Recoverable Energy Research Articles

Local defect structure design enhanced energy storage performance in lead-free antiferroelectric ceramics

Antiferroelectrics (AFEs) are ideal candidates in dielectric, electromechanical, and electrothermal applications. NaNbO3 (NN), as a lead-free antiferroelectric (AFE) material under extensive investigation, exhibits ferroelectric (FE)-like polarization–electric field (P-E) hysteresis loops, characterized by high remnant polarization and large hysteresis. Herein, the local defect structure design is proposed to achieve high energy storage (ES) density in NN-based AFE ceramics. The pinning effect of defect dipoles and the enhancement of local structural disorder stabilize the AFE phase and reduce hysteresis losses. Consequently, an excellent ES performance of large recoverable energy density (Wrec) of 9.70 J/cm3 and high efficiency (η) of 88.75 % is concurrently obtained in NN-based relaxor AFE ceramics, with outstanding charge–discharge performance (PD∼413.2 MW/cm3, WD∼4.47 J/cm3), which are significantly improved compared to other reported values in lead-free ES ceramics. This indicates that NN-based ceramics are candidates for advanced ES capacitors and provides a feasible modulation approach for the development of new lead-free high-performance dielectric materials.

High energy storage performance of KNN-based relaxor ferroelectrics in multiphase-coexisted superparaelectric state

Although K0.5Na0.5NbO3 (KNN) possesses large maximum polarization and relatively high breakdown strength, the large remnant polarization constrains their practical applications as energy storage materials. In this work, through multi-element doping, (K0.5−0.5xNa0.5−0.5xBix)(Nb1−xSn0.2xZn0.6xTa0.2x)O3 relaxor ferroelectrics were prepared. As the superparaelectric states (SPE) were adjusted to room temperature, orthorhombic, tetragonal, and cubic phases coexisted, accompanied by the highly dynamic polar nanoregions (PNRs). In particular, a high recoverable energy storage density of 4.5 J/cm3 and an energy storage efficiency of 83% were achieved for the x = 0.125 ceramic, with the variations less than 11% and 4%, respectively, in the wide temperature range of 20–180 °C. These results demonstrate that the multiphase PNRs in the SPE state is an effective strategy for improving the energy storage performance of KNN-based ceramics.

Optimizing energy storage performance of lead zirconate-based antiferroelectric ceramics by a phase modulation strategy

Dielectric energy storage has gained considerable significance owing to the high energy requirements of human society. Lead zirconate-based (PZ) antiferroelectric materials have received much attention due to their fast discharge rate, high power density, and low cost. Nevertheless, their low energy storage density seriously limits their practical applications. To overcome this limitation, the phase modulation strategy via chemical modification was adopted to optimize the breakdown strength and phase switching field. Specifically, the antiferroelectric ceramics of (Pb0.97−xGd0.02Srx)(Zr0.87Sn0.12Ti0.01)O3 were prepared by the tape-casting method. An apparent multistage phase transition behavior revealed for x ≥ 0.05 is rarely discussed in reported Sr2+ modified PZ system. This is attributed to the coexistence of the main orthorhombic phase and the tetragonal phase. Although the transition near the lower field reduces the energy storage slightly, the disruption of the long-range order stabilizes the antiferroelectricity of the orthorhombic phase, hence elevating its transition field. In addition, the tetragonal phase with lower polarization suppresses the electrostrain thus improving the breakdown strength. Consequently, an ultrahigh recoverable energy storage density of 14.5 J/cm3 with a high energy efficiency of 81 % is achieved at a high electric field of 717 kV/cm for (Pb0.92Gd0.02Sr0.05)(Zr0.87Sn0.12Ti0.01)O3. Moreover, the fatigue resistance of this composition is excellent within 26,000 fatigue cycles. Besides, it exhibits a high discharge energy density of 9.4 J/cm3 and a great power density of 387 MW/cm3. These results confirm that the energy storage properties of PZ-based antiferroelectric materials can be effectively optimized via a phase modulation strategy.

