Storage Capacitor Research Articles

Giant energy storage and power density negative capacitance superlattices.

Dielectric electrostatic capacitors1, because of their ultrafast charge-discharge, are desirable for high-power energy storage applications. Along with ultrafast operation, on-chip integration can enable miniaturized energy storage devices for emerging autonomous microelectronics and microsystems2-5. Moreover, state-of-the-art miniaturized electrochemical energy storage systems-microsupercapacitors and microbatteries-currently face safety, packaging, materials and microfabrication challenges preventing on-chip technological readiness2,3,6, leaving an opportunity for electrostatic microcapacitors. Here we report record-high electrostatic energy storage density (ESD) and power density, to our knowledge, in HfO2-ZrO2-based thin film microcapacitors integrated into silicon, through a three-pronged approach. First, to increase intrinsic energy storage, atomic-layer-deposited antiferroelectric HfO2-ZrO2 films are engineered near a field-driven ferroelectric phase transition to exhibit amplified charge storage by the negative capacitance effect7-12, which enhances volumetric ESD beyond the best-known back-end-of-the-line-compatible dielectrics (115 J cm-3) (ref. 13). Second, to increase total energy storage, antiferroelectric superlattice engineering14 scales the energy storage performance beyond the conventional thickness limitations of HfO2-ZrO2-based (anti)ferroelectricity15 (100-nm regime). Third, to increase the storage per footprint, the superlattices are conformally integrated into three-dimensional capacitors, which boosts the areal ESD nine times and the areal power density 170 times that of the best-known electrostatic capacitors: 80 mJ cm-2 and 300 kW cm-2, respectively. This simultaneous demonstration of ultrahigh energy density and power density overcomes the traditional capacity-speed trade-off across the electrostatic-electrochemical energy storage hierarchy1,16. Furthermore, the integration of ultrahigh-density and ultrafast-charging thin films within a back-end-of-the-line-compatible process enables monolithic integration of on-chip microcapacitors5, which can unlock substantial energy storage and power delivery performance for electronic microsystems17-19.

Capacitive-Controlled Prussian White with a Nickel Iron Hexacyanoferrate Composite Cathode for Rapid Sodium Diffusion.

Prussian blue analogues receive tremendous attention owing to their spacious three-dimensional skeleton, high theoretical specific capacity, facile synthesis procedure, and high cost-effectiveness as among the most promising candidates for cathode materials in sodium-ion batteries (SIBs). Nonetheless, the practical specific capacity, especially under high current, is particularly frail due to the sluggish ion diffusion. In this study, the strategy of Ni substitution and formation of water-coordinated Fe is applied to lower the crystal field energy and elevate the active low-spin (LS) Fe content, which leads to a capacitive sodium storage mechanism, resulting in a substantial specific capacity under high current density. The delivered specific capacity of PW-325@2NiFe-55 is 95 mAh g-1 at 50 C, which is 72.5% capacity retention of the one at 0.5 C. Also, it maintains 80.2% of its initial specific capacity after 500 cycles at 5 C. Furthermore, a hypothesis of a joint diffusion-controlled and capacitive mechanism for high-spin (HS) Fe and a mere capacitive mechanism for LS Fe is put forward and verified through potentiastatic tests, operando 57Fe Mössbauer spectroscopy, and ex situ XRD, which provides a new horizon to enhance the electrochemical performance for SIBs.

Enhanced relaxation behavior and energy storage properties in (Al0.5Nb0.5)4+ complex ions modified Na0.5Bi0.5TiO3-based ceramics under low electric field

In recent decades, high polarization and low residual polarization lead-free relaxor ferroelectric ceramics have attracted lots of focus due to their great potential in dielectric capacitors for energy storage. In this work, Na0.35Bi0.35Sr0.3Ti(1-x)(Al0.5Nb0.5)xO3 (x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05) lead-free ceramics have been fabricated by the traditional solid-stated reaction method. By doping (Al0.5Nb0.5)4+ complex ions into 0.7Na0.5Bi0.5TiO3-0.3SrTiO3, pure perovskite phases and reduced grain sizes are obtained. Increasing the AN concentration not only moves the Ts toward the lower temperature, but also keeps the permittivity at a high average value, which shows a good thermal stability of the dielectric properties (εr150°C∼3903 ± 15% in the range of 42–232 °C). Furthermore, Na0.35Bi0.35Sr0.3Ti(1-x)(Al0.5Nb0.5)xO3 presents a reduced residual polarization due to the improved relaxor behavior, and achieves a moderate energy storage property at low electric field of 155 kV/cm (when x = 0.04, Wrec is 1.85 J/cm3, and η is 89.0%). More importantly, the ceramic also possesses great frequency, temperature and cycle stability. Hence, the (Al0.5Nb0.5)4+ modified 0.7Na0.5Bi0.5TiO3-0.3SrTiO3 ceramics have exhibited a potential application in dielectric capacitors for energy storage.

