Dielectric Capacitors Research Articles

Embedding Plate‐Like Pyrochlore in Perovskite Phase to Enhance Energy Storage Performance of BNT‐Based Ceramic Capacitors

AbstractNext‐generation electrical and electronic systems rely on the development of efficient energy‐storage dielectric ceramic capacitors. However, achieving a synergistic enhancement in the polarization and in the breakdown field strength (Eb) presents a considerable challenge. Herein, a heterogeneous combination strategy involving embedding a high Eb plate‐like pyrochlore phase in a high‐polarization perovskite phase is proposed. The embedded plate‐like pyrochlore increases the breakdown field strength and promotes the dynamic polarization response. Meanwhile, the strong spin–orbit coupling effect of the 5d electrons is conducive to the maintenance of the high polarization value of the perovskite. Consequently, the prepared multilayer ceramic capacitor (MLCC) exhibits an ultrahigh Eb and a high polarization. More specifically, an energy storage density (Wrec) of 14.9 J cm−3 with an efficiency of up to 93.4% is achieved for the optimized pyrochlore/perovskite phase. Furthermore, the MLCCs also exhibits an Wrec of ≈ 7.7 J cm−3 ± 4.5% in the temperature range of −50–180 °C. Therefore, this heterogeneous combination strategy therefore provides a simple and effective method for improving the energy‐storage performances of dielectric ceramic capacitors.

Achieving an appropriate polarization-breakdown synergy of multilayer films for dielectric energy storage through temperature gradient annealing

Large polarization and high breakdown strength are the key to achieving an idea energy storage density in dielectric capacitors, but unfortunately the trade-off problem between them is difficult to evade, particularly for those dielectrics with different crystalline degrees. Herein, we propose an appropriate polarization-breakdown synergistic strategy of dielectric multilayer films through temperature gradient annealing. The dielectric properties of a serials of (Pb, La)(Zr, Ti)O3/SrTiO3/(Pb, La)(Zr, Ti)O3 (PLZT/STO/PLZT) structures with different annealing temperature for each layer are compared. The optimum recoverable energy density of 57.9 J/cm3 is achieved at a high breakdown electric field of 5.78 MV/cm and a moderate maximum polarization of 22.5 μC/cm2. In addition to the role of suppressing the carriers transport of interlayer STO, the balance between polarization and breakdown strength in bottom and top PLZT layers with individual dielectric characteristics should be responsible for the enhanced energy storage performance (ESP). The results suggest that it is a feasible way to optimize the ESP of dielectric multilayer films through designing different stacking layer via temperature gradient annealing heat treatment.

Enhanced comprehensive energy storage properties of lead-free KNN based ceramics through composition optimization strategy

As one of the most potential lead-free dielectric capacitors in pulsed power systems, K0.5Na0.5NbO3 (KNN)-based ceramic possesses comparatively high dielectric breakdown strength (BDS) due to its particular submicron grains. Nonetheless, it is hard to improve both the energy efficiency η and the recoverable energy density Wrec of potassium sodium niobate ceramic at the same time. Herein, a composition optimization strategy is used, Bi(Li0.5Nb0.5)O3 (BLN) as a second component and NaNbO3 (NN) as a third component are introduced into KNN-based ceramic. It is corroborated that BLN content facilitates the growth of polar nano-regions (PNRs), and then strengthens the relaxation behavior, lows the remnant polarization Pr and upgrades the maximum polarization Pmax value of the ceramic. A transition from ferroelectricity to relaxation ferroelectricity occurred and an ultrahigh Wrec of 10.03 J/cm3 with a η of 64.15 % and the BDS of 1140 kV/cm are gained in KNN-0.100BLN-NN ceramic, Wrec of 8.25 J/cm3, η of 71.26 % and the BDS of 840 kV/cm are obtained in KNN-0.075BLN-NN ceramic. Besides, the KNN-0.075BLN-NN ceramic exists not only fine energy storage properties, but also high hardness and good temperature and frequency stability, confirming it’s a feasible material to be applied in pulsed power systems

High energy density and efficiency of laminated polymeric blend-based composites via introducing ultra-low content micrometer sheets