Introduction of Bi(Zn2/3Sb1/3)O3 to BaTiO3-based ceramics for high energy storage performance

In this study, (1-x)BaTiO3-xBi(Zn2/3Sb1/3)O3 ((1-x)BT-xBZS) ceramics were designed and tested. With the introduction of BZS, it was found that the grain size of the ceramics was increased, which increased the breakdown field strength (Eb) of the ceramics and further improved the energy storage density. The 0.84BT-0.16BZS ceramic achieved both high recoverable energy density (Wrec = 2.32 J/cm3) and energy efficiency (η = 89.7 %) at 620 kV/cm. In addition, excellent temperature stability (20-160 °C) and frequency stability (1–200 Hz) of recoverable energy density have been obtained under 300 kV/cm. A high power density of 28.93 MW/cm3 and transient discharge time (t0.9 = 1.07 μs) were achieved for 0.84BT-0.16BZS ceramic under 200 kV/cm.

Energy storage properties, transmittance and hardness of Er doped K0.5Na0.5NbO3-based ceramics

Transparent energy storage ceramics can balance energy storage characteristic and optical characteristic, and are expected to be used in areas such as transparent pulse capacitors. However, excellent energy storage performance and dramatic light transmittance are difficult to achieve simultaneously, limiting their subsequent development in the actual applications. The paper proposes a way to improve the transparent energy storage properties of KNN-based samples by regulating domain and grain size. By introducing an appropriate amount of Er2O3, fine cube grains and nanodomains are constructed. When doping 0.20 mol% Er2O3, the ceramics exhibited excellent recoverable energy storage density Wrec ∼ 6.2 J/cm3, superior energy-storage efficiency η ∼ 71.3 %, large dielectric breakdown strength Eb ∼ 670 kV/cm, ultrahigh hardness value of 6.9 GPa, and a maximum transmittance T ∼72 % at 880 nm. Dense microstructure, nanoscale grains, symmetrical lattice structure and relaxor behavior are the main reasons for obtaining high energy storage and transparency properties.

High Energy Storage Performance in Pb1−xLax(Hf0.45Sn0.55)0.995O3 Antiferroelectric Ceramics

Energy storage efficiency (η) and large recoverable energy density (Wre) are necessary for antiferroelectric materials in order to develop antiferroelectric-based dielectric capacitors with exceptional energy storage capacity. In the present paper, the effect of doping La3+ on the energy storage capacity of Pb1−xLax(Hf0.45Sn0.55)0.995O3 antiferroelectric ceramics was studied. Adjusting the content of La and changing the phase structure of PLHS from antiferroelectric to relaxor ferroelectric gradually, which narrowed its hysteresis loop, yielded a high energy storage efficiency of 81.9% and the maximum breakdown field strength of 200 kV/cm when x = 2 mol%. In addition, the recoverable energy density and energy storage efficiency both showed excellent temperature stability and frequency stability in the temperature range of 10–110 °C and the frequency range of 10–100 Hz, suggesting that Pb0.98La0.02(Hf0.45Sn0.55)0.995O3 are favorable materials candidates for the preparation of pulsed-power capacitors that can be used in a wide range of conditions.

Realizing enhanced energy storage performance of Na0.47Bi0.47Ba0.06TiO3-based relaxors with weak coupling behavior by manipulating phase fraction

