Electrostatic Capacitors Research Articles

A New TiO2‐Based Cathode Material with Interface‐Dominated Storage Mechanism for Aqueous Zinc‐Ion Batteries

AbstractAqueous zinc‐ion batteries (AZIBs) are highly desirable for large‐scale energy storage applications, yet the lack of suitable cathode materials hinders their deployment. Here, for the first time, a new and promising TiO2‐based cathode material (TOC‐AI) is reported for AZIBs and unveil a novel energy storage mechanism that enables Zn2+ storage predominantly originating from the interface. The TOC‐AI composed of ultrafine TiO2 nanocrystals embedded within an amorphous carbon matrix, featuring abundant atomic interfaces and strong interactions, triggers a decoupled and rapid transport of Zn2+ ions and electrons in the interfacial space charge region, similar to an electrostatic capacitor. Moreover, the presence of titanium vacancies facilitates Zn2+ intercalation into the TiO2 bulks, contributing extra capacity to the composite. Finally, a high capacity of 111 mAh g−1 and excellent cycling performance with 77% capacity retention after 17 000 cycles are achieved. Such interface‐dominated storage mechanism has also been successfully extended to other composite systems, broadening the scope of potential applications for materials traditionally deemed inactive for Zn2+ storage.

Spatially-confined self-assembly boron nitride nanosheet interlayer in polymer nanocomposites significantly enhances the Capacitive energy storage performance

High-performance electrostatic capacitors are urgently needed of advanced electronic devices. Traditional nanodielectric designs, such as polyvinylidene fluoride (PVDF)-based nanocomposites with uniformly distributed nanofillers, necessitate laborious filler interface modification and yield limited energy density (Ue) and efficiency (η). Herein, boron nitride nanosheet (BNNS) intercalated polymer nanocomposites were innovatively prepared by plasma treatment and BNNS spatially-confined self-assembly techniques. The oriented dense interlayered BNNS substantially suppresses leakage current and bolsters the breakdown strength of nanocomposite films, outperforming randomly or oriented distributed BNNS systems, thus obtaining a higher Ue of ∼24.1 J/cm3. Moreover, the relaxation loss of PVDF could be effectively mitigated by polymethyl methacrylate and trace intercalated BNNS, maintaining an ultrahigh η (76 %) at 600 MV/m and greatly enhances the energy storage performance. Significantly, this newly designed nanocomposites necessitate only traces of BNNS (0.2 wt%) without filler-surface-modification. These findings afford insight into the programming and manufacture of high-performance electrostatic capacitors.

DeepLPos: a comprehensive hybrid deep learning model for lying position recognition using a tactile sensor array system

Abstract Unpredictable limb movements or turning motions can significantly disrupt the accurate extraction of physiological signals, such as respiratory and heart rates. In clinical environments, reliable detection of lying positions is crucial for continuous patient monitoring, particularly during sleep. In this paper, a smart sleeping position recognition system is proposed, which employs a tactile pressure sensor array based on the unique structure of ‘the electrostatic double-layer capacitors’. The sensor array, comprising 64 rows and 32 columns (2048 nodes), captures four types of healthy lying positions using an 8-bit AD module. Despite challenges arising from limited experimental samples for accurate training, we propose DeepLPos, a hybrid deep learning approach combining generative adversarial networks and the you only look once network. To tackle the differentiation challenge between supine and prone positions, we introduce an SPD Conv attention module to enhance the resolution of detailed descriptions in pressure images. The model is further pruned to optimize both structure and parameters, enabling efficient real-time detection. Evaluated on the SLP dataset, the proposed system achieves an accuracy of 97.5% with a real-time processing speed of 0.069 s per frame, demonstrating its potential for practical, high-precision measurement and monitoring applications in healthcare.

Ultrahigh Energy-Storage in Dual-Phase Relaxor Ferroelectric Ceramics.

