Pulsed Capacitors Research Articles

Improved energy storage performance of Ba(Ti,Ca)O3 ceramics through tailoring phase structure and ferroelectric polarization

A novel strategy was adopted to prepare (1 − x)Ba(Ti0.97Ca0.03)O2.97–x(Bi0.51Na0.47)0.94Ba0.06TiO3 (abbreviated as (1 − x)BTC–xBNBT, x = 0.03–0.15) relaxor ferroelectric ceramics by precisely tailoring the phase structure and ferroelectric polarization. Significant enhancements in both polarization and dielectric breakdown strength are successfully achieved by realizing the phase structure dominated by the tetragonal phase in relaxor ferroelectrics. Notably, the 0.9BTC–0.1BNBT ceramic simultaneously shows an outstanding recoverable energy density of 2.17 J cm−3 and a high efficiency of 84.5% at 240 kV cm−1, as well as superior temperature (20 °C–160 °C) and frequency (1–100 Hz) stability. In addition, the charge–discharge test results show that the 0.9BTC–0.1BNBT ceramic has an ultra-fast discharge rate of t 0.9 ∼ 75 ns, an ultra-high power density of 27.7 MW cm−3 and a high discharge energy density of 0.58 J cm−3. This work not only provides a promising energy storage material for pulse capacitors, but also presents an effective method for developing new high-performance BaTiO3-based dielectric materials.

Structural, dielectric and complex impedance analysis of Pb-free BaTiO3-Bi(Mg0.5Ce0.5)O3 ceramics

(1–x)BaTiO3–xBi(Mg0.5Ce0.5)O3 (0.00 ≤ x ≤ 0.10) ceramics were prepared via a solid-state sintering route to investigate their structural, dielectric, impedance and energy storage properties. Phase analysis revealed tetragonal to pseudo-cubic phase transition in compositions with x ≥ 0.06. Doping of BaTiO3 with Bi(Mg0.5Ce0.5)O3 decreased the average grain size from ≥ 10 µm to submicron level which decreased the electrical conductivity and increased the electrical breakdown strength up to 250 kV cm−1. The observed decrease in bulk resistance with an increase in temperature demonstrated a typical negative temperature coefficient of resistance-type behavior for these ceramics. The x = 0.08 composition exhibited a high energy storage density (∼1.84 J cm−3) with a recoverable energy density (∼1.26 J cm−3) and an electrical breakdown strength ∼250 kV cm−1. The obtained results demonstrate that this ceramic can be considered to be a good candidate for application in advanced pulsed power capacitors.

Pulsed thermo-induction-dynamic welding and pressing of dissimilar materials

To obtain permanent joints from diversified parts and powder compositions, it is proposed to use discharge-pulse processes with the accumulation of stored energy in a capacitor bank. Technological difficulties in the manufacture of structures from non-ferrous metal and alloy parts of different thicknesses are listed. The thermal effect is carried out by passing the discharge current from the batteries of pulse capacitors, and the power effect is realized through the use of an inductive-dynamic drive. A scheme for the series connection of a compacted powder with an induction-dynamic drive, consisting of a flat inductor with a pusher, is proposed. The physical essence of the formation of compounds is described. The processes responsible for the formation of permanent connections by a pulsed current discharge have been identified. A picture of the relationship between the main parameters of the pressing process – sintering in time, as well as the results of measuring the temperature of the sintering process of powders by the photoemission method is presented. The results of energy consumption for the consolidation of powder compositions with simultaneous welding to a steel base are given.