Lead-free dielectric capacitors have attracted considerable attention as the core energy storage element of pulsed power systems due to their advantages of fast charging capability, high power density and environmental friendliness. However, the low recoverable energy storage density (Wrec) and narrow operating temperature range have become the bottleneck technical problems limiting its practical application. In this work, a class of weakly coupled relaxor ferroelectrics with excellent Wrec (9.06 J/cm3) and energy storage efficiency (η ∼ 85.3 %) were designed and prepared by manipulating phase fraction. Moreover, the materials exhibit excellent temperature stability with regard to energy storage, with a change in Wrec and η of less than 8 % over a wide temperature range (25 °C − 200 °C). The introduction of Sm(Mg0.5Hf0.5)O3 (SMH) enhances the insulating properties while refining the grains, effectively increasing the breakdown field strength (Eb) of the material. The emergence of weakly coupled nano-microdomains has the effect of suppressing the nonlinear polarization response of the material, which in turn results in a high polarization difference (ΔP). The preceding work presents a universal strategy for the future design and preparation of BNT-based lead-free dielectric capacitors with high energy storage properties (ESP) and good temperature stability.

Enhanced energy storage properties in (Bi0.5Na0.5)0.5Sr0.5TiO3- modified lead-free NaNbO3 antiferroelectric ceramics

The lead-free antiferroelectric material NaNbO3 (NN) is highly regarded for its exceptional breakdown electric field strength (Eb) and substantial recoverable energy storage density (Wrec). However, the significant energy loss of NN reduces its Wrec and η under a strong electric field, constraining its application in energy storage domains. This study explores a novel approach by integrating the relaxation ferroelectric (Bi1/2Na1/2)1/2Sr1/2TiO3 (BNST) into NN to create NN-BNST relaxation anti-ferroelectrics, aiming to enhance their energy storage capabilities. The incorporation of BNST not only effectively reduces the grain size of NN but also disrupts its long-range ordered structure, forming polar nanoregions (PNRs) that mitigate energy density loss. Both Wrec and η of NN ceramic are significantly improved with increasing the concentration of BNST. Optimal results are achieved with the 0.75NN-0.25BNST ceramics, which demonstrate a high energy storage density (Wrec = 3.83 J/cm3) and conversion efficiency (η = 76 %) while achieving an Eb of 236 kV/cm. The analysis of Eb enhancement in NN-BNST ceramics is conducted through considerations of grain size, band-gap width, and activation energy, offering a robust framework for developing new NN-based antiferroelectrics for energy storage applications.

High‐Entropy Design Toward Ultrahigh Energy Storage Density Under Moderate Electric Field in Bulk Lead‐Free Ceramics

AbstractElectrostatic capacitors with ultrahigh energy‐storage density are crucial for the miniaturization of pulsed power devices. A long‐standing challenge is developing dielectric materials that achieve ultrahigh recoverable energy density Wrec ≥ 10 J cm−3 under moderate electric fields (30 ≤ E ≤ 50 kV mm−1). Herein, a specific high‐entropy strategy is proposed to modulate the phase structure and interfacial polarization of medium‐entropy base materials using linear dielectrics. This strategy ensures a sufficient polar phase and a high enough electric field for complete polarization, thereby achieving ultrahigh Wrec by enhancing polarization strength. The validity of this strategy is demonstrated in the (Na0.282Bi0.282Ba0.036Sr0.28Nd0.08)TiO3‐xCa0.7Bi0.2TiO3 (NBBSNT‐xCBT) (x = 0–0.15) system. The CBT‐modulated samples exhibit a polyphase structure of R3c, P4bm, and Pm‐3m with reduced remnant polarization (Pr). Additionally, the addition of CBT effectively suppresses interfacial polarization, enhancing the maximum polarization (Pmax). These factors significantly improve the value of ∆P = Pmax − Pr. As a result, an ultrahigh Wrec of 10.5 J cm−3 with a high‐efficiency η of 80.3% is obtained in the x = 0.1 sample under a moderate electric field of 45 kV mm−1 for the first time. This work paves the way for achieving superior energy‐storage performance under moderate electric fields.

