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Recent advances in lead-free dielectric materials for energy storage
Abstract
To better promote the development of lead-free dielectric capacitors with high energy-storage density and efficiency, we comprehensively review the latest research progress on the application to energy storage of several representative lead-free dielectric materials, including ceramics (ferroelectrics–relaxor ferroelectrics–antiferroelectrics), glass-ceramics, thin and thick films, and polymer-based composites. The results indicate that lead-free dielectric materials with large maximum polarization, high breakdown electric field, small remnant polarization, and slim polarization-electric field loops are more appropriate for developing dielectric capacitors with high energy density and efficiency. However, some significant drawbacks in current lead-free dielectric materials hinder the energy storage performance of these materials. Based on this, we review herein some new strategies to improve the energy-storage capacity of dielectric materials.
... Electrostatic capacitors that are based on dielectric or antiferroelectric materials are promising energy storage components in various electronic applications because of their higher power density, faster charging and discharging rates, and better stability when compared with supercapacitors and batteries [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. However, their relatively low energy density is the main bottleneck towards energy storage applications, while intensive efforts have been devoted to find novel compounds with improved storage properties. ...
... A phenomenological model is further proposed to rationalize such striking features. DOI: 10.1103/PhysRevMaterials. 5.L072401 Electrostatic capacitors that are based on dielectric or antiferroelectric materials are promising energy storage components in various electronic applications because of their higher power density, faster charging and discharging rates, and better stability when compared with supercapacitors and batteries [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. However, their relatively low energy density is the main bottleneck towards energy storage applications, while intensive efforts have been devoted to find novel compounds with improved storage properties. ...
... To maximize both energy density and efficiency, one can in fact imagine a nonlinear-type dielectric material that can combine the advantages of a ferroelectric and a linear dielectric, i.e., possessing large polarization under high field and being nonpolar under zero field as well as reversible. This would require the nonlinear dielectrics to have large ε r and high E break [11][12][13][14][15][16]. A promising candidate is the III-Vsemiconductor-based systems made by mixing AlN and ScN to form Al 1−x Sc x N solid solutions or AlN/ScN superlattices, which have been attracting much attention due to their potential for high piezoelectric and electro-optic responses [20][21][22][23][24][25][26][27][28][29]. ...
Dielectric and antiferroelectric materials are particularly promising for high-power energy storage applications. However, relatively low energy density greatly hinders their usage in storage technologies. Here, we report first-principles-based calculations predicting that epitaxial and initially nonpolar AlN/ScN superlattices can achieve an ultrahigh energy density of up to 200J/cm3, accompanied by an ideal efficiency of 100%. We also show that high energy density requires that the system be neither too close nor too far from a ferroelectric phase transition under zero electric field. A phenomenological model is further proposed to rationalize such striking features.
... Electrical energy storage has attracted extensive research interest due to the implementation of renewable energy sources for applications in electronic devices and high power system [1][2][3][4]. Compared to the electrochemical capacitors and the batteries, dielectric capacitors have the characteristics of fast charge/discharge speed and high power density that is attractive in the pulsed power electronic devices, such as the microwave communication systems, some pulse weapon guns and new hybrid electric vehicles [5][6][7]. Nowadays the dielectric capacitors focus on the polymers and the dielectric ceramics. The polymer dielectric capacitors are commercially applied in the pulsed power capacitor systems, and they have the advantage of high breakdown strength, but they typically have very small dielectric constants and low energy densities [3]. ...
... By contrast, dielectric ceramics exhibit high dielectric constants and favorable electrical and mechanical fatigue resistance, but their energy storage performance is mainly bound by the low breakdown strengths (BDS) [8]. The dielectric ceramic film capacitors attract increasing attentions due to their ultrahigh energy densities and energy efficiencies under large breakdown strengths for applications in miniaturized integrated microelectronic systems [7,9]. ...
The 0.55Na0.5Bi0.5TiO3-0.45Sr0.7Bi0.2TiO3 (0.55NBT-0.45SBT) thin films with Mn doping were fabricated on the platinum-buffered Si substrates using the sol–gel technique. The impacts of Mn doping on the structure and properties of the thin films were systematically studied. Mn doping into the thin films can limit the valence transition of Ti cations to improve the insulation performance, and advance the ferroelectric properties. Ordered B-site cation displacement can be observed from the HADDF-STEM image, which can only be maintained in a single nano-sized crystal grain, and its order scale is limited by the grain size. The 0.55NBT-0.45SBT-0.01Mn film exhibited relatively high recoverable energy storage density (∼30.5 J/cm²) and efficiency (∼65%) at 2800 kV cm⁻¹. Frequency stability in a wide range (0.5 ∼ 20 kHz) and long-term antifatigue stability (1 × 10⁸ switching cycles) were also obtained, indicating their future applications in advanced dielectric capacitors for energy storage.
... In the last few decades, energy storage has become one of the vital topics in the scientific research, because it consists of preserving an energy generated for later use [1]. With the excessive consumption of traditional resources like fossil fuels, the acceleration of environmental pollution, and the extensive demand of the electronics industry, the development of new dielectric materials for ecological energy storage has become a mandatory challenge [2][3][4][5]. Recently, dielectric capacitors have attracted a great attention due to their highest power density compared to other energy storage devices like fuel cells, batteries, and super-capacitors because of the fast charge-discharge rate [6][7][8][9]. ...
... The lead-free BaTiO 3 (BT) ceramic with relatively high dielectric permittivity and low loss features is a promising eco-friendly material for energy storage applications [4,23]. Recently, BT has also been recognized as a potentially promising lead-free ceramic for future solid-state electrocaloric cooling applications [24][25][26]. ...
Perovskite-type Ba0.9Sr0.1Ti0.9Sn0.1O3(BSTSn) ceramic was synthesized by the sol-gel method. The P-E hysteresis loops were recorded at different temperatures to investigate the ferroelectric and energy storage properties of BSTSn ceramic. Enhanced recoverable energy density and high energy storage efficiency were found to be 58.08 mJ/cm³ and 84.36%, respectively at room temperature (RT) under a moderate applied electric field of 20 kV/cm. The electrocaloric effect (ECE) in the BSTSn ceramic was explored using two different approaches based on P – E hysteresis loops, and pyroelectric current measurements. The largest electrocaloric (EC) temperature change, ΔTmax ≈ 0.63 K was determined using the Maxwell relationship obtained near RT under 20 kV/cm. The corresponding EC responsivity (ξmax) value of 0.31 K mm/kV is one of the highest reported values in lead-free ferroelectrics near RT. This study demonstrates that the BSTSn ceramic is a promising candidate for solid-state cooling and energy storage applications.
... Dielectric capacitors which can operate at high-temperature with high energy densities are required for various industrial applications [1][2][3][4][5][6][7]. The capacitors made by ceramics can withstand harsh environments including high-temperature. ...
... At 185 kV/cm, W st =1.33 J/cm 3 , W re =1.18 J/cm 3 , and g = 88.5%. These values are comparable with leadfree bulk ceramics [2]. If the electrical energy density was evaluated by the formula for linear dielectrics according to dielectric permittivity W ¼ 1 2 0 r E 2 , the energy density is 1.39 J/cm 3 , indicating the dielectric behavior of 0.25BiFeO 3 -0.30BaTiO 3 -0.45SrTiO 3 -0.02Mn is similar to linear dielectrics at the electric field less than 185 kV/cm. ...
Recently, it is shown that the thin films of BiFeO3–BaTiO3–SrTiO3 have ultrahigh-energy storage density. However, the energy storage properties of BiFeO3–BaTiO3–SrTiO3 ternary bulk ceramics have not been studied. In this work, the BiFeO3–BaTiO3–SrTiO3 ceramics have been prepared by a conventional solid-state reaction method and the dielectric and electrical energy storage properties have been studied in detail. The ceramic with the composition of 0.25BiFeO3–0.30BaTiO3–0.45SrTiO3 is experimental evidenced to be the best with the highest dielectric permittivity in the ternary system. To suppress the dielectric loss and leakage current, 0.25BiFeO3–0.30BaTiO3–0.45SrTiO3 has been doped with Mn. Mn-doped ceramics have the same perovskite structure but the fine grains are formed and the number of pores decreases. Mn-doping reduces dielectric loss, enlarges the thermally stable zone of the dielectric, and improves the electrical energy storage density simultaneously. 2 mol% Mn-doped 0.25BiFeO3–0.30BaTiO3–0.45SrTiO3 has the most optimized electrical energy storage properties. The energy storage density is 1.33 J/cm3 and the efficiency is 88.5% at 185 kV/cm. The discharge energy density is 2.7 times that of undoped 0.25BiFeO3–0.30BaTiO3–0.45SrTiO3 and 90% stored energy can release in 120 ns.
... Among versatile nonlinear lead-free dielectric materials, BaTiO 3 -based ferroelectric materials attract our research attention whereas their energy-storage density (also called recoverable stored energy) and efficiency under low electric field are relatively low [6]. It is well known that high relative density, small grains size, high E b value, large polarization difference between maximum polarization P max and remnant polarization P r (∆P = P max − P r ) and slim polarization-electric-field (P-E) hysteresis loops are crucial factors for developing high performance dielectric capacitors [4,7]. Doping of BaTiO 3 and adding sintering aid provide effective methods to fulfill such purposes. ...
... The relative density of the BST-BiMT-0.1 ceramics sintered at 1200°C is higher than 95% TD (theoretical density) and the resistivity of the BST-BiMT-x ceramics exceeds 10 10 Ω·mm (Table 1), which are favourable factors to acquire large dielectric breakdown electric-field E b . Thus, these BST-BiMTx ceramics are expected to present excellent energystorage performance [4,7]. ...
Perovskite (1-x)Ba0.9Sr0.1TiO3-xBi(Mg1/2Ti1/2)O3 (BST-BiMT-x) ceramics were prepared by sintering the corresponding powders synthesized by combining of solid state reaction method with citrate sol-gel and selfcombustion techniques. Submicron grains morphology, high density and large resistivity were obtained in the BST-BiMT-x ceramics. In addition, the BST-BiMT-0.1 and BST-BiMT-0.075 ceramics exhibit ferroelectric hysteresis loops with slim shape which lead to enhanced energy-storage properties. The energy-storage density of these two ceramics increases almost linearly with increasing the applied electric filed. The energy-storage density and efficiency at 25 kV/cm of the BST-BiMT-0.1 and BST-BiMT-0.075 ceramics sintered at 1200?C are 141.2mJ/cm3 and 79.3%, and 158.1mJ/cm3 and 76.7%, respectively, surpassing many recently reported values for ferroelectric/antiferroelectric ceramics. The enhanced energy-storage density and efficiency under low electric field can be attributed to the slim polarization-electric field hysteresis loops, high density accompanied by submicron grains morphology and pure perovskite structure.
... It is well known that ferroelectrics possess excellent dielectric constant. Hence, ferroelectric ceramic capacitors should have superior capability of energy storage [36]. In fact, for the sake of polarization hysteresis, ceramics fail to behave as paraelectrics, which release entire polarization energy after unloading, but rather a part of electric energy provided by a power source must be afforded to irreversible domain reorientation-that is, energy loss. ...
