High-performance Supercapacitor Electrode Research Articles

SiC-induced modification of MnCo2O4 nanoneedles fabricated on Ni foam for binder-free electrodes in high-performance asymmetrical supercapacitors

Supercapacitors with large energy densities are required for commercial applications. Herein, the urchin-like and hexagonal MnCo2O4/SiC composite is prepared in situ on Ni foam. The urchin-like MnCo2O4/SiC consists of nanoneedle clusters with a length of about 10 μm and a diameter of 20 nm. The MnCo2O4/SiC||AC asymmetrical supercapacitor (ASCs) shows an energy density of 90.3 Wh/kg (1.73F cm−2) at a power density of 1.25 kW/kg together with 92.1 % retention of the specific capacitance after 10,000 cycles. The results reveal excellent properties and large commercial potential.

Biomass-derived heteroatom-doped carbons: Unlocking the potential of cellulose, hemicellulose, and lignin co-pyrolysis with ammonium polyphosphate for high-performance supercapacitors

Carbon materials were prepared via cellulose, hemicellulose, and lignin co-pyrolysis with ammonium polyphosphate (APP) to scrutinize the influence of these biomass constituents on the materials’ electrochemical performance. During co-pyrolysis, the synergistic interaction between APP and the three components facilitated the doping of heteroatoms including nitrogen, oxygen, and phosphorus. APP with polymerization n > 1000 exhibited the best doping performance. The incorporation of KHCO3 effectively tailored the carbon materials into a hierarchically porous structure predominantly composed of micropores. The cellulose-derived carbon materials outperformed with a remarkable specific capacitance of 398 F/g at 0.5 A/g. Its exceptional electrochemical performance was credited to a notable N content of 3.73 % and a high specific surface area of 1851 m2/g. Our research underscored the potential of cellulose as a readily available and affordable feedstock for crafting carbon materials, suitable for the electrodes in high performance supercapacitors.

Honeycomb-like N, S dual-doped porous carbons derived from pomelo peel by effective exogenous doping strategy for supercapacitor electrodes

Biomass has emerged as a pivotal precursor to synthesize supercapacitor electrode materials owing to its low-cost and plentiful resources. The optimization of heteroatoms and porous structures is believed to be a viable method to enhance the electrochemical properties of biomass-generated carbons. Herein, pomelo peel as a precursor using KOH as an activator and heteroatom dopants (urea and sodium sulfide) was successfully converted into N, S dual-doped porous carbons under the high temperature. The effective exogenous doping strategy realizes a high abundance of N/S heteroatoms, and KOH chemical activation promotes the development of nanopores and interconnected porosities. The resultant carbon CNS-800 with a high specific surface area of 1823.8 m2 g−1 and rich heteroatoms of N (2.51 wt%) and S (1.36 wt%) anticipately exhibits the outstanding electrochemical properties, including the excellent specific capacitance of 329.2 F g−1 at 1 A g−1 in a three-electrode (3E) system and the superb capacitance retention rate of 74.12 %. The fabricated CNS-800-based symmetric two-electrode (2E) supercapacitor demonstrates a good capacitance of 243.7 F g−1 and excellent cycling stability, as well as a superb energy density of 14.3 Wh kg−1. This work provides a compelling and cost-effective approach to transform biomass waste like pomelo peels into high-performance electrodes for supercapacitors.

Nanostructured nickel doped manganese oxide/polypyrrole/graphitic carbon nitride hydrogel as high-performance supercapacitor electrodes

Nanostructured nickel doped manganese oxide/polypyrrole/graphitic carbon nitride hydrogel as high-performance supercapacitor electrodes

Porous activated carbon electrodes derived from Eleusine coracana biowaste in electric double layer capacitors: Nanoarchitectonics and performance

