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Improvement techniques aimed at enhancing the dielectric strength and minimizing the dielectric loss of insulation materials have piqued the interest of many researchers. It is worth noting that the electrical breakdown traits of insulation material are determined by their electrochemical and mechanical performance. Possible good mechanical, electrical, and chemical properties of new materials are considered during the generation process. Thermoplastic polyurethane (TPU) is often used as a high-voltage insulator due to its favorable mechanical properties, high insulation resistance, lightweight qualities, recovery, large actuation strain, and cost-effectiveness. The elastomer structure of thermoplastic polyurethane (TPU) enables its application in a broad range of high-voltage (HV) insulation systems. This study aims to evaluate the feasibility of using TPU on transformer windings as a solid insulator instead of pressboards. The investigation conducted through experiments sheds light on the potential of TPU in expanding the range of insulating materials for HV transformers. Transformers play a crucial role in HV systems, hence the selection of suitable materials like cellulose and polyurethane is of utmost importance. This study involved the preparation of an experimental setup in the laboratory. Breakdown tests were conducted by generating a non-uniform electric field using a needle–plane electrode configuration in a test chamber filled with mineral oil. Various voltages ranging from 14.4 kV to 25.2 kV were applied to induce electric field stress with a step rise of 3.6 kV. The partial discharges and peak numbers were measured based on the predetermined threshold values. The study investigated and compared the behaviors of two solid insulating materials under differing non-electric field stress conditions. Harmonic component analysis was utilized to observe the differences between the two materials. Notably, at 21.6 kV and 25.2 kV, polyurethane demonstrated superior performance compared to pressboard with regards to the threshold value of leakage current. [ABSTRACT FROM AUTHOR]

Flexible capacitive pressure sensors play an important role in electronic skin and human–machine interaction due to their high sensitivity and convenient preparation, comparing with those resistive/piezoresistive sensors. However, due to the complexity of the application environment, reported capacitive sensors often experience signal instability by electromagnetic interference and proximity effects. The great challenge for capacitive sensors is to maintain sensitivity and wide linear range while reducing interference. This study proposes a high anti‐jamming capacitive flexible pressure sensor with polyvinylidene fluoride (PVDF)@AgNWs@TiO2 film as the dielectric layer. Core–shell structure‐based AgNWs@TiO2 is embedded into the PVDF film. The introduction of the core–shell structure not only enhances the initial capacitance but also balances the dielectric constant, dielectric loss, and breakdown strength of the dielectric layer. The sensor is validated to exhibit a high signal‐to‐noise ratio for a variety of interference sources and is demonstrated with an intelligent glove sensing system, which provides a new idea for developing a high anti‐jamming capacitive flexible pressure sensor. [ABSTRACT FROM AUTHOR]

Na 0.5 Bi 0.5 TiO 3 (NBT)-based ceramics are promising lead-free candidates for energy-storage applications owing to their individual crystal structure and phase transition information. However, the high coercive field (E C) and large remnant polarization (P r) are detrimental for practical applications. In this work, the composition-dependent phase structure, micromorphology, dielectric and energy storage properties of (1-x)(0.94Na 0.5 Bi 0.5 TiO 3 -0.06BaTiO 3)-xBi(Mg 2/3 Nb 1/3)O 3 (NBBT-100xBMN, x = 0.18, 0.20, 0.22 and 0.25) ternary ceramics were hereby investigated. The addition of BMN facilitates the phase transformation from rhombohedral (R3c) to tetragonal (P4bm), which is beneficial for the enhancement of relaxation behavior, and meanwhile impels the grain growth. Combined with the influence of grain size on breakdown field strength, an optimal recoverable energy storage density (W rec) of 1.88 J/cm3 with a high energy storage efficiency (η) of 82.15% was achieved in the NBBT-20BMN ceramic composition under the dielectric breakdown strength (DBS) of 150 kV/cm, accompanied by the excellent temperature stability from room temperature to 200 °C. All these manifest that the NBBT-20BMN ceramics have an attractive application prospect in the energy storage field. [ABSTRACT FROM AUTHOR]

The development of electric pulse technologies for the destruction of solids states (rocks)—drilling, cutting and crushing requires reduction of high pulse voltages. In this work, for the first time, studies are proposed and carried out to determine the breakdown voltages of various dielectric media (air, water, rocks) while simultaneously supplying two pulses to the electrode system by two high voltage generators of different polarity—positive and negative, which halves the operating impulse voltage each generator. In addition, experiments have shown that for all media there is a decrease in breakdown voltage in comparison with a monopolar voltage pulse, which reaches 28%—for the breakdown of sandstone, 23%—granite, 24%—water, 25%—air. A physical explanation of the discovered effect is given. [ABSTRACT FROM AUTHOR]

High voltage insulation is one of the most important components of electrical power systems. Polymeric materials have lately supplanted ceramic materials as insulating materials due to their low weight, straightforward structure, high mechanical strength, good performance in the presence of pollution, ease of transportation, and ability to enhance voltage. The purpose of this thesis is to add micro and nano-sized aluminum oxide (Al2O3) fillers to silicone rubber (SIR) to enhance its electrical characteristics. Micro Al2O3 filler with contents of 10wt%, 20wt%, 30wt%, and 40wt% was combined with nano Al2O3 with contents of 1wt%, 3wt%, 5wt%, and 7wt% to create samples of SIR composites. The composites' dielectric strength is evaluated in a variety of environments, including dry, wet, low-salt wet, and high-salt wet circumstances. In order to boost the insulator's dielectric strength under diverse environmental conditions, this research aims to develop a weight ratio composition for such a composite. The ideal concentration of nano or micro Al2O3 fillers has been calculated using the whale optimization algorithm (WOA) and seagull optimization algorithm (SOA). [ABSTRACT FROM AUTHOR]

