Dielectric Energy Storage Applications Research Articles

Langmuir–Blodgett assisted alignment of 2D nanosheets in polymer nanocomposites for high-temperature dielectric energy storage applications

The Langmuir–Blodgett deposition technique enables a precise in-plane alignment and a densely packed arrangement of CNO nanosheets within the PEI matrix, resulting in a significant enhancement of energy storage performance at 150 °C.

Synergistic modulation of ferroelectric polarization and relaxor behavior of Sr2NaNb5O15‐based tungsten bronze ceramic

AbstractDeveloping dielectric ceramics with high energy storage performance (ESP) is essential for miniaturizing and integrating high‐power pulse capacitors. Sr2NaNb5O15‐based tungsten bronze ferroelectric ceramics have been highly investigated for dielectric energy storage applications recently. However, the difficulty in concurrently obtaining large polarization and strong relaxor characteristics greatly hinders the ESP improvement. In this work, Bi3+ and Ti4+ ions were introduced into the Sr2NaNb5O15 ceramic, aiming to modulate the ferroelectric polarization and relaxor behavior synergistically. An excellent recoverable energy density (Wrec ∼ 4.08 J/cm3) and a high efficiency (η ∼ 84.59%) were concurrently attained in the Sr1.85Bi0.15NaNb4.85Ti0.15O15 composition due to the boosted polarization and enhanced relaxor nature. Moreover, this ceramic also exhibited a high current density (863.06 A/cm2) and a large power density (94.94 MW/cm3). All these characteristics demonstrate that the Bi3+ and Ti4+ ions co‐doped Sr2NaNb5O15 ceramics possess great potential for dielectric capacitor applications.

Enhanced energy storage performance in Bi(Mg1/3Zn1/3Ta1/3)O3-doped (K1/2Na1/2)NbO3 high-entropy ceramics

Environmentally friendly high-performance dielectric capacitors are urgently required for clean energy and advanced pulse equipment. In this study, a high-entropy strategy was adopted to design (1−x)(K1/2Na1/2)NbO3-xBi(Mg1/3Zn1/3Ta1/3)O3 (KNN-BMZT) ceramics for energy storage applications. The phase compositions, dielectric properties, and energy storage performances of the KNN-BMZT ceramics were explored. The results demonstrated that all the ceramic samples exhibited a single perovskite phase with a pseudo-cubic structure and compact microstructure. More importantly, the addition of BMZT increased the disorder and configurational entropy, resulting in the formation of KNN-based high-entropy relaxor ferroelectrics. Moreover, 0.84KNN–0.16BMZT ceramic demonstrated the optimal energy storage performance, exhibiting a recoverable energy density (Wrec) of 2.72 J/cm3 and an energy storage efficiency (η) of 81.77% when an electric field of 335 kV/cm was applied. Furthermore, this ceramic exhibited an excellent temperature stability (30–135 °C) and frequency insensitivity (10–500 Hz). These results demonstrate that the 0.84 KNN–0.16 BMZT ceramic is a promising candidate for dielectric energy storage applications.

Bismuth layer-structured Bi4Ti3O12-CaBi4Ti4O15 intergrowth ferroelectric films for high-performance dielectric energy storage on Si substrate

Bismuth layer-structured ferroelectrics (BLSFs) have shown a great design capability for electrical energy storage, due to a highly anisotropic lattice and dielectric property. In this work, we add another notch to their qualifications as high energy density dielectrics, by demonstrating an ultrahigh recyclable energy density (Wrec ∼ 151.1 J/cm3 @ 4 MV/cm) and a good energy efficiency (η ∼ 72.0%) in Bi4Ti3O12-CaBi4Ti4O15 intergrowth ferroelectric films integrated on Si. This performance was achieved by the combination of a high spontaneous polarization (Ps) of the intergrown superlattice, and a polycrystalline nanograin microstructure. The high Ps is obtained through design of a special lattice, which determines the up limit of the energy density. On the other hand, the nanograin structure corresponds to a reduce remnant polarization, an intermediate dielectric constant and a delayed polarization saturation, all are ideal features for achieving a high recyclable energy density and energy efficiency. Such a structure is the consequence of a limited grain growth under the effect of a buffer layer. Lastly, a remarkable fatigue-resistance and an excellent charge-retaining ability were exhibited by these lead-free BLSF films. We expect this work will pave the way for designing high performance bismuth layer-structured ferroelectric films targeted for dielectric energy storage applications.