The characteristic transition from ferroelectric (FE) to ergodic relaxor (ER) state in (Bi 0.5 Na 0.5)TiO 3 (BNT) based lead-free ceramics provides an efficient approach to bring a highly ordered phase back to a disordered one. It would be rational to utilize this transition to improve relevant non-piezoelectric properties based on domain decomposition. In this work, different La contents were introduced to 0.93(Bi 0.5 Na 0.5)TiO 3-0.07Ba(Ti 0.945 Zr 0.055)O 3 ceramics (BNT-BZT-xLa) to induce evolution of ergodic degree. The results reveal that with increasing La content, both the FE-ER transition temperature T F-R and depolarization temperature T d shift towards room temperature, implying a deepened ergodic degree. By modulation of ergodic degree, thermally stimulated depo-larization current experiment shows a higher current density peak, and corresponding pyroelectric coefficient increases from 2.46 to 2.81 µC/(cm 2 · • C) at T d. For refrigeration, the indirect measurement demonstrates the ∆T maximum increases from 1.1 K to 1.4 K, indicating an enhanced electrocaloric effect. Moreover, the optimized energy storage effect is observed after La doping. With appearance of "slimmer" P-E loops, both calculated recoverable energy storage density W rec and storage efficiency η increase to 0.23 J/cm 3 and 22.8%, respectively. These results denote La doping conduces to the improvement of non-piezoelectric properties of BNT-based ceramics in a certain range. Therefore, La doping should be an adopted modification strategy for lead-free ceramics used in areas like refrigerator and pulse capacitors.
... Dielectric capacitors with high energy-storage density will significantly reduce the device volume (increase the volumetric efficiency), thus showing large potentials for many applications where miniaturization, light weight, low cost, and easy integration are desirable, e.g . consumer electronics, pulsed power applications, commercial defibrillators, and et al. [4][5][6][7][8][9][10][11][12][13][14][15] . Yet the energystorage density of dielectric capacitors is usually relatively low compared with other energy-storage systems. ...
With the development of energy-storage technology and power electronics industry, dielectric capacitors with high energy density are in high demand owing to their high power density. Especially for ferroic dielectrics (including ferroelectrics and antiferroelectrics) showing dipole moments in the perovskite unit cells, large dielectric response under electric fields makes them own outstanding potentials for achieving high energy-storage density. Particularly, destroying long-range ferroelectric/antiferroelectric ordering by enhancing compositional disorder is found to be effective for extremely improving energy-storage properties (both high recoverable energy-storage density and efficiency), because these macroscopic-nonpolar nanodomains are highly polarizable under strong external electric fields. Moreover, owing to the heterogeneous structure induced dielectric relaxation characteristics, excellent temperature stability can be achieved simultaneously. The recent developments of (anti)polar nanoregions with different possible local symmetries in various lead-free perovskite-structured dielectrics have been summarized in this review, together with the achieved energy-storage properties based on them. This review would provide a guidance for preparing high-performance energy-storage capacitors by local-structure engineering for next-generation pulse power applications.
... In recent years, materials with large discharge power and high energy storage density have attracted extensive research attention due to the demands for the rapid development of power systems and electric devices [1][2][3]. Among the numerous energy storage devices, dielectric ceramics are emerging as a sort of promising energy storage materials because of their high power densities, excellent endurance and good thermal stability [4][5][6][7]. ...
In this study, the energy storage performance and strain behavior of MnO-doped 0.65Bi0.5Na0.5TiO3-0.35SrTiO3 (NBT-ST-xMn) lead-free ceramics were investigated. MnO was induced as a ‘hard’ dopant to promote the formation of defect dipoles and improve relative density, enhancing the difference between the maximum and remnant polarization (Pmax-Pr) as well as the breakdown electric field (BDS) values. A high recoverable energy density of 1.14 J cm3 with a high energy efficiency of 83 % were achieved simultaneously under low electric field of 89 kV cm-1 at x = 0.5 mol%. Meanwhile, a relatively high strain of 0.22 % with ultra-low hysteresis of 14 % was attained under a moderate electric field of 60 kV/cm at x = 1.0 mol%. The results illustrate that the proper selection of base composition and effective chemical modifier make the NBT-ST an outstanding candidate for actuators and energy storage devices.
... To obtain the charge energy and discharge energy densities, the polarization axis and polarization-electric field (P-E) hysteresis loop should be integrated [40]. Formulas are described below: ...
With the wide application of energy storage equipment in modern electronic and electrical systems, developing polymer-based dielectric capacitors with high-power density and rapid charge and discharge capabilities has become important. However, there are significant challenges in synergistic optimization of conventional polymer-based composites, specifically in terms of their breakdown and dielectric properties. As the basis of dielectrics, all-organic polymers have become a research hotspot in recent years, showing broad development prospects in the fields of dielectric and energy storage. This paper reviews the research progress of all-organic polymer dielectrics from the perspective of material preparation methods, with emphasis on strategies that enhance both dielectric and energy storage performance. By dividing all-organic polymer dielectrics into linear polymer dielectrics and nonlinear polymer dielectrics, the paper describes the effects of three structures (blending, filling, and multilayer) on the dielectric and energy storage properties of all-organic polymer dielectrics. Based on the above research progress, the energy storage applications of all-organic dielectrics are summarized and their prospects discussed.
... The polarisation-field (P-E) hysteresis loops of KNN ceramics are plotted in Figure 5. From Figure 5(a)-(c), the values of polarisation are obviously tuned with T 1 and T 3 . The uniform grain growth during the sintering process is a major effect that determines the P-E loop of a sintered ceramic [28][29][30]. Hence, it indicates that the first and third step plays an important role in the uniform growth of grains. ...
In this work, a modified sintering method, i.e. the three-step sintering technology, has been applied to fabricate the K0.5Na0.5NbO3 ceramics. The impact of the detailed sintering conditions on the sinterability, dielectric and ferroelectric properties of K0.5Na0.5NbO3 is systematically investigated. Attributed to the three-step sintering, the highest density of 4.07 g cm⁻³ can be observed, which is strongly improved compared with that of the single-step sintering technique and is increased up to 90% of the theoretical density. Furthermore, through the analysis on the tunability of the dielectric and ferroelectric performances, it is found that the maxima of permittivity and polarisation can be obtained in K0.5Na0.5NbO3 sintering at 1160–1220–1120°C. These results illustrate that both the dielectric and ferroelectric behaviours can be effectively modulated through the simple modification of sintering technique, which would provide a novel route to achieve tunable electrical properties in ferroelectrics.
... Polymer-based dielectric composites have been widely applied in the industries of information, energy, electrical, and electronics thanks to their good processability, excellent mechanical properties, low dielectric loss, and high breakdown strength [1,2]. Recently, polymer-based composites with high dielectric permittivity have attracted great attention [3][4][5][6][7]. To obtain the composites, adding ceramic particles with high dielectric permittivity into the polymeric matrices is considered to be one of the most common and promising strategies, which takes the advantages of colossal permittivity of ceramic particles and good dielectric strength of polymers [8]. ...
Molecular dynamics (MD) simulation was performed to investigate the structure and dielectric permittivity of poly(vinylidene fluoride)- (PVDF-) based composites with different contents of barium titanate (BT). The β-phase PVDF model with 100 structural units and the spherical BT particle model with a radius of 0.495 nm were built and applied in the initial models with three PVDF macromolecular chains and BT particles for the MD simulations of the BT/PVDF composites. The influences of BT content on the morphological structure, the free volume fraction, and glass transition temperature of the composites were explored according to the simulated results and the experimental ones of X-ray diffraction (XRD) and scanning electron microscope (SEM). A model was proposed to predict the static dielectric permittivity of the composites, the results of which were compared with the Cole-Cole fitting results of dielectric spectroscopy. Attempts were made to reveal the structure evolution and the micropolarization mechanism with the increasing content of BT.
... The dielectric applications for power MLCC (multilayer ceramic capacitors) are historically limited by low energy density and electric breakdown strength (8 V/lm) [1][2][3][4][5][6][7][8][9][10][11][12]. Simultaneously achieving high power density and energy density in dielectrics is what we have been pursuing to replace the electrolytic capacitor [4-6, 8, 9, 13-16]. ...
Dielectric ceramics with excellent discharge properties and high-temperature stability are promising and challenging for pulse power applications. In the present work, novel (1 − x)Na0.5Bi0.5TiO3–xBaMg1/3Ta2/3O3 ((1 − x)NBT–xBMT) ceramics were designed and fabricated, which showed a high permittivity εr of 2102.688 ± 15% at 24–377 °C and a low dielectric loss tan δ ≤ 0.02 at 34–299 °C in x = 0.15 sample. After BMT modification, the NBT ceramics showed a nearly cubic tolerance factor of 1 and enhanced relaxor behavior. Consequently, a significant energy storage density Ws ~ 2.8 J/cm3 with high efficiency η ~ 78.67% was obtained in x = 0.15 sample at 175 kV/cm. Furthermore, pulse discharge testing demonstrated that this ceramic sample exhibited a satisfying discharge energy density WD ~ 0.88 J/cm3, a high power density PD ~ 59.07 MW/cm3 and a fast discharge speed (~ 50 ns) up to operating temperature of 170 °C, superior to most lead-free ceramics. The present work provides a novel composition with superior discharge properties.
... Nevertheless, due to increasing environmental and health concerns, the use of Pb containing substances is banned by the European RoHS Directive (effective since 07/01/ 2006) [25]. As a result, recent research on dielectric ceramics is driving the sustainable development of lead-free materials [26][27][28]. Various materials are investigated for energy storage applications. For instance, organic dielectric films have shown some higher storage density and mechanical flexibility [29]. ...
In pursuit of developing high-performance lead-free energy storage capacitors, strontium titanate (SrTiO3) and calcium titanate (CaTiO3) are widely recognised as promising dielectric ceramics. Both end members are completely miscible for the entire doping concentration which results in the successful formation of (Sr1 − xCax)TiO3 solid solutions. Most importantly, the Ca dopant irons the electric fields, temperature and frequency stabilities of SrTiO3 ceramic. This review encompasses up to date knowledge of crystallography, dielectric properties and recent progress on energy storage aspects of various (Sr1 − xCax)TiO3 materials. Firstly, the structural phase transition (with special attention to room temperature) behaviour has been discussed which is essential to understand the origin of functional dielectric properties. Thereafter, various strategies to improve the energy storage properties of bulk (Sr1 − xCax)TiO3-based materials have been discussed. Further, leverage of the improved properties in the bulk ceramics into the thin film regime will be essential for creating next-generation high-performance power electronic devices. In this perspective, some interesting developments reported in thin film form are also discussed. Finally, challenges and outlook of (Sr1 − xCax)TiO3-based bulk ceramics and thin films towards future research and the applications are presented.
... The large volume would also introduce a large equivalent series inductance (ESL), which may result in damage or even failure of semiconductor devices when quickly switched. This means that these capacitors cannot currently meet the requirements for application in electronic devices and systems that require compact and light integrated capacitors [5,6]. Here, the energy-storage properties of some commercial MLCCs are listed in Table 1. ...
The growing demand for high-power-density electric and electronic systems has encouraged the development of energy-storage capacitors with attributes such as high energy density, high capacitance density, high voltage and frequency, low weight, high-temperature operability, and environmental friendliness. Compared with their electrolytic and film counterparts, energy-storage multilayer ceramic capacitors (MLCCs) stand out for their extremely low equivalent series resistance
and equivalent series inductance, high current handling capability, and high-temperature stability. These characteristics are important for applications including fast-switching third-generation wide-bandgap semiconductors in electric vehicles, 5G base stations, clean energy generation, and smart grids. There have been numerous reports on state-of-the-art MLCC energy-storage solutions. However, lead-free capacitors generally have a low-energy density, and high-energy density
capacitors frequently contain lead, which is a key issue that hinders their broad application. In this review, we present perspectives and challenges for lead-free energy-storage MLCCs. Initially, the energy-storage mechanism and device characterization are introduced; then, dielectric ceramics for energy-storage applications with aspects of composition and structural optimization are summarized. Progress on state-of-the-art energy-storage MLCCs is discussed after elaboration of the fabrication process and structural design of the electrode. Emerging applications of energy-storage MLCCs are then discussed in terms of advanced pulsed power sources and high-density power converters from a theoretical and technological point of view. Finally, the challenges and future prospects for industrialization of lab-scale lead-free energy-storage MLCCs are discussed.