Electron impact scattering from C 3 F 6 O is studied in this work. The R-matrix method was used for the calculations of elastic, momentum transfer, and excitation cross sections. The attachment cross section was obtained through a parametric estimator based on the R-matrix outputs. The Binary-Encounter-Bethe (BEB) method was used for computing the ionization cross section. The obtained cross section set was used for the transport studies using the BOLSIG+ code, which is a two-term Boltzmann equation solver. The present calculation was performed for steady-state Townsend experimental conditions for E/N, covering a range of 100–1000 Td. The critical dielectric strength of pure C 3 F 6 O was found to be 475 Td, which is much greater than that of SF 6 (355 Td). The effect of the addition of different buffer gases, such as CO 2 , N 2 , and O 2 , was also examined. For the C 3 F 6 O–CO 2 , C 3 F 6 O–N 2 , and C 3 F 6 O–O 2 mixtures with 65%, 55%, and 60% C 3 F 6 O, respectively, the critical dielectric strength was determined to be essentially the same as that of pure SF 6 . The presence of synergism was confirmed for these gas mixtures. We further derived the Paschen curve using a fitting method with the transport parameters as the basic inputs. The minimum breakdown voltage of C 3 F 6 O accounted for only 55% of that of SF 6 . The buffer gas mixture improved the condition; however, the performance of CO 2 and O 2 mixtures was not satisfactory. The addition of N 2 as the buffer gas significantly improved the breakdown property of the gas. The mixture of ≥99% of N 2 or ≤1% of C 3 F 6 O gave a better breakdown characteristic than SF 6 . Any proportion ≥90% of N 2 or ≤10% of C 3 F 6 O was suitable in the higher pressure ranges. The present work demonstrates the potential of C 3 F 6 O as a substitute gas for SF 6 with a negligible environmental threat. [ABSTRACT FROM AUTHOR]

This paper considers the effect of adding niobium oxide (Nb2O5) to ferroelectric ceramics based on calcium titanate (CaTiO3), and establishes a connection between the observed alterations in strength and dielectric properties and the variation in the Nb2O5 dopant concentration in the ceramics' composition. The method of mechanochemical solid-phase synthesis was used as the main method for obtaining the ceramics, followed by thermal sintering under specified conditions in order to form a stable phase composition of the ceramics, and to initialize phase transformations in the composition. Based on the assessment of the phase composition of the resulting ceramics, it was determined that a growth in the Nb2O5 dopant concentration beyond 0.10 mol results in the formation of an orthorhombic-phase CaNb2O4 of the Pbcm(57) spatial system, the weight contribution of which grows. A growth in the Nb2O5 additive concentration results in the formation of two-phase ceramics, the formation of which allows for an enhancement in the mechanical strength of ceramics and resistance to external influences. During the study of the dependence of the strength properties on the dopant concentration alteration, a three-stage change in hardness and crack resistance was established, regarding both structural ordering and phase transformations. The measurement of dielectric characteristics showed the direct dependence of dielectric losses and the dielectric constant on the phase composition of ceramics. [ABSTRACT FROM AUTHOR]

Abstract To date, the AC dielectric breakdown strength of polyimide (PI) films, as for most polymers, is understood to follow a thickness dependency with a measured power law exponent, n ≈ 0.5. However, this work experimentally demonstrates that the AC dielectric strength of PI films is quasi‐thickness independent. Evidence is presented showing that the thickness dependency described in the literature can be explained by an extrinsic failure mode, driven by partial discharges occurring at the dielectric‐oil‐electrode triple point. Triple points can be avoided by electrode encapsulation, which subsequently recovers a purely intrinsic failure mode for PI films over a large thickness range. Consequently, the AC dielectric strength of thick PI films is intrinsic and quasi‐thickness independent, at least for film thickness up to 60 µm. For the first time, a “theoretical” AC breakdown field for PI films is reported as ≈520 Vrms µm−1. Finally, the highest experimental breakdown field values are obtained here with 505 Vrms µm−1 and 705 Vµm−1 under AC and DC fields, respectively.

We use impedance spectroscopy to investigate the dielectric response in polycrystalline, lead-free 0.5(Ba 0.7 Ca 0.3 )TiO 3 –0.5Ba(Zr 0.2 Ti 0.8 )O 3 (BCZT) ferroelectric thin films as a function of amplitude E 0 and frequency f of an applied ac electric field. Impedance spectra from f = 10 Hz to 1 MHz were collected at different E 0 on polycrystalline BCZT capacitor stacks, grown by pulsed laser deposition on platinized Si substrates and covered with Au electrodes. Deconvolution of the spectra is achieved by fitting the measured impedance to the impedance of an equivalent-circuit model of the capacitor stacks, including a recently proposed domain-wall pinning element Z DW . From an extended data analysis, we quantify the coupling strength between dielectric nonlinearity and frequency dispersion in the BCZT thin films, and we obtain a schematic diagram of the different domain-wall-motion regimes. Our results indicate that the presence of grain boundaries in BCZT reduces the coupling strength and suppresses the motion of internal domain-wall segments and also the irreversible center-of-mass motion of the domain walls. [ABSTRACT FROM AUTHOR]

The present article reports experimental evidence with a theoretical formalism on the enhancement of the dielectric breakdown strength of ferrofluids by inducing magneto-fibrillation with an external magnetic field. The dielectric breakdown strengths of oil based ferrofluids are determined, and it is further shown that the strength enhances due to the presence of a localized magnetic field in the streamer development zones. The improvement in breakdown strength is also supplemented by improvement in the reliability of the liquid dielectrics, which is established by a two parameter Weibull analysis. It is also noted that a horizontal magnetic field is more potent toward improved breakdown strength than an equivalent vertical field. The enhanced scavenging of electrons from the streamer development zones due to localized magnetic fibrillation by the nanoparticles is proposed as the crux mechanism. Microscopy studies are conducted to provide visual evidence of the fibrillation process in the ferrofluids due to the local magnetic field. A theoretical formalism is proposed to predict the ferrohydrodynamics of fibrillation, and this is further used to develop a model to predict the increment in breakdown strengths. The proposed model predictions are noted to agree well with the experimental observations. The study may find strong implications in design and development of high voltage liquid dielectrics with tunable electrical stress bearing caliber. [ABSTRACT FROM AUTHOR]

Thin-amorphous Al 2 O 3 (AO) insulating layers inserted into the SrRuO 3 -top-electrode/Pb 0.9 La 0.1 Zr 0.52 Ti 0.48 O 3 (PL)/SrRuO 3 -bottom-electrode/Si structures have been developed for enhancing the energy-storage performance of dielectric thin-film capacitors. It is found that the relaxor-paraelectric transition is observed by the insertion of the AO layer, and the paraelectric behavior of the films becomes stronger with the movement of the AO layer into the PL layer. Herein, a marked enhancement in breakdown strength from 2.5 to 5.8 MV/cm has been achieved in the PL single-film and PL/AO multilayer-film, which is the result of the simultaneous contributions of amorphous AO and pyrochlore-phase PL layers. As a result, an ultrahigh-recoverable energy-storage density of 90.7 J/cm3 and excellent energy-efficiency of 75.2% are simultaneously achieved in the PL/AO multilayer-film via the structure modulation. The findings provide an effective way to enhance the energy-storage density and breakdown strength of dielectric films via a combination of relaxor PL and amorphous AO layers. • Introduction of an amorphous Al 2 O 3 layer into the relaxor PLZT film is beneficial to enhanced breakdown strength. • PLZT film grown on Al 2 O 3 layer has a dominant pyrochlore phase. • Position of inserted Al 2 O 3 layer has enormous impact on energy-storage density. • Maximum U r of 90.7 J/cm3 and high η of 75.2% are achieved in PLZT/Al 2 O 3 /PLZT multilayer. [ABSTRACT FROM AUTHOR]

