Electrode Material For High-performance Supercapacitors Research Articles

Hierarchically fabricated nano flakes-rod-like CoMoO–S supported Ni-foam for high-performance supercapacitor electrode material

Nano-sized CoMoO has emerged as a gifted contender for renewable energy conversion storage applications. However, the limited stability and unique surface areas of oxide-based materials present challenges in the use of supercapacitors (SCs). In this work, we employed a facile hydrothermal method to hierarchically fabricate nanoflakes-rod-like CoMoO–S materials on nickel foam (NF). The resulting electrodes exhibited remarkable electrochemical activity, attributed to the synergistic properties of the well-allied CoMoO 2D nanorods. Notably, the developed CoMoO–S nanoflakes-rod (3D-2D) composites proved an excellent specific capacitance of 1087 F g−1 at 2 A/g current density, along with excellent rate capabilities surpassing those of single CoMoO nanorods electrodes. Furthermore, the CoMoO–S nanoflakes-rod composites exhibited notable cyclic stability, with a retention rate of 86.3 % above 5000 cycles. The exceptional electrochemical characteristics displayed by electrode materials typically used in batteries provide a hopeful strategy for the advancement of high-performance supercapacitors.

Selenium incorporated sodium vanadate nanobelts as high-performance electrode material for long-lasting aqueous zinc-ion batteries and supercapacitors

Aqueous zinc-ion batteries (AZIBs) have received growing attention for comprehensive energy storage owing to their affordability and high safety. Still, cathode materials that usually exhibit low capacity or poor cycling performance have hindered the practical application of AZIBs. Herein, the selenium-incorporated sodium vanadate (Na2V6O16) (NVO@Se) nanobelts (NBs) were synthesized via a facile hydrothermal method, followed by calcination under N2 flow. As a cathode for AZIBs, the NVO@Se NBs electrode delivered a high discharge capacity value of 329.15 mA h g−1 at 2 A g−1 with ∼ 99 % coulombic efficiency and excellent rate capability (284.89 and 200.21 mA h g−1 at 4 and 5 A g−1, respectively). Mechanistic analyses of the intercalation reaction in the NVO@Se NBs after cycling using ex-situ X-ray diffraction, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy techniques revealed their good structural stability and electrochemical reversibility. Developing interactive properties, the NVO@Se NBs material was also studied as a battery-type electrode for hybrid supercapacitors (HSCs). By sandwiching the NVO@Se NBs and activated carbon, the fabricated HSC exhibited good power and energy density values, along with its verification for practical applications. From all the electrochemical characteristic results, the NVO@Se NBs material has good aspects for AZIBs and HSCs, which makes new prospects for the advancement of materials in energy storage applications.

Nano-casting synthesis of nanoporous carbons from biomass tar as sustainable electrode material for high-performance supercapacitor

Asphalt and coal tar, etc., as byproducts from fossil refinery featured with polycyclic carbon, are hot precursors for diverse advanced carbon functional materials. Herein, their bio-counterpart, namely biomass tar (BT), a notorious byproduct from biomass pyrolysis/gasification was successfully converted into O, N-co-doped carbon with interconnected porous structure via nano-casting with ZnO nano-rods. The optimal product obtained at 700 °C with mass ratio of 1:2:2 for biomass tar, nano-ZnO and KOH delivered specific capacitance up to 295F/g and 204F/g at current densities of 1 A/g and 20 A/g, respectively, and the specific capacitance was maintained at 86.3 % after 10,000 cycles of charging-discharging at 20 A/g. In the two-electrode system, a single electrode made of BTC-1Z-2K-700 still has a specific capacitance of 295.2 F/g at 0.2 A/g. Symmetrical supercapacitor device assembled with 1 M Na2SO4 as the electrolyte achieves the energy density of 27.19 Wh/kg at the power density of 640 W/kg. The impressive charge storage capacity and rating performance were attributed to its hierarchical porosity, large interface and low electric resistance. This work provides a novel out path for biomass tar valorization, as well as a sustainable and cost-effective candidate for electrode material for high-performance supercapacitor.