Polymeric blend-based composites are promising for dielectric capacitor due to the excellent dielectric and energy storage properties. However, the electric displacement difference (Dmax-Dr) and dielectric constant (εr) of the polymeric blend-based composites are incompatible, which further limits the improvement of the available energy densities (Ue). In this study, we propose the solution-processable laminated polymeric blend-based composites to address this challenge. The concurrent enhancement in Dmax-Dr, εr, Ue and charge-discharge efficiency (η) of designed composites is attributed to the synergistic interaction between macroscopic layered interfaces and microscopic interfaces. The laminated polymeric blend-based composites were fabricated by utilizing a blend of 50 wt% poly(vinylidene difluoride)-hexafluoropropylene (P(VDF-HFP)) and linear poly(methyl methacrylate) (PMMA) as the outer layer and P(VDF-HFP)/PMMA incorporated with an ultralow content alumina-modified strontium titanate plates (SrTiO3@Al2O3) the inner layer. As a result, laminated polymeric blend-based composite with the optimized content (0.5 vol%) delivers a maximum Ue of 14.36 J/cm3 due to highest Dmax-Dr of 7.96 μC/cm2, εr of 6.12 (1 kHz), Eb of 400 MV/m, and η of 76.6 %, outperforms those of representative polymer blend-based composites. Specially, laminated polymeric blend-based composite also exhibits the excellent energy storage reliability of different areas. Therefore, this contribution provides a viable approach to promote polymeric blend-based composites for capacitive energy storage.

Tailoring phase evolution via high-entropy engineering for superior energy storage properties in (Na0.5Bi0.5)0.75Sr0.25TiO3-based ceramics

High-entropy engineering has garnered significant attention for innovation of dielectric capacitors. However, to meet the demands of the burgeoning market for next-generation advanced capacitors, challenges remain in optimizing the recoverable energy-storage density (Wrec). To address this, a stepwise high-entropy tactic is proposed via integrating four core effects of high-entropy systems with phase transition and energy-storage performance. This technique induces a remarkable Wrec ∼ 7.4 J/cm3 at 400 kV/cm in (Na0.5Bi0.5)0.75Sr0.25Ti1-x(Al1/4Zr1/4Hf1/4Nb1/4)xO3 ceramics (x = 0.00, 0.08, 0.12, 0.16, 0.20). The incorporation of multiple ions with diverse radii and valence states at the B-site enhances the degree of disorder and lattice distortion, contributing to tuning phase evolution and suppressing interfacial polarization, thereby delaying saturation polarization. Furthermore, impressive thermal endurance (30 ∼ 130 ℃), frequency stability (1 ∼ 100 Hz) and a rapid discharge rate t0.9 of ∼ 37.6 ns are also yielded. This work paves the way for the advancement of novel ceramics by tailoring phase transition using a high-entropy strategy.

Influence of zinc acetate on HPMC/CMC polymer blend: Investigation of their composites’ structural, optical, and dielectric properties for dielectric capacitor applications

Influence of zinc acetate on HPMC/CMC polymer blend: Investigation of their composites’ structural, optical, and dielectric properties for dielectric capacitor applications

Fluorinated Polyimides incorporated with heterogeneous ZrO2@KNbO3 as multiple carrier transport barriers for Ultra-High energy storage

Advanced electronic devices and electrical power systems require high capacitor energy storage, fast charge–discharge speed and high temperature stability. Inorganic and organic nanocomposite film can achieve this great goal, but the major obstacle is the easy failure of breakdown in harsh environments. Here, we report a seires of inorganic–organic composite films prepared by blending a novel core–shell heterogeneous ZrO2@KNbO3 with fluorinated polyimide (FPI). The ZrO2@KNbO3 forms a distinctive sandwich-like microstructure, which delivers the p-n-p heterojunction interfaces. Multiple energy barriers, arisen at the interfaces, block the charge carrier transport. As a result, the 0.3 ZrO2@KN/FPI nanocomposite film achieves ultrahigh energy densities of 11.62 J cm−3 and 7.9 J cm−3 under electric fields of 665.6 MV m−1 and 550 MV m−1 at 25 °C and 150 °C, respectively, giving rise to a concurrent enhancement in breakdown strength and electrical displacement. Additionally, the 0.3 ZrO2@KN/FPI composite film exhibits superior charge–discharge cycling stability, enduring up to 100,000 cycles. This research provides a cutting-edge perspective to regulate the charge transport path, especially to inhibit charge transport at the interfaces, demonstrating a great potential for high-temperature dielectric capacitor applications.