The development of high-performance supercapacitors from biowaste is crucial for advancing sustainable and renewable energy storage technologies. In this study, we report the fabrication of electrodes for high-performance supercapacitors using porous carbon derived from red millet (Eleusine coracana) straw. Porous carbon was synthesized via a two-step chemical activation process using KOH, resulting in a hierarchical pore structure comprising macro-, meso-, and micropores. The red millet-based porous carbon electrodes, assembled in a two-electrode symmetrical supercapacitor, exhibited a specific capacitance of 68 Fg⁻1 at a current density of 0.5 Ag⁻1 in a 1 M Na₂SO₄ aqueous electrolyte. At a mass loading of 5 mg per electrode, the system demonstrated a specific capacitance of 300 Fg⁻1 at 1 Ag⁻1, with an energy density of 9.1 Whkg⁻1 and a power density of 1.86 kWkg⁻1, as determined from galvanostatic charge-discharge measurements. Additionally, the supercapacitor showed excellent cyclic stability, retaining 98.78% of its initial capacitance after 5000 cycles at 10 Ag⁻1. These findings highlight the potential of porous carbon derived from agricultural biowaste for scalable applications in electric double-layer capacitors.

Facile Synthesis of Highly Supercapacitive Mo‐doped Titanium Nanotube Arrays and Effect of Anodization Voltage

AbstractDesigning potential architectures by the modification of conventional electrode materials is an effective approach in the development of high performance supercapacitor electrodes. The present study investigated the effect of varying anodization voltages (50, 75, and 100 V) on the morphology and electrochemical properties of titanium nanotubes (TNT). Molybdenum was doped onto TNT using a simple hydrothermal procedure, followed by thermal treatment at 450 °C. The study effectively demonstrated control over the dimensions of the nanotube structure by adjusting the anodization voltage. Additionally, it was found that the tube diameters were increased due to etching during the hydrothermal treatment with the Mo precursor, which potentially enhanced the supercapacitive performance of Mo‐doped TNT. Further, structural analysis revealed that Mo doping improved both crystallinity and electrode stability. With an optimal anodization voltage of 100 V, TNT and Molybdenum‐doped TNT could exhibit capacitance value of 13.34 and 326.54 mF cm−2 respectively, at a current density of 1 mA cm−2. Furthermore, the electrode demonstrated good cyclic stability with 88% capacitance retention and 97% coulombic efficiency after 5000 cycles. An impressive energy density of 87.03 µWh cm−2 and a power density of 799.99 µW cm−2 could be achieved with this sample in an asymmetrical device.

Fabrication of novel chitosan decorated reduced graphene oxide/cobalt oxide hybrid nanocomposite electrode material for supercapacitor applications

Supercapacitors are considered efficient electrochemical energy storage devices due to their high-power density, long cycling stability, and quick charge–discharge rates. Despite exhibiting high power density and cycling stability, the electrode materials are toxic and non-degradable, continuously affecting the environment. Biopolymers are a suitable alternative to conventional electrode materials since they possess interesting properties such as unique structure, biodegradability, abundant availability, and efficient interaction with other materials. This study aims to synthesize chitosan (CS) based nanocomposites, namely CS-rGO, CS-Co3O4, and CS-rGO-Co3O4 hybrid nanocomposites by an effective simple strategy method. XRD results show well-intensified peaks confirming the formation of nanocomposites. SEM and HR-TEM analysis indicates the cobalt oxide nanoparticles diffused in the sheet-like structure of CS-rGO which is evident for the porous nature of the CS-rGO-Co3O4 hybrid nanocomposite. A novel CS-rGO-Co3O4 hybrid nanocomposite showed surpassing electrochemical performance compared to other synthesized binary composites. The hybrid composite exhibited a high specific capacitance of 361.31 Fg−1 with an electroactive surface area of 136.880 m2g−1. In GCD, the hybrid composite demonstrates a 70 % capacitance retention and 99 % Coulombic efficiency after 10,000 cycles. An asymmetric hybrid supercapacitor is assembled using CS-rGO-Co3O4 nanocomposite as an anode and activated carbon as a cathode. The assembled AHS device delivers a high specific capacitance of 75.7 Fg−1 at 0.5 Ag−1. The energy density of the CS-rGO-Co3O4 hybrid nanocomposite is 23.6 WhKg−1 and the power density is 734.15 WKg−1. Hence, our research provides valuable insights for developing high-performance supercapacitor electrodes.