Construction of flower-like spherical CoFe2O4@Co3O4 based on zeolitic imidazolate framework as high-performance electrode materials for supercapacitors

Ferrite, a class of transition metal oxides, has emerged as a promising material for electrochemical energy storage due to its cost-effectiveness and high theoretical capacity. However, the tendency of ferrite to agglomerate hinders its practical application. Here, we report a facile method to fabricate CoFe2O4@Co3O4 flower-like sphere and form a unique core-shell structure. In this composite, flake Co3O4 pile up to form shell which cladding the CoFe2O4 core. Crumpled shell provide ultra-high specific surface area (128.54 m2/g) to expose more electrochemical active sites, benefiting effective electrons transfer. As a result, the optimized flower-like spherical structure electrode exhibited an exceptionally high capacity of 2834 F g−1 at a current density of 1 A g−1. Additionally, the electrode demonstrated outstanding rate capability, retaining 78 % of its capacity at a current density of 10 A g−1.

Biomass-based porous carbon for high-performance supercapacitor electrode materials prepared from Canada goldenrod

Preparing activated carbon from biomass materials that can be used as electrode materials for supercapacitors is crucial for realizing new green energy storage and conversion technologies to fulfill environmental requirements. Herein, activated carbon was prepared via high-temperature carbonization and KOH activation using Canada goldenrod as a raw material, which is a serious threat to the ecological environment. Using this activated carbon as the active material and 6 M KOH and 1 M TEABF4/AN as the electrolytes, aqueous and organic coin-cell symmetrical supercapacitors were prepared, respectively. The specific capacitance of activated carbon was calculated to reach 320 and 123 F/g at a current density of 0.1 A/g during its testing in a two-electrode system, corresponding to energy densities of 40 and 112.1 Wh/kg, respectively. The power density of the aqueous supercapacitor was 9 KW/Kg at 10 A/g, while that of the organic supercapacitor was 12.2 KW/Kg at 5 A/g; after 10,000 cycles of the charge–discharge test, the capacity retention rate reached 93.6 % and 86.4 %, indicating the excellent electrochemical performance of the prepared supercapacitor. In addition, the specific capacitance reached 366 and 252 F/g at capacitance densities of 0.1 and 0.5 A/g, respectively, during its testing in a three-electrode system. The results of this study indicate that Canada goldenrod is a good biomass-based precursor material for preparing porous carbon for supercapacitors.

Nanoarchitectonics on residual carbon from gasification fine slag upon two step low temperature activation for application in supercapacitors

In this paper, the carbon electrode materials were prepared by the KOH-HNO3 low-temperature activation technique using cheap residual carbon from gasification fine slag (CK) as raw materials. The results showed that the prepared material (CKN-2) which obtained by dry-wet sequential activation at 500°C for 1.5h at carbon to KOH ratio of 1:2 and further at 80°C for 1h in 2 mol/L HNO3 solution. The specific capacitance of CKN-2 reached 142 F/g at a current density of 0.5 A/g. CKN-2 was used to assemble a symmetrical (CKN-2//CKN-2) supercapacitor, which exhibited an energy density of 6.80 Wh/kg at a power density of 244.8 W/kg. The CKN-2//CKN-2 capacitor was tested for stability after 10,000 cycles, with a capacitance retention rate of 97%. These results demonstrate that residual carbon from gasification fine slag can be effectively used to produce high-performance carbon electrode materials for supercapacitors using the KOH-HNO3 low-temperature sequential co-activation technique.

Bidirectional pore-creating strategy towards lignin-based heteroatom-doped porous carbon for supercapacitors

