Electrochemical Supercapacitors Research Articles

Single‐Step One‐Pot Synthesis of NiCo2O4/Molybdate Nanocomposites for Flexible Supercapacitor Electrodes

Energy storage technology plays a critical role in integrating variable energy sources into the grid and ensuring energy consistency. Electrochemical supercapacitors are one of the most promising energy storage devices, as they present multiple advantages of high power density, rapid charge/discharge characteristics, and long‐term cycle stability. Herein, the NiCo2O4/molybdate nanocomposites are developed as electrode materials for supercapacitor applications. The NiCo2O4/molybdate nanocomposites are synthesized by a facile single‐pot hydrothermal method and are coated on a carbon cloth substrate to form flexible supercapacitor electrodes. The structures, chemical compositions, morphologies, and textural properties of these materials are carefully studied by X‐Ray diffraction, X‐Ray absorption spectroscopy, scanning electron microscopy/energy‐dispersive X‐Ray spectroscopy mapping, and N2 adsorption–desorption isotherms. The formation of spinel NiCo2O4 nanorods decorated with molybdate (AMoO4, A = Co, Ni) particles is confirmed for all samples. The NiCo2O4/CoMoO4 electrode exhibits pseudocapacitive behavior and provides the highest specific capacitance (287.28 F g−1 at current density 6 A g−1), about 5.5 times as high as that of NiCo2O4, with excellent cycle stability (107% specific capacitance retention after 1000 charge/discharge cycles at 1 A g−1). Therefore, the NiCo2O4/CoMoO4 composites can be considered as a promising pseudocapacitor electrode material.

The electrochemical performance of gallium nitride composited with g-C3N4 in bulk and oxidized forms for supercapacitors

Six composites were synthesized using g-C3N4 in two forms, namely Bulk and Oxidized, mixed with gallium nitride, and composites of materials were employed as electrode components for supercapacitors. The composites' physical and structural characteristics were analyzed and the electrochemical performance of composite materials containing varying ratios of GaN and g-C3N4 was analyzed. Galvanostatic charge-discharge investigations revealed that the Oxidized g-C3N4/GaN-1:2 composite exhibited a superior maximum specific capacitance compared to other electrode materials, achieving 200 F g−1 at a current density of 2 A g−1, which suggest that mixing GaN with different forms of g-C3N4 (Bulk and Oxidized) have the potential to produce favorable electrode materials suitable for application in electrochemical supercapacitors. The device demonstrated a remarkable high energy density of 1.5 µWh cm-² at a power density of 327.9 mW cm-², along with exceptional long-term durability.

Review on Biomass Derived Activated Carbons as Electrochemical Electrode Material for Supercapacitor Device

Abstract: To face the challenge of the finite nature of fossil fuels and large energy crises across the globe, there is an urgent requirement for sustainable and renewable energy sources. Moreover, it is essential to focus on energy storage in order to meet the demand of future generations. Among various energy storage devices such as fuel cells, batteries, capacitors, supercapacitors, flywheels, etc., it is the supercapacitor device that has elicited extensive research interest recently because of prominent features like high power density, fast recharge capability, and long cycle life. The main objective of this article is to review the enhancement of the electrochemical performance of supercapacitor devices. The electrochemical properties of the supercapacitor device majorly depend on the electrode materials used, which include carbonaceous materials, metal oxides, and conducting polymers. In order to reduce energy shortages and environmental pressure, carbon materials derived from biomass/waste materials have been considered remarkable candidates for electrode materials with the advantages of high abundance, low cost, and environmental friendliness. This review shows the complied study of various methodologies for the preparation of activated carbons derived from different biomass residues such as plants, animals, and microorganisms, which have been investigated in the past few years as electrochemical electrode materials for supercapacitors. Further, ongoing challenges and potential improvements in this area for creating efficient energy storage devices are also discussed. The goal of this review article is to aid in the creation of new insights for energy storage applications of biomass-generated carbons that will lead to sustainable energy development.