... The materials used in dielectric energy storage capacitors include organic and ceramic materials. Compared with organic and electromechanical materials, ceramic materials have higher dielectric constant (ε r ) and can maintain stable energy storage characteristics at temperatures higher than 200 °C [9][10][11]. At present, the research on energy storage dielectric ceramics focuses on four categories, i.e., linear dielectric (such as TiO 2 and SrTiO 3 ) [12,13], normal ferroelectric (FE; such as K 0.5 Na 0.5 NbO 3 , BaTiO 3 , and BiFeO 3 ) [14][15][16], relaxor ferroelectric (RFE; such as Na 0.5 Bi 0.5 TiO 3 -based) [17][18][19][20][21][22][23][24][25], and antiferroelectric (AFE; such as (Pb,La)(Zr,Sn,Ti)O3, AgNbO 3 , and NaNbO 3 ) ceramics [26][27][28][29][30][31][32][33][34][35][36][37]. ...
NaNbO3-based antiferroelectric (AFE) ceramics have the prominent advantages of stable performance and low cost. However, its energy storage property is often remarkably limited by the hysteresis of the antiferroelectric to ferroelectric phase transformation. In this work, 0.88Na(Nb1−xTax)O3–0.12Bi0.2Sr0.7TiO3 (x = 0–0.075) antiferroelectric ceramics were synthesized using a conventional mixed oxide route. Ta⁵⁺ were completely dissolved into the lattice of 0.88NaNbO3–0.12Bi0.2Sr0.7TiO3 to form a pure perovskite structure. With increased Ta content, the AFE orthogonal P phase was replaced by AFE orthogonal R phase progressively. Meanwhile, the dielectric constant curve showed relaxor-like properties. As a result, slender P–E curves with reduced hysteresis loss and decreased residual polarization were achieved. Interestingly, a large recoverable energy storage density (Wrec ~ 2.16 J cm⁻³) and high energy storage efficiency (η ~ 80.7%) were obtained simultaneously under a low driving electric field of 15 kV mm⁻¹ at doping ratio (x) of 0.075. In addition, the 0.88Na(Nb0.925Ta0.075)O3–0.12Bi0.2Sr0.7TiO3 sample exhibited excellent temperature stability, indicating an ideal candidate in future pulsed power capacitor.
... Ceramics are suitable for dielectric capacitors due to their ultrahigh dielectric constant (up to thousands for ferroelectric). [105][106][107][108][109][110] But ceramic dielectrics also have a high dielectric loss, relatively low breakdown strength and other problems that need to be solved. Many studies have been conducted on ceramic dielectric in order to achieve reinforced energy storage capability. ...
An electrostatic capacitor has been widely used in many fields (such as high pulsed power technology, new energy vehicles, etc.) due to its ultrahigh discharge power density. Remarkable progress has been made over the past 10 years by doping ferroelectric ceramics into polymers because the dielectric constant is positively correlated with the energy storage density. However, this method often leads to an increase in dielectric loss and a decrease in energy storage efficiency. Therefore, the way of using a multilayer structure to improve the energy storage density of the dielectric has attracted the attention of researchers. Although research on energy storage properties using multilayer dielectric is just beginning, it shows the excellent effect and huge potential. In this review, the main physical mechanisms of polarization, breakdown and energy storage in multilayer structure dielectric are introduced, the theoretical simulation and experimental results are systematically summarized, and the preparation methods and design ideas of multilayer structure dielectrics are mainly described. This article covers not only an overview of the state‐of‐the‐art advances of multilayer structure energy storage dielectric but also the prospects that may open another window to tune the electrical performance of the electrostatic capacitor via designing a multilayer structure. In this review, the main physical mechanisms of polarization, breakdown, and energy storage in multilayer dielectric are introduced. The preparation methods and design ideas of multilayer dielectrics are mainly described. This article covers not only an overview of the state‐of‐the‐art advances of multilayer dielectric but also opens another window to tune the electrical performance of the electrostatic capacitor via designing a multilayer structure.
... 1,2 Three kinds of typical energy storage devices including batteries, electrochemical capacitors, and dielectric capacitors are in urgent demand during last decade. [3][4][5][6][7][8] Compared to batteries and electrochemical capacitors, dielectric capacitors possess ultrahigh power density and fast chargingdischarging capability and, therefore, play a crucial role in advanced pulsed power systems such as hybrid electric vehicles, high voltage pulsed power sources, and kinetic energy weapons. [9][10][11][12][13] Ferroelectrics, featured with high permittivity induced by spontaneous polarization, are widely used as dielectric materials in dielectric capacitors. ...
The utilization of ferroelectrics in forms of ceramics, films, and composites toward energy-storage applications is of great interest recent years. However, the simultaneous achievement of high polarization, high breakdown strength, low energy loss, and weakly nonlinear polarization–electric field (P–E) correlation has been a huge challenge, which impedes progress in energy storage performance. In this work, a vortex domain engineering constructed via the core–shell structure in ferroelectric ceramics is proposed. The formation and the switching characteristics of vortex domains (VDs) were validated through a phase-field simulation based on the time-dependent Ginzburg–Landau kinetic equation. Benefiting from the smaller depth of a potential well in the energy profiles, the switching of VDs was much easier than that of conventional large-sized domains, which was found to be the origin of the lower coercive field, lower remanent polarization, and weaker nonlinear P–E correlation. Choosing BaTiO3 (BT) as a representative of ferroelectric ceramics, the shell fractions and permittivity values were varied in our phase-field simulation to optimize the energy storage performance. As a result, a large discharge energy of 6.5 J/cm³ was obtained in BT ferroelectric ceramics with a shell fraction of 5% and a shell permittivity of 20 under the applied electric field of 100 kV/mm, which is almost 140% higher than that with no shell structure. In general, the vortex domain engineering proposed in this work can serve as a universal method in designing high-performance ferroelectrics with simultaneous high breakdown strength, high discharge energy density, and high energy efficiency.
... Fig. 2 indicates that the energy storage density increases as a function of the Sn content, The BCZT:2Sn shows the highest recoverable energy density and efficiency (W rec = 19 mJ/cm 3 at 12 kV/cm and ɳ $80%) at 120°C as illustrated in Fig. 3. This could be attributed to the slim hysteresis loop behavior, which allows a high P S and low E C values [18].The enchancement of the recoverable energy density and efficiency as a function of Sn could be due to the increase of the grain size growth as shown in our previous work [8] since the increase in the grain size is followed by an easier domain wall rotation due to the raise of the domain switchability [19] hence the Sn affected the ferroelectric properties which influences the energy storage performance. Furthermore we observed a discontinuity in slope at % 40-50°C and 120°C, which could reflect the diffuse FE-PE phase transition , in the region of this diffuse phase transi- ...
The B-site-doping method of barium titanate (BaTiO3) is one of the promising route to prepare lead-free materials with enhanced dielectric and piezoelectric properties. Lead-free (Ba0.85 Ca0.15)(Zr0.1-xSnxTi0.9)O3 [BCZT:Sn] (x = 0, 0.02, 0.04 and 0.06) ceramics were synthesized using the sol-gel method. The effects of Sn content on the energy-storage performance and electric conduction mechanisms of BCZT ceramic were systematically investigated. The energy storage performance investigation showed that the recoverable energy storage has been enhanced with Sn doping rate, the composition doped x = 0.02 (BCZT: 2Sn) depicted the highest recoverable energy density and efficiency (Wrec = 19 mJ/cm³, ɳ = 81.65%). The electrical properties of the BCZT:Sn ceramics were investigated using the impedance spectroscopy technique at temperature range of 25–450 °C. The net impedance of the samples showed a significant enhancement as the Sn content increases, owing to the lattice distortion created by the relative difference in the radius of Sn⁴⁺and Zr⁴⁺ and different outer electronic shells. The AC conductivity was measured and analyzed as a function of frequency and temperature. Obtained activation energy values were associated with possible conduction mechanisms.
... At present, the energy crisis and environmental pollution have aroused widespread concern. In order to solve these problems, it is necessary to develop and utilize clean and sustainable energy sources and energy storage devices [1][2][3][4]. At present, advanced energy storage techniques include batteries, superconducting magnetic energy storage systems and electrochemical/dielectric capacitors [5,6]. ...
Ferroelectric thin film capacitors have triggered great interest in pulsed power systems because of their high-power density and ultrafast charge–discharge speed, but less attention has been paid to the realization of flexible capacitors for wearable electronics and power systems. In this work, a flexible Ba0.5Sr0.5TiO3/0.4BiFeO3-0.6SrTiO3 thin film capacitor is synthesized on mica substrate. It possesses an energy storage density of Wrec ~ 62 J cm−3, combined with an efficiency of η ~ 74% due to the moderate breakdown strength (3000 kV cm−1) and the strong relaxor behavior. The energy storage performances for the film capacitor are also very stable over a broad temperature range (−50–200 °C) and frequency range (500 Hz–20 kHz). Moreover, the Wrec and η are stabilized after 108 fatigue cycles. Additionally, the superior energy storage capability can be well maintained under a small bending radius (r = 2 mm), or after 104 mechanical bending cycles. These results reveal that the Ba0.5Sr0.5TiO3/0.4BiFeO3-0.6SrTiO3 film capacitors in this work have great potential for use in flexible microenergy storage systems.
... As shown, the maximum polarization is related to the breakdown strength, namely that high electric field owns large polarization. It is clear to see Fig. 6 [3,4,12,[44][45][46][47][48][49][50][51][52][53]. It can be observed that this poorly crystalized thin film owns promising energy storage density due to high breakdown for microstructural modulation. ...
Improving energy storage density and efficiency is the ultimate goal of dielectric materials used in ceramic capacitors. Among different dielectric materials, dielectrics in thin film state own superior energy performances due to less defects compared with ceramic. Herein, we report an optimized lead-free Zr-modified BiMg0.5Zr0.04Tix-0.04O3 composition with enhanced energy storage behavior via microstructural engineering. Rapid annealing can result in poorly crystallization in the film matrix confirmed by grazing incident X-ray diffraction GIXRD. The excess Ti source can effectively increase polarization and dielectric breakdown till to 97.0 μC/cm² and 3403 kV/cm at x = 0.775, respectively. The optimized energy properties can be achieved at x = 0.775 with a high recoverable energy storage density Wreco of 87.8 J/cm³ and an efficiency η of 50%, indicative of excellent stability of storing electricity for the applications of pulse power electronics.
... The materials used in dielectric energy storage capacitors include organic and ceramic materials. Compared with organic and electromechanical materials, ceramic materials have higher dielectric constant (ε r ) and can maintain stable energy storage characteristics at temperatures higher than 200°C [9][10][11]. At present, the research on energy storage dielectric ceramics focuses on four categories, i.e., linear dielectric (such as TiO 2 and SrTiO 3 ) [12,13], normal ferroelectric (FE; such as K 0.5 N 0.5 NbO 3 , BaTiO 3 , and BiFeO 3 ) [14][15][16], relaxor ferroelectric (RFE; such as Na 0.5 Bi 0.5 TiO 3 -based) [17][18][19][20], and antiferroelectric (AFE; such as PLZST, AgNbO 3 , and NaNbO 3 ) ceramics [21][22][23][24][25][26][27][28][29][30][31][32]. ...
