High Electrical Breakdown Strength Research Articles

Ni-modified BaTiO3 film prepared by sol-gel with high energy storage performance

The development of lead-free dielectric capacitors with high recoverable energy storage density and high energy storage efficiency is important for improving the overall performance of electronic and power systems. BaTiO3 (BTO) is one of the most common ferroelectric materials and has attracted much attention for energy storage applications in the past decades due to its excellent dielectric and ferroelectric properties. However, high remnant polarization and low electrical breakdown strength of BTO limit its development in energy storage applications. Many efforts (e.g., elements doping, interface/heterostructure, etc.) have been made to improve the energy storage density of BTO thin films. In this paper, Ba1-xNixTiO3 thin films (x = 0, 0.02, 0.04, 0.06, 0.08; abbreviated as BNxT) were synthesized via sol-gel and spin-coated method. The effect of Ni doping on the structural, dielectric, ferroelectric and energy storage properties of BTO thin films has been studied. The results confirmed that with the increase of Ni doping, a second phase arises and the dielectric constant decreases. While appropriate Ni doping led to the improvement of the breakdown strength, further increase of Ni deteriorated the energy storage because of the high oxygen vacancy. Finally, optimized energy storage performance was obtained for BN0.04T thin film: dielectric constant of 401, dielectric loss of 0.002, recoverable energy density of 20.2 J/cm3 and energy storage efficiency of 83.6% at 965 kV/cm. Meanwhile, the remnant and maximum polarization of the films were 0.06 μC/cm2 and 50 μC/cm2, respectively. BN0.04T thin film has an excellent application prospect and is expected to appear as a component in the future composite energy storage film system.

Heterostructured n-ZnO@p-CuO nanosheets filled in a polymer matrix for enhanced electrostatic energy storage performance.

Metallized film capacitors use plastic films as the dielectric spacer, and these polymer films generally have low dielectric constants. To boost the electrostatic energy storage density of a film capacitor, advanced high-k films with high electrical breakdown strength and low dielectric loss are highly desired. Herein, polymer nanocomposite films were made by filling ZnO@CuO nanosheets into poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)]. The n-type ZnO nanosheets are synthesized in an aqueous solution. Through a calcination process, thin layers of p-type CuO are coated over the ZnO nanosheets. Compared to pure P(VDF-HFP) and ZnO/P(VDF-HFP) films, the ZnO@CuO/P(VDF-HFP) films exhibit higher dielectric constant and higher breakdown strength. The optimal content of ZnO@CuO nanosheet in the polymer matrix is determined to be 3 wt%, which leads to a dielectric constant of 15.6 at 1 kHz and the highest energy density of 5.6 J cm-3. The efficacy of ZnO@CuO nanosheets in enhancing the dielectric performance of the polymer nanocomposite is elucidated in detail. This research provides a scalable and low-cost strategy to produce polymer nanocomposite films with high capacitive energy storage performance.

Room-temperature ferromagnetic semiconductor Fe-doped β-Ga2O3 thin films with high saturation magnetization and low coercivity.

Emergent ferromagnetism in β-Ga2O3 with an ultra-wide bandwidth and high electrical breakdown strength offers exciting opportunities for fabricating robust spintronic devices. One pertinent obstacle in the material has been the low saturation magnetization, which precludes its practical application in magnetic devices. In this work, large-scale Fe-doped β-Ga2O3 diluted magnetic semiconductor (DMS) films are synthesized using a polymer-assisted deposition method, and the effect of Fe doping on their structural and magnetic properties is investigated. Remarkably, the optimal sample exhibits a high saturation magnetization (70 emu cm-3 at 300 K), much larger than those in previously reported stable oxide DMS films, as well as a low coercivity (12 Oe at 300 K). Further analysis shows that our samples manifest a typical bound magnetic polaron (BMP) model and the high saturation magnetization originates from the strong ferromagnetic coupling between the BMPs which is enhanced by Ga vacancies. The Fe-doped β-Ga2O3 thin films with high saturation magnetization and low coercivity may provide a promising platform for related semiconductor spintronics.