Core-shell NiCo2S4@C with three dimensional carbon frameworks for enhanced asymmetrical supercapacitor and lithium storage performance

Transition-metal sulfides have been considered as promising candidates for electrochemical supercapacitor and lithium ion batteries. Unfortunately, the shortcomings including large volume change, low conductivity as well as severe structural exfoliation from conductive substrate or current collector inhibit their practical application. Herein, the hydrothermal and solvothermal approach are developed for the controllable synthesis of core-shell NiCo2S4@C with three dimensional carbon frameworks. As an asymmetric supercapacitor, the NiCo2S4@C/YP-50 F displays a high energy density of 46.7 Wh kg−1 at a power density of 0.8 kW kg−1 and the good cycling stability (∼110 % of the initial capacitance retention at 16 kW kg−1 over 2000 cycles). Furthermore, the NiCo2S4@C exhibits the specific capacity of 414 mAh g−1 after 500 cycles at 2000 mA g−1 when evaluated as anode for lithium ion batteries. The excellent performance can be ascribed to the core-shell structure and the three dimensional carbon frameworks. The synthetic approach can be extended to fabricate other high performance metal sulfides for energy storage.

Chemically activated carbons derived from cashew nut shells as potential electrode materials for electrochemical supercapacitors

Supercapacitors are widely recognized as energy storage solutions due to their high power densities and long cycle lives. Furthermore, there is growing scientific and technological interest in converting biomass waste into carbon materials for manufacturing supercapacitor electrodes. In addition to their abundance and cost-effectiveness, the appeal of carbons derived from biomass lies in their tunable porosity, which enables the rational design of carbon materials to achieve the desired performance of supercapacitors. Here, we present the synthesis of activated carbons from cashew nut shells via potassium hydroxide (KOH) activation at different temperatures (650, 750, and 850 °C). The resulting materials exhibited amorphous and predominant microporous structures. Increasing the activation temperature led to a rise in specific surface area from 1534 to 2034 m2 g−1 and an increased proportion of mesopores. The electrochemical properties of these activated carbons for supercapacitor applications were investigated by cyclic voltammetry, galvanostatic charge–discharge, and impedance spectroscopic techniques in a 1 M sodium sulfate (Na2SO4) electrolyte. Using a three-electrode system, the activated carbons treated at 750 °C exhibited a maximum specific capacitance of 106 F g−1 at a current density of 0.5 A g−1 with a good rate capability; they retained 75 % at 10 A g−1 over a 1.0 V voltage window. Furthermore, a symmetric supercapacitor coin-cell, fabricated with activated carbons treated at 750 °C as the positive and negative electrodes, demonstrated an energy density of 2.43 Wh kg−1 at a power density of 1002 W kg−1. The cell exhibited 87 % capacitance retention at 1.0 A g−1 after 10,000 cycles. This work showcases the efficient and sustainable utilization of cashew nut shells as a carbon source for supercapacitor applications and highlights their value in a circular economy.

Preparation of Ni Nanowires Covalent Organic Framework Composites with High Electrochemical Stability and Supercapacitor Performance

Preparation of Ni Nanowires Covalent Organic Framework Composites with High Electrochemical Stability and Supercapacitor Performance

Effect of air-annealing on the structure, surface morphology, and supercapacitive properties of the 2D-BiOCl nanosheets

Upright-standing nanosheets of bismuth oxychloride (BiOCl), synthesized via a facile chemical synthesis method and air-annealed from 50 to 600 ℃ temperatures (named BOC-50–600), are envisaged as electrochemical supercapacitor electrodes. These electrodes are initially screened for their surface morphology, elemental configuration, phase purity, and binding energy by various means. Due to changes in the surface morphology, phase, charge transfer resistance, and binding energy, the one annealed at 150 ℃ i.e., BOC-150 has offered targeted supercapacitive performance due to quasi-faradaic redox reactions in 6 M KOH electrolyte solution. The specific capacitance of the BOC-150 electrode, measured at 1.40–5.0 A/g current densities, varies from 264.6 to 95 F/g. The as-assembled BOC-150//BOC-150 symmetric supercapacitor device (SSD) demonstrates an efficient supercapacitive performance with a maximum 86.87 Wh/kg energy density and 3735 W/kg power density. Additionally, the as-designed SSD endows an admirable capacity retention of 81.6% for 5000 charge-discharge cycles, approving moderate chemical stability and considerable mechanical robustness for use in commercial electronic items.

