Pulsed Capacitors Research Articles

Combined Fuzzy Time Series Prediction Method for Fault Prediction of EML Pulse Capacitors

Metallized film capacitors are an important part of the electromagnetic rail launch system. It is of great significance to predict its failure. In engineering, the failure law of capacitor is obtained by cyclic pulse accelerated life test of capacitor module with a small number of samples, and is used to predict the actual failure of capacitor in electromagnetic launch (EML) system. This method has the following problems: first, there are few samples of capacitor in life test at affordable cost, which cannot include all capacitor characteristics; second, the time interval of actual EML missions and the voltage of the capacitors are both changing and inconsistent with the conditions used in the life test; third, the statistical law is affected by the measurement and other errors. For these reasons, the prediction accuracy of the existing methods is limited. In this article, a new combined time series prediction method is proposed by using the high-order fuzzy time series prediction theory. Based on the capacitor used in the prototype of an electromagnetic railgun, the life test data of 20 pulse capacitors are used as the prior knowledge input, and the prediction model is obtained. Five groups of capacitor life test data simulating real launch conditions are used as test data to verify that the prediction accuracy of the proposed method is better than that of the traditional method, and the prediction accuracy of capacitor capacitance, which made by different processes, is much higher than that of the traditional method.

Influence of pulse-plasma modification with titanium and silicon carbide of the surface of hard VK10KS alloy on its structure and properties

Electro-explosive alloying as a method of pulse-plasma treatment consists in accumulation of energy by a battery of pulsed capacitors and its subsequent discharge for 100 μs through a conductor in form of titanium foil with silicon carbide powder, while conductor is under explosive destruction. Method of electro-explosive alloying of tungsten-cobalt hard alloy includes melting of surface and its saturation with explosion products, followed by self-hardening by removing heat deep into the material and environment. On the surface of VK10KS hard alloy, the coating was obtained with thickness of up to 15 – 20 microns with nanohardness of 26,000 MPa. Using X-ray phase analysis and scanning electron microscopy, it has been established that new phases of TiC, W2C, (W, Ti)C1 – x , WSi2 with high hardness were formed in the surface layer. As a result, friction coefficient decreased to 0.18 compared to the initial 0.41. Investigations with transmission electron microscopy have revealed changes during electro-explosive alloying that occur in surface carbide and near-surface cobalt phases. Dislocations accumulations were found in the carbide phase. In cobalt binder, deformation bands (slip bands), single dislocations, and finely dispersed precipitates of tungsten carbides were revealed. This change can be explained by stabilization of cubic modification of cobalt, crystal lattice of which has a large number of slip planes upon deformation and greater ability to harden in comparison with hexagonal modification of cobalt. Additional alloying with cobalt binder in heat affected zone after pulse-plasma treatment have a positive effect on the service life of tungsten-cobalt hard alloys as a whole due to their stabilization.

Theoretical substantiation of the influence of electric pulse processing on the process of obtaining juice from grapes and fruits

The article presents the theoretical basis of the effect of electrical pulse processing on the process of obtaining juice from grapes and fruits. High-voltage pulsed electrical processing technology for biological products has a higher damaging effect on living cells than other electrical effects, and this can be achieved due to the passage of large discharges of current through tissues and cells in a short period of time. It has been found that high efficiency in killing living cells by secretion can be achieved as a result of a pulsed energy effect. In order to develop energy-efficient electrical technology for extracting juice from fruits and grapes, it has been found that high-voltage electric pulse discharge treatment of grapes and apples before extracting juice has a good effect. Analytical expressions between electrical impulse processing parameters (pulse energy and capacitor capacity) and juice output were determined. The degree of damage to fruit and grape cells depends on the capacitance of the capacitor, the discharge voltage, and the number of pulses.