PDMS-based composites such as silicone elastomers are commonly found in high-voltage engineering, especially in outdoor insulation as coatings or structural elements or at interfaces between network elements, such as cable sealing ends (CSE). They are also promising prospects for dielectric elastomer generators (DEG), which are retrieving electrostatic energy from large strain amplitudes. The upper limit of energy conversion from these transducers is determined by the dielectric breakdown strength (DBS). Therefore, developing reliable systems that operate under high electric fields and variable repeated strains requires a thorough understanding of the mechanisms behind electrical breakdown and its coupling to mechanical cycling. In this study, the effect of Mullins damage and mechanical fatigue on silicone elastomers has been investigated. An electro-mechanical instability model that considers cyclic softening allows for predicting the evolution of the breakdown strength depending on the loading history. The results highlight the importance of the "first cycle," where up to a 30% reduction in the mean DBS was measured. However, subsequent mechanical fatigue only marginally contributes to the degradation, which is a promising perspective for the long-term performance of any silicone elastomer as long as the precise impact of the first cycle is known. [ABSTRACT FROM AUTHOR]

Dielectric capacitors with excellent energy storage performance (ESP) are in great demand in the power electronics industry due to their high power density. For the dielectric materials, the dielectric breakdown strength (BDS) is the key factor to improve ESP, which is the focus and bottleneck of current research, especially in the relaxor ferroelectric (RFE) materials with already low residual polarization (Pr). Here, we stimulate the ESP of the BaTiO3 (BT)‐based RFE ceramics by band structure engineering. The Ta element is selected to enhance the band gap of doped ceramics, occupying Ti‐site in supercell of BT and optimizing the bonds length of Ti‐O bond to increase the energy band of Ti 3d states. In this way, the band gap of the doped ceramics is efficiently enhanced from 1.8 eV to 2.22 eV resulting in the large BDS. Prospectively, combined with the advantage of fine grain size, the highest recoverable energy storage density (Wrec) of 2.85 J/cm3 is obtained at 350 kV/cm and the ultra‐high energy efficiency (η) of 95.26% is found at 200 kV/cm. Our work reveals the relationship between elements doping in B‐site and band structure, being expected to benefit for designing energy storage materials. [ABSTRACT FROM AUTHOR]

A dielectric elastomer actuator (DEA) is regarded as an intelligent actuator that can reproduce the performance of human muscle. A core–shell structured dielectric filler is synthesized by modifying carbon nanotube (CNT) with polydopamine (PDA) noncovalently and 3‐mercaptopropyl ethyoxyldi (tridecyl‐pentaethoxy) silane (Si747) covalently, designated as PDA‐Si747@CNT. Then, the filler is incorporated into an epoxy natural rubber (ENR) matrix to yield dielectric elastomer composites, denoted as PDA‐Si747@CNT/ENR. The PDA and Si747 modifications improve not only the filler dispersion but also the dielectric strength of the ENR composites. More importantly, Si747 is involved in vulcanization and provides chemical bonds between CNT and ENR chains. The maximum actuated strain of the PDA‐Si747@CNT/ENR composites increases to 17.9% at 55.5 kV mm−1, which is 152% higher than that of CNT/ENR composites (7.1% at 30 kV mm−1). Furthermore, the ENR composite‐based DEA demonstrates excellent stability and reliability, which is advantageous for practical applications. © 2023 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

In this study, we developed an analytic model to design a trench metal–insulator–semiconductor (MIS) field plate (FP) structure for the edge termination of a vertical GaN PN diode. The key parameters considered in the trench MIS FP structure include trench depth, MIS dielectric material and thickness, and interface charge density of MIS. The boundary conditions are defined based on the maximum allowed electric field strengths at the dielectric and semiconductor regions. The developed model was validated using TCAD simulations. As an example, a 1 kV GaN vertical PN diode was designed using the optimized FP structure, which exhibited the same breakdown voltage characteristics as an ideal one-dimensional PN diode structure without edge effects. This proposed simple analytic model offers a design guideline for the trench MIS FP for the edge termination of vertical PN diodes, enabling efficient design without the need for extensive TCAD simulations, thus saving significant time and effort. [ABSTRACT FROM AUTHOR]

Epoxy resin has long been used as an insulating material in high-voltage apparatus, although its poor recyclability greatly limits its future application. Fiber network reinforced polyethylene terephthalate (PET), as a low-cost and recyclable material, has great potential to substitute epoxy resin as a high-voltage insulation material. The enhanced fiber network combined with the PET matrix form a semi-'steel-reinforced concrete' structure, and can collaboratively improve the tensile strength by more than 50% and the dielectric strength by 25.4%. Furthermore, the breakdown path as well as the fiber distribution are clearly rebuilt in 3D coordinates based on a 3D x-ray microscope for the first time. Experimental and computational evidence show that the fiber network lengthens the breakdown path and improves the dielectric strength. This work provides new perspectives for subsequent research on the electrical properties of bone-enhanced dielectric polymer composite. [ABSTRACT FROM AUTHOR]

Polymer‐based dielectric nanocomposites with excellent high‐temperature energy storage performance are highly desirable in advanced electronic and power systems, but it remains a challenge to achieve superior breakdown strength at elevated temperatures. In this work, two‐dimensional (2D) magnesium oxide nanosheets (MgO NSs) are prepared by a hydrothermal method and used as fillers to fabricate MgO NSs/polyetherimide (PEI) dielectric nanocomposites. The effect of MgO NSs addition (1–4 wt%) on breakdown strength of MgO NSs/PEI nanocomposites is studied from 25 to 150°C. As a result, the nanocomposites containing 3 wt% MgO NSs obtain maximum breakdown strength of 538 kV mm−1 at 150°C, which is 25% higher than that of pure PEI and remains 92% of the room‐temperature value, accompany with an excellent discharged energy density of 3.66 J cm−3. The enhancement of breakdown strength could be attributed to the 2D structure and wide band gap (~7.8 eV) of MgO NSs, which act as barriers to suppress the electrical tree growth and create deep traps to capture charge, thus inhibiting the migration of charge carriers and suppressing electrical conduction. This work provides an effective approach for developing high‐temperature polymer‐based dielectric nanocomposites with high breakdown strength and discharged energy density. [ABSTRACT FROM AUTHOR]