Enhanced energy storage performance of 0.85BaTiO3–0.15Bi(Mg0.5Hf0.5)O3 films via synergistic effect of defect dipole and oxygen vacancy engineering

Dielectric capacitors are widely used in electronic devices due to their ultra-fast charge/discharge rate and ultra-high power density, but their lower energy density and poor thermal stability limit their further application. In contrast to the traditional strategy of suppressing defects, this work combines oxygen vacancies with defect dipoles to improve the breakdown strength and polarization behavior of ferroelectric films. Low concentration of oxygen vacancies and defect dipoles can trap charge carriers and increase breakdown strength, but if the concentration is too high, it can easily make films prone to breakdown. Moreover, the defect dipoles can reduce Pr by providing intrinsic restoring force for polarization switching, while excessive defect dipoles and oxygen vacancies can pin domain walls and increase Pr. By delicately controlling the concentration of oxygen vacancies and defect dipoles in the film, the BT-BMH film deposited at 0.135 mbar achieved the maximum breakdown strength and slim P-E loops, inducing the energy density to reach 108.9 J·cm-3 with an efficiency of 79.6 % at room temperature and excellent thermal stability in the wide temperature range of -100∼350 °C with the energy density of 69.1 J·cm-3. This work reveals the important significance of reasonable defect control for improving energy storage performance and provides an effective method for developing high-performance dielectric capacitors.

Linear dielectric ceramics for near-zero loss high-capacitance energy storage

High energy-density (Wrec) dielectric capacitors have gained a focal point in the field of power electronic systems. In this study, high energy storage density materials with near-zero loss were obtained by constructing different types of defect dipoles in linear dielectric ceramics. Mg2+and Nb5+ are strategically chosen as acceptor/donor ions, effectively replacing Ti4+ within Ca0.5Sr0.5TiO3-based ceramics. The results indicate that under an applied electric field, specific defects such as [MgTi″−VO··] and [NbTi·−Ti3+], can effectively regulate VO·· and electron movement, significantly reducing losses. Furthermore, high-density insulating grain boundaries, reduced VO·· concentrations and diminished carrier mobility contribute to enhanced resistivity, resulting in high Wrec ∼7.62 J/cm3 and η ∼92 % at 640 kV/cm, making it one of the most promising linear dielectrics to date. Notably, Wrec and η remain remarkably stable across a broad range of frequencies (1–500 Hz), temperatures (25–175 °C) and numerous cycles (up to 106). Additionally, finite element software was used to simulate the distribution of dielectric constant, electric potential, and local electric field, further verifying the correlation between microstructure and breakdown resistance. This innovative work provides a sustainable strategy to optimize the energy storage capacity of lead-free ceramics over a wide temperature range through strategic manipulation of defects.

An investigation of the electrochemical characteristics of NiO-Co3O4/graphite/PVDF composites for the development of a supercapacitor with ultrahigh stability

Abstract Supercapacitor is a groundbreaking electrical energy storage technology that falls between batteries and dielectric capacitors which has undergone significant progress in recent years. Among the several elements influencing a supercapacitor's capacitance, the choice of electrode materials plays a crucial role. Nanomaterials formed from transition metal oxides with incorporated 3-D graphite are said to possess high capacitance, conductivity, increased area of active site, distinct redox properties, and several valence shells, making them an appropriate material for electrode synthesis. Therefore, in this study, three composites of NiO and Co3O4 are prepared in the ratio 2:8, 3:7 and 4:6 using facile sol-gel method. To the prepared composites, graphite and PVDF are added in equal quantities. The resultant samples are characterized using XRD, SEM, FTIR and UV-Vis spectroscopy. The samples are further integrated on an FTO electrode and subjected to CV, GCD and EIS for electrochemical study. The highest specific capacitance is obtained for NiO and Co3O4 composite in the ratio 3:7 and is equal to 156.66F/g at a sweep rate of 10 mV/s. This material is further used for a two-electrode study to check the feasibility of a symmetric solid-state device, which demonstrated a specific capacitance of 36F/g with 100% capacitive retention.