Significant pursuits have been committed to manufacturing high-performance lignin carbon-based supercapacitor electrode materials due to their high carbon content, abundant raw resources, and environmentally-friendly. However, the pessimistic accessible porous structure and appetency to the electrolyte of electrode materials are two vital factors for restricting its performance. Here, a bidirectional pore-creating strategy is proposed to construct heteroatom-doped lignin-based porous carbon (HLPC) materials with a high electrochemical active area at supramolecular-level. In this process, activated-mediates with different pore-forming functions are assembled into lignin-based supramolecules by electrostatic forcing, and then hierarchical pore-creation and heteroatom doping are accomplished simultaneously in the pyrolysis process. The obtained carbon materials possess a tunable specific surface area of 543.4–1502.3 m2 g−1 and high heteroatom content of 9.4–16.2 at.%. Benefit from its admirable physicochemical properties, the HPLCs deliver a high ions appetency, ultrahigh capacitance of 380.5 F g−1 at 0.2 A g−1, and extremely long cyclic stability (100% after 10,000 cycles), which is superior 2.5-fold than that of YP-80F at the same mass loading. More promising, symmetrical electrode devices based on HLPCs possess a preeminent energy density of 30.0 Wh kg−1 in aqueous electrolyte. Overall, this protocol provides a new avenue for promoting the advancement of electrode materials in industrial-scale supercapacitors and manufacturing high-value-added products from plentiful bio-waste.

Investigation of supercapacitor electrode performances of phosphorus-doped graphene oxide electrodes in various deep eutectic solvents and symmetric supercapacitor application

A one-step preparation method of phosphorus-doped graphene oxide electrode (P-GOE) was used as electrode material for high-performance supercapacitors. Phosphorus-doped graphene oxides were synthesized on pencil graphite electrodes in one step with easy, cheap, and non-toxic chemicals by using the chronoamperometric process. Electrochemical analyses were carried out to examine the capacitive behavior of the electrodes in different deep eutectic solvents (DESs) (choline chloride:ethylene glycol (ChCl:EG), choline chloride:urea (ChCl:U), choline chloride:phenol (ChCl:Ph)). The electrolytes used make research valuable because these electrolytes were environmentally friendly, non-toxic, and inexpensive. Electrodes were analyzed by cyclic voltammetry at different scan rates, charge-discharge test at different current densities, 1000-cycle galvanostatic charge-discharge test, and electrochemical impedance spectroscopy (EIS). Structural and morphological properties of the electrodes were investigated by FTIR, XRD, SEM, BET, and XPS. As a result of the characterization and electrochemical analysis, it was seen that the phosphorus doping to the electrodes were carried out successfully. The maximum areal capacitances of phosphorus-doped graphene oxide electrodes were calculated to be 450 mF.cm−2, 140 mF.cm−2, and 400 mF.cm−2 in electrolytes for supercapacitor applications. In this study, high-performance P-doped graphene oxide electrodes were produced with an easy method using inexpensive and non-toxic solvents, providing an important contribution as environmentally friendly and sustainable electrode materials for supercapacitor applications.

Fabrication of Ni-MOFs/MWCNTs by in situ growth for high-performance supercapacitor electrode materials

Fabrication of Ni-MOFs/MWCNTs by in situ growth for high-performance supercapacitor electrode materials

FeCo2S4@Carbyne as a newer electrode material for High-Performance supercapacitors and Non-Enzymatic glucose sensors

Designing electrodes made of multicomponent with multiscale nanostructures serves as a footpath to accelerate the growth and practical applicability of supercapacitors and non-enzymatic glucose sensors. FeCo2S4@Carbyne is prepared by a deposition followed by a solvothermal process onto the nickel foam (substrate). The substrate acts as a conductive bridge providing more active sites, enhancing the charge transport and structural stability of FeCo2S4@Carbyne nanohybrid. Accounting for the above said advantages, the prepared nanohybrid results in an output of 2403.3 F g−1 at 1 A g−1. In addition, the assembled device generates 51.5 Wh kg−1 (energy density) at 0.84 KW kg−1 (power density). Furthermore, the fabricated FeCo2S4@Carbyne non-enzymatic sensor exhibits a limit of detection of about 0.057 mM with a sensitivity of about 157 µA mM−1cm−2. As a result, this work provides insight to develop metal sulphide complexes for multifunctional applications .

Construction of Binder-Free, Self-Supported, Hetero-Core-Shell Honeycomb Structured CuCo2 O4 @Ni0.5 Co0.5 (OH)2 with Abundant Mesopores and High Conductivity for High-Performance Energy Storage.

