Electrode Materials For Supercapacitors Research Articles

Design and Fabrication of MoCuOx Bimetallic Oxide Electrodes for High-Performance Micro-Supercapacitor by Electro-Spark Machining.

Transition metal oxides, distinguished by their high theoretical specific capacitance values, inexpensive cost, and low toxicity, have been extensively utilized as electrode materials for high-performance supercapacitors. Nevertheless, their conductivity is generally insufficient to facilitate rapid electron transport at high rates. Therefore, research on bimetallic oxide electrode materials has become a hot spot, especially in the field of micro-supercapacitors (MSC). Hence, this study presents the preparation of bimetallic oxide electrode materials via electro-spark machining (EM), which is efficient, convenient, green and non-polluting, as well as customizable. The fabricated copper-molybdenum bimetallic oxide (MoCuOx) device showed good electrochemical performance under the electrode system. It provided a high areal capacity of 50.2 mF cm-2 (scan rate: 2 mV s-1) with outstanding cycling retention of 94.9% even after 2000 cycles. This work opens a new window for fabricating bimetallic oxide materials in an efficient, environmental and customizable way for various electronics applications.

PRODUCTION OF HIGH-PERFORMANCE SUPERCAPACITOR ELECTRODES BASED ON GRAPHENE-LIKE CARBON OBTAINED FROM TEA WASTE

This article presents the results of a study on the production of active material for supercapacitor electrodes from graphene-like carbon obtained from tea waste, carbonization at a temperature of 550°C, followed by thermochemical activation using potassium hydroxide in a ratio of 1:4 at a temperature of 850°C in a quartz tube furnace. The structure and morphology of the resulting porous graphene-like carbon based on tea waste were investigated using scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), X-ray diffraction, and Raman spectroscopy. The surface area of activated porous graphene-like carbon from tea waste was 2407 m2/g. Electrochemical characterization of the assembled supercapacitor using GLC-TW was performed on an Elins P-40X electrochemical workstation and showed high specific capacitance values of 182 F/g, as well as a Coulombic efficiency of 96% at a current density of 1 A/g and the material also demonstrated a low charge transfer resistance of about 1.5 Ohms. These results highlight the effectiveness of using graphene-like carbon derived from tea waste, demonstrating its potential as a promising material for supercapacitors.

Probing Photo-Assisted Charge Storage Mechanism Using Bi-Fe Perovskite Oxide Electrode for Solar Supercapacitor.

In this study, the rhombohedral crystalline pure phase BiFeO3 (BFO) of irregularly shaped spherical particles of ≈100 nm and energy bandgap of ≈2.31 eV are synthesized by sol-gel auto-combustion method and explored as electrode material for photo-assisted supercapacitor. The electronic structure studies revealed that the coexistence of heterovalent Bi and Fe elements accelerated the electrochemical redox kinetics and photo-assisted charge storage properties. The resonant photoemission studies confirmed that near the Fermi level, the valence band spectra comprised the Fe3d and O2p hybridized states. The Fe-O hybridized state felicitates the charge transfer transitions (O2p (h+) + hυ ↔ Fe3+ + e- ↔ Fe2+), which assists the intercalation/de-intercalation process of OH- anions. Therefore, BFO has delivered 26.77% photo efficiency and the enhanced specific capacity of 21 Cg-1 at 2 Ag-1 in aq. 3m KOH under illumination, which is attributed to the accelerated photo-generated charge carrier separation and storage with surface polarization effect. BFO also delivered capacitance retention of 77.5% even after 1000 continuous GCD cycles under visible light irradiation.

Coexistence of Redox-Active Metal and Ligand Sites in Copper-Based Two-Dimensional Conjugated Metal-Organic Frameworks as Active Materials for Battery-Supercapacitor Hybrid Systems.