In-situ growth of FeCo layered double hydroxide nanorods on MXene for high-performance supercapacitor electrodes

In the pursuit of clean energy solutions, supercapacitors have gained attention due to their exceptional energy storage capabilities. Layered double hydroxide (LDH), a notable material in this field, faces some challenges such as slow charge transfer speed and volumetric expansion. To tackle these issues, a novel FeCo-LDH/MXene composite was synthesized through in-situ hydrothermal growth of FeCo layered double hydroxide (FeCo-LDH) nanorods on MXene using ionic self-assembly, forming a three-dimensional (3D) composite with enhanced rate capability and cycling stability due to the synergetic coupling of MXene and LDH. The FeCo-LDH/MXene electrode significantly improves surface capacitance control performance and exhibits exceptional electrochemical performance, achieving a specific capacitance of 2058.2 F g−1 at 1 A g−1 and maintaining 1732.7 F g−1 at 10 A g−1, with 82.4 % capacity retention. Furthermore, the assembled supercapacitor delivers an energy density of 48.8 Wh kg−1 at 750 W kg−1 and 25.7 Wh kg−1 at 15000 W kg−1, demonstrating excellent rate performance, as well as 80.3 % capacitance after 5000 cycles at 2 A g−1, highlighting its durability. This advancement not only overcomes the specific capacitance challenge of MXene electrodes but also enhances the conductivity and cyclic stability of LDH, making FeCo-LDH/MXene a promising candidate for future high-performance energy storage applications.

Probing structural and electrochemical properties of a 2D CoMoO4@hBN nanocomposite as pseudocapacitive electrode for high-performance supercapacitors

The effectiveness of energy storage is largely determined by the electrode material's performance in critical areas. Enhancements in ion transport, cyclic stability, rate capability, and specific capacitance directly boost the supercapacitors' overall performance and broaden their application potential. This study aims to enhance these properties by incorporating hexagonal boron nitride (hBN) into cobalt molybdate (CoMoO4) material in a 1:1 stoichiometric ratio. The CoMoO₄@hBN nanocomposite was synthesized using a hydrothermal method followed by ball milling. The X-ray diffraction (XRD) analysis confirmed the formation of a single-phase CoMoO4@hBN composite, with a significant increase in crystallite size from 18.21 nm in pure CoMoO₄ to 25.6 nm, along with a slight shift in diffraction peaks, indicating enhanced crystallinity and structural defects due to the substitution of oxygen with boron atoms. Raman spectroscopy revealed that the composite retains the characteristic peaks of both CoMoO₄ and hBN, with stable sharp peaks at 936 cm−1 (Mo=O bond) and 1367 cm−1 (E2g peak of hBN) even after 20 depth measurements, confirming successful conjugation and consistent vibrational properties. The X-ray photoelectron spectroscopy (XPS) showed a slight shift in Co 2p and Mo 3d binding energies to higher values, suggesting improved electronic interactions between CoMoO4 and hBN, which could enhance the composite's conductivity. The electrochemical analysis demonstrated that incorporating h-BN significantly boosts the electrode's performance compared to pristine CoMoO4, with about 37 % increase in specific capacitance at 1 A g−1, reduced charge transfer resistance (0.11 Ω), and superior cyclic stability with 96 % capacitance retention after 5000 cycles. These findings indicate that hBN enhances both the electrical conductivity and structural integrity of CoMoO4, positioning the CoMoO4@hBN composite as a promising material for high-performance supercapacitors.

Cascaded utilization of magnetite nanoparticles@onion-like carbons from wastewater purification to supercapacitive energy storage.