NaNbO 3 -based antiferroelectric (AFE) ceramics have the prominent advantages of stable performance and low cost. However, its energy storage property is often remarkably limited by the hysteresis of the antiferroelectric to ferroelectric phase transformation. In this work, 0.88Na(Nb 1 − x Ta x )O 3 –0.12Bi 0.2 Sr 0.7 TiO 3 ( x = 0–0.075) antiferroelectric ceramics were synthesized using a conventional mixed oxide route. Ta ⁵⁺ were completely dissolved into the lattice of 0.88NaNbO 3 –0.12Bi 0.2 Sr 0.7 TiO 3 to form a pure perovskite structure. With increased Ta content, the AFE orthogonal P phase was replaced by AFE orthogonal R phase progressively. Meanwhile, the dielectric constant curve showed relaxor-like properties. As a result, slender P–E curves with reduced hysteresis loss and decreased residual polarization were achieved. Interestingly, a large recoverable energy storage density ( W rec ≈ 2.16 J cm − 3 ) and high energy storage efficiency ( η ≈ 80.7%) were obtained simultaneously under a low driving electric field of 15 kV mm − 1 at doping ratio ( x ) of 0.075. In addition, the 0.88Na(Nb 0.925 Ta 0.075 )O 3 –0.12Bi 0.2 Sr 0.7 TiO 3 sample exhibited excellent temperature stability, indicating an ideal candidate in future pulsed power capacitor.
With the rapid development of electronic information technology and the rising environmental concerns as well as the tendency of electronic devices towards miniaturization and integration, enhancing the energy storage properties of lead-free ceramic capacitors is one of the imperative issues. Although a large number of efforts have been contributed to optimize the energy storage properties of lead-free ceramics, the conflict between the polarization and electric breakdown strength seriously impedes the improvement of energy storage density significantly. Herein, inspired by the layered composites of sandwich, the sandwich structured lead-free ceramics based on Bi0.5Na0.5TiO3 were designed and fabricated to overcome the above challenge effectively. The theoretical simulations and experiment results demonstrate that the polarization and electric breakdown strength can be optimized synchronously via the sandwich structured design. An ultrahigh recoverable energy storage density of ∼6 J cm⁻³ and a nearly ideal energy conversion efficiency of ∼95% can be obtained for the prepared sandwich structured lead-free ceramics. Meanwhile, the maximum applied electric field can be enhanced to more than 500 kV cm⁻¹. The energy storage capabilities also exhibit outstanding stability over a broad temperature range, frequency range and cycle numbers. These results reveal that the Bi0.5Na0.5TiO3-based lead-free ceramics of this study have a great potential for high energy storage capacitors applications.
A series of lead-free (Bi0·5Na0.5)0.84Sr0·16Ti1-x(Y0·5Nb0.5)xO3 (abbreviated as BNST-100xYN) relaxor ferroelectric ceramics were prepared by solid state reaction sintering. The micro morphology, dielectric properties, and energy storage properties of the ceramics with increasing doping content were systematically studied, and their conductive mechanism was also studied. The perovskite structure was not significantly changed with the addition of (Y0·5Nb0.5)⁴⁺ complex ions, but it led to a certain amount of flake grains appear and element precipitation with increasing composition. And the larger dielectric breakdown strength (DBS) and lower remanent polarization (Pr) were attained with the recoverable energy storage density (Wrec) of ∼1.0433 J/cm³ for x = 0.04 composition. In addition, it showed outstanding dielectric temperature stability and cycle stability. These results indicated that BNST-4YN ceramics are an excellent candidate for energy storage device and temperature-stable dielectric equipment.
In the current study, a series of CeO2-doped (x = 0.01, 0.015, 0.02, 0.025 mol) ceramic samples were prepared, and the valence of Ce in the perovskite was analyzed in detail, revealing the polarization contribution and effect mechanism of the doped Ce element in the 0.65BaTiO3–0.35Sr0.7Bi0.2TiO3 ceramic. The phase structure and electrical stored energy performance of the resulting ceramics were also characterized. It was found that adding an appropriate amount of CeO2 to BaTiO3 was helpful for improving the relaxor behavior, promoting electric storage, and releasing ceramic materials. Particularly, the electric breakdown strength of the 0.02Ce-doped specimen reached 330 kV/cm, and the corresponding density and efficiency were 2.57 J/cm³ and 81.30%, respectively. In addition, doping with Ce caused the ceramics to exhibit good stability at frequencies of 1–300 Hz and over a temperature range of 30–150 °C. A high current density (CD) and power density (PD) were obtained in charge–discharge tests.
In the past few decades, ceramic/polymer nanocomposites have been extensively studied due to their relatively large dielectric constant, high electric energy density, and large charge-discharge efficiency. Antiferroelectric (AFE) materials possess a low remnant polarization (P r) and relatively high saturation polarization (P s), which can induce higher storage energy density than relaxor ferroelectric materials. In this investigation, AgNbO3-based AFE ceramic nanoparticles were grafted with a layer of poly(methyl methacrylate) (PMMA) to form AgNbO3-g-PMMA nanoparticles and then the obtained nanoparticles were embedded into a poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) matrix to form an AgNbO3-g-PMMA/PVDF-HFP (AN-g-PMMA/HFP) nanocomposite film. After characterization, it was found that the dielectric constant of the AN-g-PMMA/HFP-5 (5% AgNbO3) nanocomposite film was 12.3, which was 43% higher than that of the pristine PVDF-HFP film. The AN-g-PMMA/HFP-5 nanocomposite film exhibited the largest breakdown field of 500 MV m-1 and the highest energy density of 13 J cm-3, which was increased by 32.5% (from 9.82 to 13 J cm-3), as compared with that of the pristine PVDF-HFP film. The AN-g-PMMA/HFP-5 film exhibited a charge-discharge efficiency of 69.5% at 500 MV m-1, which is 9.5% higher than that of the pristine PVDF-HFP film. This AgNbO3-based nanocomposite film shows great promise for AFE nanocomposite for high energy density capacitor applications.
Dielectric capacitors have drawn increasing attention due to their fast charge/discharge rates and high power density. Among all known ceramic dielectric materials, antiferroelectrics are more attractive for their unique double ferroelectric hysteresis loops and higher energy densities. Here, a series of antiferroelectric ceramics x(0.95Bi0.5Na0.5TiO3-0.05SrZrO3)-(1-x)NaNbO3 (xBNTSZ-(1-x)NN, x = 0.23, 0.30, 0.35, 0.50) have been prepared. By stabilizing the antiferroelectric phase and postponing the critical electric field of the antiferroelectric-ferroelectric phase transition, an impressive discharge energy storage density of 4.08 J/cm³ at a breakdown strength of 370 kV/cm was achieved for the 0.35BNTSZ-0.65 N N. A superior comprehensive performance for the 0.50BNTSZ-0.50 N N ceramic with a discharge energy storage density (Wdis) of 3.78 J/cm³ and an efficiency of 86 % at an electric field strength of 320 kV/cm along with excellent frequency, temperature, and fatigue stabilities (fluctuations of Wdis≤±5% within 0.01∼100 Hz, Wdis≤10 % over 20∼140 °C, and Wdis≤1% over 10⁶ cycle numbers) is realized. Furthermore, 0.50BNTSZ-0.50 N N ceramics simultaneously exhibit a high current density (622.5 A/cm²), high power density (112 MW/cm³), and fast discharge rate (t = 47 ns), all of which make it an excellent candidate for the pulsed power devices.
Lead-free ceramics play a vital role in the context of sustainable development for energy storage applications due to their high power density, excellent high temperature resistance and nontoxicity. Nevertheless, the low energy density and small energy conversion efficiency of lead-free ceramics caused by the contradictory relation of polarization and electric breakdown strength restrict the urgent need for electronic components towards miniaturization and achieving light weight. Herein, to overcome this challenge and optimize the energy storage properties of lead-free ceramics, unlike the traditional approaches of oxide doping, adopting new sintering techniques and optimizing the composition, samples with a spatial sandwich structure were constructed and prepared by the tape casting technique. Obviously, the opposite relationship between the polarization and the electric breakdown strength can be resolved very wellviathis design strategy. The recoverable energy storage density reaches 6.3 J cm⁻³together with high energy conversion efficiency (93.61%) and high applied electric field (540 kV cm⁻¹). An ultrahigh power density of 215 MW cm⁻³and a fast discharge time of 140 ns can also be realized. In addition, the energy conversion efficiency is higher than 90% and the variation of recoverable energy storage density is less than ±2% within 1-100 Hz and 1-10⁵fatigue cycles. Meanwhile, the change of recoverable energy storage density is also less than ±6.5% from 30 °C to 160 °C. The above results indicate that the current study helps to promote the development of eco-friendly ceramics for high energy storage applications.
Compared with fuel cells and electrochemical capacitors, dielectric capacitors are regarded as promising devices to store electrical energy for pulsed power systems due to their fast charge/discharge rates and ultrahigh power density. Dielectric materials are core components of dielectric capacitors and directly determine their performance. Over the past decade, extensive efforts have been devoted to develop high-performance dielectric materials for electrical energy storage applications and great progress has been achieved. Here, we present an overview on the current state-of-the-art lead-free bulk ceramics for electrical energy storage applications, including SrTiO3, CaTiO3, BaTiO3, (Bi0.5Na0.5)TiO3, (K0.5Na0.5)NbO3, BiFeO3, AgNbO3 and NaNbO3-based ceramics. This review starts with a brief introduction of the research background, the development history and the basic fundamentals of dielectric materials for energy storage applications as well as the universal strategies to optimize their energy storage performance. Emphases are placed on the design strategies for each type of dielectric ceramic based on their special physical properties with a summary of their respective advantages and disadvantages. Challenges along with future prospects are presented at the end of this review. This review will not only accelerate the exploration of higher performance lead-free dielectric materials, but also provides a deeper understanding of the relationship among chemical composition, physical properties and energy storage performance.
AgNbO3 has broad research prospects in dielectric energy storage due to its unique antiferroelectric properties. The enhancement of ferroelectric/antiferroelectric phase stability can be achieved by tuning the tolerance factor t of AgNbO3-based ceramics. On the other hand, the stability of the antiferroelectric and ferroelectric phases can be improved by adjusting the phase transition temperature of AgNbO3-based ceramics. This is of great significance and value to the research and development of lead-free energy storage materials. Although there have been many studies on the energy storage performance of AgNbO3-based ceramic materials, there are still challenges in achieving high energy storage density and energy efficiency at the same time. This review discusses the optimization strategy, preparation technology, and sintering technology of AgNbO3-based ceramics, summarizes the current research progress and obstacles, and puts forward the development direction for the application of AgNbO3-based ceramics.
Aiming at the problem that power density and energy density are difficult to obtain simultaneously under low field, a novel composition (1-x)Na0·5Bi0·5TiO3-xBaZn1/3Ta2/3O3((1-x)NBT-xBZT) was designed and fabricated via solid-state methods. With the addition of BZT, the crystal lattice, structural symmetry, grain size, and dense degree were all increased proved by XRD, Raman, and Archimedes drainage method et al. Because of the enhancement of relaxor behavior, the x=0.10 sample displayed a high permittivity εr of 2871±15% and a low dielectric loss tan δ ≤ 0.025 in the wide temperature range of 60–400 oC. This ceramic also showed maximum recoverable energy density Wd (2.07 J/cm³) with high efficiency η (71.5%) under a low field of 150 kV/cm. Moreover, pulse discharge testing proved that this ceramic possessed both a significant discharge energy density WD (0.96 J/cm³) and a record high power density PD (108.54 MW/cm³). This work provided a promising material for high power and energy applications.