Improved energy storage density and efficiency of (1−x)Ba0.85Ca0.15Zr0.1Ti0.9O3-xBiMg2/3Nb1/3O3 lead-free ceramics

The improvement of energy density and efficiency is currently the main challenge in the application of lead-free dielectric energy-storage materials. Relaxor ferroelectric ceramics are the most commonly selected materials for pulsed power capacitors because of their inherent advantages, such as ultra-high power density, fast charging/discharging, and long lifetime. In this study, BiMg2/3Nb1/3O3 (BMN) was doped to enhance energy density and efficiency in the (1−x)Ba0.85Ca0.15Zr0.1Ti0.9O3-xBiMg2/3Nb1/3O3 systems based on the adjusted breakdown strength and polarization. As a result, a giant recoverable energy density of 3.81 J/cm3 and a high energy efficiency of 90.5% were simultaneously achieved in the 0.925BCZT-0.075BMN ceramic, which the energy density is 26 times as large as that of BCZT ceramic. Excellent temperature (−25 to 100 °C) and frequency (1–100 Hz) stability of recoverable energy density and energy efficiency were confirmed with the fluctuations below 4.5%. Domain engineering on the nanoscale was designed in relaxor ferroelectrics, which effectively improved the energy storage performance. Our study provides a feasible guideline to develop lead-free ceramics for electrical energy storage applications.

Optimization of synergistic energy storage density and efficiency for eco-friendly (Na0.5Bi0.5)0.6Sr0.4TiO3-based relaxor ferroelectric ceramics

Inspired by increasing demand of advanced pulsed power capacitors, the development of lead-free dielectric ceramic capacitors with high energy storage density and temperature-insensitive performance are extremely crucial. Herein, the lead-free relaxor ferroelectric ceramics based on (1-x) (Na0.5Bi0.5)0.6Sr0.4TiO3- xSr0.7La0.2ZrO3 [abbreviated as (1-x)NBST-xSLZ] are prepared by the solid-state reaction route. The large recoverable energy density (Wrec) of 3.45 J/cm3 and efficiency (η) of 90.1% are simultaneously realized in 0.86NBST-0.14SLZ ceramic due to increased breakdown strength. Furthermore, both the Wrec and η of 0.86NBST-0.14SLZ ceramic display superior of thermal stability (20–180 °C), frequency stability (1–1000 Hz), and cycle stability (104) within a satisfactory range of variation. In addition, the 0.86NBST-0.14SLZ ceramic can also achieve a large current density (CD) of 625 A/cm2, an ultrahigh power density (PD) of 50 MW/cm3 and a fast discharge rate (τ0.90) of 160.8 ns at 160 kV/cm. These results demonstrate that the 0.86NBST-0.14SLZ ceramic could be a highly competitive and eco-friendly relaxor ferroelectric material for next-generation pulsed power capacitors.

Optimization of polarization and electric field of bismuth ferrite-based ceramics for capacitor applications

• Optimization of polarization and electric field for BF-based ceramics. • High W rec of 5.57 J cm −3 was achieved for BFBT-NBN ceramics at 410 kV cm −1 . • The η maintain ~89% and the variation of W rec is less than ±2% after 10 4 cycles. • Energy storage properties of the BFBT-NBN ceramics exhibit outstanding stability. For the purpose of meeting the requirements of protecting environment and sustainable development, bismuth ferrite (BiFeO 3 , BF)-based lead-free ceramics have gained immense attention for pulsed power capacitor applications due to their large spontaneous polarization, low sintering temperature as well as non-toxic and harmless. However, the low energy storage properties (ESPs) and unstable performance of BF-based ceramics are not good for practical applications. In this work, novel bismuth ferrite-based lead-free ceramics of (1-x)(0.67BiFeO 3 -0.33BaTiO 3 )-xNa 0.73 Bi 0.09 NbO 3 ((1-x)BFBT-xNBN) were designed and fabricated successfully by optimizing the polarization and electric field. With increasing the content of NBN, the remnant polarization decreased rapidly as well as the slim and pinched polarization-electric field loops together with high electric field can be observed. Notably, ultrahigh ESPs with the total energy storage density (W tot ) of 6.65 J cm −3 and the recoverable energy storage density (W rec ) of 5.57 J cm −3 can be achieved at high electric field of 410 kV cm −1 . At the same time, the η is greater than 80% and the variation of W rec is less than ±5% over a broad frequency range (1–100 Hz) and temperature range (30–150 °C). In addition, the η is stabilized around 89% and the variation of W rec is less than ± 2% after 10 4 cycles. Therefore, the (1-x)BFBT-xNBN lead-free ceramics not only possess ultrahigh ESPs but also the ESPs exhibit outstanding stability, which is promising candidates for high performance pulsed power capacitor applications.