Corrections to “A Synchronized Switch Harvesting Rectifier With Reusable Storage Capacitors for Piezoelectric Energy Harvesting”

Corrections to “A Synchronized Switch Harvesting Rectifier With Reusable Storage Capacitors for Piezoelectric Energy Harvesting”

A Novel Ternary Pseudocapacitive Electrode with Synergistic Contributions

AbstractTernary electrodes represent an exciting strategy to substantially enhance the performance of supercapacitors beyond what binary electrodes offer. However, the interplays among ternary constituents and their possible synergies remain poorly understood. This study investigates a ternary electrode design, wherein ferric oxyhydroxide (FeOOH) and magnesium dioxide (MnO2) are co‐deposited onto carbon nanotube (CNT) mats. The results reveal that the ternary electrode demonstrates a 33.3% reduction in internal resistance and a 59% increase in areal capacitance compared to its binary MnO2/CNT counterpart. Furthermore, the ternary electrode achieves a 25% increase in capacitance compared to the combined capacitances of separate MnO2/CNT and FeOOH/CNT electrodes. These findings demonstrate that combining FeOOH and MnO2 can synergistically enhance electrical conductivity and pseudocapacitance beyond their binary counterparts. This design yields a surface capacitance exceeding 3500 mF cm−2 at an active material loading up to 15 mg cm−2. By pairing with a binary FeOOH/CNT electrode, the resulting asymmetric supercapacitor exhibits an operational voltage window to 1.6 V. To demonstrate the potential of the new design, ternary electrodes are integrated into wearable and structural supercapacitors. The new synergistic ternary electrode approach provides a promising avenue for enhancing energy storage capacitance and expanding the scope of energy storage structure applications.

Influence of sintering temperature on the electrical properties of SrTiO3–BaZrTiO3 ceramics for energy storage applications

The impact of the sintering temperature on the phase composition and electrical properties of 5%SrTiO3–95%BaZr0.15Ti0.85O3 (ST-BZT) ceramics fabricated by solid-state method and consolidated by two-step sintering is presented. A systematic analysis of the phase composition, microstructures, dielectric, ferroelectric, and energy storage characteristics. A di-phase SrTiO3–BaZrTiO3 composite is obtained at low sintering temperatures below 1400 °C. Increasing the sintering temperature causes a shift of the Curie temperature from 62 °C to 55 °C together with changes of permittivity values and of the ferroelectric loops, thus indicating a progressive interdiffusion process at the interfaces, together with a better densification. Remarkably, the ST-BZT composition sintered at 1500 °C exhibits characteristics of a single phase (Ba,Sr) (Zr,Ti)O3 solid solution, with high room temperature permittivity around 2950 and good ferroelectric response (saturation polarization Pmax = 12.6 μC/cm2 and remnant polarization Pr = 2.16 μC/cm2). Consequently, this composition displays a much greater recoverable energy density (Wrec = 54.5 mJ/cm3) in comparison to the ones of the di-phase ST-BZT composites and the parent phases. However, the (Sr0.05Ba0.95) (Zr0.14Ti0.86)O3 solid solution, demonstrates a lower energy efficiency (72%) in comparison to the ST-BZT di-phase composites sintered at lower temperatures, which exhibit higher energy efficiency values around 86%. In addition, the charge-discharge experiments were performed under different electric fields to disclose the difference in energy storage properties in 5%SrTiO3–95%BaZr0.15Ti0.85O3 ceramics. This suggests that the sintering strategy plays a crucial role in determining the energy efficiency of the obtained ceramics. Additionally, all the investigated ST-BZT ceramics present high energy efficiency at low-applied electric fields, suggesting their potential as candidates for energy storage capacitors operating at moderate fields.