Developing high-performance carbon-based materials for environmental and energy-related applications produces solid waste with secondary pollution to the environment at the end of their service lives. It is still challenging to utilize these functional materials in a sustainable manner in different fields. In this study, we demonstrate a cascaded utilization of an Fe3O4@onion-like carbon (Fe3O4@OLC) structure from wastewater adsorbents to a supercapacitor electrode. The structure was formed by carbonizing Fe3O4@oleic acid monodisperse nanoparticles into interconnected Fe3O4@OLCs and subsequent insufficient acid etching. The hollow OLCs in the outside region of the hybrid structure provide high surface area and the encapsulated Fe3O4 nanoparticles in the inside region offer high ferromagnetism. The three-dimensionally interconnected graphitic layers are advantageous for efficient separation and high conductivity. As a result, the maximum saturation adsorption capacity of insufficiently etched interconnected Fe3O4@OLCs can reach up to 90.2 mg g-1 and they can be efficiently separated under a magnetic field. Furthermore, the hybrid structure is thermally transformed into N-doped HOLCs, which are demonstrated to be a high-performance supercapacitor electrode with high specific capacitance and high electrochemical stability. The cascaded utilization of the hybrid structure in this study is meaningful for eco-friendly development of functional materials for environmental and energy storage applications.

Rapid and controllable microwave synthesis of nickel cobalt sulfide electrodes for high-performance asymmetric supercapacitors

The efficient and controllable synthesis method of high-performance energy storage electrode materials is crucial for advancing the development of energy storage technologies. Herein, by leveraging microwave heating technology in the sulfidation of nickel cobalt MOF, we effectively enhanced the efficiency of the synthesis process. Notably, sulfidation time emerged as a pivotal factor in tuning the crystalline phase structure and conductive properties of the material, leading to the successful development of NCS2 electrode material with a unique structure through optimized sulfidation conditions. Electrochemical performance tests of the NCS2 material revealed exceptional results; it exhibited a specific capacity of 1311 Fg[Formula: see text] at a current density of 1 Ag[Formula: see text] and retained 73.4% of its initial capacity when the current density increased to 10 Ag[Formula: see text], demonstrating outstanding rate performance. The composite NCS2//AC supercapacitor exhibits an energy density of 24.2 Whkg[Formula: see text] at power density of 800 Wkg[Formula: see text], even though after 1000 consecutive charge-discharge cycles, the capacity retention rate remained high at 77.1%, validating the exceptional stability and reliability of the NCS2 material during cycling. This work employs microwave sulfidation for the rapid and controlled synthesis of nickel cobalt sulfides, providing a green and efficient synthetic strategy for metal sulfide active materials.

Electrochemical evaluation of cobalt oxide incorporated MoS2 ex/PANI ternary composite as a promising electrode for high-performance symmetric and asymmetric supercapacitors

Electrochemical evaluation of cobalt oxide incorporated MoS2 ex/PANI ternary composite as a promising electrode for high-performance symmetric and asymmetric supercapacitors

Preparation of nanowire-like core–shell Ni3Se4@NiCo2O4/NF composite electrodes for high-performance supercapacitors

Preparation of nanowire-like core–shell Ni3Se4@NiCo2O4/NF composite electrodes for high-performance supercapacitors

Ag-decorated ZnCo2S4/SiO2 nanocomposite as a high-performance supercapacitor electrode