Transient Electrical and Optical Characteristics of Electron and Proton Irradiated SiGe Detectors.

The particle detector degradation mainly appears through decrease of carrier recombination lifetime and manifestation of carrier trapping effects related to introduction of carrier capture and emission centers. In this work, the carrier trap spectroscopy in Si1−xGex structures, containing either 1 or 5% of Ge, has been performed by combining the microwave probed photoconductivity, pulsed barrier capacitance transients and spectra of steady-state photo-ionization. These characteristics were examined in pristine, 5.5 MeV electron and 1.6 MeV proton irradiated Si and SiGe diodes with n+p structure.

ВЛИЯНИЕ ЭЛЕКТРОГИДРАВЛИЧЕСКОЙ ОБРАБОТКИ НА СОДЕРЖАНИЕ НИТРАТНОГО АЗОТА В ПОЛИВНОЙ ВОДЕ

The introduction of mineral fertilizers has a negative impact on the agrobiocenosis. An increase the concentration of nitrate nitrogen in irrigation water in order to use it as a nitrogen fertilizer that does not have a negative impact on the environment seems relevant. The change in the content of nitrate nitrogen was determined in irrigation water, which was used as the flowing water of the city water supply (Moscow); pond water (Moscow region); potassium nitrate solution with a concentration of 50.9 mg/l. Three types of irrigation water were processed using a high-voltage installation. The experimental electrohydraulic installation consisted of a TVI-50/70 transformer with a rectifier unit; DC electric energy storage systems (high-voltage pulse capacitors); arresters designed to generate pulsed spark discharges with a short rise time; controls that allow changing technological modes during experiments; working units. During the research, an ITAN pH meter/ionometer was used according to the RD 52.24.367-2010 method. The technological mode of operation of the electro-hydraulic unit provides for the following characteristics: operating voltage 42 kV; capacitance of capacitors 0.05 μF; number of spark discharges n = 1 ... 5 thousand pieces; forming the gap between the ball arresters FP = 14 mm; working gap between working high-voltage electrodes 10 mm. Electrohydraulic treatment of water increases the concentration of nitrate nitrogen compounds in the running water of city water supply by 3.7 times (from 2.9 to 10.9 mg/l), in pond water - by 7 times (from 1.2 to 8.4 mg/l), in a solution of potassium nitrate - 1.3 times (from 50.9 to 68.4 mg/l). In water treated electrohydraulically, the content of nitrate nitrogen increases, which expands the possibilities for its use when watering plants.

Ameliorative energy-storage properties stemmed from the refined grains in PBLZS antiferroelectric ceramics via introducing liquid phase sintering

The low breakdown strength (BDS) of antiferroelectric ceramics, which become failure before undergoing electrical field induced antiferroelectric-ferroelectric phase transition, have seriously restricted the progress of pulsed power capacitors. The method of refining grain sizes via the incorporation of glass additive is supposed to be an outstanding strategy to boost the BDS. Herein, the (Pb0.91Ba0.015La0.05)(Zr0.6Sn0.4)O3 (PBLZS) antiferroelectric ceramics with the introduce of BaO-B2O3-Al2O3-SiO2 (BBAS) glass are designed and synthesized by a traditional solid-state reaction. When the glass content is 0.4 wt%, the recoverable energy storage density (Wrec) increases by 215 % from 2.0 J/cm3 to 6.3 J/cm3, together with a greatly enhanced BDS up to 390 kV/cm versus 270 kV/cm of pure ceramics. Meanwhile, the corresponding sintering temperature is remarkably decreased from 1300℃ to 1100℃. The superior charge and discharge performance can be obtained under the electrical field of 310 kV/cm, including a giant current density (1184.7 A/cm2), a high power density (184.2 MW/cm3), and an ultra-fast discharge period (40 ns). The prominent energy storage properties and low sintering temperature make it become a good candidate for fabricating multilayer pulsed power ceramic capacitors.