Design and energy storage performance of (Bi0.4K0.2Na0.2Ba0.2)TiO3- Sr(Mg1/3Ta2/3)O3 high-entropy Relaxor ceramics

Designing perovskite ceramics using high-entropy strategies provide new opportunities for the development of high-performance dielectric energy storage materials. However, only a few studies have been reported in this area so far. In this study, novel high-entropy perovskite ceramics have been designed for the (1-x)(Bi0.4K0.2Na0.2Ba0.2)TiO3–xSr(Mg1/3Ta2/3)O3 system by considering various synergistic effects. The structures and properties of the ceramics were systematically studied. The results showed that the ceramics exhibited strong relaxation behavior and excellent energy storage performance. The ceramic with x = 0.12 had a recoverable energy density of 3.40 J/cm3 and an energy storage efficiency of 86.3% under a medium electric field of 290 kV/cm. The results also showed that the ceramic exhibited outstanding thermal stability, frequency stability, fatigue resistance, and good reliability. The results suggest that ceramics are potential candidates for dielectric energy storage applications in low-to-medium electric fields.

2D‐Nanofiller‐Based Polymer Nanocomposites for Capacitive Energy Storage Applications

High‐energy‐density storage devices play a major role in modern electronics from traditional lithium‐ion batteries to supercapacitors for a variety of applications from rechargeable devices to advanced military equipment. Despite the mass adoption of polymer capacitors, their application is limited by their low energy densities and low‐temperature tolerance. Polymer nanocomposites based on 2D nanomaterials have superior capacitive energy densities, higher thermal stabilities, and higher mechanical strength as compared to the pristine polymers and nanocomposites based on 0D or 1D nanomaterials, thus making them ideal for high‐energy‐density dielectric energy storage applications. Here, the recent advances in 2D‐nanomaterial‐based nanocomposites and their implications for energy storage applications are reviewed. Nanocomposites based on conducting 2D nanofillers such as graphene, reduced graphene oxide, MXenes, semiconducting 2D nanofillers including transition metal dichalcogenides such as MoS2, dielectric 2D nanofillers including hBN, Mica, Al2O3, TiO2, Ca2Nb3O10 and MMT, and their effects on permittivity, dielectric strength, capacitive energy density, efficiency, thermal stability, and the mechanical strength, are discussed. Also, the theory and machine‐learning‐guided design of polymer 2D nanomaterial composites is learnt and the challenges and opportunities for developing ultrahigh‐capacitive‐energy‐density devices based on these nanofiller polymer composites are presented.

Nanofiber-reinforced polymer nanocomposite with hierarchical interfaces for high-temperature dielectric energy storage applications

Flexible polymer nanocomposites reinforced by high-dielectric-constant ceramic nanofillers have shown great potential for dielectric energy storage applications in advanced electronic and electrical systems. However, it remains a challenge to improve their energy density and energy efficiency at high temperatures above 150°C. Here, we report a nanofiber-reinforced polyetherimide nanocomposite employing BN-BaTiO3 heterogeneous nanofibers as fillers, where the BN nanoparticles were embedded inside BaTiO3 nanofibers to create BN/BaTiO3/PEI hierarchical interfaces. The high dielectric constant and the geometric large aspect ratio of the BN-BaTiO3 heterogeneous nanofibers lead to simultaneously increased dielectric constant and breakdown strength of the nanocomposite over a broad temperature range. In particular, the emerging hierarchical BN/BaTiO3/PEI interfaces enable promoted density and energy level of traps for the mobile charges, which further suppresses the conduction loss and improves the breakdown strength under high temperatures, as confirmed by a combination of thermally stimulated depolarization current measurement and phase-field simulation. Finally, the nanocomposite with hierarchical interfaces boosts an ultrahigh energy density of 5.23 J cm−3 with an energy efficiency of > 90% at 150°C, which is the highest energy density reported so far in nanofiber-reinforced polymer nanocomposites and also outperforms most nanocomposites counterparts dispersed with nanoparticles and nanosheets. Our work demonstrates hierarchical interface engineering as an effective strategy to promote the high-temperature energy storage performance of fiber-reinforced polymer nanocomposites, which is of significance for their applications in high-temperature harsh conditions.