Boosting electrochemical energy storage properties of SrGd2O4 through Yb3+ and Tm3+ rare earth ion doping

Electrochemical supercapacitors represent advanced energy storage devices that excel in the swift storage and delivery of electrical energy, effectively bridging the gap between conventional capacitors and batteries. The present work, aimed to investigate charge storage properties of SrGd2O4 and rare earth ions Yb3+ and Tm3+ doped in SrGd2O4. Both materials were prepared via simple sol-gel synthesis and characterized by XRD, XPS, and FE-SEM with EDS. Characterization confirmed the presence of Tm3+ and Yb3+ in the SrGd2O4 matrix with a uniform distribution of elements. The charge storage behavior of pure SrGd2O4 and SrGd2O4:Yb4Tm1 in various electrolytes was thoroughly explored. Large electrochemical potential windows were shown by both electrode materials in aqueous 6 M KOH (1.7 V), which is essential for supercapacitors to achieve high specific energy. Furthermore, SrGd2O4:Yb4Tm1 demonstrated a substantially more pronounced charge storage effect in 6 M KOH electrolyte, with almost double times higher specific capacitance values compared with an un-doped SrGd2O4 sample. The main impact on the electrochemical window had matrix SrGd2O4, while the main impact on specific capacitance had rear earth dopants (Yb3+ and Tm3+). Improved charge storage characteristics of SrGd2O4:Yb4Tm1 were also evident through a notable reduction in overall resistance observed in electrochemical impedance spectroscopy experiments. Concerning the two-electrode GCD measurements, the SrGd2O4:Yb4Tm1 electrode in 6 M KOH showed a specific capacitance of 143 F g−1, with the specific energy of 12.5 Wh kg−1 at 0.6 A g−1. These findings demonstrate the potential of rare earth ion doping in enhancing the energy storage properties of SrGd2O4, offering promising avenues for the development of high-performance supercapacitors.

Enhancing sp3 content in diamond-like carbon thin film electrodes by pulsed laser annealing for durable charge storage performance

In this work, diamond-like carbon (DLC) thin film electrodes were grown on Si substrate by pulsed laser deposition (PLD) technique, and the implication of pulsed laser annealing (PLA) treatment on their electrochemical supercapacitor performance was examined by three electrode systems in 1 M Na2SO4 electrolyte solutions. The SEM micrographs exhibit a sheet-like wrinkled surface of DLC film on Si which later transformed into tiny hierarchical heap-like structures with enhanced surface roughness. The Raman spectra confirm signature of the D and G peaks of pristine DLC film at ∼1352 cm−1 (1356 cm−1 after PLA) and 1591 cm−1 (1589 cm−1 after PLA), and appearance of minor T2g (diamond) (1332 cm−1) peaks with an increment of the sp3 content after PLA treatment. The X-ray photoelectron spectroscopy (XPS) spectra were deconvoluted into three different contributions CC (sp2), CC (sp3), and CO, and their sp3 percentages were estimated ∼48.9 %, and 64.7 % before and after annealing. The area under cyclic voltammetry (CV) curve and galvanostatic charging discharging (GCD) performance of PLA-treated DLC film were improved and the highest areal-specific capacitance was obtained to be ∼48.25 mF/cm2 for scan rate of 5 mV/s and 36.01 mF/cm2 for current density of 2 mA/cm2, respectively. Excellent charging discharging cyclic stability of PLA treated electrode was observed over 5000 cycles, and Coulombic efficiency and capacitance retention were determined to be ∼93.5 % and ∼ 97.3 %, respectively. The electrochemical impedance spectroscopy (EIS) was performed to obtain the Nyquist plot (Z′vs.Z′′) of both electrodes before and after the stability test, and a small degradation in impedance was observed. The Nyquist plots were fitted with the well-known Randles equivalent circuit model Rs(Cdl(RctZw)) and substantial curtailment of Warburg resistance (Zw) in PLA-induced DLC electrode signifies the dominance of the diffusion-controlled region in the charging-discharging process. Minor changes in the Nyquist plot before and after the stability test manifest the enduring charge kinetics of both electrodes and PLA-treated DLC exhibits better cyclic stability. PLA techniques have a great impact on upgrading the areal-specific capacitance, capacitance retention with high Coulombic efficiency, and stability with negligible impedance loss of the DLC film electrodes.