SrTiO3‐modified Bi0.5Na0.47Li0.03Ti0.99Sn0.01O3 relaxor ferroelectric ceramics with high energy storage performance

Abstract(1 − x)Bi0.5Na0.47Li0.03Ti0.99Sn0.01O3–xSrTiO3 (BNLST–xST) lead‐free ceramics were synthesized by traditional solid phase sintering. When x = 0.4, the ceramic achieves a high energy storage density Wrec of 3.78 J/cm3 as well as a superior efficiency η of 90.3% under 360 kV/cm. The charge–discharge curves related to temperature and cycle show that the 0.6BNLST–0.4ST sample has good temperature stability (20–180°C) and cycling reliability (variation of WD < 5%). Moreover, a fast discharge rate (t0.9 = 0.219 μs) and a large discharge energy density (WD = 1.89 J/cm3) are achieved at 220 kV/cm. The results show that BNLST–xST energy storage ceramics are promising materials for devices with pulsed power capacitor.

Boosting dielectric temperature stability in BNBST‐based energy storage ceramics by Nb2O5 modification

AbstractExploring environment‐friendly energy storage ceramics simultaneously featuring large recoverable energy storage density (Wrec), high‐energy storage efficiency (ƞ), and excellent temperature stability is highly desirable for the application of pulsed power systems. Herein, Nb2O5 was introduced to modify BNBST‐based lead‐free relaxor ferroelectric ceramics in an effort to enhance the dielectric temperature stability. (Bi0.5Na0.5)0.65(Ba0.3Sr0.7)0.35(Ti0.98Ce0.02)O3 (BNBSTC) + x wt%Nb2O5 (0 ≤ x ≤ 4) ceramics were prepared by a solid‐state reaction method. The phase structure, microstructure, dielectric, and energy storage properties of the ceramics have been systematically studied. It was found that the εr–T curve was flattened, and the dielectric temperature stability was effectively improved due to the addition of Nb2O5. A noticeable Wrec (1.44 J/cm3) with high η (84.1%) was obtained in BNBSTC + 2 wt%Nb2O5 ceramics at a low electric field of 90 kV/cm, which was mainly due to a refined P–E loop induced by Nb2O5. In addition to excellent frequency and anti‐fatigue cycle stability, this ceramic provides a new solution for designing pulsed power capacitors with high energy density and high temperature stability under low voltage driving conditions.

Simultaneously achieving high energy storage performance and low electrostrictive strain in BT‐based ceramics

AbstractDielectric ceramics with high recoverable energy storage density (Wrec) and high energy storage efficiency (η) are urgently needed due to their potential application in pulse capacitor devices. However, the low η and breakdown strength (BDS) have produced a bottleneck for achieving high Wrec at high electric field. Here, we introduce Bi(Mg0.5Ti0.5)O3 (BMT) into Ba(Ti0.92Sn0.08)O3 (BTS) matrix to enhance the relaxor character of BTS–xBMT and reduce the electrostrictive strain generated during electric field loading. The enhanced relaxor character is beneficial for increasing the efficiency, whereas the reduced electrostrictive strain is profitable to increase the BDS. Furthermore, the BDS is significantly improved by the polymer viscous rolling process. Finally, the electrostrictive effect was considerably lowered in an optimized BTS–0.1BMT composition. More crucially, a high Wrec of 4.34 J/cm3 was attained accompanied by excellent temperature stability (variation ≤±5% between 30 and 120°C). The current results show that the developed dielectric ceramics can be used in pulse capacitor devices for energy storage.

Tailoring relaxor P4bm+P21ma phases in BNT-based ceramics for enhancing comprehensive energy storage properties

Tailoring relaxor phase is an effective strategy to enhance energy-storage properties (ESP) for Bi0.5Na0.5TiO3 (BNT)-based ceramics. Herein, we incorporate Na0.91Bi0.09Nb0.94Mg0.06O3 (NBNM) into BNT matrix to form a solid solution of BNT-xNBNM with x = 0.1–0.4. Rietveld refinements reveal that the composition with x = 0.3 has 46% relaxor tetragonal P4bm phase and 54% relaxor orthorhombic P21ma one, thus exhibiting a large normalized energy-storage density (Wrec/E = 0.015 J kV−1 cm−2) and a high efficiency (η = 87%) at 370 kV cm−1. The optimized composition also presents superior temperature stability with a variation of <±5% in the range of 20 °C–150 °C, outstanding frequency reliability with a variation of <±4% in the range of 5 Hz–500 Hz and excellent charge-discharge properties (discharge rate of 76 ns, current density of 1032 A cm−2 and power density of 129 MW cm−3 at 250 kV cm−1). The results demonstrate a successful strategy to design high performance Pb-free relaxor ferroelectrics for pulsed power capacitor applications.