Synergistic optimization of antiferroelectric ceramics with superior energy storage properties via phase structure engineering

Dielectric capacitors with high energy storage density and high efficiency exhibit potential applications in lightweight, miniaturized microelectronic devices. Here, (Pb, La)(Zr, Sn)O3 (PLZS) based ceramics with Ba substitution were selected and studied with in-situ Raman spectra and in-situ synchrotron X-ray diffraction. Results show that the room temperature phase structure consists of two coexisting antiferroelectric phases of OI and OII (O refers to orthorhombic), and between them the latter possesses lower forward phase-switching electric field (EAF) and should be the origin of FE(I). Meanwhile, Polarization-electric field (P-E) loops and Raman spectrum under variable temperature reveal optimal Ba content of 0.02. Suitable Ba substitution forms balanced coexisting structure and therefore achieves ultrahigh recoverable energy storage density (Wrec) of 12.8 J/cm3 and simultaneously high energy storage efficiency (η) of 84.2% under an electric field of 450 kV/cm. Extremely short discharge period of 51.6 ns and high Wrec support ultrahigh power density (PD) of 327 MW/cm3 and high discharge current density (Ddis) of 1815 A/cm2. Reasonable phase structure design after clarifying the relationship between structure and performance shows guiding significance, and the improved ultra-high Wrec and PD enhance the possibility of applications of antiferroelectric ceramics in pulsed power capacitor.

Effective strategy to realise excellent energy storage performances in lead-free barium titanate-based relaxor ferroelectric

High-performance capacitors, which possess a high energy storage density, large power density and fast charge/discharge rate, are in high demand in pulsed power systems. Although several studies have been conducted to obtain excellent energy storage performances, the scientific and feasible guidance is lacking on how to quickly and efficiently find a material system with high recoverable energy storage density (Wrec), large energy storage efficiency (η), and excellent thermal stability. Herein, a strategy is proposed to concurrently regulate the temperature corresponding to the maximum dielectric constant (Tm) to around room temperature and enhance the relaxor characteristic. To our satisfaction, excellent energy storage performances with a high Wrec of 3.05 J/cm3, large η of 95%, and wide temperature stability (20–180 °C) were achieved in 0.85BaTiO3-0.15Bi(Mg05Sn0.5)O3 (0.15BMS) ceramics. In addition, these ceramics also exhibited a large discharge energy density (Wdis = 0.74 J/cm3) and fast discharge time (t0.9 = 105 ns) over a broad temperature range (20–180 °C), which confirms their significant application potential in the high-temperature field. These results indicate that this work can provide an effective guideline approach to attain high-performance capacitors for application in pulsed power capacitors.

Novel NaNbO3–Sr0.7Bi0·2TiO3 lead-free dielectric ceramics with excellent energy storage properties

NaNbO3 (NN) is considered to be one of the most prospective lead-free antiferroelectric energy storage materials due to the merits of low cost, nontoxicity, and low density. Nevertheless, the electric field-induced ferroelectric phase remains dominant after the removal of the electric field, resulting in large residual polarization, which prevents NN ceramics from obtaining superior energy storage performance. In this work, the relaxor ferroelectric Sr0·7Bi0·2TiO3 (SBT) was chosen to partially replace the NN ceramics, and the introduction of the nanodomain of the relaxor ferroelectric hinders the generation of field-induced ferroelectric phases, allowing the material to combine the large polarization strength of the relaxor ferroelectric with the near-zero residual polarization of the antiferroelectric. Large recoverable energy storage density (4.5 J cm−3) and ultra-high energy storage efficiency (90.3%) were gained in NN-20SBT under an electric field of 288 kV cm−1. Furthermore, superior temperature (25–120 °C) and frequency (1–500 Hz) stabilities were acquired. These performances demonstrate that NN-20SBT ceramics are potential candidates as dielectric materials for high energy storage density pulsed power capacitors.