Lead-free dielectric capacitors have attracted much attention in pulsed power systems due to their rapid charge/discharge rate. However, their recoverable energy storage density (Wrec) and efficiency (η) still need further improvement to meet the requirements for their application in energy storage devices. In this article, SrTiO3 (ST) and MnO2 were introduced to Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) to obtain a (1 - x)BCZT-xST solid solution, where morphotropic phase boundary ferroelectric BCZT possesses high polarization, paraelectric ST has a high dielectric breakdown strength (Eb), and the 0.3 mol% MnO2 contributes to the dense and fine-grained microstructure as a sintering aid. A high Eb of 436 kV cm⁻¹, large ferroelectric polarization of 33.0 μC cm⁻², and small remnant polarization of 2.1 μC cm⁻²were obtained in the 0.3BCZT-0.7ST ceramic. As a result, a large Wrec of 5.36 J cm⁻³and a high η of 82.2% were simultaneously achieved. Moreover, the 0.3BCZT-0.7ST ceramic exhibits a large DC discharge energy density of 5.63 J cm⁻³and an ultrafast discharge time (t0.9) of 46 ns, and therefore an extremely high power density (PD) of 367.8 MW cm⁻³and a large current density (CD) of 1337.6 A cm⁻², two essential parameters for practical application in high-power devices. These results highlight the potential applications of the 0.3BCZT-0.7ST ceramic in pulsed power capacitors with high energy storage density and provide a comprehensive guideline for the control of BaTiO3-based dielectric capacitors.
Low energy-storage density hinders the miniaturization of energy-storage devices. Therefore, improving the dielectric constant and field strength of dielectric materials has become a research focus for energy storage. In this study, a novel type of transparent AgNbO3 antiferroelectric ceramic co-doped with Eu³⁺ and Hf⁴⁺ ions was prepared using the traditional solid-phase sintering method. The effects of Eu³⁺ and Hf⁴⁺ additions on the phase, microstructure, transmittance, and energy-storage performance of AgNbO3 transparent antiferroelectric ceramics were systematically studied. The results show that a few Hf⁴⁺ ions doped into the AgNbO3 matrix do not change the perovskite structure of AgNbO3. Meanwhile, Eu³⁺ doping can induce a phase red-shift. This reveals that the co-doping of Eu³⁺ and Hf⁴⁺ can reduce the phase transition temperatures of the monoclinic M1-M2 and M2-M3 phases. The (Ag0.91Eu0.03) (Nb0.96Hf0.05)O3 ceramic possesses high transparency, with an optical transmittance of 42% at 780 nm, and its energy-storage density and energy efficiency can reach 4.08 J/cm³ and 65.0%, respectively, at an electric field of 320 kV/cm. Furthermore, the as-prepared antiferroelectric sample exhibited satisfactory thermal stability at 20–120 °C. All the aforementioned merits make it a most promising original energy-storage material.
Polymer dielectrics with unique advantages of high electrical breakdown strength and high-power energy storage are very essential in the development of advanced thin-film capacitors. Herein, nanocomposite film capacitors with maleic anhydride functionalized polypropylene (PP-g-MAH) as matrix and organic Na+-MMT (org-MMT) as nano-modifier were prepared by simple melt blending and hot pressing method. The polarity of PP-g-MAH was beneficial to the uniform dispersion of org-MMT in the nanocomposites. The addition of org-MMT had no influence on the crystal form of PP-g-MAH but decreased its spherulite size because of the heterogeneous nucleation of org-MMT. Compared with the normal PP, the polar PP-g-MAH behaved a much higher dielectric constant and had a similar dielectric loss. The introduction of org-MMT slightly reduced the dielectric constant of the nanocomposites due to the interfacial chain movement limitation of PP-g-MAH. On the other hand, org-MMT improved the breakdown strength of the nanocomposites due to the inhibited electrical tree development. The PP-g-MAH nanocomposite film with an optimized org-MMT content of 0.4wt% possessed a strong breakdown strength of 530 MV/m, an excellent discharged energy density of 5.21 J/cm3, and high efficiency of 94.9%. This research provides a new direction for the development of PP based thin film capacitor towards energy storage application.
Dielectric ceramic materials with high energy-storage density and excellent charge-discharge performance are desirable for use in dielectric capacitors. In this study, (Na0.5Bi0.5)0.75Sr0.25TiO3–xNb2O5 (denoted as NBSTNx) lead-free ceramics were prepared by a solid-state reaction method. Polarization-electric field hysteresis loops (P–E loops) reflected the energy storage characteristics of the NBSTNx ceramics. Introducing Nb into a pure NBST ceramic can reduce the large remnant polarization (Pr) and make the P–E loops slimmer. Through repeated trials and calculations, the maximum recoverable energy-storage density (Wrec ~ 3.25 J/cm³) and energy storage efficiency (η ~ 74.5%) were achieved for the NBSTN0.03 ceramic at 140 kV/cm. We also tested the stability performance of the NBSTNx ceramics, where the NBSTN0.03 ceramic exhibited the highest thermal stability (30–100 °C) and frequency stability (10–1000 Hz). The NBSTN0.03 ceramic also had a fast discharge rate (<300 ns) and a good discharge energy-storage density (Wd ~ 1.80 J/cm³). Therefore, the NBSTN0.03 ceramic with a good energy-storage density and charge-discharge performance has excellent application prospects for practical dielectric capacitors.
In this work, a new type of Yb³⁺/Er³⁺ co-doped lead-free glass-ceramics (GCs) containing Ba2NaNb5O15 nanocrystals was synthesized via traditional melt-quenching and controlled crystallization. The research results illustrate that a transparency of GCs can reach 50% at wavelength of 600 nm and the up-conversion (UC) luminous performance of GCs has been improved obviously compared with precursor glass (PG). And the dual-mode temperature measurement was carried out by fluorescence intensity ratio technology. Using thermally/non-thermally coupled energy levels (TCELs/non-TCELs), the maximum absolute sensitivities of Sa-max (TCELs) and Sa-max (non-TCELs) are 0.65 % K⁻¹ and 0.68 % K⁻¹, and the maximal relative sensitivities of Sr-max (TCELs) and Sr-max (non-TCELs) are 1.19 % K⁻¹ and 0.90 % K⁻¹, respectively. Furthermore, the discharge energy density (Wd) of 1.53 J cm⁻³ and the instantaneous discharge power density of 370 MW cm⁻³ with ultra-fast discharge time of 7 ns are simultaneously achieved in the GCs. These findings reveal the potential applications of new lead-free transparent Yb³⁺/Er³⁺ co-doped Ba2NaNb5O15 GCs for optical temperature measurement and energy storage.
In this work, 0.7BaTiO3-0.3Sr0.2Bi0.7TiO3 (0.7BT-0.3SBT) ceramics with 0.15 mol% various rare-earth oxides doped are designed and synthesized by the conventional solid-state route. All prepared samples exhibited a single perovskite phase and dense microstructure with fine grain size (0.2–0.5 μm) after sintering at 1180 °C. Especially, the Gd-doped 0.7BT-0.3SBT ceramics exhibited excellent energy storage performances; the corresponding recoverable energy density and efficiency were 3.2 J/cm³ and 91.5% under an electric field of 330 kV/cm, respectively. Meanwhile, doping with Gd caused the BT-based ceramics to possess excellent temperature (30–150 °C) and outstanding frequency stabilities (10–1000 Hz). Moreover, the pulsed charge-discharge experiments revealed that a high power density of 59 MW/cm³ and a fast discharge speed of 110 ns with outstanding temperature stability could be synchronously obtained in the Gd-doped composition. All these features are attractive for pulsed power applications.
The macroscopic physical properties of functional ceramics are strongly affected by grain morphology, almost resulting from the sintering process. For a given ceramic material, it has been experimentally confirmed that the enhancement of dielectric breakdown strength Eb can largely increase energy storage density (W). An effective method to increase Eb of ceramic materials is the control of grain morphology. Herein, the (Ba0.95Sr0.05)(Zr0.2Ti0.8)O3 ceramics have been intensively investigated by different sintering techniques to improve grain morphology. Compared with single-step sintering, two-step sintering can sharply inhibit grain growth and make size distribution uniform, which is conducive to the increase in the Eb. A competitive energy storage capacity can be achieved with a high Wch of 3.78 J/cm³, a high Wdi of 3.50 J/cm³, and a high η of 92.6% by two-step sintering due to large Eb of 350 kV/cm, accompanied with good thermal stability till to 160 °C and good fatigue characteristics up to 10⁵ cycles, indicating that two-step sintering is an effective strategy of engineering grain morphology.
With the development of electrical industry, demand for a ceramic-based capacitor with high energy storage density has been increased gradually. The efficiency considered as a key factor of energy storage density is sensitive to temperature change. In this study, using the aerosol deposition (AD) method, we have fabricated lead-free 6Bi0.5Na0.5TiO3(BNT)-4Sr0.7Bi0.2TiO3(SBT) nano-grain composites to improve the energy storage properties and thermal stability. Through the novel AD method, artificially engineered ferroelectric thick films with nano-grain can be fabricated at room temperature. The thick films of 6BNT-4SBT post-annealed at 550°C had an energy storage density of 10.4 J/cm3, high efficiency of 64.5% at 900 kV/cm, and excellent thermal stabilities (ΔWrec < ~9% and Δη < ~30%) heating to 140°C. These results reveal that 6BNT-4SBT thick films fabricated by the AD method have excellent dielectric properties and thermal stabilities as a lead-free material.
A series of single-phase (La0.5Li0.5)x[(Bi0.5Na0.5)0.25Ba0.25Sr0.25Ca0.25]1-xTiO3 high-entropy perovskite ceramics were designed and successfully synthesized via conventional solid state reaction method. The results of dielectric properties indicate that all samples in different proportions exhibit excellent frequency stability at a wide frequency range (10²–10⁶ Hz) and quintessential relaxation phenomenon. An optimal dielectric constant (εr = 920) with low dielectric loss (tanδ = 0.015) was achieved for x = 0.20, which is represented as equimolar high-entropy ceramic. It can be demonstrated that an amazing energy storage efficiency of 95.3% and a discharge density of 1.23 × 10⁻² J/cm³ can be simultaneously achieved in x = 0.24 ceramics. Furthermore, it is confirmed by X-ray photoelectron spectroscopy that the charge compensation mechanism and the oxygen vacancies synergistically cause more Ti⁴⁺ to be reduced, which rationalizes the elevated dielectric properties. We believe that entropy engineering is a credible strategy for tailoring material properties.
Dielectrics that undergo electric-field-induced phase changes are promising for use as high-power electrical energy storage materials and transducers. We demonstrate the stepwise on/off switching of large polarization in a series...
30BiFeO3–70SrTiO3 ceramic is a novel dielectric material with high permittivity and a low-temperature coefficient of capacitance at high temperatures. To reduce its dielectric loss, Mn doping was performed. The relation between the doping quantity of Mn and the electrical properties of 30BiFeO3–70SrTiO3 ceramics were studied comprehensively. A general rule of Mn doping for ceramics with Fe elements is proposed. The optimized doping concentration is 1%, which reduces dielectric loss and leakage current simultaneously. Under a moderate electric field of 150 kV/cm, the energy storage density of 1% (mole) Mn-doped 30BiFeO3–70SrTiO3 is 1.86 J/cm³ and the efficiency is 0.70. These results indicate that Mn-doped 30BiFeO3–70SrTiO3 ceramic is a promising candidate for electrical energy storage applications at high temperatures.
The intricacies in identifying the appropriate material system for energy storage applications have been the biggest struggle of the scientific community. Countless contributions by researchers worldwide have now helped us identify the possible snags and limitations associated with each material/method. This review intends to briefly discuss state of the art in energy storage applications of dielectric materials such as linear dielectrics, ferroelectrics, anti-ferroelectrics, and relaxor ferroelectrics. Based on the recent studies, we find that the eco-friendly lead-free dielectrics, which have been marked as inadequate to compete with lead-based systems, are excellent for energy applications. Moreover, some promising strategies to improve the functional properties of dielectric materials are discussed.