In this paper, alumina (Al2O3) coatings were prepared via atmospheric plasma spraying. To improve the insulation performance of the as-sprayed coatings, infiltration sealing treatment processes were performed using silicone resin and epoxy resin sealants. The mechanical properties and dielectric strength of the coatings were characterized. For the as-sprayed coating, the average microhardness was 914.94 HV0.2, and the bond strength was 38.07 MPa. The phase composition of the coatings was presented by γ-Al2O3, as the primary phase, and α-Al2O3, as the second phase. The dielectric strengths of the as-sprayed, silicone resin-sealed, and epoxy resin-sealed coatings were 10.27, 15.78, and 17.91 kV/mm, respectively. The results indicate that the porosity of the coatings was reduced, and the dielectric strength was enhanced by the sealing treatment. Sealants filled the pores of the coatings and prevented the accumulation of electric charges, thereby increasing the dielectric strength. The dielectric breakdown of the coatings was due to combined mechanisms of intrinsic, corona discharge, and thermal breakdown. [ABSTRACT FROM AUTHOR]

The incorporation of carbon fiber (CF) and thermoplastic resin in wind turbine rotor‐blade represents a challenge for lightning events because CF conducts electricity and the behavior of thermoplastic resins is not well known. A comparative study with laminates with epoxy or thermoplastic resins was performed, using lightning and dielectric strength tests. Lightning tests revealed that resins behaved similarly; the current preferentially flowed in fiber direction and in zones with high contact between fibers (e.g., criss‐crossed fibers at panel edges); the level of through‐thickness damage was inversely related to panel thickness; current flow did not affect the tensile properties in fiber direction, but produced a drop in bending strength; the adequate integration of earth terminals in CF laminates was critical for a proper lightning discharge. In dielectric tests, it was concluded that panels with glass fiber covering CF laminates behaved as through‐thickness insulators; the thermoplastic reduced the laminate's dielectric strength, while the incorporation of CF, or laminate aging in a salt spray chamber showed no difference. Electrical resistance tests showed that the results were not dependent on the type of resin, but on the level of fiber‐to‐fiber and fiber‐to‐terminal contact. The lowest linear resistance was obtained in the longitudinal fiber direction, followed by the transverse and through‐thickness ones. [ABSTRACT FROM AUTHOR]

Thermo‐responsive dielectric materials are in urgent demand owing to the rapid development of smart electronic/electrical systems. Although different types and structures of thermally responsive dielectric materials have been continuously reported, their dielectric response behaviors all originate from thermodynamic phase transitions. Herein, it is demonstrated that structural relaxation in poly(vinylidene fluoride) (PVDF), a non‐thermodynamic phase transition, can induce a significant thermal dielectric pulse at room temperature. The dielectric pulse strength of up to 6.3 × 105 at 20 Hz, with a dielectric pulsing temperature of 24 °C, is achieved from polyethylene glycol (PEG)‐PVDF coaxial nanofibrous films (PVDF@PEG), fabricated via a continuous blow spinning method. Moreover, the films exhibit excellent flexibility, adjustable strength and toughness, switchable hydrophilicity/hydrophobicity, and effective thermal management capability. The relaxation‐induced dielectric pulsing effect, outstanding multifunctionality, and simple preparation combine to promote further scalability and prospects of PVDF@PEG. In particular, the work contributes to the discovery of the relaxation‐induced dielectric response mechanism, which provides a new strategy for the generation of thermo‐responsive dielectric materials. [ABSTRACT FROM AUTHOR]

This paper offers a short overview of epoxy resins, encompassing their diverse characteristics, variants, chemical modifications, curing processes, and intriguing electrical properties. Epoxies, valued for their multifunctional attributes, serve as fundamental materials across industries. In the realm of dielectric strength, epoxy resins play a crucial role in electrical insulation. This paper discusses the mechanisms governing dielectric breakdown, strategies to enhance dielectric strength, and the impact of various fillers and additives on insulation performance. Through an exploration of recent research and advancements, this paper delves into the spectrum of epoxy properties, the array of subspecies and variants, their chemical adaptability, and the intricacies of curing. The examination of electrical resistance and conductivity, with a focus on their frequency-dependent behavior, forms a pivotal aspect of the discussion. By shedding light on these dimensions, this review provides a concise yet holistic understanding of epoxies and their role in shaping modern materials science. [ABSTRACT FROM AUTHOR]

This paper gives information on the electrical and physiochemical characteristics of six different types of palm oil compared with traditional mineral oil. We found that natural processed crude palm oil (PO-C) had a higher resistance to AC breakdown voltage than other types of palm oil, including traditional mineral oil. The results of the positive lightning impulse voltage test for PO-C were still the highest compared to other types of palm oil, including traditional mineral oil, at 58.26%. The summarised dissipation factors of all tested crude palm oils were significantly higher than those of mineral oils, which will make the palm oil less insulating, especially in PO-A palm oil (36.197%), where the values were higher than those of other oils, while mineral oil has a slightly increased dispersion factor. For relative permittivity, all palm oils were compared, and it was found that PO-C had a lower relative permittivity than the other oils. In terms of physical and chemical properties, in the moisture content test on all oils, PO-C had the percentile with the highest moisture content decrease of 58.74%. In the case of testing the surface tension value, it was found that traditional mineral oil had the highest value (48.46 m/Nm) when compared to palm oil. On the other hand, the acidity in traditional mineral oil is the lowest (0.03 mg KOH/g) compared to all palm oils. Results from studies demonstrate the possibility of using natural processed crude palm oil, or PO-C, as a replacement for traditional mineral oil. This is consistent with the results of electrical properties that show PO-C is higher than other types of palm oil and includes traditional mineral oil. [ABSTRACT FROM AUTHOR]

Glass-ceramics have demonstrated excellent dielectric properties in low-temperature co-fired ceramic (LTCC) technology used in 5G/6G wireless devices. This work studies the mechanical strengths and dielectric properties from microwave to millimeter-wave frequencies in the CaO–SiO 2 glass-ceramics modified via the P 2 O 5 as a nucleating agent. The β-wollastonite phase was identified as the primary structure with the preferred (20 2 ‾) orientation and parallel plate-like structure in the matrix as P 2 O 5 content increases up to 3.5∼5.5 wt%. The P 2 O 5 nucleating agent increases degree of long-range crystallization. Elevated mechanical flexural strength of approximately 170 MPa, hardness of ∼720 MPa, and outstanding high-frequency dielectric properties were obtained in the 3.5–5.5 wt% P 2 O 5 -added CaO–SiO 2 glass-ceramics, due to the enhanced interatomic Si–O bonding in the network. The improved mechanical and dielectric characteristics of the P 2 O 5 –added CaO–SiO 2 glass-ceramics make the crystallized wollastonite materials for the 5G/6G devices possible. [ABSTRACT FROM AUTHOR]