Enhanced dielectric and energy storage properties of P(VDF-HFP) through elevating β -phase formation under unipolar nanosecond electric pulses

Structural manipulation of electroactive β-phase of poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] is of great importance in high-energy-density polymer devices. In this Letter, an efficient way to improve dielectric and energy storage properties of P(VDF-HFP) films by inducing a high β-phase content and lowering the crystallite size through repetitive unipolar nanosecond electric pulses (nsEP) is proposed. It is found that the percentage of the β-phase in P(VDF-HFP) can be significantly enhanced to ∼84% under a low unipolar nsEP of 5 V/mm vs only 35% in pristine P(VDF-HFP). Meanwhile, the orientation of the amorphous chains is also achieved, which improves the dielectric constant, electric breakdown, and energy storage properties of P(VDF-HFP). Specifically, the P(VDF-HFP) film processed under nsEP of 5 V/mm exhibits a high breakdown field of 541 MV/m, and discharged energy density of 14 J/cm3, which is 28.8% and 127% higher than those of the pristine polymer, respectively. This work provides a facile approach to optimize the crystalline morphology of P(VDF-HFP) polymers for dielectric energy storage applications.

Comparative studies of relaxor-ferroelectric Pb0.92La0.08(Zr0.52Ti0.48)O3 thin films deposited by pulsed laser deposition and sol-gel spin coating

In this study, the energy storage properties of relaxor Pb0.92La0.08(Zr0.52Ti0.48)O3 (PLZT) thin films grown on Pt/Si substrates using pulsed laser deposition (PLD) and sol-gel methods were investigated. The PLZT thin films deposited by PLD possessed a columnar growth microstructure and mixed orientations of (100) and (110) while a dense microstructure and preferred orientation of (100) were achieved by sol-gel deposition. Although the electric breakdown strength (EBD) of the sol-gel-deposited PLZT thin films (EBD=2200 kV/cm) was slightly higher than that of the films deposited using PLD (EBD=2100 kV/cm), the PLD-deposited PLZT thin films had a larger recoverable energy storage density (Ureco) and energy storage efficiency (η), which can be explained by its slimmer polarization loop, higher maximum polarization, and lower remanent polarization. At corresponding EBD values, the Ureco and η values were 33.2 J/cm3 and 67.5% for the PLD-deposited films and 27.5 J/cm3 and 62.2% for the sol-gel-deposited films. Although the sol-gel-deposited PLZT thin films had lower energy storage performance, the sol-gel method remains a promising method for the fabrication of thin films for dielectric energy storage applications due to its unique advantages of low fabrication cost, simple preparation process, and easy control of chemical composition.

Enhancing Comprehensive Energy Storage Properties in Tungsten Bronze Sr0.53Ba0.47Nb2O6-Based Lead-free Ceramics by B-Site Doping and Relaxor Tuning.