High energy storage of PbZrO3 antiferroelectric thin films via constructing phase composition

In this paper, we fabricated PbZrO3 (PZ) thin films by the way of sol–gel spin on LaNiO3 buffered SiO2/Si substrates, and annealed them at different given temperatures by rapid thermal annealing (RTA). By controlling annealing temperature, PZ thin films showed different microstructures and phase compositions, whose impact of electrical properties and energy storage performance were researched. According to the research findings, the phase composition of film presents a general rule with the decrease of annealing temperature: PZ thin films crystallize into perovskite phase, pyrochlore phase, and amorphous phase. The films annealed at 620 °C crystallized into a state of coexistence of pyrochlore phase and perovskite phases, which also show moderate recoverable energy density and the highest energy storage efficiency (8.7 J cm−3 and 93.1%). This energy storage performance can be attributed to the synergistic effect of high electric breakdown strength of dense pyrochlore phase structure and high maximum polarization of perovskite phase. The findings of this paper help to explain the influence of pyrochlore phase on the energy storge performance of thin films. Thus, it is useful way to improve the energy storage performance of thin films.

Epitaxial Stabilization of Perovskite ATeO3 Thin Films

Tellurium oxides of the ATeO3 form typically do not crystallize in perovskite structures. Here, we show that perovskite-like ATeO3 (A = Ca, Sr, Ba) thin films can be grown on perovskite single-crystal substrates via epitaxial stabilization. These films are stable with high optical bandgaps, low dielectric losses, and a high electric breakdown strength. Hysteretic dielectric behavior found in SrTeO3 and BaTeO3 strongly suggests the presence of antiferroelectricity and ferroelectricity, respectively. These properties make perovskite tellurium oxides possibly appealing candidates for thin film coating or insulator materials in advanced microelectronics. Tellurium oxides constitute a largely unexplored class of materials that might show new and interesting functionalities in epitaxial thin-films. Our work encourages new work within this field.

Improved dielectric temperature stability and energy storage properties of BNT-BKT-based lead-free ceramics

The lead-free ceramics (1-x)(0.84Bi0.5Na0.5TiO3-0.16Bi0.5K0.5TiO3)-xBiMg2/3Nb1/3O3 (denoted as (1-x)BNKT-xBMN) and (1-y)(0.85BNKT-0.15BMN)-ySr0.7La0.2TiO3 with y = 0.3 (denoted as BNKMN-0.3SLT) were prepared by means of a conventional solid state sintering method. Effects of introduction of BiMg2/3Ni1/3O3 and Sr0.7La0.2TiO3 on phase structure, microstructure, and dielectric, ferroelectric and energy storage properties of the ceramics were studied in detail. The ceramics (1-x)BNKT-xBMN show pure perovskite structure, while BNKMN-0.3SLT appears a secondary phase. All ceramics exhibit dense microstructures with mean grain sizes between 0.56 μm and 1.36 μm. The introduction of SLT into BNKMN causes obvious decrease in dielectric constant around Curie temperature, inducing the widest temperature window of 263 °C from 29 °C to 292 °C for TCC≤±15 %. The ceramic BNKMN-0.3SLT shows high electric breakdown strength (Eb ∼ 300 kV/cm), large maximum polarization (Pm ∼ 36.48 μC/cm2), and low remanent polarization (Pr ∼ 1.70 μC/cm2), inducing high energy storage density of 4.03 J/cm3 as well as high energy storage efficiency of 85.2 %.

Recent Advances in W–Cu Composites: A Review on the Fabrication, Application, Property, Densification, and Strengthening Mechanism

Tungsten–copper (W–Cu) composite is a pseudoalloy prepared by powder metallurgy method with tungsten and copper as the main components, which are widely used in electrical contacts, electrical discharge machining electrodes, electronic packaging, aerospace, and military fields due to its good conductivity, thermal conductivity, high melting point, high electrical breakdown strength, low contact resistance, high welding resistance, and high heat resistance. Herein, the recent advances of W–Cu composites are reviewed systematically. First, the preparative techniques of W–Cu composites are introduced in detail, and their advantages and disadvantages are evaluated objectively. Second, an introduction of the main application fields and corresponding characteristics advantages for W–Cu composites are provided. Subsequently, the densification techniques and strengthening mechanisms and their effects on microstructure, mechanical properties, and physical properties of W–Cu composites are mainly discussed. Finally, based on a comprehensive review of W–Cu composites, its future development trends and potential research challenges are summarized and prospected.