Significantly improved energy storage performance of Na0.5Bi0.5TiO3–BaTiO3 ferroelectric ceramics with a wide temperature range via high-entropy doping

The emergence of high-entropy perovskite materials provides a new research idea to solve the problem of high remnant polarization and low recoverable energy storage density (Wrec) of relaxor ferroelectrics. In this study, barium-based high-entropy perovskite oxides Ba(Zr0.2Sn0.2Hf0.2Nb0.2Ti0.2)O3 (BZSHNT) were introduced into the 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (BNT-6BT) ceramic by the conventional solid state sintering method. The 0.2BZSHNT doped BNT-6BT ceramic demonstrates significantly improved Wrec of 3.57 J/cm3 and a high efficiency of 81.6 % compared to those of the BNT-6BT ceramic, which is only 0.5 J/cm3 and 60 % respectively. The doped BZSHNT refines the hysteresis loops and drastically reduces the remnant polarization, which lead to the increase of the polarization difference. The 0.8(BNT-6BT)-0.2BZSHNT ceramics show high discharge energy density, good temperature stability (25–200 °C), excellent frequency stability (10–300 Hz) and superior discharge rate (t0.9 = 83 ns) because of its increased TiO6 lattice distortion, atomic disorder, relaxation degree and band gap, as well as the disruption of the long-range ordered ferroelectric domains. Our findings make BNT-6BT doped BZSHNT based ceramics one of the most promising lead-free dielectric energy storage candidates.

Diffusosphere engineering in BNT-based multilayer heterogeneous film capacitors for high performance

Combining layers with high breakdown resistance and high polarization is a promising approach for designing dielectric capacitors with high energy density and efficiency. However, such combinations often accompany strong interfacial polarization, magnification of local electric fields, leading to premature breakdown. This work addresses this issue via controlled formation of diffusospheres. We constructed multilayer heterogeneous films using two Bi0.5Na0.5TiO3 (BNT)-based substances with high breakdown resistance and high polarization properties. Experimental results and finite element simulations demonstrate that the energy storage capacity of these films effectively harnesses the advantages of both phases. Notably, the interface polarization is minimal. Instead, a solid solution-like diffusosphere, formed by the mutual diffusion of ions between the two phases, plays a crucial role. The diffusosphere acts as a transition zone, mitigating charge aggregation at the interfaces and optimizing the relaxor and breakdown characteristics of the capacitor. With six diffusospheres, the multilayer heterogeneous capacitor achieves a recoverable energy storage density of 94 J/cm3, a significant advancement in BNT-based energy storage films. This work proposes and validates the concept of diffusospheres and their role in reducing interfacial polarization in multilayer heterogeneous films, enhancing the understanding of heterogeneous composite structures and advancing the field of dielectric energy storage.

Outstanding comprehensive energy storage performances in multiscale synergistic regulation-engineered (Bi0.5Na0.5)TiO3-based multilayer ceramics

Environmentally friendly dielectric ceramics with superior energy storage performances (ESP) are strongly demanded in pulsed power capacitor applications. Unfortunately, it is challenging to achieve simultaneously large recoverable energy density (Wrec), high Wrec/E (E as electric field) and broad operating temperature range in those ceramics. Herein we propose a multiscale synergistic regulation strategy to enhance comprehensive ESP of (Bi0.5Na0.5)TiO3 (BNT)-based ceramics. We introduce Ca(Zr0.8Ti0.2)O3 (CZT) into the BNT to increase atomic chaos and lattice distortion, which enhances relaxor behavior and lowers domain-switching barriers, thus effectively reducing remanent polarization. Besides, both suppressed oxygen vacancy and refined submicron grains improve extrinsic resistivity, which works synergistically with the enlarged intrinsic bandgap and multilayer structure design, producing substantially enhanced breakdown strength. Encouragingly, a very large Wrec of 13.4 J/cm3, an ultrahigh Wrec/E of 160 J/(kV∙m2), and a high efficiency η of 90.2 % are simultaneously achieved in the novel (Bi0.5Na0.5)TiO3-Ca(Zr0.8Ti0.2)O3 (BNT-CZT) multilayer ceramics, together with outstanding energy storage stability over a broad working temperature range (20–180 °C). The comprehensive ESP of our multilayer ceramics are superior to most of previously reported lead-free ones. This work provides a feasible pathway for substantially improving comprehensive ESP of lead-free ceramics, and also highlights advanced energy storage potential of the BNT-CZT for high-performance pulsed power applications.