Enhancing the energy storage performance of titanium dioxide electrode material by green doping of Nd2O3 nanoparticles for electrochemical supercapacitors

Doping of sesquioxide alloy onto TiO2 nanomaterials was carried out in a novel green chemistry method using Corallo carpus epigaeus to fabricate the electrodes for pseudocapacitors. The conducted X-ray diffraction studies demonstrated the tetragonal phase of TiO2 and hexagonal phase of Nd2O3 nanomaterials. Morphological analysis revealed the irregular shape of TiO2 materials, each exceeding 100 nm in size, while Nd2O3 materials exhibited a spherical shape within the range of 10–20 nm. Electrochemical investigations unveiled a quasi-rectangular shape in cyclic voltammetric studies and a triangular shape in galvanostatic reactions, suggesting superior electrochemical performance of the electrodes. The doped electrodes exhibited a higher specific capacitance value (785.71 F/g) compared to pure TiO2 (707.14 F/g) at a current density of 1 A/g. These findings affirm the suitability of doped electrode materials for applications in electrical energy storage.

Porous cobalt phosphide nanoflakes supported on ordered mesoporous carbon for superior electrochemical performance supercapacitor and hydrogen evolution reaction

In this study, we synthesized cobalt phosphate flake-like nanostructures anchored to the OMC matrix using a simple and cost-effective hydrothermal process followed by an environmentally friendly phosphidation process. The physicochemical characterization of the CoP@OMC composite indicated that the porous CoP nanoflakes made up of bundles of ultrathin nanosheets with an approximate thickness of 30 nm are anchored on rod-like hexagonal OMC with a diameter of 110–140 nm, allowing remarkable enhancement of mesoporosity and active surface area. The CoP@OMC composite was employed as a new material for modification of electrode surface used in supercapacitor and hydrogen evolution reaction (HER). Interestingly, CoP@OMC acquired a specific capacitance of 3182 Fg−1 at current density of 1 A g−1, in 6 M KOH. Asymmetrical CoP@OMC//CB cell showed a capacity of 194 Fg−1 at the current density of 1 A g−1 with a maximum energy density of 77.9 Wh kg−1 and a power density of 17 kW kg−1. CoP@OMC composite also showed an excellent HER performance with only 111 mV overpotential to drive a current density of 10 mA cm−2 and a low Tafel slope of 43.8 mV dec−1 in 1 M KOH. Therefore, CoP(OMC) as an environmentally friendly material with high efficiency and significant catalytic / electronic properties is expected to be a good candidate for future energy storage & conversion systems.

Nanoporous Carbon Materials Derived from Zanthoxylum Bungeanum Peel and Seed for Electrochemical Supercapacitors.