Antiferroelectric nano-heterostructures filler for improving energy storage performance of PVDF-based composite films

Incorporating high permittivity inorganic ferroelectric in polymer dielectrics is the most prevalent and straightforward approach to improve their energy storage capacity, which has an extensive application prospect in power electronic circuits owing to their higher power density. However, the discharged energy density attained with these materials are mainly restrained by the high remnant electric displacement of ferroelectric and the large discrepancy in permittivity between inorganic and organic substance. Herein, we proposed a novel antiferroelectric (Pb0.875La0.05Sr0.05)(Zr0.595Sn0.4Ti0.005)O3@Al2O3 (PLSZST@AO) nano-heterostructure as fillers to fabricate nanocomposite films, wherein the Al2O3 layer with wide band gap and dielectric constant close to that of the PVDF matrix was encapsulated onto the antiferroelectric nanoparticle PLSZST to alleviate the discrepancy in permittivity and enhance the breakdown strength. Especially, the experimental results and computational simulations confirmed that the presence of Al2O3 layer is capable of effectively enhancing the electric displacement and breakdown strength, while reducing the remnant displacement and impeding the formation of electrical trees. As a result, the nanocomposite films exhibited an impressive discharged energy density of 18.2 J/cm3 along with a remarkably enhanced energy storage efficiency of 70 % near the high electrical breakdown strength of 594.7 MV/m when the fillers content was 3 wt%, which was far surpassed the pristine PVDF (Ud = 5.34 J/cm3 and η = 51.8 %). Together with its excellent mechanical strength, the monolayer film was verified to be an outstanding performance dielectric material, outperforming the current PVDF-based composite dielectrics for high-power energy storage capacitors. This work allowed for more versatility in designing and manufacturing flexibility nanocomposite films, which can contribute to improving their performance and practicality.

Modified (Ba,Sr)(Sn,Ti)O3 via hydrothermal synthesis for electrocaloric application

Electrocaloric cooling systems require components with large entropy change at the desired working temperature, high electric breakdown strength and low dielectric losses. We here report on hydrothermal synthesis (HTS) route for preparation of lead-free electrocaloric (EC) material Ba0.82Sr0.18Sn0.065Ti0.935O3 (BSSnT-18-6.5) with a median particle size of d50 = 150 nm. Influence of molar ratio (Ba,Sr):(Sn,Ti) on the purity and particle size of hydrothermally synthesized powders is investigated. The sintering behavior and the resulting microstructure of bulk ceramic samples prepared with HTS powders as well as their dielectric, ferroelectric, and electrocaloric properties are analyzed and discussed in detail. By using HTS powders we could significantly reduce sintering temperature from 1400 °C to 1275 °C. Samples prepared with a molar ratio (Ba,Sr):(Sn,Ti) of 1.6 show a maximum EC temperature change |ΔTEC| of 0.59 K around 30 °C with a broad peak of |ΔTEC| > 0.3 K in the temperature range from 5 °C to 65 °C under an applied electric field change of 5 V μm−1. Our results show that hydrothermal synthesis is well suited to produce starting powders of lead-free electrocaloric materials for future fabrication of multilayer ceramic (MLC) components.

A novel salt-barrier method of preparation flexible temperature resistant full-component nanocellulose membranes

With the simplification and diversification of separation technologies, nanocellulose membranes have become widely used as insulating materials. Recently, study of nanocellulose membrane modification has become a hot topic. However, the application of nanocellulose membrane has been limited due to their inadequate heat resistance and flexibility. Herein, based on the pyrolytic and thermoplastic properties of cellulose, we innovatively introduced a salt barrier scheme to regulate the degree of hydrogen bonding and thermoplastic bonding between fibers. This was achieved by adding a salt barrier agent, NaCl, in the middle of the nanocellulose to prepare and obtain flexible, high-temperature-resistant nanocellulose film materials. The full-component cellulose films thus prepared exhibited high tensile strength (8 MPa), excellent flexibility (105 mN), high electrical breakdown strength (67 KV/mm), and volume resistivity meeting the standard of insulation materials (3.23 × 1013 Ω·m). This scheme adheres to the principles of low cost, green, non-toxic and non-hazardous, providing a brand new approach for the research and development of high temperature resistant cellulose membrane materials, which is of significant commercial value and industrialization prospect.