Plasma-Treated Cobalt-Doped Nanoporous Graphene for Advanced Electrochemical Applications

Metal–carbon nanocomposites are identified as key contenders for enhancing water splitting through the oxygen evolution reaction and boosting supercapacitor energy storage capacitances. This study utilizes plasma treatment to transform natural graphite into nanoporous few-layer graphene, followed by additional milling and plasma steps to synthesize a cobalt–graphene nanocomposite. Comprehensive structural characterization was conducted using scanning and transmission electron microscopy, X-ray diffraction, Raman spectroscopy, gas sorption analysis and X-ray photoelectron spectroscopy. Electrochemical evaluations further assessed the materials’ oxygen evolution reaction and supercapacitor performance. Although the specific surface area of the nanoporous carbon decreases from 780 to 480 m2/g in the transition to the resulting nanocomposite, it maintains its nanoporous structure and delivers a competitive electrochemical performance, as evidenced by an overpotential of 290 mV and a Tafel slope of 110 mV/dec. This demonstrates the efficacy of plasma treatment in the surface functionalization of carbon-based materials, highlighting its potential for large-scale chemical-free application due to its environmental friendliness and scalability, paving the way toward future applications.

Electrochemical Capacitance Traces with Interlayer Spacing in Two‐dimensional Conductive Metal–Organic Frameworks

AbstractElectrically conductive metal–organic frameworks (MOFs) are promising candidates for electrochemical capacitors (EC) for fast energy storage due to their high specific surface areas and potential for redox activity. To maximize energy density, traditional inorganic pseudocapacitors have utilized faradaic processes in addition to double‐layer capacitance. Although conductive MOFs are usually comprised of redox active ligands which allow faradaic reactions upon electrochemical polarization, systematic studies providing deeper understanding of the charge storage processes and structure‐function relationships have been scarce. Here, we investigate the charge storage mechanisms of a series of triazatruxene‐based 2D layered conductive MOFs with variable alkyl functional groups, Ni3(HIR3‐TAT)2 (TAT=triazatruxene; R=H, Et, n‐Bu, n‐Pent). Functionalization of the triazatruxene core allows for systematic variation of structural parameters while maintaining in‐plane conjugation between ligands and metals. Specifically, R groups modulate interlayer spacing, which in turn shifts the charge storage mechanism from double‐layer capacitance towards pseudocapacitance, leading to an increase in molar specific capacitance from Ni3(HIH3‐TAT)2 to Ni3(HIBu3‐TAT)2. Partial exfoliation of Ni3(HIBu3‐TAT)2 renders redox active ligand moieties more accessible, and thus increases the dominance of faradaic processes. Our strategy of controlling charge storage mechanism through tuning the accessibility of redox‐active sites may motivate further design and engineering of electrode materials for EC.

Non-destructive Moisture Content Testing for Soil Brick Using Capacitive Measurement With 50 MHz Radio Frequency

This research paper presents a soil brick moisture measurement by capacitive measurement with radio frequency of 50 MHz and the soil brick as the dielectric material sandwiched between the conductive plates of the capacitor. The moisture content of the soil brick was considered from the capacitance storage capacity of the capacitor. The proposed measurement consisted of a voltage-controlled oscillator, capacitance measurement circuit, radio frequency amplifier, radio frequency detector, and microcontroller unit. After that, a circuit was built and assembled to the radio frequency soil moisture meter of soil bricks for evaluate the soil brick with width of 20 cm, length of 40 cm and the thickness of 20 cm. There are four types of soil brick with moisture of 10% to 30% and 10 times of iterations. From measured results, it was found that the dielectric constant and capacitive value are directed variation with moisture content of soil bricks. Therefore, the moisture content of soil bricks can be found by capacitive measurement. From the measured results, it accurate when comparing the standard measurement with an error of 4–16%.