Ultra-high energy storage density in PBSLZS antiferroelectric thick film ceramics

Superior recoverable energy density (Wrec) and efficiency (η) are crucial parameters for capacitors used in pulse-power devices. Here, we achieved an ultrahigh Wrec and high η in (Pb0.95-xBa0.02SrxLa0.02)(Zr0.65Sn0.35)O3 (PBSLZS) antiferroelectric thick film ceramics. All ceramics exhibit an orthorhombic structure, and the forward switching field increases with the increase of Sr2+ ionic content. The PBSLZS (x = 0.03) ceramics exhibit maximum value of total energy density (Wtot) and Wrec of 14.9 J/cm3 and 12.9 J/cm3, respectively, along with a high η of 86.6% at 570 kV/cm. Furthermore, we investigated the impact of multi-field coupling, i.e., the electric field and temperature, on the energy storage performance. An electric field (E) versus temperature (T) phase diagram was also obtained. The outstanding energy storage performance observed in PBSLZS ceramics demonstrates the potential for energy storage capacitors.

Excellent energy storage performance in BSFCZ/AGO/BNTN double-heterojunction capacitors via the synergistic effect of interface and dead-layer engineering

Dielectric films with ultra-high energy storage density and efficiency are urgently needed due to the energy crisis. Here, we construct novel ferroelectric/dead-layer/superparaelectric (FE/DL/SPE) double-heterojunction capacitors, utilizing interface and dead-layer engineering to achieve outstanding energy storage performance. Bi0.9Sm0.1Fe0.9Co0.05Zn0.05O3 (BSFCZ) with large polarization, Ba0.985Na0.015Ti0.95Ni0.05O3 (BNTN) with low hysteresis and high breakdown strength (Eb), and artificial Al0.9Ga0.1O3 (AGO) with wide band-gap were chosen as the FE, SPE, and DL phases, respectively. Interface engineering enables the BSFCZ/AGO/BNTN films to maintain a high polarization of 55 μC cm−2, while the linear dielectric AGO and SPE BNTN substantially suppresses the remnant polarization. This can be clarified by the evolution of domains in the BSFCZ layer: nanodomains are scaled down to polar clusters, reducing polarization hysteresis while maintaining relatively high polarization. Simultaneously, two opposing intrinsic electric fields are formed to offset a portion of the external electric field, and the low dielectric constant AGO layer bears a significant part of the applied electric field due to electromagnetic boundary conditions. Consequently, the Eb is significantly increased from 4.4 MV cm−1 of BSFCZ/BNTN to 5.5 MV cm−1 of BSFCZ/AGO/BNTN, resulting in a giant recoverable energy density of 132 J cm−3 and a high efficiency of 84 % in BSFCZ/AGO/BNTN films. Moreover, the BSFCZ/AGO/BNTN films excel in temperature stability (RT∼200 °C), fatigue resistance (up to 107 cycles), and frequency stability (200 Hz to 20 kHz), alongside an exceptionally rapid discharge rate of 2.6 μs. This innovative approach suggests new possibilities for producing environmentally friendly, large-area, high-performance dielectric capacitors.

