared nanomaterials were carried out with the help of the CV, GCD, and EIS techniques. The specific capacitance of the synthesized nanomaterials with different concentrations of Ni dopant in SnO2 was analyzed at different scanning rates. Interestingly, a 5% Ni-doped SnO2 nanocomposite exhibited a maximum specific capacitance of 841.85 F g-1 at 5 mV s-1 in a 6 M KOH electrolyte. Further, to boost the electrochemical performance, a redox additive electrolyte was utilized, which exhibited a maximum specific capacitance of 2130.33 at 5 mV s-1 and an excellent capacitance retention of 93.22% after 10,000 GCD cycles. These excellent electrochemical characteristics suggest that the Ni/SnO2 nanocomposite could be utilized as an electrode material for high-performance supercapacitors.

Structure, Properties, and Preparation of MXene and the Application of Its Composites in Supercapacitors

Two-dimensional transition metal carbides/nitrides (MXenes) are emerging members of the two-dimensional material family, obtained by removing the A layer of the MAX phase through methods such as liquid-phase etching. This article summarizes the structure and properties of MXenes, as well as several preparation methods, including etching with hydrofluoric acid and fluoride salts, alkali-based etching, electrochemical etching, Lewis acid molten salt etching, and direct synthesis. Due to their unique two-dimensional structure and surface chemistry, MXenes exhibit good metallic conductivity, hydrophilicity, excellent flexibility, and ion intercalation properties, showing great potential in the research and application of supercapacitors and attracting widespread attention. The combination of MXene with other types of materials, including polymers, metal hydroxides, metal oxides, and carbon materials, takes advantage of composites to improve energy storage performance and shows great potential in the research and application of supercapacitors. This article provides a detailed summary of MXene composite materials and capacitor performance and introduces the research progress of MXene materials in the field of supercapacitor energy storage applications, aiming to provide references for the preparation of high-performance MXene supercapacitor electrode materials.

Fabrication of nickel foam/MXene/CoAl-layered double hydroxide by electrodeposition as electrode material for high-performance asymmetric supercapacitor

Layered double hydroxides (LDH) have become one of the highly promising electrode materials due to large specific area, excellent cycling stability and high energy density. However, the large internal resistance limits their applications in energy storage. The introduction of highly conductive materials is expected to solve this problem. In here, nickel foam (NF)/MXene/CoAl-LDH is prepared by electrodepositing CoAl-LDH on the surface of MXene-coated NF, and the effects of Co:Al ratio on the electrochemical properties are investigated in detail. The best electrochemical performance of the composite is obtained when Co:Al=2:1, with a specific capacitance of 646.7 F g−1 at 0.5 A g−1 and 450.8 F g−1 at 5 A g−1. Furthermore, the asymmetric supercapacitor is assembled with NF/MXene/CoAl-LDH as the positive electrode and activated carbon (AC) as the negative electrode. The voltage window of the device can reach 1.6 V. The specific capacitance of the device is 126.87 F g−1 at a current density of 0.5 A g−1. At the power density of 400 W kg−1, the energy density of 45.11 Wh kg−1 is provided. Even at the high power density of 4000 W kg−1, the energy density can still reach 17.88 Wh kg−1. After 5000 cycles at a current density of 5 A g−1, it still maintains a capacity retention rate of 92.9%. The asymmetric device with its high specific capacitance, long term stability and good power density and energy density has a great potential in energy storage applications.

3D Nanoflower-like and core-shell structured heterogeneous CuCo2O4@CuCo2S4@Ni(OH)2 electrode materials for high-performance asymmetric supercapacitor

The planning and synthesis of nanocomposite materials with reasonable core-shell heterostructure are of great significance in enhancing the energy density, structural stability as well as long cycle life of asymmetric supercapacitors. We have successfully prepared CuCo2O4@CuCo2S4@Ni(OH)2 core-shell 3D nanoflower array electrode material, resulting in outstanding performance of the assembled supercapacitor. Firstly, CuCo2O4 (CuC) nanowires are grown directly on nickel foam (NF) through hydrothermal and calcination reactions, followed by the formation of heterogeneous CuCo2O4@CuCo2S4 (CuC@CuS) nanoflowers via a hydrothermal reaction by using Na2S·9H2O as a vulcanizing agent. Finally, CuCo2O4@CuCo2S4@Ni(OH)2 electrode material is obtained via the electrodeposition method under a constant voltage. The prepared electrode material is composed of conductive CuC@CuS nanoflowers as the core and deposited Ni(OH)2 nanosheets as the shell, which effectively promotes ion diffusion, increases the reactive area and thereby enhances the electrochemical performance. Impressively, the composite electrode CuC@CuS@Ni(OH)2/NF material achieves an exciting high capacitance of 3753.6 F g−1 (1 A g−1), and the cycle stability is reduced by only 7.1 % after 10,000 cycle tests in the standard three-electrode system. Furthermore, the asymmetric supercapacitor (ASC) device composed of activated carbon (AC) and CuC@CuS@Ni(OH)2 exhibits 729.75 W kg−1 power density under 59.11 Wh kg−1 energy density. The aforementioned findings demonstrate that the CuC@CuS@Ni(OH)2 nanoflower array is a very potential energy storage material.

Design and construction of conductive polymer PPy anchored NiCo bi-metal sulfide composite electrode materials for high-performance hybrid supercapacitor and electrochemical hydroquinone sensor

The development of green energy materials has a crucial role in the energy crisis and environmental issues. The dual-functional oriented strategy was used to prepare new electrode material PPy@NCS by using glycerol as a template. The electrode material PPy@NCS-5 exhibits a higher specific capacitance of 2011.6 F g−1 at 1 A g−1 and delivers excellent long-term cycling stability with 93.3 % of its specific capacitance retained at 20 Ag−1 after 5000 cycles. A hybrid supercapacitor (HSC) combining PPy@NCS-5 and activated carbon (AC) yields a high energy density of 44.6 Wh kg−1 at a power density of 15,005.6 W kg−1. Furthermore, the as-prepared PPy@NCS-5/GCE can be used as an HQ sensor, which displays high sensitivity (0.026 μA/μM), an extraordinary linear response ranging (0.5–1923 μM), and a low detection limit (0.026 μM).

Synergistic effects of CoS-decorated Ni-MOF with hierarchical structures for high-performance supercapacitor electrode materials

To further improve the electrochemical performance of supercapacitor, the construction of composite based electrode material was proved to be an effective strategy. Herein, CoS-decorated Ni-MOF composites with hierarchical structures and obvious synergistic effects were synthesized by one-step hydrothermal and subsequent electrodeposition route. Benefitting from the increased surface roughness with more exposed active sites, the hierarchical structure with high space utilization rate for rapid ion transport as well as the improved conductivity and entire robustness, the optimal composites exhibited an excellent specific capacitance (2167.5 F g−1 at 1 A g−1), outstanding rate performance (up to 70.1% even at 5 A g−1) and the good cycle stability (80.12% capacity retention after 3500 cycles). The corresponding assembled asymmetric supercapacitors could reach an energy density 92.18 Wh kg−1 when the power density of was 1626.71 W kg−1, which overwhelmed most other reported works. What is more, the capacity retention could maintain 73.34% even after 7000 cycles, indicating the excellent cycle stability. Overall, to our knowledge, this is the first report on a synergistic effect of a combination of Ni-MOF and CoS. The constructed composites exhibited great potential as promising candidates for high-performance energy storage devices.