A Brief Review of Sodium Bismuth Titanate-Based Lead-Free Materials for Energy Storage: Solid Solution Modification, Metal/metallic Oxide Doping, Defect Engineering and Process Optimizing

With the ever-increasing demand for energy, research on energy storage materials is imperative. Thereinto, dielectric materials are regarded as one of the potential candidates for application in advanced pulsed capacitors by reason of their ultrahigh energy-storage density, low energy loss, and good thermal stability. Among the numerous dielectric materials for energy storage, sodium bismuth titanate (Bi0.5Na0.5TiO3, BNT) with high saturation polarization, as one of the successful alternatives to lead-based materials, has been extensively studied. However, degraded dielectric and ferroelectric properties as a consequence of chemical alterations usually produced by inhomogeneity in microstructure and composition due to the ion volatilization during preparing, thus affecting performance of devices. Hence, this review served to encompass the current state and progress on the optimization of energy storage performance in lead-free BNT-based materials over the past few years, including ceramics, multilayer ceramics, thin films, and thick films, involved in solid solution modification, metal/metallic oxide doping, process optimization and other related aspects to optimize energy storage performance. Furthermore, some prospective approach in the improvement of energy storage performance for BNT-based materials were also provided in this work according to the existing theoretical and experimental results, to impel their practical application.

Superior Energy Storage Properties and Optical Transparency in K0.5 Na0.5 NbO3 -Based Dielectric Ceramics via Multiple Synergistic Strategies.

Eco-friendly transparent dielectric ceramics with superior energy storage properties are highly desirable in various transparent energy-storage electronic devices, ranging from advanced transparent pulse capacitors to electro-optical multifunctional devices. However, the collaborative improvement of energy storage properties and optical transparency in KNN-based ceramics still remains challenging. To address this issue, multiple synergistic strategies are proposed, such as refining the grain size, introducing polar nanoregions, and inducing a high-symmetry phase structure. Accordingly, outstanding energy storage density (Wtotal ≈7.5 J cm-3 , Wrec ≈5.3 J cm-3 ) and optical transmittance (≈76% at 1600nm, ≈62% at 780nm) are simultaneously realized in the 0.94(K0.5 Na0.5 )NbO3 -0.06Sr0.7 La0.2 ZrO3 ceramic, together with satisfactory charge-discharge performances (discharge energy density: ≈2.7 J cm-3 , power density: ≈243 MW cm-3 , discharge rate: ≈76ns), surpassing previously reported KNN-based transparent ceramics. Piezoresponse force microscopy and transmission electron microscopy revealed that this excellent performance can be attributed to the nanoscale domain and submicron-scale grain size. The significant improvement in the optical transparency and energy storage properties of the materials resulted in the widening of the application prospects of the materials.

Achieving ultrahigh energy storage properties with superior stability in novel (Ba(1-x)Bix)(Ti(1-x)Zn0.5xSn0.5x)O3 relaxor ferroelectric ceramics via chemical modification