Herein, a study on the dielectric properties of ZnO–P2O5–SeO2 glass ceramics containing varied contents of Ag2O is presented. Structural analysis of the samples by X‐ray diffraction, transmission electron microscopy, differential scanning calorimetry, Fourier transform infrared spectra, and optical absorption techniques indicated that the glasses are embedded with Ag3PO4, Ag2SeO3, and Zn3(PO4)2 anisotropic crystal phases along with Ag+ ions and Ag0 particles. Dielectric properties, ac conductivity (σac), and dielectric breakdown strength (DBS) are investigated as functions of Ag2O concentration. The results show the maximal concentration of Ag+ ions and Ag0 metallic particles in the sample containing 0.6 mol% of Ag2O. Dielectric parameters and (σac) increase with increasing Ag2O up to 0.6 mol%, while the DBS and electrical impedance decrease. The observed dipolar effects are quantitatively analyzed and possible dipoles are identified. Ionic contribution is predominant up to 0.6 mol% of Ag2O, beyond which the polaronic tunneling phenomenon prevails. These findings indicate that 0.6 mol% of Ag2O is the optimal concentration for using these glass ceramics as solid electrolytes in ionic batteries. Moreover, glass ceramics containing Ag2O beyond 0.6 mol% have exhibited larger polaronic conductivity, hence such glasses can be considered suitable candidates for electrodes in ionic batteries. [ABSTRACT FROM AUTHOR]

In this work, (Bi 0.65-0.65 x Ba 0.35-0.35 x Nd x)(Fe 0.65-0.65 x Ti 0.35-0.35 x Nb x)O 3+ x (abbreviated as: BFBT- x NN, x = 0, 0.04, 0.08 and 0.12) ceramics were fabricated through a solid-state reaction method, aiming to obtain high-performance capacitor materials. BFBT ceramics have attracted increasing attention as potential energy storage materials because of their excellent dielectric and ferroelectric properties. However, two handicaps limit the large improvement of their energy storage performance (ESP). One is the large hysteresis of their polarization (P)-electric field (E) loops; the other is the low dielectric breakdown strength (E b), which has a close correlation with the inevitable defects present in BF-based ceramics. Herein, we designed a co-doping strategy to overcome the two handicaps in order to achieve high ESP in BFBT ceramics. In this strategy, the trivalent rare earth Nd3+ ions and high valence Nb5+ ions are simultaneously introduced at the perovskite A- and B-sites of BFBT ceramics, which is called NN co-doping. The NN co-doping enhances the relaxor properties of BFBT ceramics due to the enhanced composition and charge fluctuations and promotes the formation of the Bi-rich phases, which contribute to the appearance of a slim P - E loop. Meanwhile, the E b of BFBT ceramics is enhanced, which is ascribed to the significantly decreased oxygen vacancy concentration, the reduced grain size and the Bi-rich phases. Benefitting from these factors, a high recoverable energy storage density (W rec) of 3.64 J/cm3 and energy storage efficiency (η) of 88% are simultaneously obtained under an enhanced E b of 330 kV/cm in BFBT-0.08NN ceramics. Moreover, the ESP of BFBT-0.08NN ceramics shows good thermal stability (30–150 °C) and charge-discharge properties. These results indicate that BFBT-0.08NN ceramics could be a promising capacitor material. [ABSTRACT FROM AUTHOR]

Innovation in the economy is closely tied to energy development, encompassing the exploration of new energy sources, increased energy production efficiency, and the integration of diverse energy sources for safe and effective supply to industries and households. Outdated energy infrastructure disrupts electricity continuity and hampers economic innovation. Power interruptions lead to higher SAIDI and SAIFI reliability indices. Quality and reliability requirements have sparked interest in enclosed energy devices. Vacuum technology has been pivotal in electrical switchgear insulation and arc-quenching for over four decades. However, the lack of real-time pressure monitoring systems for vacuum equipment, especially enclosed disconnectors, limits their use as isolation connectors. Potential insulation failure poses risks to power line maintenance teams and can lead to unplanned shutdowns, further compromising energy supply quality. This article explores an innovative pressure monitoring system for vacuum interrupters, utilizing fiber optic Bragg grids as a measuring sensor, enabling pressure measurement within the vacuum chamber ranging from 2 × 101 Pa to 5 × 105 Pa. [ABSTRACT FROM AUTHOR]

With the increasing demand for energy, how to store and release energy efficiently and stably has become an urgent research topic. Polymer dielectrics have become a kind of ideal dielectric materials in electrostatic capacitors for energy storage due to their advantages of light weight, easy fabrication, low cost, and high breakdown strength. It has a wide application prospect in smart power grids, new energy vehicles, pulse power weapons, electromagnetic guns, and lasers. However, existing polymer dielectrics cannot simultaneously possess the characteristics of high energy density, high breakdown field intensity, high charge and discharge efficiency, and low dielectric loss, thus limiting the development of compact, efficient, and reliable electronic power technology. In addition, the inherent thermal/field charge injection, excitation, and transport phenomena of polymer dielectrics make the resistivity and dielectric energy storage properties of polymer dielectrics decrease sharply under the combined action of high temperature and high electric field. In order to optimize the energy storage performance of polymer dielectrics (including room temperature and high temperature dielectrics), it has been obtained excellent dielectric breakdown strength, energy storage density, energy storage charge, and discharge efficiency from polymer nanocomposites, polymer/small molecule composites, polymer/polymer blends, new synthetic polymers, multilayer polymers, and other material systems. Based on these material systems, this review summarizes and compares these material systems, points out their advantages and disadvantages including the key problems, and puts forward suggestions for the future research. [ABSTRACT FROM AUTHOR]

In this work, the neglected role of the dielectric breakdown strength (BDS) in piezoelectricity of bismuth layer-structured ferroelectrics (BLSFs) is revealed, enhanced initial polarization and BDS work together to improve the piezoelectricity of CaBi 4 Ti 4 O 15 (CBT) ceramics via Li/Bi co-substitution. The experimental work, first-principles calculations and finite element simulation are carried out to investigate the effect of Li/Bi co-substitution in depth. The stronger spontaneous polarization (P s) from the lattice distortion and the more favorable domain switching from the improved grain growth both contribute to an enhanced initial polarization. Besides, the changed grain-scale microstructure improves the hardness and inhibits the local discharge, the higher resistivity related to strong defect dipoles suppresses the heat generation during the poling process, all resulting in an increase of BDS by about 100%, and allowing more domains to align. This work demonstrates an effective strategy to develop BLSFs with enhanced piezoelectricity for high temperature piezoelectric applications. [ABSTRACT FROM AUTHOR]