Improved high‐temperature energy storage density at low‐electric field in BOPP/PVDF multilayer films

AbstractBiaxially oriented polypropylene (BOPP) is the most favorable commercial dielectric energy storage film due to its low dielectric loss and high electric breakdown strength. However, its low dielectric constant always leads to relatively low energy storage density. In this study, we propose an efficient strategy to increase the dielectric constant of BOPP films by laminating with high dielectric polyvinylidene fluoride (PVDF). Utilizing the high dielectric constant of PVDF and optimizing its thickness and layers, the high‐temperature energy storage density at low‐electric field is significantly improved. When the thickness of interlayer PVDF is 5 μm and the total number of stacked layers is 7, the BOPP/PVDF multilayer films deliver excellent high‐temperature energy storage performance. The dielectric constant of BOPP/PVDF multilayer films increases to 3.54, 1.74 times higher than pure BOPP films. At a low electric field of 200 kV/mm, the discharged energy storage density of BOPP/PVDF multilayer films increases to 1.02 and 0.99 J/cm3 at 100 and 125°C. (BOPP ~0.50 and 0.48 J/cm3@200 kV/mm). This work provides an efficient way to improve the high‐temperature energy storage density of BOPP films by constructing all‐organic multilayer structure.

Al@SiO2 Core-Shell Fillers Enhance Dielectric Properties of Silicone Composites.

Over the past decade, there has been significant interest in polysiloxane-based dielectric elastomers as promising soft electroactive materials. Nevertheless, the natural low permittivity of polydimethylsiloxane has limited its practical applications. In this study, we have developed silicone rubber/Al@SiO2 composites with a high dielectric constant, low dielectric loss, and high electrical breakdown strength by controlling the shell layer thickness and the content of the core-shell filler. We also investigated the dielectric behavior of the composites. The use of core-shell fillers has increased the Maxwell-Wagner-Sillars (MWS) relaxation process while reducing the dielectric loss of direct current conductance in silicone rubber composites. Moreover, the temperature dependence of the MWS relaxation time in the composites follows the Arrhenius equation. This strategy of increasing the permittivity of silicone composites through core-shell structural fillers can inspire the preparation of other high dielectric constant composites.

Graphene nanosheet stabilized Pickering emulsion and its polystyrene nanocomposites

AbstractHigh thermal conductivity and electrical insulation materials are necessary for packaging materials of miniaturized electronic equipment at present. Graphene nanosheets (GNs) have great potential in polymer composites due to its excellent thermal conductivity. However, the ultra‐high conductivity of GNs will reduce the insulation of polymer composites, so that the GN composites have good thermal conductivity and electrical insulation has become the focus of research. Herein, the closed cell polystyrene nanocomposites are polymerized by using a Pickering emulsion route. Based on the exfoliating effect of pristine graphite at the oil–water interface and the amphiphilic properties of GNs during the preparation of emulsion, the resulting graphite can achieve good dispersion in the polystyrene resin. Furthermore, the high heat transfer rate of the resulting graphite makes the temperature of polystyrene resin increase by 60.2°C at room temperature within 1 min. Meanwhile, the high volume electrical resistivity (3.63 × 109 Ω·m) and breakdown strength (33.8 kV·mm−1) confirms the PNGL0.610%/PS composite keep excellent electrical insulation at 10.0 wt% filler loading.