Relaxor ferroelectrics are receiving widespread attention due to their excellent energy storage properties (ESPs). In this study, (Ba(1-x)Bix)(Ti(1-x)Zn0.5xSn0.5x)O3 (abbreviated as BBTZS-x, x = 0.08, 0.10, 0.12, 0.14, 0.16, 0.18) ceramics were synthesized via a solid-state reaction route, and the effects of chemical modification on their structure and properties were investigated in detail. The introduction of Bi/Zn/Sn (BZS) elements into BaTiO3 (BT) systems induced the change from normal to relaxor ferroelectric behavior, which caused the enhancement of comprehensive ESPs. Significantly, BBTZS-0.12 ceramics acquired the preeminent total energy density (Wtot = 5.8 J/cm3), recoverable energy density (Wrec = 4.99 J/cm3) and efficiency (η = 86.1%) at high field strength of 550 kV/cm because of the existence of polar nanoregions (PNRs) therein. The dynamic response of PNRs to the external field was found to be propitious to the enhancement of energy-storage performance. In particular, excellent current density (CD = 721.5 A/cm2), power density (PD = 151.5 MW/cm3) and the time of release of up to 90% of the discharge energy density value (t0.9 = 53 ns) were simultaneously achieved in BBTZS-0.12 ceramics at 420 kV/cm. Moreover, BBTZS-0.12 ceramics were found to be the most optimal for the long-term applications under different environmental conditions because of their outstanding temperature (30–150 °C), frequency (1–500 Hz), and fatigue cycle (cycle numbers: 1–100000) stabilities. Therefore, exceptional ESPs make BBTZS-x ceramics promising for advanced pulsed power capacitors and energy storage applications.

Research on Magnetic Energy Recovery of Pulsed Alternator in Separate Excitation Mode

Pulsed alternator is widely concerned in the field of pulse power supply, and the heat generation of the field coil is an important reason for the temperature rise of the rotor, which is unfavorable to the thermal management of the pulsed alternator. Therefore, a parallel excitation and serial recovery magnetic energy recovery topology for the separate excitation pulsed alternator is proposed in this article. In contrast with the conventional (no recovery) topology, there are two changes in this topology. One is that the diode is replaced by a thyristor in freewheeling circuit, which can realize the switching of the field current from the freewheeling state to the recovery state. The other is that serial recovery topology is used, which can realize the rapid recovery of magnetic energy. First, the analytical expressions of the field current and the pulse capacitor voltage are derived under the three states of parallel excitation, freewheeling, and serial recovery. Second, four performance parameters for evaluating topology are derived based on the obtained analytical expressions. Third, the influence of the number of serial modules <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n$</tex-math> </inline-formula> on the four performance parameters is analyzed. Finally, the maximum value of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n$</tex-math> </inline-formula> is solved, and the simulation models under different <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n$</tex-math> </inline-formula> values are built. The simulation results verify the correctness of the analytical model and the benefits and losses of the magnetic energy recovery topology are discussed.

Achieving high energy storage performance by LaMg0.5Ti0.5O3 modification of multiphase engineered Bi0.5Na0.5TiO3–based ceramics

High performance lead–free ceramic capacitors are a key factor in the practical application of new pulsed power systems, which require higher energy storage density, energy efficiency, and the ability to operate stably in extreme environments. Therefore, this paper proposes a strategy for multiphase engineering of induced polar nanoregions (PNRs) and the design of (1-x)(0.94Bi0.5Na0.5TiO3–0.06BaTiO3)–xLaMg0.5Ti0.5O3 lead–free ceramics. The content of the tetragonal (T) and rhombohedral (R) phases is controlled by adjusting the content of LaMg0.5Ti0.5O3 to enhance the energy storage properties of the ceramics. The introduction of the broadband oxide MgO and the rare earth ion La3+ optimizes the grain size of the ceramics to achieve higher breakdown strengths, which can be confirmed in the first principles calculations. The higher breakdown strength leads to a larger saturation polarization further resulting in a higher recoverable energy density. The introduction of these dopants causes structural disorder, resulting in enhancement of the relaxation properties and a thin P–E loop, thus achieving an extremely high recoverable energy density (3.72 J/cm3) and energy efficiency (82.3%). At the same time, the ceramic has a high temperature stability (η varies less than 3.9%) and frequency stability (η varies less than 3.7%). All of the above work shows that the design has great potential for application in the field of pulsed capacitors.