Dielectric ceramics with relaxor characteristics are promising candidates to meet the demand for capacitors of next-generation pulse devices. Herein, a lead-free Sb-modified (Sr0.515Ba0.47Gd0.01) (Nb1.9-xTa0.1Sbx)O6 (SBGNT-based) tungsten bronze ceramic is designed and fabricated for high-density energy storage capacitors. Using a B-site engineering strategy to enhance the relaxor characteristics, Sb incorporation could induce the structural distortion of the polar unit BO6 and order-disorder distribution of B-site cations as well as the modulation of polarization in the SBGNT-based tungsten bronze ceramic. More importantly, benefiting from the effective inhibition of abnormal growth of non-equiaxed grains, Sb introduction into SBGNT-based ceramics could effectively suppress the conductivity and leakage current density, enhancing the breakdown strength, as proved by the electrical impedance spectra. Consequently, a remarkable comprehensive performance via balancing recoverable energy density (∼3.26 J/cm3) and efficiency (91.95%) is realized simultaneously at 380 kV/cm, which surpasses that of the pristine sample without the Sb dopant (2.75 J/cm3 and 80.5%, respectively). The corresponding ceramics display superior stability in terms of fatigue (105 cycles), frequency (1∼200 Hz), and temperature (20∼140 °C). Further charge-discharge analysis indicates that a high power density (89.57 MW/cm3) and an impressive current density (1194.27 A/cm2) at 150 kV/cm are achieved simultaneously. All of the results demonstrate that the tungsten bronze relaxors are indeed gratifying lead-free candidate materials for dielectric energy storage applications.

Realizing enhanced energy density in ternary polymer blends by intermolecular structure design

Polymer nanocomposites have been extensively studied for dielectric energy storage applications, however, the relatively low breakdown strength due to inevitable defects and voids limits themselves in the development of the high energy density capacitors while large-scale manufacturing. Herein, we propose a facile strategy to improve the breakdown strength and thus energy density by synergistically designing the intermolecular structure in a ternary polymer blend composed of poly(methyl methacrylate), poly(vinylidene fluoride), and poly(vinylidene fluoride-hexafluoropropylene). We show that the appropriate quenching temperature can decrease crystal size and increase the fraction of the amorphous phase. Meanwhile, by designing the mass ratio of the ferroelectric poly(vinylidene fluoride) and poly(vinylidene fluoride-hexafluoropropylene), it will successfully introduce the intermolecular interaction, which stabilizes the γ-phase in ferroelectric polymers and leads to dense chain packing. All the phenomena contribute to the ultrahigh breakdown strength (850 MV/m), and the optimized blend exhibits a record high discharged energy density of 30 J/cm3. Of particular importance is that a large-area dielectric film with high property uniformity can be fabricated, demonstrating that the proposed design approach can be used as a general technology for mass production.

NaNbO3 modified BiScO3-BaTiO3 dielectrics for high-temperature energy storage applications

Among the lead-free compositions identified as potential capacitor materials, BiScO3-BaTiO3 (BS-BT) relaxor dielectrics exhibit good energy storage performance. In this research, 0.4BS-0.6BT is considered as the parent composition, with NaNbO3 (NN) addition intended to substitute the A and B site cations. The NN modified BS-BT ceramics exhibit excellent temperature stability in terms of their dielectric properties, with the room-temperature dielectric constant on the order of 500–1 000 and variation less than 10% up to 400 °C. In addition, NN has a high band-gap energy leading to increased breakdown strength and energy storage properties in modified compositions. The highest breakdown strength was achieved for 0.4BS-0.55BT-0.05NN, being on the order of 430 kV/cm, and a high energy density of 4.6 J/cm3 with high energy efficiency of 90% was simultaneously achieved. Of particular importance is that the variation of the energy density was below 5% due to the temperature-insensitive dielectric constant, while ∼90% energy efficiency was retained over the temperature range of 25–160 °C. The improved temperature stability with NN addition makes this composition promising for high temperature capacitor and dielectric energy storage applications.

Improved dielectric and energy storage properties of polymer composites with BNNSs/AgNPs hybrid nanofiller

ABSTRACT The development of polymer nanocomposites with superior dielectric performances is critical for flexible capacitive energy storage applications. However, the common approach to fabricate polymer composites with high-dielectric-constant ceramics as fillers always bring about exaggerate dielectric losses, hence low energy density and energy efficiency of polymer composites. In this work, BNNSs/AgNPs nanohybrids, where Ag nanoparticles were deposited on the surface of boron nitride nanosheets (BNNSs), are employed as fillers for poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) based nanocomposites. The contributions by enhanced interface polarisation and the internal barrier layer capacitor (IBLC) effect generated by the uniform distribution of conductive Ag nanoparticles on the insulative BNNSs, result in a large increase in dielectric constant and electric displacement meanwhile simultaneously suppressed dielectric losses. The BNNSs/AgNPs/PVDF-HFP nanocomposites exhibit much higher energy density and energy efficiency than the pristine PVDF-HFP and the BNNSs/PVDF-HFP composites counterparts, being great potential for dielectric energy storage applications.