Multilayer Ceramic Capacitors: An Overview of Failure Mechanisms, Perspectives, and Challenges

Along with the growing of population and social and technological improvements, the use of energy and natural resources has risen over the past few decades. The sustainability of using coal, oil, and natural gas as the main energy sources faces, however, substantial obstacles. Fuel cells, batteries, and super-capacitors have the highest energy densities, but due to their high-power density and rapid charge-discharge speed, regular dielectric capacitors are becoming more popular for pulsed power applications. High electric breakdown strength and high maximum but low-remnant (zero in the case of linear dielectrics) polarization are necessary for high energy density in dielectric capacitors. The high performance, multi-functionality, and high integration of electronic devices are made possible in large part by the multilayer ceramic capacitors (MLCCs). Due to their low cost, compact size, wide capacitance range, low ESL and ESR, and excellent frequency response, MLCCs play a significant role in contemporary electronic devices. From the standpoint of the underlying theories of energy storage in dielectrics, this paper emphasizes the significant problems and recent advancements in building extremely volumetric-efficient MLCCs. Following a thorough examination of the state-of-the-art, important parameters that may be used to improve energy-storage qualities are highlighted, such as controlling local structure, phase assembly, dielectric layer thickness, microstructure, conductivity, different failure modes, and the specific performance during the failure mechanism. The summary of some conclusions on the impending need for innovative materials and diagnostic methods in high-power/energy density capacitor applications appears at the end of the paper.

Regulating local electric field to optimize the energy storage performance of antiferroelectric ceramics via a composite strategy

Electrostatic energy storage technology based on dielectrics is the basis of advanced electronics and high-power electrical systems. High polarization (<i>P</i>) and high electric breakdown strength (<i>E</i>_b) are the key parameters for dielectric materials to achieve superior energy storage performance. In this work, a composite strategy based on antiferroelectric dielectrics (AFEs) has been proposed to improve the energy storage performance. Here, AlN is selected as the second phase for the (Pb_0.915Ba_0.04La_0.03)(Zr_0.65Sn_0.3Ti_0.05)O₃ (PBLZST) AFEs, which is embedded in the grain boundaries to construct insulating networks and regulate the local electric field, improving the <i>E</i>_b. Meanwhile, it is emphasized that AFEs have the AFE–FE and FE–AFE phase transitions, and the increase of the phase transition electric fields can further improve the recoverable energy density (<i>W</i>_rec). As a result, the <i>E</i>_b increases from 180 to 290 kV·cm⁻¹ with a simultaneous increase of the phase transition electric fields, magnifying the <i>W</i>_rec to ~144% of the pristine PBLZST. The mechanism for enhanced <i>E</i>_b and the phase transition electric fields is revealed by the finite element simulation method. Moreover, the PBLZST:1.0 wt% AlN composite ceramics exhibit favorable temperature stability, frequency stability, and charge–discharge ability, making the composite ceramics a promising candidate for energy storage applications.

High Energy Storage Performance of PZO/PTO Multilayers via Interface Engineering.

Antiferroelectric thin-film capacitors with ultralow remanent polarization and fast discharge speed have attracted extensive attention for energy storage applications. A multilayer heterostructure is considered to be an efficient approach to enhance the breakdown strength and improve the functionality. Here, we report a high-performance multilayer heterostructure (PbZrO3/PbTiO3)n with a maximum recoverable energy storage density of 36.4 J/cm3 due to its high electric breakdown strength (2.9 MV/cm) through the heterostructure strategy. The positive effect of interfacial blockage and the negative effect of local strain defects competitively affect the breakdown strength, showing an inflection point at n = 3. The atomic-scale characterizations reveal the underlying microstructure mechanism of the interplay between the heterointerface dislocations and the decreased energy storage performance. This work offers the potential of well-designed multilayers with high energy storage performance through heterostructure engineering.

Extremely high energy density and long fatigue life of nano-silica/polymethylvinylsiloxane dielectric elastomer generator by interfacial design