Ultra-fast charge-discharge and high-energy storage performance realized in K0.5Na0.5NbO3-Bi(Mn0.5Ni0.5)O3 ceramics

Lead-free relaxor ceramics (1 − [Formula: see text])K[Formula: see text]Na[Formula: see text]NbO3 − [Formula: see text]Bi(Mn[Formula: see text]Ni[Formula: see text])O3 ((1 − [Formula: see text] )KNN- [Formula: see text]BMN) with considerable charge–discharge characteristics and energy storage properties were prepared by a solid state method. Remarkable, a BMN doping level of 0.04, 0.96KNN–0.04BMN ceramic obtained good energy storage performance with acceptable energy storage density [Formula: see text][Formula: see text] of 1.826 J/cm3 and energy storage efficiency [Formula: see text] of 77.4%, as well as good frequency stability (1–500 Hz) and fatigue resistance (1–5000 cycles). Meanwhile, a satisfactory charge–discharge performance with power density [Formula: see text][Formula: see text] [Formula: see text] 98.90 MW/cm3, discharge time [Formula: see text][Formula: see text] &lt; 70 ns and temperature stability (30–180∘C) was obtained in 0.96KNN–0.04BMN ceramic. The small grain size ([Formula: see text]150 nm) and the high polarizability of Bi[Formula: see text] are directly related to its good energy storage capacity. This work proposes a feasible approach for lead-free KNN-based ceramics to achieve high-energy storage and ultra-fast charge–discharge performance as well as candidate materials for the application of advanced high-temperature pulse capacitors.

Superior Energy Storage Capability and Stability in Lead-Free Relaxors for Dielectric Capacitors Utilizing Nanoscale Polarization Heterogeneous Regions.

The development of high-performance lead-free dielectric ceramic capacitors is essential in the field of advanced electronics and electrical power systems. A huge challenge, however, is how to simultaneously realize large recoverable energy density (Wrec ), ultrahigh efficiency (η), and satisfactory temperature stability to effectuate next-generation high/pulsed power capacitors applications. Here, a strategy of utilizing nanoscale polarization heterogeneous regions is demonstrated for high-performance dielectric capacitors, showing comprehensive properties of large Wrec (≈6.39 J cm-3 ) and ultrahigh η (≈94.4%) at 700 kV cm-1 accompanied by excellent thermal endurance (20-160 °C), frequency stability (5-200 Hz), cycling reliability (1-105 cycles) at 500 kV cm-1 , and superior charging-discharging performance (discharge rate t0.9 ≈ 28.4 ns, power density PD ≈161.3 MW cm-3 ). The observations reveal that constructing the polarization heterogeneous regions in a linear dielectric to form novel relaxor ferroelectrics produces favorable microstructural characters, including extremely small polar nanoregions with high dynamics and multiphase coexistence and stable local structure symmetry, which enables large breakdown strength and ultralow polarization switching hysteresis, hence synergistically contributing to high-efficient capacitive energy storage. This study thus opens up a novel strategy to design lead-free dielectrics with comprehensive high-efficient energy storage performance for advanced pulsed power capacitors applications.