High-performance dielectric energy-storage ceramics are beneficial for electrostatic capacitors used in various electronic systems. However, the trade-off between reversible polarizability and breakdown strength poses a significant challenge in simultaneously achieving high energy density and efficiency. Here a strategy is presented to address this issue by constructing a dual-phase structure through in situ phase separation. (Bi0.5Na0.5)TiO3-BaTiO3-based relaxor ferroelectric ceramics are developed, creating a grain-separated dual perovskite phase structure using a facile solid-state reaction method. These ceramics feature two interactive relaxor phases with diversified nanoscale polar structures and heterogeneous grain boundaries, synergistically contributing to high polarization with low hysteresis, substantially increased resistivity, and suppressed electrostrain. Remarkably, a record-high energy density of 23.6Jcm-3 with a high efficiency of 92% under 99kVmm-1 is achieved in the bulk ceramic capacitor. This strategy holds promise for enhancing overall energy-storage performance and related functionalities in ferroelectrics.

An Intragranular Segregation Structure Enables an Excellent Energy Storage Performance in Composite Dielectrics through Delayed Saturation Polarization.

An electrostatic capacitor for energy storage is an important basic component of pulse power electronics. The electrical breakdown strength (Eb) of normal ferroelectrics is low, which limits their application in dielectric energy storage. Constructing a 0-3-type composite dielectric, that is, introducing an insulating metallic oxide into the ferroelectric matrix, can greatly enhance Eb. Unfortunately, an intergranular secondary phase typically forms that causes large attenuation of the dielectric constant, which leads to limited improvement of energy storage performance. In this work, a composite ceramic with an intragranular segregation structure was intentionally designed using the BaTiO3-BaZrO3-CaTiO3 (BCZT) system as an example. Compared with those of a BCZT solid solution without a secondary phase and a BCZT composite with a grain-boundary secondary phase, the rationally designed BCZT composite with an intragranular secondary phase delivered a large recoverable energy density of 5.86 J/cm3 and high efficiency of 86.7% at a moderate electric field of 550 kV/cm. Such performance was achieved because the intragranular segregation structure displayed delayed saturation polarization with a high Eb. This microstructural engineering strategy is generally applicable to optimize composite dielectrics to meet the demands of high-performance energy storage capacitors.

Enhanced high-temperature energy storage performances in polymer dielectrics by synergistically optimizing band-gap and polarization of dipolar glass

Polymer dielectrics play an irreplaceable role in electrostatic capacitors in modern electrical systems, and have been intensively studied with their polarization and breakdown strength (Eb) optimized for high discharged energy density (Ud) at elevated temperatures. Small molecules have been explored as fillers, yet they deteriorate thermal stability of matrix which limits their optimal loading to ~1 wt%. Herein, we develop a polymer blend dielectric consisting of common polyimide and a bifunctional dipolar glass polymer which are synthesized from two small molecule components with wide band-gap and large dipole moment. The bifunctional dipolar glass with large molecular weight not only maintains thermal stability of polymer blends even at a high loading of 10 wt%, but also induces substantial enhancement in polarization and Eb than any of individual components does, achieving an ultrahigh Ud of 8.34 J cm−3 (150 °C) and 6.21 J cm−3 (200 °C) with a charge-discharge efficiency of 90%.

Study on the Effect of Electron/Hole Injection on the Energy-Storage Properties of Polymer Dielectrics.