Polymer-based dielectrics with excellent energy storage properties are highly desirable as electrical energy storage materials for advanced electronics and electrical power. However, the most maturely commercial film capacitor, biaxially oriented polypropylene (PP), is limited to a wider range of applications due to its low energy storage density. Herein, a one-step melt blending method was utilized to prepare PP-based nanocomposites to improve the energy storage performance of PP. Polypropylene-graft-maleic anhydride (PP-g-MAH) was used as a polar compatibilizer to promote the uniform dispersion of organic Na⁺-montmorillonite (org-MMT) in the PP matrix. Furthermore, the introduction of PP-g-MAH improved the dielectric constant of PP nanocomposites and increased charge traps. The org-MMT enhanced the crystallinity and reduced the crystal size of PP. On the other hand, the layered structure of org-MMT inhibited electric tree branching and growth. The PP-based nanocomposites possess a relatively high dielectric constant of 3.35 and an extremely low dielectric loss of 0.0012 at 1000 Hz. The PP/PP-g-MAH/org-MMT nanocomposite with an optimized org-MMT content (0.2 wt%) exhibited a discharged energy density of 5.2 J/cm³ at the electric field of 500 MV/m with a superior charge–discharge efficiency of 93.5%, which were favorable for its application as film capacitor materials.
The exploration of ferroelectric hybrid materials is highly appealing due to their great technological significance. In line with this, we herein report the development of a new ferroelectric relaxor: (CH3NH3)2Sn(SCN)2Cl2 was synthesized and studied by single-crystal X-ray diffraction, powder XRD, Differential scanning calorimetry (DSC), IR spectroscopy and dielectric measurements. The phase purity was confirmed by Rietveld refinement of the X-ray powder diffraction pattern. It crystallizes, at room temperature, in the orthorhombic system with the Pnm21 space group. The crystal structure is formed of discrete ionic entities (CH3NH3)⁺ and (Sn(SCN)2Cl2)²⁻. The methylammonium cations are bonded to these chains by hydrogen-bonding contacts. DSC measurement shows that this compound exhibits a diffuse ferro–paraelectric phase transition around 355 K. Dielectric study exhibits a relaxor behavior characterized by the transition temperature shifts toward higher temperature with the rise of frequency. This behavior was validated by the modified Curie–Weiss law. The diffuseness parameter was the γ is approach to 1.96 at 2000 KHz.
Miniaturization is the key for development of lightweight energy storage ceramics. Here, lead-free ceramics with the formula (1-x) (0.94Bi0.5Na0.5TiO3-0.06BaTiO3)-xSr0.7La0.2TiO3 (BNT-6BT-xSLT) were successfully sintered using traditional solid-phase synthesis. The phase structure, micro-morphology, ferroelectricity, and energy storage efficiency and density of BNT-6BT-xSLT were investigated in this work. We found that the introduction of SLT does not alter the multi-phase coexistence of the ceramics, but inhibits the growth of crystal grains. Further, doping with Sr²⁺ and La³⁺ destroys the ferroelectric long-range order and enhances the ionicity of A-site ions, and thus increases energy storage property. As a result, the BNT-6BT-0.08SLT ceramic maintains a high Ps value of 40.77 μC/cm³ and exhibits excellent energy storage performance (W = 1.76 J/cm³, η = 60.1%).
Relaxor ferroelectric materials are highly favorable for pulse power devices owing to the fast charge-discharge speed and large power density. However, the low energy density is still a shortcoming for energy-storage applications. In this work, the excellent energy-storage properties are achieved in 0.5Na0.5Bi0.5TiO3-0.5Sr1-1.5xSmxTiO3 (NBT-SST) relaxor ferroelectric ceramics by a synergistic effect of microstructures based on Sm³⁺ doping. It is proposed that the introduction of Sm³⁺ decreases the grain size and tunes the domain structure, leading to the increase of breakdown strength and the enhancement of relaxation characteristics. The maximum recoverable energy-storage density reaches 3.81 J/cm³ coupled with an energy efficiency of 84.7% when x=0.2. Meanwhile, the ceramic exhibits superior energy-storage stability in the temperature (20-200 ℃) and frequency (10-400 Hz) ranges. Moreover, a high-power density of 135 MW/cm³ and a fast charge-discharge speed of 89 ns are also achieved for ceramic with x=0.2. These results suggest the NBT-SST ceramic is a potential candidate material in energy-storage capacitor applications.
Ferroelectric barium titanate nanoparticles (BTO NPs) may play critical roles in miniaturized passive electronic devices such as multi-layered ceramic capacitors. While increasing experimental and theoretical understandings on the structure of BTO and doped BTO have been developed over the past decade, the majority of the investigation was carried out in thin-film materials; therefore, the doping effect on nanoparticles remains unclear. Especially, doping-induced local composition and structure fluctuation across single nanoparticles have yet to be unveiled. In this work, we use electron microscopy-based techniques including high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), integrated differential phase contrast (iDPC)-STEM, and energy dispersive X-ray spectroscopy (EDX) mapping to reveal atomically resolved chemical and crystal structure of BTO and strontium doped BTO nanoparticles. Powder X-ray diffraction (PXRD) results indicate that the increasing strontium doping causes a structural transition from tetragonal to cubic phase, but the microscopic data validate substantial compositional and microstructural inhomogeneities in strontium doped BTO nanoparticles. Our work provides new insights into the structure of doped BTO NPs and will facilitate the materials design for next-generation high-density nano-dielectric devices.
(Pb,La)(Zr,Sn,Ti)O3 (PLZST) antiferroelectric (AFE) materials have been widely investigated for advanced pulsed power capacitors because of their fast charge-discharge rates and superior energy-storage capacity. For practical applications, pulsed power capacitors require not only large energy density but also high energy efficiency, which are very difficult to achieve simultaneously. To address this problem, we herein investigate the energy-storage properties of PLZST AFE ceramics with a high Sn content by considering that the introduction of Sn can make the polarization versus electric-field (P-E) hysteresis loops slimmer. The results show that an optimum Sn content leads to the realization of both large recoverable energy density (Wre) and high energy efficiency (η) in a single material. With a Sn content of 46%, the PLZST AFE ceramic exhibits the best room-temperature energy storage properties with a Wre value as large as 3.2 J/cm³ and an η value as high as 86.5%. In addition, both its Wre and η vary very slightly in the wide temperature range of 20–120 °C. The high Wre and η values and their good thermal stability make the Pb0.97La0.02(Zr0.50Sn0.46Ti0.04)O3 AFE ceramic a promising material for making pulsed power capacitors usable in various conditions.
The high energy storage density reported in lead‐free AgNbO3 ceramics makes it a fascinating material for energy storage applications. The phase transition process of AgNbO3 ceramics plays an important role in its properties and dominates the temperature and electric field dependent behaviour. In this work, the phase transition behaviour of AgNbO3 ceramics was investigated by polarization hysteresis and dielectric tunability measurements. It is revealed that the ferrielectric (FIE) phase at room temperature possesses both ferroelectric (FE)‐like and antiferroelectric (AFE)‐like dielectric responses prior to the critical AFE‐FE transition point. A recoverable energy storage density of 2 J/cm³ was achieved at 150 kV/cm due to the AFE‐FE transition. Based on a modified Laudau phenomenological theory, the stabilities among the antiferroelectric, ferroelectric and ferrielectric phases are discussed, laying a foundation for further optimization of the dielectric properties of AgNbO3.
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Novel A-site deficient (1-x-y)Bi0.5Na0.5TiO3-xBaTiO3-yBi0.2Sr0.7TiO3 lead-free relaxor ferroelectrics have been explored for energy storage property. Particularly slim polarization hysteresis (P-E) loops are observed in 0.655Bi0.5Na0.5TiO3-0.065BaTiO3-0.28Bi0.2Sr0.7□0.1TiO3 (6.5BNBT-BST) at ambient temperature resulting in a giant recoverable energy density (Wrec = 1.5 J cm⁻³) and extremely high efficiency (η = 90%) at 100 kV cm⁻¹, which are closed related to the track of P-E loops. As the addition of Bi0.2Sr0.7TiO3 (BST) content, the ergodic relaxor phase becomes dominant with dynamic polar nano-regions attributed to the absence of ferroelectric domain in the relaxor phase. Furthermore, the recoverable energy density exhibits small variation in elevated temperature where the depressed polarization is compensated by almost hysteresis free loops (η up to 97%). The achievement of these characteristics in P-E loops provides that Bi0.2Sr0.7TiO3 tailoring by A-site vacancies is a potential route when designing new relaxor ferroelectrics for energy-storage applications.
Developing high-performance film dielectrics for capacitive energy storage has been a great challenge for modern electrical devices. Despite good results obtained in lead titanate-based dielectrics, lead-free alternatives are strongly desirable due to environmental concerns. Here we demonstrate that giant energy densities of ~70 J cm-3, together with high efficiency as well as excellent cycling and thermal stability, can be achieved in lead-free bismuth ferrite-strontium titanate solid-solution films through domain engineering. It is revealed that the incorporation of strontium titanate transforms the ferroelectric micro-domains of bismuth ferrite into highly-dynamic polar nano-regions, resulting in a ferroelectric to relaxor-ferroelectric transition with concurrently improved energy density and efficiency. Additionally, the introduction of strontium titanate greatly improves the electrical insulation and breakdown strength of the films by suppressing the formation of oxygen vacancies. This work opens up a feasible and propagable route, i.e., domain engineering, to systematically develop new lead-free dielectrics for energy storage.
Srx(Na0.5Bi0.5)1−xTi0.99Mn0.01O3 (x = 0.2, 0.4, 0.6, and 0.8) relaxor ferroelectric thin films were grown on Pt/Ti/SiO2/Si substrates by the Sol-Gel method. The influence of the Sr content on the microstructures, ferroelectric properties, and energy-storage performances of the thin films were investigated in detail. The Sr0.6(Na0.5Bi0.5)0.4Ti0.99Mn0.01O3 thin film exhibits very slim hysteresis loops with the highest electric breakdown field strength due to reduced oxygen vacancies. Owing to the high breakdown field strength of 3134.3 kV/cm, the Sr0.6(Na0.5Bi0.5)0.4Ti0.99Mn0.01O3 thin film shows a giant recoverable energy-storage density of 33.58 J/cm³. These results indicate that the Sr0.6(Na0.5Bi0.5)0.4Ti0.99Mn0.01O3 thin film is promising for applications of advanced capacitors with high energy-storage density.
Lead-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, dense bismuth ferrite (BF)-based, lead-free 0.75(Bi1-xNdx)FeO3-0.25BaTiO3 (BNxF-BT) ceramics and multilayers were fabricated. A transition from a mixed pseudocubic and R3c to a purely pseudocubic structure was observed as x increased with optimum properties obtained for mixed compositions. Highest energy densities, W ~ 4.1 J/cm3 and Wrec ~ 1.82 J/cm3 were achieved for BN15F-BT, due to the enhanced breakdown field strength (BDS ~ 180 kV/cm) and large maximum polarization (Pmax ~ 40 μC/cm2). Multilayers of this composition possessed both high Wrec of 6.74 J/cm3 and η of 77% and were stable up to 125 °C. Nd doped BF-based ceramics with enhanced BDS and large Wrec are therefore considered promising candidates for lead-free energy storage applications.
Understanding the dielectric breakdown behavior of polymer nanocomposites is crucial to the design of high-energy-density dielectric materials with reliable performances. It is however challenging to predict the breakdown behavior due to the complicated factors involved in this highly nonequilibrium process. In this work, a comprehensive phase-field model is developed to investigate the breakdown behavior of polymer nanocomposites under electrostatic stimuli. It is found that the breakdown strength and path significantly depend on the microstructure of the nanocomposite. The predicted breakdown strengths for polymer nanocomposites with specific microstructures agree with existing experimental measurements. Using this phase-field model, a high throughput calculation is performed to seek the optimal microstructure. Based on the high-throughput calculation, a sandwich microstructure for PVDF–BaTiO3 nanocomposite is designed, where the upper and lower layers are filled with parallel nanosheets and the middle layer is filled with vertical nanofibers. It has an enhanced energy density of 2.44 times that of the pure PVDF polymer. The present work provides a computational approach for understanding the electrostatic breakdown, and it is expected to stimulate future experimental efforts on synthesizing polymer nanocomposites with novel microstructures to achieve high performances.