In order to prepare biomass-derived carbon materials with high specific capacitance at a low activation temperature (≤700 °C), nanoporous carbon materials were prepared from zanthoxylum bungeanum peels and seeds via the pyrolysis and KOH-activation processes. The results show that the optimal activation temperatures are 700 °C and 600 °C for peels and seeds. Benefiting from the hierarchical pore structure (micropores, mesopores, and macropores), the abundant heteroatoms (N, S, and O) containing functional groups, and plentiful electrochemical active sites, the PAC-700 and SAC-600 derive the large capacities of ~211.0 and ~219.7 F g-1 at 1.0 A g-1 in 6 M KOH within the three-electrode configuration. Furthermore, the symmetrical supercapacitors display a high energy density of 22.9 and 22.4 Wh kg-1 at 7500 W kg-1 assembled with PAC-700 and SAC-600, along with exceptional capacitance retention of 99.1% and 93.4% over 10,000 cycles at 1.0 A g-1. More significantly, the contribution here will stimulate the extensive development of low-temperature activation processes and nanoporous carbon materials for electrochemical energy storage and beyond.

High-energy density cellulose nanofibre supercapacitors enabled by pseudo-solid water molecules

Compared with conventional electrochemical supercapacitors and lithium-ion batteries, the novel amorphous cellulose nanofibre (ACF) supercapacitor demonstrates superior electric storage capacity with a high-power density, owing to its fast-charging capability and high-voltage performance. This study unveils introduces an ACF supercapacitor characterised by a substantial energy density. This is achieved by integrating a singular layer of pseudo-solid water molecules (electrical resistivity of 1.11 × 108 Ω cm) with cellulose nanofibers (CNFs), establishing forming an electric double layer at the electrode interface. The enhanced energy storage in these high-energy density capacitors (8.55 J/m2) is explicated through the polarisation of protons and lone pair electrons on oxygen atoms during water electrolysis, commencing at 1.23 V. Improvements in energy density are attainable through CNF density enhancements and charging-current optimisation. The proposed ACF supercapacitor offers substantial promise for integration into the power sources of flexible and renewable paper-based electronic devices.

Carbon quantum dots decorated NiCo layered double hydroxide for electrochemical oxygen evolution reaction and supercapacitor application

Carbon quantum dots decorated NiCo layered double hydroxide for electrochemical oxygen evolution reaction and supercapacitor application

Synthesis and characterization of SnO2-La2O3 for electrochemical supercapacitor performance in redox additive electrolyte

Synthesis and characterization of SnO2-La2O3 for electrochemical supercapacitor performance in redox additive electrolyte

Structural, morphological, optical, and magnetic properties of NiO-added NiCo2O4 electrode materials synthesized by sol-gel, Co-precipitation and ultrasonication methods and their electrochemical supercapacitor response

In this study, NiO-added NiCo2O4 composite samples were prepared using three distinct synthesis methods to study the impact of synthesis technique and NiO addition on the electrochemical performance of NiCo2O4. The chosen methods, sol-gel, co-precipitation, and ultrasonication, represent a range of approaches that yield different particle structures and morphologies. The structural and morphological studies of composite samples were investigated using X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM), respectively. XRD analysis revealed the crystalline composition, revealing the presence of two distinct phases: NiO and NiCo2O4. The Rietveld analysis of the composite samples supports the dual phases in the samples. FESEM analysis confirms the change in size and shape of the particles with the synthesis procedure. Optical properties, measured via UV–visible absorbance spectra, demonstrated that the energy gap varied with the synthesis method. The sol-gel samples exhibited the highest energy gap at 2.20 eV. The magnetic properties were measured using the vibration sample magnetometer (VSM), and the results confirm that the synthesis procedure influences magnetic loops and coercivity. The electrochemical performance of the samples in a 3 M potassium hydroxide electrolyte revealed that the co-precipitation method produced the highest capacitance of 398 Fg-1 at a 10 mV/s sweep rate, indicating superior energy storage capacity compared to pure NiCo2O4. Adding NiO phase to the NiCo2O4 matrix is believed to enhance electrochemical performance by creating additional charge at the grain boundaries, leading to a synergistic effect and improved electron and ion transport. The exceptional electrochemical performance of these composite materials suggests that the synthesis methods and the addition of NiO play a critical role in determining the overall efficiency and applicability of battery-type supercapacitors. These findings pave the way for further research into optimizing synthesis parameters to enhance energy storage capacity and inspire the development of advanced spinel metal oxide composite electrodes for supercapacitors and other energy storage applications.