Two-dimensional (2D) conjugated metal-organic frameworks (c-MOFs) are promising materials for supercapacitor (SC) electrodes due to their high electrochemically accessible surface area coupled with superior electrical conductivity compared to traditional MOFs. In this work, porous and non-porous HHB-Cu (HHB=hexahydroxybenzene), derived through surfactant-assisted synthesis are studied as representative 2D c-MOF models with different characteristics, showing diverse reversible redox reactions with Na+ and Li+ in aqueous (10 M NaNO3) and organic (1.0 M LiPF6 in ethylene carbonate and dimethyl carbonate) electrolytes, respectively. These redox activities were here deployed to design negative electrodes for hybrid SCs (HSCs), combining the battery-like property of HHB-Cu at the negative electrode and the high capacitance and robust cyclic stability of activated carbon (AC) at the positive electrodes. In the organic electrolyte, porous HHB-Cu-based HSC achieves a maximum cell specific capacity (Cs) of 22.1 mAh g-1 at 0.1 A g-1, specific energy (Es) of 15.55 Wh kg-1 at specific power (Ps) of 70.49 W kg-1, and 77 % cyclic stability after 3000 gravimetric charge-discharge (GCD) cycles at 1 A g-1 (specific metrics calculated on the mass of both electrode materials). In the aqueous electrolyte, porous HHB-Cu-based HSC displays a Cs of 13.9 mAh g-1 at 0.1 A g-1, Es of 6.13 Wh kg-1 at 44.05 W kg-1, and 72.3 % Cs retention after 3000 GCD cycles. The non-porous sample, interesting for its superior electrical conductivity despite its limited surface area compared to its porous counterpart, shows lower Es performance but better rate capability compared to the porous one. This study indicates the potential of assembling a battery-SC hybrid system by rationally exploiting the battery-like behavior of 2D c-MOFs and the electrochemical double-layer capacitance of AC.

Metallic 1T Phase MoS2 Nanosheets Covalently Functionalized with BBD Molecules for Enhanced Supercapacitor Performances.

Metallic 1T phase molybdenum disulfide (MoS2) is among the most promising electrode materials for supercapacitors, but its capacitance and cyclability remain to be improved to meet the constantly increasing energy storage needs in portable electronics. In this study, we present a strategy, covalent functionalization, which achieves the improvement of capacitance of metallic 1T phase MoS2. Covalently functionalized by the modifier 4-bromobenzenediazonium tetrafluoroborate, the metallic MoS2 membrane exhibits increased interlayer spacing, slightly curled layered architecture, enhanced charge transfer, and improved adsorption capabilities toward electrolyte molecules and ions. Thanks to these boosted properties, the functionalized metallic MoS2 membrane exhibited excellent supercapacitor performances in a 0.5 M TBABF4 (acetonitrile as the solvent) electrolyte (with a specific capacitance of 135.67 F/cm3 at 1 A/g, more than three times that of the unfunctionalized metallic MoS2 membrane) and good stability, which can maintain a capacitance retention of 76.0% after 10 000 charge-discharge cycles.

One-pot synthesis of Bi/BiVO4 yolk-shell and hollow nanospheres as novel negative electrode material for supercapacitor

One-pot synthesis of Bi/BiVO4 yolk-shell and hollow nanospheres as novel negative electrode material for supercapacitor

Enhancing Supercapacitor Performance with Biomass-Derived Carbon Materials: A Review of Dimensional Innovations

Supercapacitor high-power density, rapid charge/discharge rates, long lifespan, and environmental friendliness have positioned them as extremely promising energy storage options. This study examines the physical and chemical characteristics of several biomass materials and their impact on supercapacitor performance. Additionally, we delve into the classification and fundamental concepts of supercapacitors. Biomass-derived carbon compounds exhibit abundant surface features and naturally occurring hierarchical structures that enhance electrochemical reactions, including diffusion and ion transfer. Historically, biomass has been the primary raw material for synthesizing innovative porous carbon compounds, representing a significant advancement in electrode materials for supercapacitors. Our study emphasizes the potential applications of one-, two-, and three-dimensional carbon compounds derived from biomass as electrode materials for supercapacitors by reviewing the latest research in this field. Additionally, we discuss the challenges faced today and the opportunities for enhancing the efficiency of carbon-based supercapacitor electrodes in the future.