DEVELOPMENT OF METHODS FOR SURFACE HARDENING OF HARD ALLOY VK10KS

The results of studies of the VK10KS hard alloy after various surface treatments (using concentrated energy flows) are presented. The TiN + ZrN ion-plasma coating from separate titanium and zirconium cathodes was applied using the Kvant-6 installation. The zirconium alloy cathode was located in a chamber between two titanium alloy cathodes.Metallographically, after applying an ion-plasma coating of TiN + ZrN composition, a poorly etched layer with a thickness of 15 microns consisting of microlayers was revealed. The two phases (TiN and ZrN) found in the diffractograms in the coating confirm the micro-thickness of its structure, which will help to increase the adhesion of the coating itself with a carbide base. The boundary between the micro-layers of the coating will inhibit the growth of the crack. It was found that the introduction of zirconium TiN compound into the coating leads to an increase in nanohardness by 23% (up to 39 GPa). Electric spark treatment was carried out on the UR – 121 installation. It consists of erosion of the hardening electrode during spark discharge. At the same time, the erosion products are transferred to the part. A hard alloy VK6-OHM was used as the electrode. X-ray phase analysis revealed the presence on the surface of the hard alloy VK10KS of a newly formed phase with high hardness (divolfram carbideW2C), which has a hardness greater than that of tungsten monocarbideWC. Nanoindentation of the VK10KS alloy after electric spark treatment showed an increase in surface hardness up to 22 GPa. A hardened surface layer consisting of titanium diboride TiB2, carbides TiC, W2C with a nanohardness of 28 GPa was obtained by electroexplosive alloying (EVL) with titanium and boron on a hard alloy VK10KS. The essence of EVL is the accumulation of energy by a battery of pulse capacitors up to 10 kJ and its subsequent discharge within 100 microseconds through a conductor that experiences explosive destruction. At the same time, the treated surface is heated and saturated with explosion products, followed by self-quenching due to heat removal into the environment and deep into the material.

Energy storage performance of SrSc0.5Nb0.5O3 modified (Bi,Na)TiO3‐based ceramic under low electric fields

AbstractDielectric ceramics with a high recoverable energy density (Wrec) and high efficiency are desirable for the development of pulsed power capacitors under low electric fields. In this study, through the introduction of SrSc0.5Nb0.5O3 into (Bi0.5Na0.5Ti0.95Al0.025Nb0.025O3) [(1‐x)BNTA‐xSSN], a considerable recoverable energy storage density (Wrec) of approximately 2.7 J/cm3 and energy storage efficiency (η) of approximately 76 % at 210 kV/cm are achieved at x = .1; additionally, η is further improved to 85 % at x = .2. Moreover, η and Wrec of .9BNTA‐.1SSN exhibit outstanding stability (thermal and frequency stability) at 150 kV/cm, which is superior to that of other lead‐free ceramics. The excellent energy storage performance is attributed to the increased relaxation degree and the formation of ferroelectric nanodomains, whereas the enhanced Eb is ascribed to the increased electrical resistivity and decreased grain size upon modification. These results indicate the potential of (1‐x)BNTA‐xSSN as an ideal candidate for energy‐storage applications.

PLUSPULS: A transcranial magnetic stimulator with extended pulse protocols

Transcranial magnetic stimulation (TMS) is increasingly applied in basic neuroscience while its field of usage for diagnosing and treating various neurological diseases broadens steadily. A TMS device generates a current pulse in the reach of several thousand ampére to produce a magnetic pulse which induces an electric field around neurons. This electric field, if high enough to depolarize the neuron membrane, generates an action potential at the neuron which travels down the neurons connected to it. The PLUSPULS TMS generates this magnetic pulse by pre-charging a pulse capacitor C with the voltage VC0 and connecting it with a stimulation coil L. The oscillation of the resonance circuit is cut off after one period and is called a biphasic pulse. PLUSPULS is a high frequency stimulator with inter stimulus intervals (ISI) down to 1ms which enables different pulse protocols as paired pulse or quadri theta burst stimulation. A GUI on PC allows a flexible control of PLUSPULS with varying amplitudes and ISI in one burst. The modular hardware and the control via GUI on PC allows for an easier adjustment on requirements to come. The article provides design considerations, hardware, firmware and software to reconstruct a modular biphasic TMS with enhanced charging network to enable extended pulse protocols.