Clever and rational design of structural hierarchy, along with precise component adjustment, holds profound significance for the construction of high-performance supercapacitor electrode materials. In this study, a binder-free self-supported CCO@N0.5 C0.5 OH/NF cathode material is constructed with hierarchical hetero-core-shell honeycomb nanostructure by first growing CuCo2 O4 (CCO) nanopin arrays uniformly on highly conductive nickel foam (NF) substrate, and then anchoring Ni0.5 Co0.5 (OH)2 (N0.5 C0.5 OH) bimetallic hydroxide nanosheet arrays on the CCO nanopin arrays by adjusting the molar ratio of Ni(OH)2 and Co(OH)2 . The constructed CCO@N0.5 C0.5 OH/NF electrode material showcases a wealth of multivalent metal ions and mesopores, along with good electrical conductivity, excellent electrochemical reaction rates, and robust long-term performance (capacitance retention rate of 87.2%). The CCO@N0.5 C0.5 OH/NF electrode, benefiting from the hierarchical structure of the material and the exceptional synergy between multiple components, demonstrates an excellent specific capacitance (2553.6 F g-1 at 1 A g-1 ). Furthermore, the assembled asymmetric CCO@N0.5 C0.5 OH/NF//AC/NF supercapacitor demonstrates a high energy density (70.1Wh kg-1 at 850W kg-1 ), and maintains robust capacitance cycling stability performance (83.7%) after undergoing 10000 successive charges and discharges. It is noteworthy that the assembled supercapacitor exhibits an operating voltage (1.7V) that is well above the theoretical value (1.5V).

Constructing Interconnected Microporous Structures in Carbon by Homogeneous Activation as a Sustainable Electrode Material for High-Performance Supercapacitors.

Microporous carbon attracts attention as an electrode material for supercapacitors. However, a large number of deep and distorted mesoporous and macroporous structures are usually created by non-uniform etching, resulting in underutilized internal space. Homogeneous activation has been considered by researchers as a necessary condition for the formation of interconnected microporous structures in carbon materials. Herein, a simple strategy of hydrothermal introduction of defects followed by homogeneous activation for the preparation of microporous carbon was developed for the synthesis of electrode materials for high-performance supercapacitors. The optimized sample with defect-enriched microporous structure and large specific surface area has a specific capacity of 315 F g-1 (1 A g-1) in KOH solution, and the assembled symmetric supercapacitor achieves a high energy density of 7.3 Wh kg-1 at a power density of 250 W kg-1. This work is interesting because it not only demonstrates that rational design of electrode materials is important to boost the performance of supercapacitors, but also provides inspiration for the design of efficient supercapacitors in the future.

MoS2 blended MWCNT hybrid nanocomposites and its enhanced super capacitive features

The present work addresses a simple and sensitive approach to synthesize a 2D bare MoS2 and graphene analog MoS2/MWCNT nanocomposites as an effective electrode material for high-performance supercapacitors. The MoS2/MWCNT nanocomposites were prepared via simple hydrothermal treatment. The structural, functional, and morphological analysis were accessed through XRD, HRTEM, FESEM, FTIR, and RAMAN Spectroscopy augmenting the successful formation of MoS2/MWCNT nanocomposites. The structural analysis confirms the formation of the hexagonal phase. The morphological analysis possesses the nano-sphere-like structure which is made up of crumpled nanosheets. The chemical bonding and the location of Mo–S and CC bands were confirmed at 428 and 1651 C m-1 respectively. Detailed electrochemical analysis through cyclic voltammetric study, Galvanostatic Charge/discharge and electrochemical impedance techniques shows that as prepared m-M10 sample exhibits excellent super capacitive performances when compared to other samples. This electrode obtained a maximum specific capacitance of 848 F g-1 with a current density 1 A g-1. This material retains 82% of its initial capacitance after 5000 repeated charge-discharge cycles. It exhibits very less charge transfer resistance 0.2Ω and lesser than other electrodes.