Enhancing sustainability in irrigation networks: A multicriteria method for optimizing flow distribution and reducing environmental impact

Irrigation systems significantly enhance agricultural productivity but are also substantial consumers of water, energy, and natural resources. The need to optimize their design encouraged agronomic engineering to develop various methods for improving the design and management of these irrigation networks. This development focuses on creating a tool to define the optimal flow distribution according to the system's irrigation or consumption needs, thereby determining the design flows. The aim is to optimize the design of pipe diameters to improve sustainability (i.e., reducing CO2 emissions, minimizing service pressure, and maximizing recoverable energy within the system). These principles ensure a better evaluation of sustainable development goals within agricultural production. The proposed procedure develops a strategy to define the best-fitting distribution using a multicriteria solution. As novel, the research develops a tool, which characterizes flow distributions deviating from the classic Clement's formulation used in irrigation systems. The proposed method was applied in a Mediterranean irrigation system in Spain, achieving a correlation coefficient above 0.9 in the model. This methodology addresses design criteria in terms of sustainability and reduces energy consumption in networks. It achieved material savings of 6.01 % compared to the observed network, reducing CO2 emissions between 5.61 and 5.72 TnCO2/ha over its lifecycle.

Optimization of energy storage and electrocaloric performance in Pb(Zr,Ti)O3 via A-Site La and Bi Co-doping

Lead-based ferroelectrics are one of the most fascinating candidates in the field of state-of-the-art electronic technology. Their intriguing properties are further enriched via the realization of morphotropic phase boundaries. Moreover, the A-site chemical substitution provides insight into the emergence of various exotic phases. Here, we employ co-doping of La3+ and Bi3+ at the A-site of Pb(Zr,Ti)O3 (PZT) ferroelectric to broaden the practical perspective of relaxor systems. Here, we emphasize that the A-site co-doping approach introduces technologically appealing amendments in the well-established temperature composition phase diagram of the PZT system. La3+ and Bi3+ doping favors the evolution of a novel response to thermal and field fluctuations. The maximum values of −ΔS are found to be ∼0.157, 0.118 and 0.176 J (kg·K)−1 for x=0.01, 0.02 and 0.03 , respectively. We employ the electrocaloric characteristics and Arrott plot as probing tools. The observation of a negative electrocaloric effect and the systematic reversal of Arrott lines, followed by a poling effect on the dielectric constant, reveals the emergence of ergodic phase as a novel phase. This further reveals that the Bi doping approach leads to the emergence of exotic characteristics in the chemically modified PZT system. The maximum observed recoverable energy for the composition for x = 0.01 is 0.0479 J cm−3 at a temperature of 388 K.

Improvement of energy storage properties of NN-based ceramics by high-entropy strategy and A-site cation vacancies

High-entropy dielectric capacitors have recently drawn increasing attention in the field of energy storage. In this study, NiO has been incorporated into [(Na0.7Bi0.1)0.8Sm0.02Ca0.02Sr0.02Ba0.02]Nb0.8Sb0.1Ta0.1O3-based ceramics. We applied the concept of high-entropy design to introduce cation vacancies at the A-site, enhancing conformational entropy. This approach led to the successful preparation of a novel type of energy-storage ceramics with an ABO3 perovskite structure, denoted as (1-x)NBSCSBNST-xNiO (x = 0, 0.02, 0.04, & 0.06). We conducted a systematic study of the microstructural, dielectric, and ferroelectric characteristics, along with an exploration of the influence of the high-entropy strategy on their performance. The ΔSconfig increases with NiO doping, and the Eb of the NBSCSBNST-0.02Ni sample exhibits a significant increase to 730 kV/cm from 550 kV/cm of NBSCSBNSTN. This enhancement is accompanied by a recoverable energy density (Wrec) of 4.43 J/cm3 and an efficiency (η) of 75.9 %. As the content of NiO increases from x = 0 to x = 0.06, the phase transition diffusion behavior strengthens. Additionally, the permittivity (εr) spectrum becomes more uniform, and the activation energy of the prepared ceramic samples increases from 1.03 eV to 1.76 eV. This effect suppresses the emergence of localized electric branching, eventually improving the breakdown strength of NBSCSBNST-xNi ceramic materials. The obtained results indicate that the concept of high-entropy design to introduce cation vacancies at the A-site is an efficient approach to improve the energy storage characteristics of lead-free dielectric capacitors.