Dielectric capacitors, although presenting faster charging/discharging rates and better stability compared with supercapacitors or batteries, are limited in applications due to their low energy density. Antiferroelectric (AFE) compounds, however, show great promise due to their atypical polarization-versus-electric field curves. Here we report our first-principles-based theoretical predictions that Bi 1 'x R x FeO 3 systems (R being a lanthanide, Nd in this work) can potentially allow high energy densities (100-150 J cm '3) and efficiencies (80-88%) for electric fields that may be within the range of feasibility upon experimental advances (2-3 MV cm '1). In addition, a simple model is derived to describe the energy density and efficiency of a general AFE material, providing a framework to assess the effect on the storage properties of variations in doping, electric field magnitude and direction, epitaxial strain, temperature and so on, which can facilitate future search of AFE materials for energy storage.
Antiferroelectric materials that display double ferroelectric hysteresis loops are receiving increasing attention for their superior energy storage density compared to their ferroelectric counterparts. Despite the good properties obtained in antiferroelectric La-doped Pb(Zr,Ti)O3 -based ceramics, lead-free alternatives are highly desired due to the environmental concerns, and AgNbO3 has been highlighted as a ferrielectric/antiferroelectric perovskite for energy storage applications. Enhanced energy storage performance, with recoverable energy density of 4.2 J cm(-3) and high thermal stability of the energy storage density (with minimal variation of ≤±5%) over 20-120 °C, can be achieved in Ta-modified AgNbO3 ceramics. It is revealed that the incorporation of Ta to the Nb site can enhance the antiferroelectricity because of the reduced polarizability of B-site cations, which is confirmed by the polarization hysteresis, dielectric tunability, and selected-area electron diffraction measurements. Additionally, Ta addition in AgNbO3 leads to decreased grain size and increased bulk density, increasing the dielectric breakdown strength, up to 240 kV cm(-1) versus 175 kV cm(-1) for the pure counterpart, together with the enhanced antiferroelectricity, accounting for the high energy storage density.
In this work, the effects of Zr⁴⁺ addition on the phase structure and energy storage properties of (Pb0.97La0.02)(ZrxSn0.945-xTi0.055)O3 (PLZST) antiferroelectric (AFE) ceramics were investigated, aiming to optimize the composition for enhanced energy storage properties. Due to the substitution of Zr⁴⁺ with larger ion radius for Sn⁴⁺, the tolerance factor of PLZST AFE ceramics decreased and thus the AFE state transformed gradually from tetragonal phase to orthorhombic phase with higher ferroelectric-antiferroelectric phase switching electric field (EA) with increasing Zr⁴⁺ content from x = 0.65 to 0.85. The increase of EA led to the improvement of recoverable energy density (Ure) from 3.18 J/cm³ (x = 0.65) to 4.38 J/cm³ (x = 0.8). However, when Zr⁴⁺ content was more than 0.8, the Ure decreased from 4.38 J/cm³ to 4.12 J/cm³ (x = 0.85) due to the reduction of the saturation polarization. The best energy storage properties were achieved in PLZST orthorhombic AFE ceramic with Zr⁴⁺ content of x = 0.8, which exhibited a maximum Ure of 4.38 J/cm³ and very small Ure variation (< 2.1%) in the range of 30–90 °C. The good temperature stability was attributed to the high Curie temperature of the ceramic which stabilized the AFE phase in a wide temperature range. The high energy storage density and good temperature stability demonstrate that (Pb0.97La0.02)(Zr0.8Sn0.145Ti0.055)O3 antiferroelectric ceramic is a promising material for developing high-performance pulse power capacitors usable in wide temperature range.
Large energy storage density (ESD) of 30.4 J/cm3 and high energy efficiency of 81.7% under electrical field of 3 MV/cm was achieved at room temperature by the fabrication of environment-friendly lead-free BaZr0.2Ti0.8O3 epitaxial thin films on Nb doped SrTiO3 (001) substrates by using radio frequency magnetron sputtering system. Moreover, the BZT film capacitors exhibit great thermal stability of the ESD from 16.8 J/cm3 to 14.0 J/cm3 with efficiency of beyond 67.4% and high fatigue endurance (up to 106 cycles) in wide temperature range from RT to 125 oC. Compared to other BaTiO3-based energy storage capacitor materials and even Pb-based systems, BaZr0.2Ti0.8O3 thin film capacitors show either high ESD or great energy efficiency. All these excellent results revealed that the BaZr0.2Ti0.8O3 film capacitors have huge potential in the application of modern electronic, such as locomotive and pulse power, in harsh working environment.
The demand for dielectric capacitors with higher energy-storage capability is increasing for power electronic devices due to the rapid development of electronic industry. Existing dielectrics for high-energy-storage capacitors and potential new capacitor technologies are reviewed toward realizing these goals. Various dielectric materials with desirable permittivity and dielectric breakdown strength potentially meeting the device requirements are discussed. However, some significant limitations for current dielectrics can be ascribed to their low permittivity, low breakdown strength, and high hysteresis loss, which will decrease their energy density and efficiency. Thus, the implementation of dielectric materials for high-energy-density applications requires the comprehensive understanding of both the materials design and processing. The optimization of high-energy-storage dielectrics will have far-reaching impacts on the sustainable energy and will be an important research topic in the near future.
Compared to conventional single-layered thin films, spatial organization of the polymer matrix and ceramic nanofillers into three-dimensional sandwich structures is a promising route to dielectric materials for enhanced energy storage properties (ESPs) that enable the dielectric capacitors for a number of applications in advanced electronic and electrical power systems. In this study, a systematic study of the sandwich-structured ceramic/polymer nanocomposites composed of pristine poly(vinylidene fluoride) (PVDF) as the middle layer and barium titanate (BT)/PVDF nanocomposites as two outer layers has been presented. Experimental results indicate that the ESP of the sandwich BT/PVDF composites, including breakdown strength, discharge efficiency, and energy density, can be significantly improved by tailoring the BT content. As verified by finite element simulations, the ESP of sandwich films is mainly governed by the electric field distribution owing to the introduction of high-dielectric-constant BT into the layered structures. The rational design of BT content leads to the electric field distribution capable of enhancing the dielectric strength and reducing the electrical conductivity for high energy density and improved discharge efficiency. An ultrahigh energy density of 16.2 J cm⁻³ has been achieved at the breakdown strength of 410 MV m⁻¹ in the optimized sandwich-structured nanocomposites. The understanding of the influence of filler content on electric field distribution achieved in this work provides a viable way for exploiting novel layered dielectrics with exceptional ESPs for energy storage devices.
The lead-free (1−x)Bi0.5Na0.5TiO3–xSrTiO3 antiferroelectric ceramics were synthesized by two-step sintering method. The influences of SrTiO3 contents, second sintering temperatures and soaking times on phase structure and energy-storage density were investigated in detail. As the content of SrTiO3 increases, the ceramics transform from rhombohedral ferroelectric phase into the tetragonal antiferroelectric phase (or pseudocubic phase). The appropriate soaking time and second sintering temperature are beneficial to obtain dense ceramics with fine homogeneous grains, whose the external breakdown electric field and maximum polarization have a large improvement. The optimum electrical performances with low remanent polarization (3.21 μC/cm²), a large maximum polarization (31.05 μC/cm²), and a large energy density (0.95 J/cm³) at 10 Hz were obtained at 1160 °C for BNT–35ST ceramics.
The development of electronic device towards integration, miniaturization and environmental friendliness has propelled much recent research of lead-free dielectric capacitors for energy storage, however, high energy-storage density is still an extremely challenging task for lead-free dielectric materials. Here, a novel lead-free relaxor ferroelectric (1-x)(Bi0.5Na0.5)TiO3-xBi(Ni0.5Zr0.5)O3 (NBT-xBNZ, x = 0-0.4) thick film (1μm) was fabricated by a water-based sol-gel method. BNZ dopant into the NBT host promoted the formation of polar nanoregions (PNRs), domain switching of which become easier, leading to an improved energy-storage performance. Surprisingly, an ultrahigh recoverable energy density of 50.1 J/cm3 and a high energy-storage efficiency of 63.9% under 2200 kV/cm were achieved simultaneously with x = 0.4, which are both more than 100% larger than those of the pure NBT sample. This excellent energy-storage performance can be perfectly comparable with that of lead-based films. Furthermore, the NBT-0.4BNZ thick film showed strong fatigue endurance after 6×107 cycles, and possessed good thermal and frequency stability. Pulsed discharge current waveform demonstrated that the NBT-0.4BNZ thick film showed a very fast discharge speed (210 ns).This study gives NBT-based materials an unexpected role as a lead-free family in the field of energy storage and could stimulate the design and fabrication of NBT-based dielectrics with ultrahigh energy-storage performance
New generation dielectric materials toward capacitive energy storage have been driven by the rise of high-power applications such as electric vehicles, aircraft, and pulsed power systems. Here we demonstrate remarkable improvements in the energy density and charge–discharge efficiency of the poly(vinylidene fluoride) (PVDF) upon the incorporation of core-satellite structures NaNbO3(NN)@polydopamine (PDA)@Ag nanowires. As compared to the NN NWs/PVDF, NN@PDA NWs/PVDF nanocomposites, the NN@PDA@Ag NWs/PVDF nanocomposites exhibit greatly enhanced energy density and significantly suppressed energy loss. As a result, the NN@PDA@Ag NWs/PVDF nanocomposite films with optimized filler content illustrate an excellent discharge energy density of 16.04 J cm-3 at 485 MV m-1, and maintain a high discharge efficiency of 62.8 %. Moreover, the corresponding nanocomposite films illustrate a superior power density of 2.1 MW cm-3 and ultra-fast discharge speed of 153 ns. Ultimately, the excellent dielectric and capacitive properties of the polymer nanocomposites could pave away for widespread applications in modern electronics and power modules.
Poor compatibility of polymer/ceramic composites used as high-pulse capacitors with high permittivity suffers from the reduced breakdown strength (Eb) and lowered energy density (Ue). Herein, mussels-inspired poly(dopamine) (PDA) modified BaSrTiO3 nanoparticle (mBST) and PVDF matrix are bonded together to fabricate nanocomposites with crosslinked 3D network and enhanced compatibility. The significantly improved Eb of 466 MV/m and the highest Ue of 11.0 J/cm3 for PVDF-based polymer/BST composites have been obtained. By comparing the properties of three series of composites with different structure, the contribution of ferroelectric relaxation, interface polarization and leakage conduction to the dielectric loss has been well addressed. Notably, the surface modification of BST with PDA could remarkably enhance the compatibility of the two components and structural homogeneity of the composite. The improved bonding between polymer matrix and filler chemically or physically is responsible for the reduced dielectric loss from both conduction loss and interfacial polarization, which is the key to improve the Eb, Ue and of the composite. It has been revealed that enhancing the homogeneity of the composites by modifying ceramics and constructing 3D networks between polymer matrix and filler might be a facile strategy to achieve high energy storage performance in polymer composite.
Excellent thermal stability with high energy storage density in ultra-wide range of temperatures is the extremely important property of capacitors for applications in cold polar regions, extreme altitudes and high temperature regions. Here, we report on designing and preparing the BaZr0.15Ti0.85O3/BaZr0.35Ti0.65O3 (BZT15/BZT35) multilayer thin film capacitors. Under a given total thickness, the energy storage performances of the multilayer films can be optimized by controlling the number of interfaces. For the capacitor with an optimum period number N = 6, the markedly enhanced breakdown strength and large dielectric constant are achieved, which leads to a giant energy storage density (Wre) of ~83.9 J/cm³ with the efficiency (η) of ~78.4% and a superior power density of 1.47 MW/cm³ at room temperature. Moreover, the N = 6 multilayer capacitor also exhibits ultra-stable Wre of 69.1 J/cm³ (efficiency: 84.9%) to 63.2 J/cm³ (efficiency: 66.9%) from − 100 °C to 200 °C and a good reliability in Wre and η even after 10⁶ cycles at 200 °C. The excellent performances demonstrate that the multilayer films are a promising material system to meet the wide requirements of future applications, ranging from portable electronics to hybrid electric vehicles and aerospace power electronics.