Energy storage performance in Dy doped Na0.425Bi0.425Ca0.15TiO3 Pb-free ceramics

High capacity for the dielectric capacitors are necessary for practical applications. Additionally, dielectric capacitors should have some degree of temperature and frequency stability to allow them to adapt to environmental changes. To fulfil these requirements, Na0.425Bi0.425Ca0.15TiO3-xDy (x = 0, 2, 5, and 10 at‰) (NBCT-xDy) energy storage ceramics were produced using a traditional solid-state synthesis method. NBCT-5Dy achieved an excellent energy storage density of 2.35 J/cm3 and a good efficiency of 78.32% at 210 kV/cm. In addition, the sample was tested at 150 kV/cm under variable temperature and frequency conditions, showed a stable energy storage density of ~1.3 J/cm3 and maintains excellent efficiency at 30–150 °C and 0.2–200 Hz. Furthermore, the dielectric constant of the sample was measured at 0–40 kV/cm, and exhibited less than 2% change over this range. These results confirmed that the sample had excellent energy storage density and good stability. In the pulse discharge performance test, a high power density (46.31 MW/cm3 at 150 kV/cm) was obtained, indicating that this material has great application prospects in the pulse capacitor field in the future.

Development of a 200-kJ Capacitive Pulsed Power System for Vehicular Electrothermal-Chemical Launcher

This article has designed a 200-kJ pulsed power system (PPS) for electrothermal-chemical (ETC) guns to be installed in combat vehicle. The PPS consists of a pulse-forming network, a primary power, a high-voltage (HV) charger, and a remote control system. Two independent 100-kJ pulsed power units (PPUs) are integrated in a compact frame to build the pulse-forming network. A charging system consisting of a primary power and a 30-kW charger charges two PPUs simultaneously, and it is also integrated into the PPS. In each PPU, a pulse capacitor, a semiconductor switch stack, an inductor, a dump device, and a data acquisition system are integrated. The PPU is designed to achieve a peak output current up to 30 kA at a maximum charging voltage of 10 kV. After all the subsystems are integrated, the equivalent experiments are carried out with resistive load. The experimental results show that the PPS can flexibly adjust the output current waveform to meet the application requirements. The design ideas and results in this article have engineering application value in improving the performance of a PPS-based ETC launch system.

Realizing Stable Relaxor Antiferroelectric and Superior Energy Storage Properties in (Na1-x/2Lax/2)(Nb1-xTix)O3 Lead-Free Ceramics through A/B-Site Complex Substitution.

The development of environmentally friendly energy storage dielectrics with high energy storage density has attracted increasing attention in power electronics. The combination of antiferroelectric ceramics with relaxor characteristics proves to be an efficient way to greatly improve energy storage properties. In this work, a novel (Na1-x/2Lax/2)(Nb1-xTix)O3 lead-free bulk ceramic exhibits excellent energy storage properties of a giant recoverable energy storage density Wrec ≈ 6.5 J/cm3, a relatively high efficiency η ≈ 66%, and an ultrafast discharge speed t0.9 ≈ 50 ns at x = 0.18, showing outstanding potential for pulsed power capacitors. The Rietveld structural refinement and Raman spectra suggest a relaxor antiferroelectric orthorhombic R phase at room temperature as x > 0.16. Obviously enhanced breakdown strength can be ascribed to ultrafine grains of ∼0.21 μm and largely improved resistivity after BaCu(B2O5) doping. The detailed analysis of high-resolution transmission electron microscopy and in situ field Raman spectra clearly discloses the existence and rapid response feature of antipolar nanoregions and the resulting high driving field (∼30 kV/mm) for the antiferroelectric-to-ferroelectric phase transition, laying a solid foundation for the achievement of desirable energy storage characteristics. These results would provide a reliable strategy and a good understanding for designing new energy storage capacitor dielectrics.