Optimizing high-temperature energy storage in tungsten bronze-structured ceramics via high-entropy strategy and bandgap engineering

As a vital material utilized in energy storage capacitors, dielectric ceramics have widespread applications in high-power pulse devices. However, the development of dielectric ceramics with both high energy density and efficiency at high temperatures poses a significant challenge. In this study, we employ high-entropy strategy and band gap engineering to enhance the energy storage performance in tetragonal tungsten bronze-structured dielectric ceramics. The high-entropy strategy fosters cation disorder and disrupts long-range ordering, consequently regulating relaxation behavior. Simultaneously, the reduction in grain size, elevation of conductivity activation energy, and increase in band gap collectively bolster the breakdown electric strength. This cascade effect results in outstanding energy storage performance, ultimately achieving a recoverable energy density of 8.9 J cm−3 and an efficiency of 93% in Ba0.4Sr0.3Ca0.3Nb1.7Ta0.3O6 ceramics, which also exhibit superior temperature stability across a broad temperature range up to 180 °C and excellent cycling reliability up to 105. This research presents an effective method for designing tetragonal tungsten bronze dielectric ceramics with ultra-high comprehensive energy storage performance.

Superior energy storage performance achieved in tungsten bronze SBCN-based ceramics through tape-casting

Simultaneously integrating outstanding energy storage density and good energy storage efficiency in advanced ferroelectrics is crucial to implementing the application of dielectrics in high-power pulse devices. In this work, (Sr0.5Ba0.5)2Ca0.5Nb5-xSbxO15 ceramics were designed and prepared by adopting the B sites substitution engineering together with combining strategies of tape-casting method and two-step sintering process. Benefiting from the refined grain size and high density, the breakdown field of (Sr0.5Ba0.5)2Ca0.5Nb4.8Sb0.2O15 (SBCNS0.2) was promoted to 400 kV/cm. By the substitution of Sb5+ in the B sites, the weaker interaction force of Sb-O bond in BO6 octahedral polar unit induced the occurrence of polar nanoregions (PNRs) at room temperature to strengthen the dielectric relaxation behavior. Then it is noteworthy that SBCNS0.2 ceramics simultaneously obtained excellent recoverable energy density (Wrec, 3.9 J/cm3), energy storage efficiency (η, 90.5 %), power density (PD, 156.0 MW/cm3), and current density (CD, 1356.7 A/cm2). In addition, the SBCNS0.2 ceramics exhibited an ultrafast discharge time (t0.9, 67 ns). These results reveal prospective potential of unfilled tungsten bronze SBCNS0.2 ceramics in power capacitor applications and provide an effective strategy for improving excellent energy storage properties from the perspective of preparation methods.

Superior dielectric energy storage performance of ultrafine-grained BNT-SBT solid-solution ceramics by solution combustion synthesis

The micrometer scale grain size and large remnant polarization of Bi0.5Na0.5TiO3 (BNT) ferroelectric ceramics severely constrain the breakdown strength and energy efficiency, respectively, restricting their energy storage application despite their large polarization. Hereby, superior energy storage performance is reported by a synergistic strategy of introducing Sr0.7Bi0.2TiO3 (SBT) relaxor ferroelectrics and a solution combustion synthesis (SCS) method. The BNT-SBT solid-solution ceramics are comparatively investigated by the two methods, conventional sintering (CS) and SCS. An ultrafine average grain size of ∼0.39 μm was obtained in the SCS-derived ceramic, and thus exhibits an ultra-high critical electric field of 548 kV/cm, and a high recoverable energy density of ∼5.69 J/cm3. Those key energy storage parameters are superior to those of the previous reported samples prepared by the CS method. Meanwhile, a high energy efficiency ∼90 %, a large power density of ∼130.44 MW/cm3 (at 320 kV/cm), and an ultrafast discharge time of ∼61.7 ns are also achieved. This study indicates that grain engineering combing with chemical design is an effective way to enhance the dielectric energy storage performance.