The rapid development of modern electrical equipment has led to urgent demands for electrical insulating materials with mechanical reliability and excellent dielectric properties. Herein, basalt nanosheets (BSNs) with high aspect ratios (≈780.1) are first exfoliated from basalt scales (BS) through a reliable chemical/mechanical approach. Meanwhile, inspired by the layered architecture of natural nacre, nacre‐mimetic composite nanopapers are reported containing a 3D aramid nanofibers (ANF) framework as a matrix and BSNs as ideal building blocks through vacuum‐assisted filtration. The as‐prepared ANF‐BSNs composite nanopapers exhibit considerably enhanced mechanical properties with ultralow BSNs content. These superiorities are wonderfully integrated with exceptional dielectric breakdown strength, prominent volume resistivity, and extremely low dielectric constant and loss, which are far superior to conventional nacre‐mimetic composite nanopapers. Notably, the tensile strength and breakdown strength of ANF‐BSNs composite nanopapers with a mere 1.0 wt% BSNs reach 269.40 MPa and 77.91 kV mm−1, respectively, representing an 87% and 133% increase compared to those of the control ANF nanopaper. Their properties are superior to those of previously reported nacre‐mimetic composite nanopapers and commercial insulating micropapers, indicating that ANF‐BSNs composite nanopapers are a highly promising electrical insulating material for miniaturized high‐power electrical equipment. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the temperature's effect on the dielectric response of 2D random RC networks (RRCNs) modelling heterogeneous/composite materials. We presented a comparative analysis for the conductivity behaviour using the modified effective medium approximation (EMA) and Franck and Lobb (FL) algorithm. We showed that the Summerfield frequency, the characteristic frequency ω c of the conductivity and the loss frequency ω max , all followed an Arrhenius dependence; they could be used as scaling frequencies. Using the loss frequency ω max for different temperatures, we could represent each dielectric property in a master curve form. This latter exhibited a behaviour related to the time–temperature superposition principle (TTSP). We showed that the DC conductivity and ω max exhibited the Barton–Nakajima–Namikawa (BNN) relationship σ dc ′ = a Δ ε ′ ω max for which a ∼ 1 as found in the literature, where Δ ε ′ is the dielectric loss strength. In addition, we showed that for capacitors' proportion p = 0.40 , random RC networks preserved their universal power-law (UPL) behaviour when the temperature was considered with a slight difference in the exponent value differing from the capacitors proportion. We found that the normalized conductivity and complex permittivity both scaled as σ ′ / σ dc ∝ (ω / ω max) n and ε / ε s ∝ (ω / ω max) n - 1 , respectively, reflecting the universal dielectric response (UDR). [ABSTRACT FROM AUTHOR]

Silicone gel is widely used to encapsulate power modules, and improvement of its dielectric strength has been required. So, the purpose of our research is to improve dielectric strength of silicone gel encapsulant, and we focus on crosslinking degree of silicone gel. Previous studies have shown that growth mechanism of electrical tree changes with crosslinking degree of silicone gel. This suggests the possibility that the presence of the interface by different crosslinking degrees inhibits the tree growth. In this paper, we have investigated the tree growth and breakdown characteristics in silicone gel—crosslinking degrees graded layer materials. The interfaces in our study are arrange as being vertical to the line of electric force. Consequently, it was clarified that barrier effect of interface by different crosslinking degrees and the relaxation of electric field in low crosslinking degree region retards on tree growth, which improves the dielectric strength. [ABSTRACT FROM AUTHOR]

In recent years, nanocomposites have obtained a lot of interest. It is feasible to achieve extremely useful dielectric material, which can be used in capacitors, by combining some amount of the nanoparticles inside the base epoxy resin. Polymers are the preferred insulating materials for various electrical purposes because of their simplicity of manufacture, lighter volume, and relatively inexpensive nature. However, because of its poor relative permittivity and low electric field stress handling capability, they have created an impediment, and efforts have been made to remove them. The addition of nanosized fillers having comparable high relative permittivity to epoxy resin is one way for getting better dielectric material as the relative permittivity of the dielectric material should be high. The relative permittivity and the electric field stress are used to determine dielectric strength. Three-dimensional models have been created by using finite element software in this work that is COMSOL Multiphysics, which has simulated distinctive nano-composites based on epoxy resin with alumina, silica, TiO2 and MgO nanofillers in order to estimate their relative permittivity values and electric field stress. The selected nanofillers are spherical, cubic and cylindrical shaped. Simulations are performed by changing their concentration(vol%), kind and number of particles. Relative permittivity enhances as the concentration of nano filler enhances. However, an increasing number of particles of nano filler gives a very slight change in relative permittivity values. Cylindrical-shaped TiO2 nano fillers give relatively better results than spherical and cubic shaped nano fillers. At the beginning, electric field stress decreases with increasing concentration and then the number of nanofillers particles has suddenly increased. The validation of results simulation outcomes has been compared with hardware tests results, which shows that the breakdown strength of alumina-based nanocomposite is higher than any other composite. [ABSTRACT FROM AUTHOR]

The granite waste generated from the granite cutting and polishing industries contributes to lot of environmental contamination and health hazards. In the present work, an attempt has been made to assess the method to minimise environmental problems associated with granite dust pollution to the possible extent by converting the granite dust waste into value added high voltage electrical insulator products. Two types of epoxy matrices comprising bisphenol-A diglycidyl ether-phenalkamine (ER-1) and bisphenol-A diglycidyl ether-methyl hexahydrophthalic anhydride (ER-2) separately reinforced with varying weight percentages of (20, 40, 60, 80 and 100 wt%) of granite dust. The matrices and composites obtained were characterized for their structural, morphology, hydrophobic properties, thermal stability, mechanical strength, thermal conductivity, thermal resistivity, electrical resistivity, breakdown voltage and dielectric strength behaviour using appropriate analytical testing methods. Data resulted from different studies, it was inferred that the composites prepared using ER-2 possess better properties than those of ER-1. The composites with 100 wt% of cutting waste granite fly dust reinforced ER-2 possesses the higher values of electrical surface resistivity (5.22 × 1012 Ω), and electrical volume resistivity (5.60 × 1013 Ω) than those of neat ER-2 matrix (surface resistivity 4.82 × 109 Ω and volume resistivity 2.48 × 1013 Ω). The breakdown voltage and dielectric strength of ER-2 matrix were increased from 28 ±1 kV and 14 ± 0.5 kV/mm to 34 ±1 kV and 17 ± 0.5 kV/mm respectively, when reinforced with 100 wt % granite dust. The value of breakdown voltage was increased by 22% for 100 wt% granite dust reinforced composites when compared to that of neat epoxy matrix.