Lead-free 0.9BaTiO3-0.1(Bi0.9Na0.1)(In0.8Zr0.2)O3 (0.9BT-0.1BNIZ) ferroelectric relaxor ceramic was synthesized by solid-state reaction method. A dense microstructure and fine grain size was obtained with addition of BNIZ content. The dielectric behaviors indicated the dominance of ergodic relaxor phase. The 0.9BT-0.1BNIZ ceramic was found to possess an enhanced recoverable energy density (WR∼1.33 J/cm³) and efficiency (η∼88%) under 18 kV/mm at room temperature. What's more, WR is maintained ≥0.53 J/cm³ with η ≥ 94% under 10 kV/mm and the variation of WR is less than 15% over 25∼140 °C. The high stability of energy storage properties is mainly ascribed to the characteristics of ergodic relaxor phase. The stored energy was released in sub-microseconds (∼0.19 μs). The superior current density (CD∼796 A/cm²) and the power density (PD∼39.8 MW/cm³) were obtained simultaneously. The enhanced WR and the superior charge-discharge performances strongly demonstrate that the BT-based ceramics are promising candidates of high-power pulse capacitor applications.
New lead-free ferroelectric (0.94-x)Bi0.5Na0.5TiO3-0.06BaTiO3-xSrTi0.875Nb0.1O3 (BNBT-STN, x = 0 and 0.2) are synthesized by using a solid state reaction process. In this work, an obvious evolution of dielectric relaxation behavior and slim P–E hysteresis loops with high Pmax and low Pr is observed for BNBT-0.2STN, indicating the dominant of ergodic relaxor phase with dynamic polar nano-regions (PNRs). A relatively large recoverable energy density (Wrec = 1.17 J/cm³) with high energy efficiency (η = 91%) is obtained. Furthermore, it shows small variation (9%) in the temperature range of 30–150 °C and fatigue-free behavior, which can be attributed to the absence of ferroelectric domain in the relaxor phase. The achievement of these characteristics provides that tailoring by B-site vacancies is a potential route when designing a new energy-storage system for BNT-based relaxor ferroelectric materials.
Adding functional fillers is a simple but efficient way to improve the dielectric properties of polymer materials. However, the improvement of dielectric constant is usually accompanied with a decrease of breakdown strength (BDS), and vice versa, which results in only a limited increase of energy storage density of polymer composites. In this work, boron nitride nanosheets (BNNSs), the insulator with high theoretical BDS (800 kV/mm), were used to improve the dielectric properties of poly(vinylidene fluoride) (PVDF). To improve the dispersion of BNNSs and the interfacial interaction with PVDF matrix, the grafting of hydroxyl groups onto the surface of BNNSs was first carried out to obtain surface modified BNNSs (OH-BNNSs). Interestingly, the surface hydroxylation of BNNSs could realize a simultaneous enhancement both in BDS and dielectric constant. Therefore, a high energy storage density of 13.1 J·cm-3 has been achieved for PVDF/OH-BNNS nanocomposites with only 6 wt% filler content, which represents an impressive enhancement compared with neat PVDF (440%) or PVDF/BNNS (166%) nanocomposites. Moreover, the decreased dielectric loss tangent, improved thermal and mechanical properties of PVDF have also been obtained by adding OH-BNNSs. This research provides a new dimension of the surface modification of BNNSs and broadens their practical applications in the fields of dielectric energy storage.
Leed-free ferroelectric (1-x)(0.65Bi0.5Na0.5TiO3−0.35Bi0.1Sr0.85TiO3)-xKNbO3 (BNBST-xKN) ceramics were prepared by the conventional solid state sintering method. The dielectric, ferroelectric and energy-storage properties were systematically investigated. Temperature dependent permittivity curves showed the relaxation properties of BNBST ceramics enhanced with the increase of KNbO3. BNBST-15KN exhibited a high permittivity of 3484 and low dielectric loss of 0.003 at 150 °C. Furthermore, Δε/ε150 °C varied no more than 10% within the tmperature range of 30–297 °C, indicating an excellent dielectric temperature stability. The introduction of KNbO3 gave rise to a large Pm while P-E loops kept slim in shape. Therefore, the optimum energy-storage performance was realized in BNBST-15KN with an energy-storage density Wrec of 1.32 J/cm³ and energy-storage efficiency η of 82.5% at 95 kV/cm, accompanied with superior temperature stability and fatigue performance. The results demonstrated that BNBST-xKN system was a promising lead-free candidate for energy-storage applications.
Homogeneous (Na0.5Bi0.5)(1-x)BaxTi(1-y)SnyO3 ceramics were densified by a combination of cold isostatic pressing and microwave sintering (CIP&MS strategy) and their phase transition and ferroelectric properties were investigated. XRD analysis proves that the reaction between Na0.5Bi0.5TiO3 (NBT) and BaSnO3 (BSN) was suppressed by fast sintering when x<0.3. The grain size of homogeneous ceramic sample was about 1 μm and the uniform elements distribution was detected by EDS mapping when x0.3. The x=0.2 sample possesses a modest dielectric constant (~2000), low dielectric loss (tanδ < 0.015) and highly diffusive and dispersive relaxor-like behavior. The weakly polar phase gradually increases and the energy loss gradually decreases with BSN addition. When x=0.2, a high transparency in the visible spectra (∼50%) and the high discharge energy density (WD) of 2.347 J/cm3 were achieved as a result of high homogenous sample, meanwhile the Pm was as high as 35.75 μC/cm2. Then, a homogenization model was utilized to explain the produce of high energy storage properties.
Thin film ferroelectric capacitors (TFFCs) with excellent energy storage have attracted increasing attention due to the electronic devices toward miniaturization and integration. BiFeO3 (BF)/Bi3.25La0.75Ti3O12 (BL) based thin films are prepared by chemical solution deposition for energy storage. Ultrahigh energy storage with a recoverable energy density Ure of 54.9 J/cm³ and an efficiency η of 74.4% is observed in the bilayered BF/BL thin films. Further improvement of energy storage is realized in trilayered BL/BF/BL thin films with a Ure of 65.5 J/cm³ and an efficiency η of 74.2% at an electric field of 2753 kV/cm as well as excellent fatigue endurance up to 10⁹ cycles. The results suggest that BF/BL based thin films can be used as lead-free TFFCs in energy storage applications.
lead-free (0.8-x)SrTiO3-0.2Na0.5Bi0.5TiO3-xBaTiO3 ceramics (abbreviated as (0.8-x)ST-0.2NBT-xBT) were prepared by the conventional solid-state sintering method, and their crystal structure, dielectric properties, relaxor behavior and energy-storage property were investigated as a function of BT concentration. X-ray diffraction results reveal a pure perovskite structure with a pseudo-cubic phase. The dielectric measurements exhibit a relaxor behavior for all samples and the Tm gradually increases (from −49.67 °C to 67.91 °C) with increasing x. The pinched polarization-electric field (P-E) loops were observed in the samples with x ≤ 0.40 and the maximum polarization (Pm) increased from 11.37 μC/cm² to 20.79 μC/cm² at 8 kV/mm while x = 0.20–0.55. The maximum discharge energy-storage density (Jd) (1.78 J/cm³) is obtained in x = 0.35 ceramic with a relatively high Pm (29.19 μC/cm²) under an electric field of 17 kV/mm, which makes (0.8-x)ST-0.2NBT-xBT ceramics may be promising lead-free materials in practical high energy storage application.
Many applications, such as hybrid vehicles, pulsed power generators, and power factor correction, require capacitors of high energy density to reduce the size or weight of the related systems. For these applications, dielectric film capacitors are often used because of their fast discharge speed and high power density. The energy density of commercial available film capacitors is relatively low and cannot meet the demands for those applications. In the past decade, different polymer-based dielectric materials have been intensively investigated to improve the energy density of the materials. In this article, the progress in developing high energy density polymer-based dielectric materials will be reviewed, and the strategies to improve the energy density of dielectric polymers will be summarized and discussed. Because PVDF-based polymers possess relatively high dielectric properties and have been intensively studied for the energy storage applications, the discussion of this article will be mainly focus on the PVDF-based polymers and composites. An outlook for the future directions and problems that we will tackle to further improve the energy density of dielectrics will also be provided and discussed at the end of the article.
[0.9(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-0.1NaNbO3]-xZnO (NBT-BT-NN-xZnO, x=0, 0.5wt%, 1.0wt%, 1.5wt%, and 2.0wt%) ferroelectric ceramics were fabricated using a conventional solid-state reaction method. The effects of ZnO content on dielectric, energy-storage and discharge properties were systematically investigated. Dielectric constant and difference between maximum and remanent polarization were significantly improved by ZnO doping. Dielectric constant of NBT-BT-NN-1.0-wt% ZnO was 3218 at 1kHz and room temperature, i.e. one time bigger than that of pure NBT-BT-NN ceramic. As a consequence, a maximum energy-storage density of 1.27J/cm³ with a corresponding efficiency of 67% was obtained in NBT-BT-NN-1.0-wt% ZnO ceramic. Moreover, its pulsed discharge energy density was 1.17J/cm³, and 90% of which could be released in less than 300ns. Therefore, ZnO doped NBT-BT-NN ceramic with a large energy-storage density and short release time could be a potential candidate for applications in high energy-storage capacitors.
Multifunction alantiferroelectric (Pb0.92-xBa0.05La0.02Dyx)(Zr0.68Sn0.27Ti0.05)O3 multilayer ceramic capacitor (MLCC) was prepared successfully by the tape-casting method. The MLCC with ten thick layers exhibits compact structure, excellent energy-storage and strain properties. For energy-storage performance, the pulsed discharge current reveals that the stored energy can be released in a quite short time of about 600 ns. The maximum discharge energy density was obtained in the sample with x = 0.04 at 300 kV/cm, which was 3.8 J/cm³ calculated by the hysteresis loop and 2.7 J/cm³ by the pulsed discharge current, respectively. Meanwhile, the MLCC possesses large strain property, where the sample with x = 0.04 shows a high field-induced strain of 0.71% at room temperature. In addition, the temperature dependence of energy-storage and strain demonstrates that the MLCC has good temperature stability. The results indicate that the multifunctional MLCC can be a promising candidate for the application in energy and sensor fields.
The dielectric capacitor with high electric energy density is demanded for modern electronic and electrical power systems. However, their energy density is considerably limited by a low dielectric constant and low breakdown strength. Here, thin flexible polymer nanocomposites with high energy density are obtained by only adding a small loading of 2D monolayer titania along with concurrent improvements of dielectric constant and breakdown strength. This work not only first reveals that monolayer titania is an excellent filler that can be comparable to existing fillers in nanocomposite capacitors but also provides a facile approach to thin flexible compact dielectric films with ultrahigh energy density and breakdown strength for energy storage applications.
In this study, we present an effective strategy to enhance the energy storage properties of Ba0.4Sr0.6TiO3 (BST) lead-free ceramics by the addition of Bi2O3-B2O3-SiO2 (BBS) glass, which were prepared by the conventional solid state sintering method. The phase structure, microstructure and energy storage properties were investigated in detail. It can be found that the Ba0.4Sr0.6TiO3-x wt%(Bi2O3-B2O3-SiO2) (BST- x wt%BBS, 0≤x≤12) ceramics possess large maximum polarization (P max), low remanent polarization (Pr ) and slim polarization electric field (P