Contribution of electron localization and delocalization zones in the performance of electrochemically reduced graphene oxide based supercapacitors: An experimental and the first-principles study

Graphene oxide (GO) has been investigated as a promising electrode material for supercapacitors due to its intriguing physical and chemical properties. However, the interpretation of the pseudocapacitance and charge storage mechanism in GO and its derivatives is still debated and is yet to be understood. Here, we report a detailed and comprehensive analysis of the pseudocapacitive charge storage mechanism in GO and electrochemically reduced GO electrodes using cyclic voltammetry, electrochemical impedance spectroscopy combined with first principles calculations. Contrary to conventional believes, our results reveal that pseudocapacitive charge storage mechanism is due to conduction built by the electron delocalization region in GO during reduction rather than localized electron transfer. It is observed that the removal of oxygen functional groups from the surface of the GO leads to decrease in diffusion current and the reconstructed electron delocalization region contributes to increased specific capacitance. This work provides a clear and fundamental understanding of pseudocapacitive charge storage mechanisms in GO derivatives that will be also helpful in exploration of GO-based novel and hybrid electrode materials for high-performance supercapacitors.

Cobalt phosphide/nickel–cobalt phosphide heterostructured hollow nanoflowers for high-performance supercapacitor and overall water splitting

In this work, a novel CoP/NiCoP heterostructure with hollow nanoflower morphology is designed and constructed. Benefiting from the hollow nanoflower morphology and tuned electronic structure, the heterostructured CoP/NiCoP hollow nanoflowers are demonstrated as both high-performance supercapacitor electrode materials and superior bifunctional electrocatalysts in overall water splitting. The CoP/NiCoP delivers a high capacitance of 1476.6 F g−1 at 1.0 A g−1 and shows enhanced rate capability. The constructed asymmetric supercapacitor achieves a high energy density of 32.4 Wh kg−1 at 800.5 W kg−1 and high power density of 16.5 kW kg−1 at 20.0 Wh kg−1. The CoP/NiCoP hollow nanoflowers are also proven to be remarkable hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalyst which achieves the current density of 10.0 mA cm−2 under an overpotential of 110.4 mV for HER and 310.7 mV for OER with superior stability in alkaline solution. In addition, the constructed CoP/NiCoP||CoP/NiCoP cell with CoP/NiCoP as both cathode material and anode material only requires 1.63 V @ 10.0 mA cm−2 for overall water splitting. This study sheds lights on the rational design and construction of bimetallic phosphides for both supercapacitor and overall water splitting.

Hierarchical porous nickel tin sulfide nanosheets as a binder free electrode for hybrid supercapacitor

The utilization of free-standing sulfide-based hybrid nanostructures plays a paramount role in supplying the steadily increasing demand for energy storage devices. Herein, this report presents the growth of outstanding binder-free Ni-Sn sulfide thin films for high-performance supercapacitors via the revised successive ionic layer adsorption and reaction (r-SILAR) method. Molar concentration ratios between Ni/Sn have been studied, and the optimum designed mesoporous Nix-Sn1.0xS/Ni foam (NF), a single cathode electrode material, successfully achieved outstanding specific capacitance of 2890 F/g at 5 A/g, capacitance retention of 85 %, and coulombic efficiency of 100 % after 10,000 cycles. Moreover, the constructed Nix-Sn1.0xS/NF//activated carbon (AC) hybrid supercapacitor device delivers an ultrahigh power density of 53.469 KW/Kg and capacitance retention of 95 % with robust long-term cycling stability up to1000 cycles. The superior electrochemical performance of the prepared Nix-Sn1.0xS electrode could be attributed to: (i) the synergistic effect of the two binary metal sulfides (Ni/Sn) into reversible faradaic redox reaction; (ii) the growing mechanism of the ultra-thin film (1.2 nm) as a binder-free electrode, enhance the ions insertion/extraction, and (iii) the formation of hierarchically flower-like architecture with uniform mesopores provides a high surface area (62.2 m2/g) and intensifies active sites for faradaic redox reactions. These encouraging results present a novel avenue for constructing advanced free-standing electrode materials for high-performance supercapacitors.