Electrochemical advancements: MnO2-based electrode materials for supercapacitors

Electrochemical advancements: MnO2-based electrode materials for supercapacitors

Application of Defect Engineering via ALD in Supercapacitors

Supercapacitors are a kind of energy storage device that lie between traditional capacitors and batteries, characterized by high power density, long cycle life, and rapid charging and discharging capabilities. The energy storage mechanism of supercapacitors mainly includes electrical double-layer capacitance and pseudocapacitance. In addition to constructing multi-level pore structures to increase the specific surface area of electrode materials, defect engineering is essential for enhancing electrochemical active sites and achieving additional extrinsic pseudocapacitance. Therefore, developing a simple and efficient method for defect engineering is essential. Atomic layer deposition (ALD) technology enables precise control over thin film thickness at the atomic level through layer-by-layer deposition. This capability allows the intentional introduction of defects, such as vacancies, heteroatom doping, or misalignment, at specific sites within the material. The ALD process can regulate the defects in materials without altering the overall structure, thereby optimizing both the electrochemical and physical properties of the materials. Its self-limiting surface reaction mechanism also ensures that defects and doping sites are introduced uniformly across the material surface. This uniform defect distribution is particularly profitable for high surface area electrodes in supercapacitor applications, as it promotes consistent performance across the entire electrode. This review systematically summarizes the latest advancements in defect engineering via ALD technology in supercapacitors, including the enhancement of conductivity and the increase of active sites in supercapacitor electrode materials through ALD, thereby improving specific capacitance and energy density of the supercapacitor device. Furthermore, we discuss the underlying mechanisms, advantages, and future directions for ALD in this field.

Electrochemical properties of PPy/rGO/NiCoFe2O4 composites as advanced electrode materials for supercapacitors: a state-of-the-art review

Electrochemical properties of PPy/rGO/NiCoFe2O4 composites as advanced electrode materials for supercapacitors: a state-of-the-art review

Compression‐Assisted Improvement of Electrochemical Performances of Carbon Nanotube in Symmetric Supercapacitors

The unique geometry of carbon nanotubes (CNTs) contributes to their excellent rate capability when used as electrode materials for supercapacitors (SCs). However, the practical application of low‐cost commercial CNTs is limited by their moderate specific capacitance due to the relatively low surface area which is around 220 m2 g−1. This limitation can be addressed by applying proper compressive stress to the CNTs, resulting in improved capacitance. The effects of compression on capacitance vary depending on the length and inner diameter of the CNTs, which have been systematically investigated. It has been found that longer and narrower CNTs exhibit more significant improvements in capacitance due to compression. Specifically, under 12 MPa, there is an ≈135% increase in specific capacitance compared to that under 1 MPa, with the optimum value of 68.2 F g−1 at 1 A g−1. An excellent rate capability of 93.5% at 40 A g−1 is also obtained by compression. Furthermore, when an light emitting diode light is powered by a compressed CNT‐based SC, both brightness and lasting time are dramatically enhanced compared to the case without compression. This cost‐efficient strategy for improving the energy storage performance of CNTs may facilitate their practical application as electrode materials for ultrafast supercapacitors.

Hydrothermally Synthesized Cobalt‐Doped NiO Nanoflakes: Enhanced Electrochemical Performance for High‐Performance Supercapacitors

This study examines cobalt‐doped nickel oxide (Co‐NiO) nanomaterials synthesized through a hydrothermal method, focusing on their potential as high‐performance electrodes for supercapacitors. By varying cobalt dopant concentrations (X = 0, 0.01, 0.05, 0.1), we aimed to enhance the electrochemical properties through strategic Co‐doping. The CoxNi1‐xO nanomaterials were characterized using several techniques, including X‐ray diffraction (XRD), UV‐visible spectroscopy, field emission scanning electron microscopy (FESEM), X‐ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), chronopotentiometry (CP), and electrochemical impedance spectroscopy (EIS). The analysis showed that Co‐doping preserved the NiO phase structure while significantly altering the morphology and electrochemical characteristics. The sample with (X = 0.1) achieved a specific capacitance of 880 F/g at a current density of 1 A/g, significantly outperforming the undoped NiO, which had a capacitance of 335 F/g. Additionally, the Co‐NiO demonstrated 83.3% capacitance retention after 1000 cycles at a current density of 10 A/g. These findings highlight the potential of Co‐NiO as an effective electrode material for supercapacitors.

Heterostructured Co-NiSe2 Nanorods on MXene Nanosheets as Synergistic Electrode Material for Supercapacitor

Heterostructured Co-NiSe₂ Nanorods on MXene Nanosheets as Synergistic Electrode Material for Supercapacitor

The Application of Porous Carbon Derived from Furfural Residue as the Electrode Material in Supercapacitors.