As a critical component of electrostatic capacitors, the polymer dielectric directly affects the performance of the capacitor. In this work, Polycarbonate (PC)/Polyvinylidene fluoride (PVDF) asymmetric bilayer polymer dielectrics were prepared, and the influence of different polymer materials' barrier characteristics on various electrical properties of composite dielectrics was studied by changing the direction of applied electric fields. Research has found that the dielectric constant of a composite dielectric is between PVDF and PC (approximately 4.8 at 10 Hz) and is independent of the relative position of PVDF and PC in the dielectric. However, the relative position of PC and PVDF has a significant impact on the energy-storage characteristics of composite dielectrics. When PVDF comes into contact with the negative electrode, even though PC has a higher hole barrier, the composite dielectric can only withstand a maximum electric-field strength of 400 MV/m, which is much lower than the maximum electric-field strength that pure PC can withstand (520 MV/m), and it only achieves an energy-storage density of 3.7 J/cm3. When the PC comes into contact with the negative electrode, the high electron barrier of the PC effectively suppresses the injection of electrons at the electrode. It can withstand the same electric-field strength as PC (520 MV/m), achieving an energy-storage density of 5.48 J/cm3, which is 1.46 times that of pure PC and 1.64 times that of PVDF. This experiment effectively combined the advantages of PC and PVDF by utilizing the electron/hole barrier of polymer materials to obtain a fully organic dielectric with excellent energy-storage performance.

Remarkable energy storage performance of BiFeO3-based high-entropy lead-free ceramics and multilayers

Electrostatic energy storage capacitors featuring fast charge–discharge capability play an indispensable role in pulsed power capacitors. However, the inverse correlation between polarization and dielectric breakdown strength (Eb) is the main obstacle limiting the access to high recoverable energy storage density (Wrec) and high efficiency (η). In this work, we designed a series of novel (1-x)BiFeO3-x(Ba0.2Sr0.2Ca0.2Bi0.2Na0.2)TiO3 (BF-xBSCBNT, x = 0.4–1.0) high-entropy lead-free relaxor ferroelectric ceramics. The synergy of refined grain size, broadened band gap, and core–shell microstructure is well-investigated by experimental results and phase-field simulations. High polarization difference is achieved by the strengthened relaxation behavior and the dominated polar nanoregions (PNRs). Both high Wrec of 6.0 J/cm3 and η of 81.1 % are achieved in the BF–0.8BSCBNT ceramics. In particular, a remarkable Wrec of 12.1 J/cm3 with a η of 86.1 % are obtained in the multilayer ceramic capacitors (MLCCs) fabricated from the x = 0.8 composition. Excellent temperature stability (<4.0 % in the range of 25–140 °C) and frequency stability (<6.2 % in the range of 1–500 Hz) are also achieved in MLCCs. The excellent energy storage performance demonstrates that high-entropy strategy is effective to develop novel lead-fee ceramics and devices for energy storage applications.

Sandwich-structured polymer dielectrics exhibiting significantly improved capacitive performance at high temperatures by roll-to-roll physical vapor deposition

Electrostatic capacitors with ultrahigh power density are the key components in modern electrical and electronic systems. Polymers are preferred dielectrics for high-voltage electrostatic capacitors, however, unable to meet the ever-growing high-temperature requirements in emerging applications, such as electric vehicles, and photovoltaic power generation. In this work, sandwich-structured Polyphenylene sulfide (PPS) films with Al2O3 as the coating layer have been prepared by using roll-to-roll magnetron sputtering. The incorporation of Al2O3 coating layers enhances the potential barrier height at the electrode/dielectric interface, thereby impeding charge injection from electrodes and suppressing high-temperature electrical conduction. Consequently, the sandwich-structured PPS films demonstrate significantly improved breakdown strengths and enhanced capacitive performance at elevated temperatures compared to neat PPS films. The roll-to-roll magnetron sputtering process employed in fabricating these sandwich-structured dielectric films is highly compatible with large-scale capacitor film production. Thus, sandwich-structured PPS films hold promise in addressing the challenge of scalable fabrication of high-performance, high-quality polymer films required for high-temperature capacitive energy storage.