Abstract In recent decades, high dielectric constant (k) polymer nanocomposites have proved excellent potential in dielectric and energy storage applications. Epoxy/silicon rubber composite materials have shown promising properties in applications such as high-voltage insulation. Three types of nanomaterials (SiO2, TiO2, and TiO2@SiO2) with distinct intrinsic properties are carefully chosen to build high-k epoxy/silicone polymer nanocomposites in this study. To raise the value of K, this work tailored the polarizing ability or permittivity of dielectric material by inserting different weight ratios of nano-fillers (SiO2, TiO2, TiO2@SiO2) in the base matrix of dielectric material in epoxy and silicon rubber blends. With a base matrix containing 75% epoxy and 25% liquid silicone rubber concentration, the maximum value of K obtained is K = 158 for 5% TiO2 and there is an increase in the dielectric strength to 398 kV/mm. The obtained results indicate that, among the three different kinds of epoxy/silicone, TiO2@SiO2 has the most potential in enhancing the energy storage capabilities of the proposed nanocomposites, owing to the largest increase in k while maintaining low dielectric loss and leakage current.

Silicone rubber (SIR) is used in high-voltage insulators because of its insulation, and excellent hydrophobicity is very important in harsh outdoor environments. To enhance the hydrophobicity and low-temperature resistance of silicone rubber, methyl vinyl silicone rubber and fluorosilicone rubber (FSIR) blend composites with different ratios were prepared. The samples were characterized and analyzed using scanning electron microscopy, tensile testing, dynamic mechanical analysis and static contact angle testing. The results showed that after blending, SIR and FSIR were well compatible. FSIR had higher elastic modulus and reduced the tensile strength to some extent in SIR/FSIR composites. The addition of a small amount of FSIR made its crystallization temperature decrease from −30 to −45 °C, meaning that the low-temperature resistance was significantly improved. The breakdown strength of SIR/FSIR composites can still be maintained at a high level when a small amount of FSIR is added. The contact angle of the composites increased from 108.9 to 115.8° with the increase in FSIR content, indicating the enhanced hydrophobicity. When the samples were immersed in water for 96 h, the hydrophobicity migration phenomenon occurred. The static contact angle of the samples with less FSIR content had a weaker decreasing trend, which illustrated that the hydrophobicity was maintained at a high level. [ABSTRACT FROM AUTHOR]

Achieving extreme deformations without electrical breakdown has been a longstanding challenge in the dielectric elastomer community. In this paper, we present a novel approach for accessing giant in-plane stretches in circular dielectric elastomer membranes by leveraging nonlinear dynamics, specifically short-duration voltage pulses. These voltage pulses-applied about nominal bias voltages where the large-stretch equilibrium does not experience dielectric breakdown-create transient stretches that, if sufficiently large, cause the membrane to dynamically snap-through to its large-stretch equilibrium. These giant deformations are reversible; pulsed voltage drops can return the membrane from its large-stretch equilibrium to its small-stretch equilibrium. Parametric analyses are used to determine the combinations of pulse amplitude and duration that result in snap-through. Corresponding through-thickness electric fields are shown to be below stretch-dependent dielectric strengths from the literature, suggesting practical feasibility. Unlike other techniques for accessing extreme stretches in dielectric elastomers, the present approach relies on voltage control alone; it therefore does not require altering the external mechanical forces that cause pre-stretch and can be applied without modifying the elastomer's mechanical compliance. This research demonstrates that carefully designed voltage pulses may permit existing and emerging soft material technologies to access extreme, large-stretch equilibria without dielectric breakdown. [ABSTRACT FROM AUTHOR]

Traditionally, low-frequency power supplies are used in dielectric barrier discharge (DBD) ozone generators. These generators require a very high output voltage. This may limit ozone production due to limitations imposed by the dielectric strength of the insulating material. Low-frequency generators also present low efficiency, large volumes, and difficulty in controlling ozone production. On the other hand, the advantages of high frequency DBD ozone generators are the increased power density applied to the chamber electrodes, and the voltage applied to the ozone chamber decreases, allowing for higher ozone production efficiency. From this point of view, in order to enhance and control the DBD ozone generator operating at high frequency, it is necessary to determine all parameter values and optimize the equivalent model for this type of generator. This work presents and proposes the practical methodologies used to extract all parameters of the high voltage high frequency (HVHF) transformer which can be used in these systems. Resonant frequency control techniques are presented in this paper. Elimination of the stray capacitance effect will also be implemented in this paper. [ABSTRACT FROM AUTHOR]

This paper describes the preparation and analysis of a new insulation composite material suitable for high-voltage applications. The material was characterized using Fourier transform infrared and X-ray diffraction spectroscopy, which revealed the presence of SiO2, confirming the successful integration of the matrix (polyester) and reinforcement material (celite filler). XRD also showed that the crystalline behavior of the composite changed as the proportion of epoxy and celite varied. Additionally, electrical characterization was conducted using ASTM D-149 and D-257, and it was found that an increase in the environmental temperature and humidity had a negative effect on the dielectric and resistivity properties of the composite. These results were both experimentally determined and theoretically verified by a one-dimensional finite element model. The results also showed that 5% celite composition is suitable for making ignition coil insulations, as it meets Indian and Japanese Industrial Standards. [ABSTRACT FROM AUTHOR]