Resource use is crucial for the sustainable growth of energy and green low-carbon applications since the improper handling of biomass waste would have a detrimental effect on the environment. This paper used nano-ZnO and ammonium persulfate ((NH4)2S2O8, APS) as a template agent and heteroatom dopant, respectively. Using a one-step carbonization process in an inert atmosphere, the biomass waste furfural residue (FR) was converted into porous carbon (PC), which was applied to the supercapacitor electrode. The impact of varying APS ratios and carbonization temperatures on the physicochemical properties and electrochemical properties of PC was studied. O, S, and N atoms were evenly distributed in the carbon skeleton, producing abundant heteroatomic functional groups. The sample with the largest specific surface area (SSA, 855.62 m2 g-1) was made at 900 °C without the addition of APS. With the increase in adding the ratio of APS, the SSA and pore volume of the sample were reduced, owing to the combination of APS and ZnO to form ZnS during the carbonization process, which inhibited the pore generation and activation effect of ZnO and damaged the pore structure of PC. At 0.5 A g-1 current density, PC900-1 (FR: ZnO: APS ratio 1:1:1, prepared at 900 °C) exhibited the maximum specific capacitance of 153.03 F g-1, whereas it had limited capacitance retention at high current density. PC900-0.1 displayed high specific capacitance (141.32 F g-1 at 0.5 A g-1), capacitance retention (80.7%), low equivalent series resistance (0.306 Ω), and charge transfer resistance (0.145 Ω) and showed good rate and energy characteristics depending on the synergistic effect of the double layer capacitance and pseudo-capacitance. In conclusion, the prepared FR-derived PC can meet the application of a supercapacitor energy storage field and realize the resource and functional utilization of biomass, which has a good application prospect.

A dual-activation strategy for enhancing the energy storage performance of MoSe2/AFCNTs in symmetric supercapacitors

The MoSe2/AFCNTs composite obtained via one-step hydrothermal process demonstrates significant promise as supercapacitor electrode material. In this process, MoSe2 nanoflowers are decorated on the surface of activated functional carbon nanotubes (AFCNTs) which are functionalized through a dual-activation method involving acid and alkaline treatment. The resulting composite benefits from plentiful active sites and low charge-transfer resistance, which together contribute to its excellent energy storage and capacitive performance. The electrochemical performance of MoSe2/AFCNTs in a three-electrode system is impressive, with a specific capacitance of 335 F g−1 at a current density of 1 A g−1. This value is much higher than that of either individual MoSe2 or carbon nanotubes, highlighting the synergistic effect between the two components. When used in a symmetric supercapacitor device, MoSe2/AFCNTs delivers a maximum power density of 1.25 kW kg−1 and an energy density of 1.39 Wh kg−1. Additionally, this device can supply power for electric watch, demonstrating that the MoSe2/AFCNTs composite is a competitive supercapacitor electrode material in practical application.

Ternary metal oxide carbon composite as high-performance electrode material for supercapacitor applications

Recently, ternary metal oxides carbon composites recognized as metal organic frameworks (MOFs) have gained striking attention for supercapacitor electrode material due to high surface area, porosity, chemical stability, tunable properties, redox activity, and eco-friendly material. ZIF-67 is a novel MOF possessing these characteristics. Therefore, the present work reports the development of ternary iron-nickel–cobalt ZIF-67 composites (FeNiCo ZIF-67) using co-precipitation method with the variation in molar concentration of iron oxide, nickel oxide, and cobalt oxide. Physico-chemical characterizations of developed materials were investigated through X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray (EDX), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) to confirm the successful formation of composites and structure, morphology. Then, the electrodes were fabricated for all three synthesized composites and electrochemical analyses such as cyclic voltammetry (CV), galvanic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) were performed. The results revealed the porous polyhedral structure of FeNiCo ZIF-67 with different compositions consisting of interconnected nanoparticles played an important role in increasing the charge storage capacity of the material. Among the composites, FeNiCo ZIF-67 (1:2:1) electrode material achieved the highest specific capacitance of 532.7 F/g at a current density of 1 A/g. FeNiCo ZIF-67 (1:2:1) exhibited maximum electrochemical active surface area 89.12. Electrochemical impedance spectroscopy (EIS) demonstrated the minimal resistance of 7.8 Ω by FeNiCo ZIF-67 (1:2:1) composite electrode compared to the other two electrode materials. Cyclic stability study revealed the capacitance retention of 91 % after 10,000 continuous charge discharge cycles at a current density of 10 A/g. Electrode material demonstrated an outstanding electrochemical performance, and this work could provide a simple strategy to fabricate FeNiCo ZIF-67 nanostructured electrode materials for supercapacitors.