Superior electric displacement and energy storage density in dielectric polymer via inserting thermoplastic polyurethane

Dielectric polymers have been broadly applied in film energy storage capacitors owing to their excellent insulating characteristics. However, low electric displacement (D) and available energy densities (Ue) of existing polymer systems restrict them for miniaturized and integration applications. Herein, thermoplastic polyurethane (TPU) is utilized as the central layer to provide high D, and poly (methyl methacrylate) (PMMA) is used as the coating layer to maintain insulating characteristics. The electric displacement difference (Dmax-Dr) value and Ue values of the all-organic composites were optimized by modifying the relative ratios of the intermediate layer TPU. Notably, the all-organic composites with optimized relative ratio (26.13 vol%) of the TPU layer exhibits the largest Dmax-Dr of 8.27 μC/cm2 at highest breakdown strength of 450 MV/m, which is 89 % higher than that of PMMA at 4.37 μC/cm2, and thus a maximum Ue of 16.23 J/cm3 is obtained, far exceeding the values for advanced polymer and their composites. This strategy provides an effective approach for the development of dielectric polymer with high energy storage capabilities.

Self-charging hybrid energy devices collaborated with enzymatic biofuel cells and supercapacitors

Enzymatic biofuel cells (EBFCs) are promising as a biocompatible power source for implantable and wearable devices, converting chemical energy of body fluids into electricity. However, they have intrinsic limitations, such as low power density and requirement for continuous fuel supply. To overcome the difficulties, hybrid energy devices (HEDs) that are combinative device of supercapacitor (SC) and EBFC are suggested in this study. They consist of anode and cathode including (i) enzymes reacting with respective fuels and (ii) mediators promoting transfer and storage of electrons. As EBFCs, HEDs exhibit exceptional fuel reactivity, achieving 0.91 and 0.51 mA/cm2 in glucose oxidation reaction and oxygen reduction reaction, while they play as SCs with excellent power and specific storage capacitance of 0.93 mW/cm2 and 307 mF/cm2. Moreover, HEDs show self-charging property that is uniquely observed in devices operated by the collaboration of enzyme and mediator. By this benefit, their open circuit voltage is well preserved in absent of fuels, while they can discharge even without supply of fuel. These features are obvious evidence that HEDs can be considered as advanced power sources for implantable and wearable devices.

Electron-interactive 1D porous vertical NiCo2O4 nanowire and 3D N-doped graphene aerogel enable high hydroxyl-ion adsorption capacity for superior energy storage

Supercapacitors are a kind of highly efficient energy-storage device with long cycle life and high power density, however, their specific capacitance is insufficient for further application and development. In this work, a novel composite with one-dimensional (1D) NiCo2O4 nanowire arrays (NiCo2O4-NWA) vertically supported on three-dimensional (3D) nitrogen-doped graphene aerogel (NGA) is designed and facilely realized by hydrothermal reaction and thermal treatment. The NiCo2O4 nanowires, with length of ∼1 μm and diameter of ∼25 nm, display a porous structure and are regularly arranged on both sides of the sheets in nitrogen-doped graphene aerogel. The aerogel-supporting NiCo2O4 nanowires demonstrate a remarkably high specific capacitance of 2742 F g−1 at 1 A g−1, and an outstanding cyclic stability with capacitance retention of 90% even after 10,000 cycles at 80 A g−1. The density functional theory calculation shows the narrow band gap (0.32 eV) and strong electronic interaction and hydroxyl-ion adsorption effect of NiCo2O4 supported on NGA, resulting in superior specific capacitance and energy storage performance. The 3D nitrogen-doped graphene aerogel supporting 1D nanowire arrays represent a promising high-performance electrode material for application in the supercapacitors and other electrochemical energy-conversion and storage equipment.

Decoupled supercapacitive electrolyzer for membrane-free water splitting.

Green hydrogen production via water splitting is vital for decarbonization of hard-to-abate industries. Its integration with renewable energy sources remains to be a challenge, due to the susceptibility to hazardous gas mixture during electrolysis. Here, we report a hybrid membrane-free cell based on earth-abundant materials for decoupled hydrogen production in either acidic or alkaline medium. The design combines the electrocatalytic reactions of an electrolyzer with a capacitive storage mechanism, leading to spatial/temporal separation of hydrogen and oxygen gases. An energy efficiency of 69% lower heating value (48 kWh/kg) at 10 mA/cm2 (5 cm-by-5 cm cell) was achieved using cobalt-iron phosphide bifunctional catalyst with 99% faradaic efficiency at 100 mA/cm2. Stable operation over 20 hours in alkaline medium shows no apparent electrode degradation. Moreover, the cell voltage breakdown reveals that substantial improvements can be achieved by tunning the activity of the bifunctional catalyst and improving the electrodes conductivity. The cell design offers increased flexibility and robustness for hydrogen production.