The electromagnetic field of a circular parallel plate capacitor excited by an AC current and AC voltage supply

Abstract This study investigates the electromagnetic field (EMF) distribution of an ideal circular parallel plate capacitor excited by a time-harmonic power source. Considering the lead wire and capacitor as a charged whole, we formulate the boundary value problems of the Helmholtz equation for the EMF in the lead wire space and capacitor space, respectively. First, we solve for the EMF generated by the total current in the lead wire space of an AC current. Following this, we solve for the EMF boundary value problem of a capacitor filled with linear, uniform, isotropic, and non-magnetic lossy dielectric under an AC current excitation, using the continuity of the total current as a basis. Second, the EMF distributions in the capacitor space and the lead wire space under an AC voltage excitation are provided, following the principles of the generalized Helmholtz theorem. Third, the EMF distribution is discussed when the electromagnetic ``standing-wave phenomenon" occurs in the ideal dielectric capacitor, and identify the ``resonance phenomenon" and the ``current-stopping phenomenon" of the capacitor's EMF when excited by an AC current and AC voltage, respectively. We also present the corresponding ``resonance frequency" and ``current-stopping frequency". Finally, we explore the quasi-stable solution of the capacitor's EMF under low-frequency condition and the static solutions of the electric and magnetic fields under DC excitation and static voltage excitation. Our findings suggest that the existing formula for the capacitor's EMF approximates our analytical solution under quasi-stable condition.

Synergistic effects in Na0.5Bi0.5TiO3-based thin film through stress field regulation for excellent capacitive energy storage

Thin film dielectric capacitors have attracted significant attention under the current trend of integration and portability in electronic devices. In this work, Na0.5Bi0.5(Fe0.03Ti0.97)O3–SrTiO3 (NBFT–STO) thin films are synthesized via sol–gel method onto flexible Pt/Mica and rigid Pt/Ti/SiO2/Si substrates, respectively to obtain NBFT–STO dielectric capacitors under different local stress fields. Synergistic effects between dielectric polarization and breakdown strength (EBD), as well as dielectric polarization and polarization hysteresis are obtained, with the rigid one exhibiting higher EBD and the flexible one possessing high polarization linearity. Excellent capacitive energy storage performance with Wrec of 28.00 J/cm3 and η of 70.44 % are obtained at 20 kHz for the NBFT–STO thin film onto Pt/Mica. These findings provide a new route to modulate polarization behavior of NBT–based thin film through stress field regulation for capacitive energy storage.

Size Effect of Negative Capacitance State and Subthreshold Swing in Van der Waals Ferrielectric Field‐Effect Transistors

AbstractAnalytical calculations corroborated by the finite element modeling show that thin films of Van der Waals ferrielectrics covered by a 2D‐semiconductor are promising candidates for the controllable reduction of the dielectric layer capacitance due to the negative capacitance (NC) effect emerging in the thin films. The NC state is conditioned by energy‐degenerated poly‐domain states of the ferrielectric polarization induced in the films under incomplete screening conditions in the presence of a dielectric layer. Calculations performed for the FET‐type heterostructure “ferrielectric CuInP2S6 film—2D‐MoS2 single‐layer—SiO2 dielectric layer” reveal the pronounced size effect of the multilayer capacitance. Derived analytical expressions for the electric polarization and multilayer capacitance allow to predict the thickness range of the dielectric layer and ferrielectric film for which the NC effect is the most pronounced in various Van der Waals ferrielectrics, and the corresponding subthreshold swing becomes much less than the Boltzmann's limit. Obtained results can be useful for the size and temperature control of the NC effect in the steep‐slope ferrielectric FETs.