Graphene quantum dots embedded silver sulfide molybdenum disulfide for efficient electrode materials for hybrid supercapacitors and electrocatalytic hydrogen generation

Graphene quantum dots embedded silver sulfide molybdenum disulfide for efficient electrode materials for hybrid supercapacitors and electrocatalytic hydrogen generation

Preparation of high density activated carbon by mechanical compression of precursors for compact capacitive energy storage

Activated carbons are widely used as the electrode material for supercapacitors owing to their large surface area, moderate conductivity, and outstanding electrochemical stability. However, large-surface-area activated carbons usually show low density and poor volumetric energy storage performance, which is difficult to meet the development of devices miniaturization. Mechanical compression is a simple and effective method to improve the density of the activated carbons. However, most of the studies focus on mechanical compression of the as-prepared porous carbon materials. Preparation of high-density activated carbons by mechanical compression of the carbon precursors has been proposed. But the surface area and porous structure evolution, and the possible mechanism have rarely investigated. Herein, we propose a universal method to improve the density of the activated carbons by mechanical compression of the precursors before activation. The influence of mechanical compression on the surface area, porous structure, and capacitive energy storage performance of the activated carbons prepared by two typical methods, outside-in activation (carbon powder/KOH mixture) and homogeneous ion activation (pyrolysis of potassium-containing salts), are studied. Mechanical compression of the precursors can generally improve the activation reaction efficiency, as well as the density and volumetric capacitive performance of the activated carbons. However, the surface area and porous structure evolution mainly depend on the carbon precursor and pore-forming process. For outside-in activation, the surface area and porosity of the activated carbons show a first increasing and then decreasing trend with the increase of mechanical pressure. This is because mechanical compression enhances the contact between the carbon precursors and activator through eliminating the voids between particles, significantly improves the activation efficiency. For homogeneous ion activation, the surface area and porosity of activated carbons show a trend of decreasing first and then increasing. The reason is deduced as compressed precursors inhibit the rapid release of active gas molecules (H2O, CO2etc.) produced during pyrolysis. These gas molecules further participate in the activation etching reaction and promote the activation efficiency. The optimized sample shows high gravimetric and volumetric capacitances of 316 ​F ​g−1/291 ​F ​cm−3 and 131 ​F ​g−1/92 ​F ​cm−3 ​at 1 ​A ​g−1 in aqueous and organic electrolytes, respectively. This work provides a simple way for design and preparation of activated carbons with large surface area and high density.

Realizing higher-performance supercapacitor using three-dimensional cadmium-based coordination polymer

In order to enhance energy density of supercapacitors, it is a route to develop new high-performance electrode materials. Coordination polymers (CPs) as the electrode materials of supercapacitors have received considerable attention, due to them owning redox active centers (metal ions/organic ligands) and the porosity, but developing high-performance and low-cost CP-based electrode materials remains a challenging task. Herein, a novel three-dimensional (3D) cadmium-based CP [Cd(BGPD)(H2O)2] (Cd−CP; BGPD = N,N′-bis(glycinyl)pyromellitic diimide) with low-cost has been synthesized by a facile method. When served as an electrode material of supercapacitors, in a three-electrode system, the specific capacitance of Cd−CP is up to 1339 F g−1 under 1 A g−1 (equivalent to a specific capacity of 167 mAh g−1). Notably, an asymmetrical supercapacitor, Cd−CP//rGO, as a two-electrode system constructed by the rGO electrode and the Cd−CP electrode, exhibits a superior energy density of 13.3 Wh kg−1 at 0.80 kW kg−1, and a general cycle capability with the capacitance retention of 61.3 % after 4000 cycles. Our work provides a new route for searching higher-performance electrode materials with low-cost and demonstrates the application potential of Cd−based CPs as the electrode materials of supercapacitors.

Effect of microstructure on performance and working mechanism of MnO2-PEDOT supercapacitors based on nonaqueous electrolytes

In this work we demonstrate the impact of synthesis conditions on the properties of stable nanostructured MnO2 and their application as electrode material in supercapacitors. Samples synthesized by hydrothermal method were characterized by XRD, XPS, SEM, BET surface area and the correlation with the electrochemical performance of constructed prototype supercapacitors was discussed. The morphological study of the as-synthesized MnO2 samples shown the morphology consisting of nanorods for pH value of 2.5 and cauliflower shape for pH of 3 and 6.5. The XRD study revealed that at low pH a α-MnO2 is formed whereas an increase of pH during synthesis leads to birnessite phase formation. The electrochemical studies, for 5 % KNO3 dissolved in dimethyl sulfoxide (DMSO) used as an electrolyte, shown that the birnessite MnO2 structure exhibits much better electrochemical behavior of constructed supercapacitors comparing to α-MnO2. The observed electrochemical behavior can be explained by the microstructure differences of prepared materials.