Crystal growth and characterization of glycine chlorzoxazone nonlinear optical crystal for energy storage capacitor applications

This research presents the synthesis of a glycine chlorzoxazone (GC) organic single crystal through a slow evaporation process using a mixed solvent of water and ethanol at room temperature. The crystal's functional group coordination is examined via fourier-transform infrared (FTIR) spectroscopy. The study delves into the linear optical properties through UV–visible spectroscopy, and thermal analyses provide insights into the material's thermal behavior. Optical nonlinearity is confirmed using the Kurtz-Perry powder technique. The investigation extends to the electrical properties of prepared crystals, incorporating a combination of AC and DC electrical studies. This comprehensive approach enhances our understanding of the multifaceted characteristics of synthesized crystal, positioning it as a promising candidate for different electronic and optical applications.

Stable dielectric properties at high-temperature of Al2O3-PESU composite for energy storage application

Dielectric capacitors, crucial in microelectronics, hybrid vehicles and inverters, are renowned for their rapid charge–discharge capabilities and high energy density. This research introduces a novel strategy to enhance the dielectric properties of polyethersulfone (PESU) matrix materials by incorporating aluminum oxide (Al2O3) powder as a filler. Employing a solution mixing technique, dielectric composite films were synthesized. The 1 wt% Al2O3-PESU composite exhibited exceptional outcomes, presenting a charge–discharge efficiency of 62 % and an impressive energy storage density of 8.4 J/cm3 at 640 kV/mm. Finite element simulations validated enhanced thermal conductivity, reduced electric field distortion, and heightened breakdown strength in the composites. Additionally, cyclic aging demonstrated outstanding stability and reliability over 50,000 cycles. This study propels dielectric material design, charting a course for high-performance energy storage capacitors, accentuating the crucial influence of temperature on dielectric behavior.

Flexible hybrid piezo/triboelectric energy harvester based on a lead-free BNT-BT-KNN ceramic-polymer composite film

Environment-friendly piezoelectric micro/nanogenerators have attracted tremendous attention due to the increasing demand for portable self-power devices. Here, the [(0.94−x)Bi0.5Na0.5TiO3–0.06BaTiO3–xK0.5Na0.5NbO3; BNT-BT-xKNN] lead-free ceramic, at x = 0, 0.02, 0.04, 0.06, 0.08 and 0.10 mol%, was prepared via the solid-state method. The doping concentration x = 0.02 mol% shows the highest dielectric properties and the lowest dielectric loss. The active layer of the hybrid device is made by mixing BNT-BT-2KNN into the PDMS to form a series of polymer-ceramic composite films ranging from 7 to 19 wt% of BNT-BT-2KNN. The electrical response of the composite film is systematically studied with the addition of different weight percentages of the particles to the PDMS matrix. It was found that incorporating BNT-BT-2KNN at 11 wt% into the PDMS matrix exhibited the optimum harvesting performance, resulting in an output voltage and current density of about 30 V and 0.28 μA/cm2, respectively. The hybridized PENG and TENG devices could operate in a long-term cyclic mode, charge the capacitor for energy storage, and also light up LEDs. This research proposed a simple device fabrication and provided a guideline for the development of high-performance microgenerators, which is crucial for device development and practical use in the future.

Usage of Energy Storage Capacitors in TE Gas Laser Pulsers

An energy storage capacitor is crucial for both electrically pumped and optically pumped pulsed lasers. In electrically pumped lasers, the energy stored in the capacitors is directly deposited into the lasing medium, while in optically pumped lasers, it energizes the flash lamp that, in turn, pumps the lasing medium. We discuss here the application of energy storage capacitors in the operation of electrically pumped pulsed gas lasers. Increasing the operating pressure of the gain medium, a prerequisite for obtaining higher energy from the laser, has resulted in great advancements in the gas laser pulse technology. This progress has led to the development of transverse electric discharge pumping, enabling easy scalability of gas pressure and achievable output power. An ideal TE pulser efficiently charges the capacitor to an appropriate voltage with minimal energy dissipation on the charging element and facilitates a rapid and uniform transfer of this stored energy into the lasing medium before a glow-to-arc transition can set in. Various types of pulser circuits employed to energize pulsed gas lasers are described in this paper.