Mo-doped ZIF-67 derived Ni, Co, Mo trimetallic sulfide/ carbon nanotubes for supercapacitors

Supercapacitors have the advantages of high power density, rapid charge and discharge rates, and extended cycling stability. However, their energy density and specific capacity are still inadequate to satisfy the current requirements for energy storage in the industry. The current work demonstrates the synthesis of Mo-ZIF-67/CNT composites through mechanical stirring and co-precipitation. After that, Ni, Co and Mo trimetallic sulfide/CNT composites (Ni-Co-Mo-S/CNT) are produced through further ion exchange/etching and vulcanization processes. The material has multiple valence states of three different metal ions, providing a large number of oxidation-reduction sites. The doping of CNT endows it with a unique coral-like structure, which helps to form its huge specific surface area and larger mesopores. Furthermore, the effect of vulcanization temperature on the electrochemical performance of the material is also studied. According to the results, the Ni-Co-Mo-S/CNT-180, which is vulcanized at 180 °C, exhibits the most outstanding electrochemical performance. The electrode exhibits impressive performance with a specific capacitance of 1728.6 F/g at a current density of 1 A/g. It also has good rate capability, maintaining 55.8 % of the specific capacitance when the current density increases tenfold. Finally, the prepared Ni-Co-Mo-S/CNT-180//AC asymmetric supercapacitor generated a high energy density of 43 Wh/kg at a power density of 735 W/kg. After 2000 charge-discharge cycles at a current density of 1 A/g, it maintains a capacity of 76.42 %. This study serves as a reference for researching multi-metal sulfides as electrode materials for high-performance supercapacitors.

Biomass activated carbon supported Keggin-type polyoxometalate as an electrode material for high-performance acidic aqueous supercapacitors

Activated carbon (SSAC-OP) with micropore and mesopore was prepared by using soybean straw as a carbon source. Redox-active H3PMo12O40 (PMo12) was introduced into SSAC-OP by solution impregnation to obtain composite PMo12/SSAC-OP. The effect of loading amount of PMo12 on the supercapacitive performance of the composite was investigated. BET and EDS results confirmed that PMo12 is adsorbed in the micropores of 1–2 nm and mesopores of SSAC-OP, as well as on the carbon wall of SSAC-OP. Meanwhile, SSAC-OP with positive charge is more firmly connected with PMo12 anions via the effect of electrostatic attraction. CV and GCD test results proved that the composite materials have both electric double layer capacitance and pseudocapacitance characteristics. The CV curve of 10-PMo12/SSAC-OP obtained from SSAC-OP impregnating the initial concentration of PMo12 solution of 10 mM shows four pairs of obvious reversible redox peaks, which indicates that the protonation of PMo12 anion in the reduction process is sufficient. The composite 10-PMo12/SSAC-OP has a specific capacitance as high as 397.02F g−1 at scan rate of 5 mV s−1. The assembled symmetric supercapacitor delivers an energy density of 23.90 Wh kg−1 under the power density of 1016.05 W kg−1, with 97.96 % capacitance retention after 10,000 cycles at 3 A g−1.

Morphological nanoflowers of Ni-doped SnS for high-performance electrode materials for supercapacitors

Herein, we report the synthesis of pure and Ni-doped SnS nanoparticles (NPs) using a simple and low-cost solvothermal method. The Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) images show the flower-like morphology of Ni-doped sample. The supercapacitor performance of pure and doped electrodes was studied through cyclic voltammetry (CV), galvanostatic charging-discharging (GCD), and electrochemical impedance spectroscopy (EIS) measurements in 2 M KOH aqueous electrolyte. The Ni-doped electrode displays a higher specific capacitance (Cp) of 47 F/g at the scan rate of 10 mV/s through CV studies. Further, the Ni-doped electrodes showed Cp of 40 F/g at the current density of 0.5 A/g, provided specific energy (SE) of 5.5 Wh/Kg and high specific power (SP) of 250 W/kg than that of the pure SnS electrode. The optimized Ni-doped electrode retained retention of 97 % with excellent coulombic efficiency of 98 % after 2000 cycles.

Thermal-assisted synthesis of reduced graphene oxide-embedded Ni nanoparticles as high-performance electrode material for supercapacitor

Thermal-assisted synthesis of reduced graphene oxide-embedded Ni nanoparticles as high-performance electrode material for supercapacitor