Dielectric elastomer generator (DEG) can harvest electrical energy from various movement in nature such as human walking and ocean waves. To achieve high energy harvesting performance of DEG, dielectric elastomer (DE) composite with strong interfacial interaction, and thus high electrical breakdown strength (Eb) and long fatigue life (NFL) at high strain is a key. In this study, nano-silica (SiO2)/polymethylvinylsiloxane (PMVS) DE composite with strong interfacial interaction for DEG with extremely high energy density (w), high power conversion efficiency (PCE) and long NFL was prepared by designing and synthesizing a new polar macromolecule coupling agent (MCA), ester group grafted liquid butadiene rubber using a photoinitiated thiol-ene click reaction. Compared with the common small molecule coupling agent (SCA) modified SiO2 (SCA@SiO2)/PMVS composite, the new MCA modified SiO2 (MCA@SiO2)/PMVS composite shows much stronger interfacial interaction owing to the largely increased co-crosslinking junction and chain entanglement, resulting in the significantly improved elongation at break and Eb at high strain (400%). As a result, MCA@SiO2/PMVS DEG exhibits an up-to-date highest w (92.2 mJ/cm3) and PCE (35.8%) among the previously reported DEG using unprestretched DE film, and its NFL reaches 141000 times, 3.9 times that of SCA@SiO2/PMVS DEG (36000 times). Thus, MCA@SiO2/PMVS DEG shows the highest full-life generating energy density (9710 J/cm3), 4.8 times and 2427 times that of SCA@SiO2/PMVS DEG and commercial VHB DEG, respectively.

Grain size engineering enhanced dielectric, ferroelectric and energy storage properties in SnO2 modified BCZT lead-free ceramics

Grain size engineering is considered as an extremely effective method to realize high electric breakdown strength and enhance the recoverable energy density. In this work, the SnO2 additive is proposed to drive the grain size smaller and enhance the energy storage performance of the (Ba0.85Ca0.15)(Zr0.2Ti0.8)O3 lead-free ceramics. The (Ba0.85Ca0.15)(Zr0.2-xSnxTi0.8)O3 with x = 0.05, 0.10, 0.15, and 0.20 for energy storage application are fabricated via the conventional solid phase reaction method. The influence of Sn4+ addition on the microstructure, dielectric, ferroelectric and energy storage properties of (Ba0.85Ca0.15)(Zr0.2-xSnxTi0.8)O3 ceramics are investigated. As expected, the smallest average grain size and highest diffused phase transition are obtained when x = 0.10. Meanwhile, a maximum electric breakdown field strength 92.08 kV/cm and a recoverable energy storage of 422 mJ/cm3 accompanied with the improved energy storage efficiency of 83.3% are noted. The mentioned results suggest that the effective control of Sn4+ amount in BCZT ceramics is helpful to reduce the grain size and then obtain higher energy storage density and efficiency at relatively low electric field strength.

Significant improvement of the thermal conductivity and dielectric properties of cyanoethyl cellulose films by introducing barium titanate decorated boron nitride nanosheet

Polymer dielectrics hold a great potential to be used in the field of power equipment and advanced electronics. However, their limited thermal conductivity fails to satisfy the imperative demand for heat dissipation in practical applications. Herein, we report a novel strategy to prepare multifunctional cyanoethyl cellulose matrix composite films by employing a hybrid filler of boron nitride nanosheets and barium titanate nanoparticles. The resultant composite films simultaneously exhibit high thermal conductivity (∼10.54 W/m·K), high dielectric constant (∼44), high electrical breakdown strength (>302 kV/mm), and low dielectric loss (∼0.01). The findings in this work enable broader application of polymer dielectrics in impulse power and energy storage devices.

Dielectric breakdown of 2D muscovite mica

Localized electrical breakdown (BD) measurements are performed on 2D muscovite mica flakes of ~ 2 to 15 nm thickness using Conduction Atomic Force Microscopy (CAFM). To obtain robust BD data by CAFM, the probed locations are spaced sufficiently far apart (> 1 µm) to avoid mutual interference and the maximum current is set to a low value (< 1 nA) to ensure severe damage does not occur to the sample. The analyses reveals that 2D muscovite mica has high electrical breakdown strength (12 MV/cm or more) and low leakage current, comparable to 2D hexagonal boron nitride (h-BN) of similar thickness. However, a significant difference compared to h-BN is the very low current necessary to avoid catastrophic damage during the BD event, even for very thin (2–3 nm) flakes. Further, for mica the BD transient always appear to be very abrupt, and no progressive BD process was definitively observed. These marked differences between mica and h-BN are attributed to the poor thermal conductivity of mica.