Emerging Capacitive Materials for On-Chip Electronics Energy Storage Technologies

Miniaturized energy storage devices, such as electrostatic nanocapacitors and electrochemical micro-supercapacitors (MSCs), are important components in on-chip energy supply systems, facilitating the development of autonomous microelectronic devices with enhanced performance and efficiency. The performance of the on-chip energy storage devices heavily relies on the electrode materials, necessitating continuous advancements in material design and synthesis. This review provides an overview of recent developments in electrode materials for on-chip MSCs and electrostatic (micro-/nano-) capacitors, focusing on enhancing energy density, power density, and device stability. The review begins by discussing the fundamental requirements for electrode materials in MSCs, including high specific surface area, good conductivity, and excellent electrochemical stability. Subsequently, various categories of electrode materials are evaluated in terms of their charge storage mechanisms, electrochemical performance, and compatibility with on-chip fabrication processes. Furthermore, recent strategies to enhance the performance of electrode materials are discussed, including nanostructuring, doping, heteroatom incorporation, hybridization with other capacitive materials, and electrode configurations.

High-temperature capacitive energy storage in polymer nanocomposites through nanoconfinement

Polymeric-based dielectric materials hold great potential as energy storage media in electrostatic capacitors. However, the inferior thermal resistance of polymers leads to severely degraded dielectric energy storage capabilities at elevated temperatures, limiting their applications in harsh environments. Here we present a flexible laminated polymer nanocomposite where the polymer component is confined at the nanoscale, achieving improved thermal-mechanical-electrical stability within the resulting nanocomposite. The nanolaminate, consisting of nanoconfined polyetherimide (PEI) polymer sandwiched between solid Al2O3 layers, exhibits a high energy density of 18.9 J/cm3 with a high energy efficiency of ~ 91% at elevated temperature of 200°C. Our work demonstrates that nanoconfinement of PEI polymer results in reduced diffusion coefficient and constrained thermal dynamics, leading to a remarkable increase of 37°C in glass-transition temperature compared to bulk PEI polymer. The combined effects of nanoconfinement and interfacial trapping within the nanolaminates synergistically contribute to improved electrical breakdown strength and enhanced energy storage performance across temperature range up to 250°C. By utilizing the flexible ultrathin nanolaminate on curved surfaces such as thin metal wires, we introduce an innovative concept that enables the creation of a highly efficient and compact metal-wired capacitor, achieving substantial capacitance despite the minimal device volume.

Metadielectrics for high-temperature energy storage capacitors

Dielectric capacitors are highly desired for electronic systems owing to their high-power density and ultrafast charge/discharge capability. However, the current dielectric capacitors suffer severely from the thermal instabilities, with sharp deterioration of energy storage performance at elevated temperatures. Here, guided by phase-field simulations, we conceived and fabricated the self-assembled metadielectric nanostructure with HfO2 as second-phase in BaHf0.17Ti0.83O3 relaxor ferroelectric matrix. The metadielectric structure can not only effectively increase breakdown strength, but also broaden the working temperature to 400 oC due to the enhanced relaxation behavior and substantially reduced conduction loss. The energy storage density of the metadielectric film capacitors can achieve to 85 joules per cubic centimeter with energy efficiency exceeding 81% in the temperature range from 25 °C to 400 °C. This work shows the fabrication of capacitors with potential applications in high-temperature electric power systems and provides a strategy for designing advanced electrostatic capacitors through a metadielectric strategy.

Ultrahigh efficiency and energy density in tri-layered ferroelectric polymer composites utilizing ultralow loading of micro-sized plates

Ferroelectric-based composites have demonstrated tremendous potential in electrostatic capacitor owing to their exceptional dielectric characteristics. However, it is extremely challenging to attain desirable energy density (Ue) and above 95% efficiency (η) under low electric fields in the ferroelectric polymer-based composites because of the dominating electrical conduction loss. Herein, ferroelectric polymer composites consisting of SrTiO3@SiO2 plates/(PVDF-co-HFP) as the inner layer and polycarbonate (PC) as the outer polymer layers are elaborately proposed. The vital role of the multiple interlaminar interfaces (electrode/dielectric interface and interlayer interface) on the reduction of conduction loss and improvement of corresponding energy storage properties of the ferroelectric polymer is verified by experimental and theoretical simulations. The resulting composite with an ultralow loading of SrTiO3@SiO2 plates (0.5 vol%) displays a record high capacitive performance (∼8.73 J/cm3) at above 95% η under the low electric field of 280 MV/m1, indicating an enormous ∼118% increment of the maximal Ue over the commercial bench-mark biaxially oriented polypropylene (∼4 J/cm3) and far outperforming those of the polymer-based dielectrics reported to date. Along with fast discharge time (9 ns), this contribution presents a versatile and competitive technology for fabricating composites with exceptional energy storage capabilities operating under low electric fields.