Ag-decorated ZnCo2S4/SiO2 nanocomposite was utilized in this study as a potential supercapacitor electrode. Ag nanoparticles demonstrate a low level of pseudo-capacitance and their capacity to improve charge transfer. The specific capacitances of the ZnCo2S4, ZnCo2S4/SiO2, and Ag@ZnCo2S4/SiO2 electrodes were 935, 1066, and 1623 Fg−1, respectively, at 1 Ag−1 current density. The Ag@ZnCo2S4/SiO2 electrode exhibits remarkable cycle stability (100 % coulombic efficiency and capacitance retention of approximately 91.7 % at 10 A g−1 after 10,000 cycles). Furthermore, the symmetric supercapacitor (Ag@ZnCo2S4/SiO2//Ag@ZnCo2S4/SiO2) possesses a broad potential window of 1.5 V, a maximal energy density of 68.6 Whkg−1, and a specific power of 23.88 kWkg−1. Furthermore, the hybrid supercapacitor device (Ag@ZnCo2S4/SiO2//Ag@ZnCo2S4/SiO2) demonstrated a coulombic efficiency of 100 % and a capacitance retention of 92.3 %. Consequently, the Ag@ZnCo2S4/SiO2 composite electrode was suitable for high-energy supercapacitors due to their high capacitance, remarkable cycle stability, and high energy density.

Co1-xS/N, S-codoped carbon loaded porous carbon cloth as flexible electrode for high performance supercapacitors

The capacitive performances of flexible electrodes highly depend on their architectures and redox activity. In this work, Co1-xS/N, S-codoped carbon (NSC) loaded porous carbon cloth (p-CC) was prepared through an etching procedure and a followed repeated-sulfurization process. Since the porous CC could accommodate more Co1-xS nanoparticles and the phase structure of Co1-xS was well controlled by the repeated-sulfurization process, the obtained p-CC/Co1-xS/NSC electrode with optimized composition and architecture exhibits high areal capacitances of 1263.8 mF cm−2 at 1 mA cm−2 and 858.6 mF cm−2 at 50 mA cm−2. The deposited NSC on Co1-xS could effectively prevent their slipping and agglomeration, and thus make the electrode exhibit high capacitance retention of 99.7 % after 20,000 charge–discharge tests. The all-solid-state symmetric supercapacitor assembled by the formed electrodes and ionic liquid/gel electrolyte shows a maximum energy density of 1.34 mWh cm−3 at the power density of 9.55 mW cm−3. These results present a new strategy for the construction of cobalt-sulfide/carbon based flexible electrode with high capacitive performances.

Cauliflower-like Ni/NiCoP@Boron-doped diamond composite electrodes for high-performance symmetric supercapacitors

Due to the lack of electrocatalytic active sites, the supercapacitors (SCs) even based on the most stable sp3 carbon material (Boron-doped diamond) suffer from poor capacitance and low energy density. Herein, a cauliflower-like biphasic Ni/NiCoP layer has been successfully deposited on the BDD film and further applied as binder-/current collector-free SC electrodes. In a redox-active aqueous electrolyte (0.05 M Fe(CN)63−/4− + 1.0 M KOH), the Ni/NiCoP@BDD electrode with exceptional cyclic stability (∼89.0 % after 10,000 cycles) delivers a specific capacitance of 256.1 mF cm−2 at a current density of 30 mA cm−2, about 2 times higher than that in inert electrolyte. Furthermore, such a symmetric PC device provides a desired energy density of 70.0 Wh kg−1 at a high power density of 3601 W kg−1.

Ag NPs-modified NiCoMn layered double hydroxides electrodes for high-performance asymmetric supercapacitors

The development of supercapacitor technology has been hindered by limitations in achieving both high power density and long cycle stability. Layered double hydroxides (LDHs) have emerged as promising candidates to address these challenges. In this study, we synthesized three distinct electrodes: NiCoMn LDH (LDH), Ag-citrate nanoparticles (Ag NPs), and a composite of Ag-citrate/NiCoMn LDH (AgNPs/LDH), to explore their electrochemical performance. The structural and morphological characteristics of the synthesized materials were confirmed using scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and raman spectroscopy. Among the materials, the Ag NPs/LDH composite exhibited superior electrochemical properties, with distinct anodic and cathodic peaks of higher current intensity and an expanded integrated area in the current-voltage curve. Additionally, impedance analysis revealed the lowest charge transfer resistance, indicating efficient charging and discharging processes. In addition, the Ag-NPs/NiCoMn composite exhibited a remarkable aerial-specific capacitance of 2764 mF.cm−2 at 5 mA cm−2 in a three-electrode configuration. Furthermore, in an asymmetric supercapacitor (ASC) device configuration of AgNPs/LDH as a working electrode and Activated carbon as a working electrode (shorthand form AgNPs/LDH ||AC ASC), a specific capacitance of 1850 mF.cm−2 at 5 mA.cm−2 was achieved. Encouragingly, the AgNPs/LDH||AC ASC device exhibited an energy density of 0.593 mWhcm−2 at a power density of 10 mW.cm−2, maintaining a 0.175 mWhcm−2 at a high-power density of 90 mWcm−2, while retaining 102 % of its capacitance after 4000 charging and discharging cycles. Overall, the AgNPs/LDH electrode material demonstrates significant potential for advancement in supercapacitor technology.