Al-Ce co-doped BaTiO3 nanofibers as a high-performance bifunctional electrochemical supercapacitor and water-splitting electrocatalyst

Supercapacitors and water splitting cells have recently played a key role in offering green energy through converting renewable sources into electricity. Perovskite-type electrocatalysts such as BaTiO3, have been well-known for their ability to efficiently split water and serve as supercapacitors due to their high electrocatalytic activity. In this study, BaTiO3, Al-doped BaTiO3, Ce-doped BaTiO3, and Al-Ce co-doped BaTiO3 nanofibers were fabricated via a two-step hydrothermal method, which were then characterized and compared for their electrocatalytic performance. Based on the obtained results, Al-Ce co-doped BaTiO3 electrode exhibited a high capacitance of 224.18 Fg−1 at a scan rate of 10 mVs−1, high durability during over the 1000 CV cycles and 2000 charge–discharge cycles, proving effective energy storage properties. Additionally, the onset potentials for OER and HER processes were 11 and − 174 mV vs. RHE, respectively, demonstrating the high activity of the Al-Ce co-doped BaTiO3 electrode. Moreover, in overall water splitting, the amount of the overpotential was 0.820 mV at 10 mAcm−2, which confirmed the excellent efficiency of the electrode. Hence, the remarkable electrocatalytic performance of the Al-Ce co-doped BaTiO3 electrode make it a promising candidate for renewable energy technologies owing to its high conductivity and fast charge transfer.

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.

AGRICULTURAL WASTE AS A PANACEA FOR HIGH COST OF ELECTROCHEMICAL DOUBLE LAYER SUPER-CAPACITOR AND SUSTAINABLE ENERGY STORAGE SOLUTION: A REVIEW

Supercapacitors, also known as ultracapacitors or electrochemical capacitors, are energy storage devices that store and release energy quickly. They are used in various applications, including renewable energy systems, electric vehicles, and electronics. Using agricultural waste as a source for supercapacitor’s electrode materials is an innovative and sustainable approach that holds promise for addressing the high cost of these materials. Agricultural wastes, such as crop residues, husks, shells, and other byproducts, often presents challenges in terms of disposal and environmental impact but have proven to be a good precursor material for the synthesis of electrochemical super capacitor’s electrode. By repurpose these waste materials for supercapacitor electrodes, the high cost of the electrode will be reduced and hence the overall cost of the supercapacitors.

Carbon nanospheres-induced enhanced capacitive dynamics in C/WS2/WO3 nanocomposites for high-performance electrochemical capacitors

This work investigates the impact of carbon nanospheres on the electrochemical performance of C/WS2/WO3 nanocomposites for electrochemical supercapacitors. The nanocomposites have been synthesized and characterized by various techniques like XRD, UV–vis spectroscopy, SEM, TEM and FTIR. The electrochemical properties of the nanocomposites have been analysed in order to study the charge transport, reaction kinetics, impedimetric properties and specific capacitance by using cyclic voltammetry (CV) and potentio electrochemical impedance spectroscopy (PEIS). The capacitive performance of the samples has been investigated by the obtained specific capacitance values and Nyquist plots. The specific capacitance of the samples has been found in a range of 0.8–2.8F/g at 20 mV/s. The sample with the least amount of carbon showed maximum specific capacitance. The electrochemical insights, combined with comprehensive material characterizations, provide valuable knowledge for tailoring the capacitive performance of C/WS2/WO3 nanocomposites through controlled carbon nanospheres and thus the suitability of materials for electrochemical capacitors.