Design of High‐Entropy Relaxor Ferroelectrics for Comprehensive Energy Storage Enhancement

AbstractFor an ideal electrostatic energy storage dielectric capacitor, the pursuit of simultaneously high energy density and efficiency presents a formidable challenge. Typically, under an applied electric field, an increase in energy density is usually accompanied with a deteriorated energy storage efficiency due to the escalated hysteretic loss, which is harmful to the reliability of the capacitor. Thus, a well‐balanced performance of improved energy density and maintained high efficiency is highly demanded. In this work, a structure with amorphous phases embedded in polycrystalline nanograins using the entropy tactic, leading to a higher transport barrier of carrier is constructed. Hence, the hysteretic loss is largely suppressed at a high electric field and the high polarization is still sustained in the high‐entropy film. Consequently, an ultrahigh energy density of 139.5 J cm−3 with a high efficiency of 87.9%, and a high figure of merit of 1153 are simultaneously achieved in the high‐entropy Ba2Bi4Ti5O18‐based relaxor ferroelectric. This work offers a promising avenue in materials structure design for advanced high‐power energy storage applications.

Improved Energy Density at High Temperatures of FPE Dielectrics by Extreme Low Loading of CQDs.

Electrostatic capacitors, with the advantages of high-power density, fast charging-discharging, and outstanding cyclic stability, have become important energy storage devices for modern power electronics. However, the insulation performance of the dielectrics in capacitors will significantly deteriorate under the conditions of high temperatures and electric fields, resulting in limited capacitive performance. In this paper, we report a method to improve the high-temperature energy storage performance of a polymer dielectric for capacitors by incorporating an extremely low loading of 0.5 wt% carbon quantum dots (CQDs) into a fluorene polyester (FPE) polymer. CQDs possess a high electron affinity energy, enabling them to capture migrating carriers and exhibit a unique Coulomb-blocking effect to scatter electrons, thereby restricting electron migration. As a result, the breakdown strength and energy storage properties of the CQD/FPE nanocomposites are significantly enhanced. For instance, the energy density of 0.5 wt% CQD/FPE nanocomposites at room temperature, with an efficiency (η) exceeding 90%, reached 9.6 J/cm3. At the discharge energy density of 0.5 wt%, the CQD/FPE nanocomposites remained at 4.53 J/cm3 with an efficiency (η) exceeding 90% at 150 °C, which surpasses lots of reported results.

AI-assisted discovery of high-temperature dielectrics for energy storage

Electrostatic capacitors play a crucial role as energy storage devices in modern electrical systems. Energy density, the figure of merit for electrostatic capacitors, is primarily determined by the choice of dielectric material. Most industry-grade polymer dielectrics are flexible polyolefins or rigid aromatics, possessing high energy density or high thermal stability, but not both. Here, we employ artificial intelligence (AI), established polymer chemistry, and molecular engineering to discover a suite of dielectrics in the polynorbornene and polyimide families. Many of the discovered dielectrics exhibit high thermal stability and high energy density over a broad temperature range. One such dielectric displays an energy density of 8.3 J cc−1 at 200 °C, a value 11 × that of any commercially available polymer dielectric at this temperature. We also evaluate pathways to further enhance the polynorbornene and polyimide families, enabling these capacitors to perform well in demanding applications (e.g., aerospace) while being environmentally sustainable. These findings expand the potential applications of electrostatic capacitors within the 85–200 °C temperature range, at which there is presently no good commercial solution. More broadly, this research demonstrates the impact of AI on chemical structure generation and property prediction, highlighting the potential for materials design advancement beyond electrostatic capacitors.