This paper investigates C4H2F6, a promising environmentally friendly insulating gas that possesses high dielectric strength and a low global warming potential. The study focuses on examining the insulation properties of C4H2F6 when combined with CO2/N2, aiming to assess its suitability as a substitute for SF6 in gas-insulated applications. Finite element analyses are performed to evaluate the field utilization factor and electric field distribution in the proposed mixture. The properties of liquefaction temperature were examined in this study to determine the optimal mixing ratio for applications that require a minimum working temperature. Extensive experimental investigations were carried out to assess the dielectric strength characteristics of the gas mixture in both uniform and quasi-uniform electric fields. It was found that pure HFO-1336mzz (E) exhibits a dielectric strength approximately 1.2–1.6 times higher than SF6. Experimental results have revealed that the insulation performance of a 30% HFO-1336mzz (E)/CO2 mixture closely resembles that of SF6, with a matching efficiency of up to 90% in a weakly uniform electric field. This remarkable performance can be attributed to a positive synergistic effect between HFO-1336mzz (E) and CO2, combined with the gas mixture's excellent self-recoverability property. These experimental findings are further supported by finite element analysis, which confirms the observed results. The 30% HFO-1336mzz (E)/CO2 gas mixture at 0.15–0.20 MPa pressure and constant 0.6 mm air gap reveal superior insulation tolerance and less sensitivity to the electric field, confirming its promising medium-voltage engineering applications. The associated results of this research provide a critical reference for the engineering application of the alternating (AC) and direct current (DC) insulation characteristics of the HFO-1336mzz (E)/CO2 gas mixture. [ABSTRACT FROM AUTHOR]

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Mineral oil (MO) is the most popular insulating liquid that is used as an insulating and cooling medium in electrical power transformers. Indeed, for green energy and environmental protection requirements, many researchers introduced other oil types to study the various characteristics of alternative insulating oils using advanced diagnostic tools. In this regard, natural ester oil (NEO) can be considered an attractive substitute for MO. Although NEO has a high viscosity and high dielectric loss, it presents fire safety and environmental advantages over mineral oil. Therefore, the retrofilling of aged MO with fresh NEO is highly recommended for power transformers from an environmental viewpoint. In this study, two accelerated aging processes were applied to MO for 6 and 12 days to simulate MO in service for 6 and 12 years. Moreover, these aged oils were mixed with 80% and 90% fresh NEO. The dielectric strength, relative permittivity, and dissipation factor were sensed using a LCR meter and oil tester devices for all prepared samples to support the condition assessment performance of the oil mixtures. In addition, the electric field distribution was analyzed for a power transformer using the oil mixtures. Furthermore, the dynamic viscosity was measured for all insulating oil samples at different temperatures. From the obtained results, the sample obtained by mixing 90% natural ester oil with 10% mineral oil aged for 6 days is considered superior and achieves an improvement in dielectric strength and relative permittivity by approximately 43% and 48%, respectively, compared to fresh mineral oil. However, the dissipation factor was increased by approximately 20% but was at an acceptable limit. On the other hand, for the same oil sample, due to the higher molecular weight of the NEO, the viscosities of all mixtures were at a higher level than the mineral oil. [ABSTRACT FROM AUTHOR]

Dielectric materials with higher energy storage and electromagnetic (EM) energy conversion are in high demand to advance electronic devices, military stealth, and mitigate EM wave pollution. Existing dielectric materials for high‐energy‐storage electronics and dielectric loss electromagnetic wave absorbers are studied toward realizing these goals, each aligned with the current global grand challenges. Libraries of dielectric materials with desirable permittivity, dielectric loss, and/or dielectric breakdown strength potentially meeting the device requirements are reviewed here. Regardless, aimed at translating these into energy storage devices, the oft‐encountered shortcomings can be caused by either of two confluences: a) low permittivity, high dielectric loss, and low breakdown strength; b) low permittivity, low dielectric loss, and process complexity. Contextualizing these aspects and the overarching objectives of enabling high‐efficiency energy storage and EM energy conversion, recent advances in by‐design inorganic–organic hybrid materials are reviewed here, with a focus on design approaches, preparation methods, and characterization techniques. In light of their strengths and weaknesses, potential strategies to foster their commercial adoption are critically interrogated. [ABSTRACT FROM AUTHOR]

The partial discharge in the converter transformer will cause the carbonization of the insulating paper. The high concentration of free carbon particles generated from the insulating paper during the operation of the converter transformer will cause partial discharge, which will aggravate the insulation performance deterioration. For the bi‐directional interaction of carbon particles and partial discharge, the mechanism of insulating paper carbonization caused by partial discharge and the effect of carbon particles on the dielectric strength of oil paper are studied. In this paper, we construct a simulation system of amorphous cellulose to study the carbonization mechanism of insulating paper from the microscopic level. Furthermore, we build a DC voltage experimental platform to carry out partial discharge damage tests of oil‐paper insulation models and to measure the changes in the breakdown voltage with different carbon particle concentrations and diameters. The results show that partial discharge speeds up the cleavage rate of cellulose, generates low molecular hydrocarbon gas and water molecules, and the carbon atoms rearrange into PAH‐like molecules with aliphatic side chains. The surface of the insulating paper will carbonize, then form free carbon particles after peeling off. Afterward, the carbon particles in insulating oil accumulate in the high electric field area and attach to the insulating paper, which will cause electric field distortion and reduce the dielectric strength of oil‐paper insulation. With the increase of carbon particle concentration and diameter, the breakdown voltage of oil‐paper insulation decreases gradually. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Dielectric film capacitors with high power density and rapid charge–discharge capability are widely used as key components in modern electronic and electrical systems, and polymers are primary dielectric for film capacitors due to their low cost, flexibility, and ease of processing. Here, a surface engineering approach is reported to improve the energy storage properties of polymer films by directly spray coating 2D nanosheets on the polymer film surface. The spraying of 2D calcium niobate nanosheets on the surface of biaxially oriented polypropylene (BOPP) films leads to remarkably increased breakdown strength and dielectric constant, resulting in a maximum 64% enhancement of energy density compared to the pristine BOPP films. Ultraviolet irradiation is further employed to improve the adhesion of nanosheets to the BOPP film surface, leading to an ultrahigh energy density of 11.6 J cm−3 with a high energy efficiency of 90%, which is the highest energy density ever achieved in polypropylene‐based films. This work provides a universal, cost‐effective, and scalable approach to improve the energy density of dielectric polymer films, which is of great significance for the application of high‐energy‐density polymer films in compact and efficient power systems. [ABSTRACT FROM AUTHOR]

Capacitor films from biaxially oriented polypropylene (BOPP) involve intensive external stress field, resulting in special crystallization and orientation characters. However, it still remains ambiguous on the relationship between crystallized morphology in BOPP bulk film and electric properties. In this work, two stretching modes, simultaneously biaxial stretching and sequentially biaxial stretching, were chosen to adjust film thickness, extended chain crystal content, fibrillar morphology, and orientation texture. Meanwhile, the working rules of these structural issues on electrical insulating properties were inspected. It reveals that extended chain crystals with thermal stability and isotropous fibrillated network favor to improved breakdown strength and lowered dielectric loss. These results offer good understanding on the processing-structure-property relation of polymer film dielectrics. [ABSTRACT FROM AUTHOR]