Exploring anti-ferroelectric thin films with high energy storage performance by moderating phase transition

Anti-ferroelectric thin films are renowned for their signature double hysteresis loops and sheds light on the distinguished energy storage capabilities of dielectric capacitors in modern electronic devices. However, anti-ferroelectric capacitors are still facing the dual challenges of low energy density and efficiency to achieve state-of-the-art performance. Their large hysteresis and sharp first-order phase transition usually results in a low energy storage efficiency and easy breakdown, severely obscuring its future application. In this study, we demonstrate that anti-ferroelectric (Pb0.97La0.02)(Zr1−xSnx)O3 epitaxial thin films exhibit enhanced energy storage performance through local structural heterogeneity to moderate the first-order phase transition by calculating the corresponding polarization as a function of switching time for the first time. The films exhibit remarkable enhanced breakdown strength (∼3.47 MV/cm, ∼5 times the value for PbZrO3) and energy storage performance. Our endeavors have culminated in the ingenious formulation of a novel strategy, namely, the postponement of polarization processes, thereby elevating the breakdown strength and total energy storage performance. This landmark achievement has unveiled a fresh vista of investigative opportunities for advancing the energy storage prowess of electric dielectrics.

Enhanced Energy Storage Properties of Four-Layer Composite Films via Strategic Macrointerface Modulation.

Dielectric capacitors play a crucial role in the field of energy storage; however, the low discharged energy density (Ue) of existing commercial dielectrics limits their future applications. Currently, further improvement in the Ue of dielectrics is constrained by the challenge of simultaneously achieving high permittivity (εr) and high breakdown electric field strength (Eb). To address this issue, we designed a series of four-layer poly(vinylidene fluoride) (PVDF)-based composite films comprising three functional layers: a sodium bismuth titanate (NBT) plus PVDF composite (NBT&PVDF) layer to achieve high εr values and a pure PVDF layer and a boron nitride (BN) plus PVDF composite (BN&PVDF) layer to achieve high Eb values. This design synergistically enhanced the εr and Eb values of the composite films by exploiting low-loss macrointerface polarization via adjustment of the functional layer stacking order, as supported by simulation analyses. Ultimately, the composite film with a topmost layer of pure PVDF, followed by an NBT&PVDF layer, another pure PVDF layer, and a BN&PVDF layer achieved an enhanced Ue value of 26.42 J·cm-3 and excellent efficiency of 80.03% at an ultrahigh Eb value of 770 MV·m-1. This approach offers an innovative pathway for developing advanced energy storage composite dielectrics via macrointerface manipulation.

Boosting Energy-Storage in High-Entropy Pb-Free Relaxors Engineered by Local Lattice Distortion.

The high-entropy strategy has shown potential in advancing the energy-storage performance of dielectric capacitors, offering benefits to a range of electronic and electrical systems. However, designing high-performance high-entropy relaxor ferroelectrics (RFEs) presents challenges due to the unclear correlation between their core effects and local polarization heterogeneity. Here, we demonstrate that by engineering the local lattice distortion, a core effect in high-entropy systems, to manipulate the local polarization configuration, a giant energy density (Wrec) of 18.7 J cm-3 and high efficiency (η) of 85% can be achieved in (Bi0.5K0.5)TiO3-based high-entropy bulk RFE ceramics. Atomic-level local structural analysis unveils that the local lattice distortion field can be flattened by introducing ions with less size mismatch. The increase in configurational entropy from 1.54 to 2.06R is associated with a smoother polar displacement vector field and a reduction in the size of polar clusters to several unit-cell sizes with weak coupling. Consequently, a substantial decrease in hysteresis and an enhancement in the breakdown field strength can be obtained, leading to a significant improvement in energy density by over 6 times and efficiency by 3 times. Our research establishes a relationship between local lattice distortion, atomic polar displacement, and energy-storage performance in complex high-entropy systems, providing insights for enhancing energy-storage performance via a local structure design.