Investigation of multielectrode multiloop with series capacitance pulse generator for EDM

A novel multielectrode multiloop with series capacitance (MEMLSC) pulse generator is developed to improve the machining efficiency of electrical discharge machining (EDM). In the multielectrode discharge circuit system, each electrode is connected to an independent discharge circuit and forms a singular discharge loop with a common workpiece. A capacitance is serially inserted between each electrode to enhance the discharge and material removal. All the electrodes are coaxial servo-fed to erode workpiece materials. Compared with conventional EDM, which can generate only a singular discharge for each pulse, the MEMLSC pulse generator can dispersedly generate multiple discharges for each pulse. The machining characteristics are evaluated under varying discharge conditions to reveal the dependence of the workpiece material removal rate (MRR) and relative wear ratio (WR) on the capacitance, electrode number, and pulse width. The results of experiments on the MEMLSC and conventional EDM pulse generators show that compared with the latter, the former not only effectively improves the MRR (by more than 6 times) but also provides good machining surface quality and a moderate tool wear ratio (TWR).

Enhanced energy storage properties of Sr(Sc0.5Nb0.5)O3 modified (Bi0.47La0.03Na0.5)0.94Ba0.06TiO3 lead-free ceramics

Excellent energy storage performance of dielectric capacitors is highly desired in all kinds of energy storage devices. In this study, Sr(Sc0.5Nb0.5)O3 was introduced to enhance the energy storage properties of (Bi0.47La0.03Na0.5)0.94Ba0.06TiO3 (BLNBT) ceramics. All ceramic samples were sintered densely, and the phase structure, microstructure, dielectric and ferroelectric properties were then systematically investigated. Two distinct dielectric anomaly peaks, which are detected from the dielectric properties as a function of temperature, suggest not only a phase transition, but also indicate typical relaxor features. The breakdown strength is significantly improved, and the polarization versus electric field hysteresis loops become slim with the increasing content of SSN. The optimum energy storage performance is achieved in 0.85BLNBT–0.15SSN ceramic with the recoverable energy density of 1.83 J/cm3 and energy efficiency of 82.32% under a moderate electric field of 185 kV/cm. The excellent energy storage performance of 0.85BLNBT–0.15SSN ceramic makes it a promising candidate material for advanced pulsed power capacitors.

High recoverable energy storage density and large energy efficiency simultaneously achieved in BaTiO3–Bi(Zn1/2Zr1/2)O3 relaxor ferroelectrics

Relaxor ferroelectrics have attracted much attention as electric energy storage materials for intermittent energy storage because of their high saturated polarization, near-zero remnant polarizations, and considerable dielectric breakdown strength (BDS). Despite the numerous efforts, the dielectric energy storage performance of relaxor ferroelectric ceramics is incomplete or unsatisfactory. The enhancement of recoverable energy storage density Wrec usually accompanies with the sacrifice of discharge-to-charge energy efficiency η; therefore, it is an important issue to achieve high recoverable Wrec and large efficiency η simultaneously. In this work, the (1-x)BaTiO3-xBi(Zn1/2Zr1/2)O3 (abbreviated as BT-100xBZZ, 0 ≤ x ≤ 0.20) ferroelectric ceramics were prepared using the conventional solid-state reaction method. The phase structure, microstructural morphology, dielectric and ferroelectric properties, relaxation behaviors, and energy storage properties of BT-BZZ ceramics were investigated in detail. X-ray powder diffraction, dielectric spectra, and ferroelectric properties confirm the transformation of tetragonal phase for normal ferroelectrics (BT) to pseudo-cubic phase for relaxor ferroelectrics (BT-8BZZ). A high recoverable energy storage density Wrec of 2.47 J/cm3 and a large energy efficiency η of 94.4% are simultaneously achieved in the composition of BT-12BZZ, which presents typical weakly coupled relaxor ferroelectric characteristics, with an activation energy Ea of 0.21 eV and a freezing temperature Tf of 139.7 K. Such excellent energy storage performance suggests that relaxor ferroelectric BT-12BZZ ceramics are promising dielectric energy storage materials for high-power pulsed capacitors.