Utilization of Capacitor Bank for Electromagnetic Pulse Crimping

Capacitors play an important role in an electrical system. They have numerous applications in the field of lasers, fast X-ray, neutron sources, electromagnetic pulse generators, electron beam accelerators, plasma generation and electromagnetic welding of materials. One of the applications of high voltage capacitors as energy storage and discharge devices is in the crimping of cables using the electromagnetic pulse forming technique. This research paper investigates the use of a high-voltage energy storage capacitor with a capacitance of 208 microfarads and rated voltage of 44 kV to perform Electromagnetic Pulse Crimping (EMPC) of lugs for 70 mm2 and 120 mm2 cables. The capacitor operates at 12 kV and is discharged to produce a high current that generates a strong magnetic field of up to 20 Tesla, which is utilized for joining the cable conductor and the lug. The study examines the performance of the capacitor under different operating values such as voltage, capacitance, and discharge time and investigates the effect of these parameters on the termination quality. The paper presents the experimental results of the crimping, which include the contact resistance, weld strength, microstructure, and defects of the welded joints. The results indicate that the capacitor-based electromagnetic pulse crimping produces welds with high strength and minimal defects. Additionally, the paper discusses the future scope of research in this area and the potential applications of such capacitors in other welding techniques. The findings of this research paper provide valuable insights for engineers and researchers working in the field of energy storage, high-voltage applications and welding.

Modification of structural, morphological, and dielectric properties of barium calcium titanate ceramics with yttrium addition

Barium calcium titanate (BCT) ceramics with varying yttrium doping concentrations were fabricated using the solid-state compaction process to explore the attributes of dopants. (Ba0.75Ca0.25) TiO3 and (Ba0.75Ca0.25) (YyTi(1-y)) O3 where, y = 0.00, 0.10, 0.15, and 0.20 ceramics were synthesized by pressing isostatically in pellet press apparatus, then sintered at 1250 °C with consequent cooling in furnace ambient. The structural, morphological, and dielectric properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and impedance spectroscopy interpretations, respectively. The XRD analysis revealed that the cubic BCT lattice was transformed into a tetragonal structure with Yttrium doping. Scanning electron microscopy (SEM) disclosed that yttrium doping countered the liquid phase formation of BCT as well as influenced grain development and microstructure, leading to the formation of distinct grain boundaries and improved densification. The average grain size (18–29 nm) of the Y-BCT increases as the doping level rises. At 60 Hz, it was reported that the dielectric constant obtained a maximum value of 70000 with a resistivity of 5 × 108 Ώ-cm for y = 0.15. The manifestation of the secondary phase confirmed from XRD, allocating an easy path for oxygen migration, might be responsible for the rise in oxygen vacancy, higher leakage current, and dielectric loss for y = 0.01. Co-doping of calcium and yttrium in BCT ceramics has modified the basic structure and ameliorated composites' structural stability and dielectric characteristics. The optimized sample, upon demonstrating outstanding efficiency, ought to be employed for specific uses such as energy storage devices and capacitors.

Constructing superparaelectric polar structure for dielectric energy storage

To meet the miniaturization demands of next-generation electronics and electrical systems, energy storage capacitors with both high energy density and efficiency have become a research hotspot. Ferroelectric-based dielectrics are primary candidates due to the existence of spontaneous polarization and versatile domain structures. Since domains are fundamental structure units that respond to the external electric field, domain engineering is a general route to realizing high energy storage performance. In this perspective, we introduce a type of dielectrics, proposed recently and termed superparaelectrics, which has ultrasmall polar clusters (several unit cells) and exhibits nearly zero hysteresis and relatively high polarization due to the highly dynamical polar structure. Fundamental concepts of superparaelectricity are overviewed, and representative examples with state-of-the-art energy storage performance are reviewed to demonstrate the advantages of superparaelectrics. Finally, perspectives are provided about the future development of superparaelectric and electrostatic energy storage fields.