High-Performance TiO2/ZrO2/TiO2 Thin Film Capacitor by Plasma-Assisted Atomic Layer Annealing.

Although laminate structures are widely used in electrostatic capacitors, unavoidable heterogeneous interfaces often deteriorate the dielectric properties by impeding film crystallization. In this study, a TiO2/ZrO2/TiO2 (TZT) laminate structure, where upper-TiO2 deposited on the heterogeneous interface was crystallized by plasma-assisted atomic layer annealing (ALA), was investigated. ALA effectively induced the phase transition of the upper-TiO2 from the amorphous or anatase phase to the rutile phase, leading to an increase in the dielectric constant, whereas the ZrO2 blocking interlayer maintained the amorphous phase owing to the extremely localized effect of ALA. Consequently, through the layer-by-layer phase control of ALA, the dielectric constant of the upper-TiO2 was enhanced by 25% by applying ALA, leading to an increase in a capacitance density of 27% of the TZT capacitor, whereas a low leakage current density of ∼10-8 A/cm2 was maintained (at 1 V). In addition, the TZT capacitor on three-dimensional structures (aspect ratio of 5:1) shows a high capacitance density of up to 461 nF/mm2 owing to ALA.

A new electrostatic tunable capacitor for wide ranges of applications

A new electrostatic tunable capacitor for wide ranges of applications

Double layer capacitors in dye sensitized solar cells with large charge and energy storage capacity and controlled shape of output voltage signals.

The output signals in natural dyes-based solar cells (DSSC) can be either rising or decaying depending on the type of ions present in the system; these ions called added ions, are introduced by the additives: mordant and brighteners. The photon-dye interaction produces electrons, which eventually reach the electrode giving place to a superficially charged electrode in contact with an electrolyte where are the added ions. This combination produces, automatically, an electrical double-layer EDL structure which has important effects on the performance of the system: a) the added ions control, to a large extent, the initial shape of the output signal, giving rise to rising or decaying profiles; b) it is possible to store large amounts of energy and charge at high electric fields. This structure is found in many other systems that have a surface charged in contact with an electrolyte like piezoelectric materials in human body. This assertion was supported by determining important parameters such as the force between charged surfaces on both sides of the interface, the charge density, the energy density, and the capacitance. The Debye length has very small values then, many important quantities depend on this; it is possible to obtain large values for energy UDL ~ 3.6x105 Jm-3 and charge density ρDL ≈ 1.1x107 Cm-3 for double layer capacitors; these values are orders of magnitude larger than the corresponding values for electrostatic capacitors: Uelec ≈ 4.5x10-3 Jm-3 and ρelec ≈ 1.2 Cm-3. A non-linear model was also developed to fit unstable oscillations found in the output profiles produced by abrupt lighting.

Lead-Free NaNbO3-Based Ceramics for Electrostatic Energy Storage Capacitors

The burgeoning significance of antiferroelectric (AFE) materials, particularly as viable candidates for electrostatic energy storage capacitors in power electronics, has sparked substantial interest. Among these, lead-free sodium niobate (NaNbO3) AFE materials are emerging as eco-friendly and promising alternatives to lead-based materials, which pose risks to human health and the environment, attributed to their superior recoverable energy density and dielectric breakdown strength. This review offers an insightful overview of the fundamental principles underlying antiferroelectricity and the applications of AFE materials. It underscores the recent advancements in lead-free NaNbO3-based materials, focusing on their crystal structures, phase transitions, and innovative strategies devised to tailor their electrostatic energy storage performance. Finally, this review delineates the prevailing challenges and envisages future directions in the realm of NaNbO3-based electrostatic energy storage capacitors, with the goal of fostering further advancements in this pivotal field.