Significantly enhanced energy storage density and efficiency of BNT-based perovskite ceramics via A-site defect engineering

In recent years, sodium bismuth titanate (Bi0.5Na0.5TiO3, BNT) -based relaxor ferroelectrics have attracted more and more attention for energy storage applications owing to their high power density, large saturated polarization (PS)/maximum polarization (Pmax) as well as meeting the needs of environment-friendly society. However, the recoverable energy storage density (Wrec) and energy storage efficiency (η) of most BNT-based relaxor ferroelectric ceramics are lower than 3.5 ​J ​cm−3 and/or 80%, respectively, in recently. In this work, the relaxor ferroelectric ceramics of 0.75Bi(0.5+x)Na(0.5-x)TiO3-0.25SrTiO3 (BNST-x) were constructed via A-site defect engineering and prepared by tape-casting method. It is worth noting that an ultrahigh Wrec of 5.63 ​J ​cm−3 together with outstanding η of 94% can be achieved simultaneously at a relative high electric field of 535 ​kV ​cm−1 with the composition of BNST-0.08, Meanwhile, for BNST-0.08 ceramic, the η is higher than 90% and the variation of Wrec is less than ±2% and ±5% within the frequency range of 1–100 ​Hz and temperature range of 30–130 ​°C, respectively. The Wrec is always higher than 3 ​J ​cm−3 and did not deteriorate significantly after 104 fatigue cycles. In addition, the BNST-0.08 ceramic also possesses ultrafast discharge speed (t0.9, less than 125 ​ns) and ultrahigh power density (PD, higher than 147 ​MW ​cm−3) within the temperature range of 30–130 ​°C at 300 ​kV ​cm−1. Therefore, the BNST-0.08 ceramic is promising candidate environment-friendly materials for advanced pulsed power capacitor applications and the energy storage properties of BNT-based relaxor ferroelectrics can be enhanced significantly via A-site defect engineering.

Ultrahigh dielectric breakdown strength and excellent energy storage performance in lead-free barium titanate-based relaxor ferroelectric ceramics via a combined strategy of composition modification, viscous polymer processing, and liquid-phase sintering

BaTiO3 (BT)-based lead-free ceramics are regarded as one kind of prospective candidates for next generation pulsed power capacitors due to their environmentally friendly and relatively high energy storage properties. Nevertheless, BT-based ceramics are still suffering from their small recoverable energy storage density (Wrec < 3 J cm−3) and relatively low electric breakdown strength (BDS < 350 kV cm−1). Herein, we proposed a combined strategy via composition modification, viscous polymer processing, and liquid-phase sintering into BT-based ceramics to improve their BDS and Wrec. Both an ultrahigh BDS (>410 kV cm−1) and a large Wrec (3.54 J cm−3) are achieved in Sr0.7Bi0.2TiO3 and Li2CO3 modified BT ceramic simultaneously. High Wrec (>2.5 J cm−3 at 300 kV cm−1) with small variation is maintained over a wide temperature range (30–150 °C) and frequency range (0.1–100 Hz), demonstrating very excellent temperature and frequency stability. The recorded ultrahigh BDS with high Wrec achieved in this work indicates that our combined strategy is effective to elevate the electric energy storage performances of BT-based dielectric ceramics and could be further generalized to other ceramic materials for the applications of advanced pulsed power capacitors.