Neodymium oxide-based hybrid phase few-layer MoS2 nanocomposite as high-performance symmetric supercapacitor electrode

The two-dimensional layered materials (for example MoS2) are potential electrodes for supercapacitors with their excellent lamellar structure, high surface area, mechanical flexibility, and potential redox activity. However, due to restacking of chemical structure and low electrical conductivity of the pure MoS2 electrodes are prevented for energy storage applications. Therefore the electrodes are made up of a composite by a mixture of MoS2 and rare-earth metals significantly addressing these issues with improved electrical conductivity, large electrochemical active surface, and shorter ion-diffusion kinetics. In the present study, the MoS2 and MoS2/Nd2O3 composite were synthesized by hydrothermal method. The structural phase identification of prepared samples was accomplished by using an X-ray diffractometer (XRD) and Raman spectra. Furthermore, TEM reveals changes in the shape of nanosheets and interlayer spacing. The GCD of symmetric MoS2/Nd2O3 composite electrodes displayed remarkable charging/discharging performance, with increased stability and rate capability. The MoS2/Nd2O3 composite shows utmost Csp of 2528.18 Fg-1 at 1 Ag-1. In addition, the CV and GCD studies suggest that the electrodes exhibit pseudocapacitive behavior and excellent energy density(E) of 191 Wh kg-1 at 1474.1 W kg-1 power density(P) in 1M H2SO4. The supercapacitor device made up of MoS2/Nd2O3 composite shows greater performance in practical LED glowing applications. Therefore, the composites make advancements in energy storage devices like batteries and supercapbatteries due to their excellent energy storage, high electrochemically active surface area, and stability.

Inkjet printing of silver/graphene flexible composite electrodes for high-performance supercapacitors

Inkjet printing of silver/graphene flexible composite electrodes for high-performance supercapacitors

Hierarchical porous MXene film with diffusion path optimization for supercapacitor

MXenes have immense potential in electrochemical energy storage owing to their outstanding physicochemical properties such as their oxygen-containing groups that impart additional pseudocapacitance to acidic electrolytes. However, during electrode assembly, MXene nanosheets undergo restacking because of hydrogen bonding and van der Waals forces, which causes electrolyte ions to traverse long diffusion pathways between the long and narrow nanosheets. Exploiting the oxidative properties of Ti3C2Tx, a hierarchical porous MXene film with micro-, meso- and macroporous structures was successfully prepared using a simple hydrothermal oxidation and etching process to create micro- and mesoporous structures, followed by ice templating to prepare three-dimensional (3D) linked macroporous structures. Because these hierarchical pores have synergistic effects on electrochemical activity and electrolyte ion diffusion, the film attained a specific capacitance of 539F/g at a current density of 2 A/g when it was used as a supercapacitor electrode, which corresponds to one of the highest values reported for MXene-based electrodes. The film retained 83% of its specific capacitance when the current density was increased to 40 A/g, and exhibited excellent cycling stability. By using this multi-porous MXene design, synergistic improvement in ion diffusion was successfully realized and thus a new strategy to prepare high-performance supercapacitor electrode materials was developed.