Investigating structural, dielectric and energy storage properties of NaNbO3 based ferroelectric ceramics

Sodium niobate (NaNbO3) based dielectric materials are getting recognition for the electric energy storage applications due to their promising ferroelectric/anti-ferroelectric properties. In the present work, (0.95-x)NaNbO3-0.05SrTiO3-xBi(Fe1/3Zn1/3Ti1/3)O3 (abbreviated as NNSTBFZT, x=0.04, 0.07 and 0.10) lead-free ferroelectric ceramics were synthesized using conventional solid-state reaction technique. A magnificent recoverable energy storage density (Wrec) and an ultrahigh energy storage efficiency (η) have been observed for x4 (∼1.05 J/cm3) and x10 (∼85 %) samples, respectively which reliant on the non-equivalent replacement of ions at the A and B sites of perovskite unit cell. Further, the phase investigation has been studied using X ray diffraction and Raman spectroscopy, which elucidate the effect of incorporation of the substituent ions at host matrix properly. A moderate dielectric constant with ultralow losses has been obtained and all the samples show diffuse phase transition, which is in favor of enhanced energy storage parameters. Moreover, the morphological analysis indicates decrease in grain size ∼ 1 µm, which also reflects the increased breakdown strength responsible for enhancing energy storage capacity. Therefore, proposed sodium niobate based ceramics become favorable for high energy dielectric capacitors applications.

Fabrication of Multilayered Polyvinylidene Difluoride Films for Dielectric Capacitor, Sensing, and Energy Harvesting Performance

Fabrication of Multilayered Polyvinylidene Difluoride Films for Dielectric Capacitor, Sensing, and Energy Harvesting Performance

Alicyclic Polyimide With Multiple Breakdown Self-Healing Based on Gas-Condensation Phase Validation for High Temperature Capacitive Energy Storage.

Polymer dielectrics with combined thermal stability and self-healing properties are specifically desired for high-temperature film capacitors. The high thermal stability of conventional polymers benefits from the abundance of aromatic rings in the molecule backbone, but the high carbon content sacrifices their self-healing properties. Here, analicyclic polyimide with a high glass transition temperature (256°C) and wide energy bandgap (4.58eV) is designed, which exhibits electric conductivity more than an order of magnitude lower than that of classical polyimide at high electric fields and high temperatures. As a result, alicyclic polyimide achieves a discharged energy density of 4.54 Jcm-3 and a charge-discharge efficiency of above 90% at 200°C, which is superior to existing dielectric polymers and composites. The alicyclic polyimide benefits from a low pyrolytic residual carbon rate, retaining 93% of the dielectric breakdown strength after four electrical breakdown cycles. Distinguishing from the current condensed-phase self-healing concept, for the first time, exploring the self-healing capability of high-temperature polyimide dielectric is presented based on dual self-healing mechanisms of gas-phase and condensed-phase. The high energy density at high temperatures and the superior self-healing capability of alicyclic polyimide further indicate the promise of polyimide dielectric film capacitors for extreme conditions.

Unleashed Remarkable Energy Storage Performance in Bi0.5K0.5TiO3-based Relaxor Ferroelectrics by Local Structural Fluctuation.

Dielectric capacitors harvest energy through an electrostaticprocess, which enables an ultrafast charging-discharging rate and ultrahigh power density. However, achieving high energy density (Wrec) and efficiency (η) simultaneously, especially when preserving them across a wide frequency/temperature range or cycling numbers, remains challenging. In this work, by especially introducing NaTaO3 into the representative ferroelectric relaxor of Bi0.5K0.5TiO3-Bi0.5Na0.5TiO3 and leveraging the mismatch between B-site atoms, we proposed a method of enhancing local structural fluctuation to refine the polar configuration and to effectively improve its overall energy-storage performances. As a consequence, the ceramic exhibits an ultrahigh Wrec of 15.0 J/cm3 and high η up to 80%, along with a very wide frequency stability of 10 - 200 Hz and extensive cycling number up to 108. In-depth local structure and chemical environment investigations, consisting of atom-scale electron microscopy, neutron total scattering, and solid-state nuclear magnetic resonance, reveal that the randomly distributed A/B-site atom pairs emerge in the system, leading to the evident local structural fluctuations and concomitant polymorphic polar nanodomains. These key ingredients contribute to the large polarization, minimal hysteresis, and high breakdown strength, thereby promoting energy-storage performances. This work opens a new path for designing high-performance dielectric capacitors via manipulating local structural fluctuations.