Improvement of Energy Storage Properties of NaNbO3-Based Ceramics through a Relaxation Strategy

NaNbO3 (NN) is a widely studied antiferroelectric ceramics in recent years. However, NN ceramics always exhibit a square P-E loop with larger P r, originating form an irreversible antiferroelectric-ferroelectric (AFE-FE) phase transition under an applied electric field and limit the further development. In this paper, a novel lead-free relaxor ferroelectric ceramic, (1−x)NaNbO3-x(0.5Bi0.5Na0.5TiO3−0.5Ba0.3Sr0.7TiO3) [(1−x)NN-xBNBST, x = 0, 0.10, 0.15, 0.20, 0.25, 0.30], was designed and prepared via a local random field relaxation strategy. Dielectric testing show that the addition of BNBST significantly improved the relaxor behavior of the NN, which is effective for enhancing the W rec and η of NN-based ceramics. When x = 0.2, the ceramic obtains a high recoverable energy storage density (W rec = 2.024 J cm−3) and energy storage efficiency (η = 63%) at a low electric field of 130 kV cm−1. Meanwhile, the polarization-electric field (P-E) hysteresis loops and charge-discharge results of the sample with x = 0.2 at different temperatures and frequencies show that it is a prospective material for pulsed energy storage capacitors.

Significantly Enhanced Energy Storage Performance in High Hardness BKT-Based Ceramic via Defect Engineering and Relaxor Tuning.

Hybrid electric cars and pulsed power technologies have increased the demand for capacitors with high energy density, wide temperature stability, high operating voltage, and good mechanical qualities. In this work, (1 - x) (0.6Bi0.5K0.5TiO3-0.4BiFeO3)-x(Na0.4Sm0.2NbO3) ((1 - x) (BKTBF)-xNSN) relaxor ceramics were prepared by constructing morphotropic phase boundary (MPB) combined with oxygen vacancy defect engineering. It is worth noting that the 0.6BKT-0.4BFO ceramics at MPB have a high Pmax ∼ 60 μC/cm2. The ultra-hard (HV = 10.7 GPa) BKTBFO-0.16NSN relaxor ferroelectric ceramic achieves a high Wrec of 6.52 J/cm3, a working temperature of 20-120 °C, and a working frequency of 1-1000 Hz. Additionally, the BKTBFO-0.16NSN ceramic demonstrates comprehensive pulse charge-discharge performance (Imax = 17.2 A, CD = 546.7 A/cm2, PD = 54.7 MW/cm3, and t0.9 = 59 ns) and excellent stability (25-125 °C and 104 charge-discharge cycles). This study offers a novel approach for the practical implementation of high-performance pulse capacitors, which will undoubtedly stimulate further research and development of high-Pmax energy storage dielectrics (such as BNT, BKT, and BFO).

High Energy Storage Density in Nd(Zn2/3Nb1/3)O3‐Doped BiFeO3–BaTiO3 Ceramics

AbstractLead‐free ceramics with high recoverable energy density (Wrec) and energy storage efficiency (η) are attractive for advanced pulsed power capacitors to enable greater miniaturization and integration. In this work, a series of perovskite structured (1‐x)(Bi0.6Ba0.4)(Fe0.6Ti0.4)O3−xNd(Zn2/3Nb1/3)O3 (BF‐BT‐NZN) ceramics with high energy storage density through the solid‐state reaction method are successfully prepared, and the breakdown strength (Eb) and energy storage density are further improved by a membrane rolling process. The highest energy densities of the 0.94(BF‐BT)−0.06NZN ceramics are Wrec ≈ 5.6 J cm−3 and η ≈ 82.9%, which are due to the enhanced breakdown field intensity (BDS ≈ 400 kV cm−1) and the maximum polarization (Pmax≈ 38 µC cm−2). These results indicate that (1−x)(Bi0.6Ba0.4) (Fe0.6Ti0.4)O3−xNd(Zn2/3Nb1/3)O3 ceramics are high‐efficiency lead‐free materials for potential application in high‐energy‐storage capacitors.