Tailoring the polarity of polymer shell on BaTiO3 nanoparticle surface for improved energy storage performance of dielectric polymer nanocomposites

Nanocomposites comprising flexible polymers and high dielectric constant inorganic nanoparticles are considered to be one of the promising candidates for electrostatic capacitor dielectrics. However, the effect of interfacial property on electrical energy storage of dielectric polymer nanocomposites is still not clear. Herein, the role of the polarity of the interfacial region is investigated. For this purpose, three polymers with different polarity, polymethyl methacrylate (PMMA), polyglycidyl methacrylate, and polymethylsulfonyl ethyl methacrylate (PMSEMA) are attached onto BaTiO3 (BT) nanoparticle surface via surface-initiated reversible addition-fragmentation chain transfer polymerization. It is found that the polarity of shell polymers shows an apparent effect on the dielectric and energy storage of dielectric polymer nanocomposites. For example, PMSEMA@BT (shell polymer possesses the highest polarity) increases dielectric loss and decreases the breakdown strength of the nanocomposites, leading to lower energy storage capability. However, PMMA@BT (shell polymer possesses the lowest polarity) can induce higher breakdown strength of the nanocomposites. As a result, the PMMA@BT nanocomposite exhibits the highest electrical energy storage capability among the three nanocomposites. This research provides new insight into the design of core-shell nanofillers for dielectric energy storage applications.

Ferroelectric polymers and their nanocomposites for dielectric energy storage applications

Dielectric capacitors deliver the highest power density and operating voltage among known energy storage devices that are integrable in modern electronic and electrical systems. Ferroelectric polymers are promising dielectric energy storage media for film capacitors due to their superiority in excellent dielectric properties, high breakdown strength, and flexibility. Polymer-based nanocomposites by incorporating high-dielectric-constant nanofillers into the ferroelectric polymer matrix exhibit great potential for superior energy storage performances. This Perspective focuses on the development and progress of high-energy-density ferroelectric polymers and their nanocomposites. First, approaches are proposed to tune the ferroelectric hysteresis for suppressed dielectric and energy losses in ferroelectric polymers, which is the premise to achieve high energy density and high efficiency. Second, the energy storage properties of ferroelectric nanocomposites greatly depend on multiple factors such as nanofiller features, polymer/filler interfaces, and spatial composite structures, and effective strategies enabling enhancements of the dielectric constant and breakdown strength in nanocomposites are discussed. In the last part, some existing challenges and future perspectives are proposed to develop high-energy-density ferroelectric polymer-based materials for energy storage applications.

Enhanced energy storage density in Ca and Ta co‐doped AgNbO3 antiferroelectric ceramics

AbstractCa and Ta co‐doped AgNbO3 antiferroelectric lead‐free ceramics were fabricated by rolling process technique, and improved energy storage properties were obtained. X‐ray diffraction and Raman spectra indicate a single perovskite structure for (Ag1‐2xCax)(Nb1‐xTax)O3 ceramics. The dielectric performances were also investigated, showing that increasing the content of Ca and Ta from 0.1 to 5 mol% gradually decreased the temperatures of the phase transition of monoclinic M1‐M2 and M2‐M3. This proved the enhanced antiferroelectricity stability associated with the enlarged low temperature phase transition region. The obtained (Ag0.90Ca0.05)(Nb0.95Ta0.05)O3 ceramics exhibit an enhanced recoverable energy storage density (3.36 J/cm3) and efficiency (58.3%) with good temperature and frequency stability. The same composition shows excellent charge and discharge properties with a discharge current as high as 91.5 A and fast discharge speed (150 ns discharge period). All these merits demonstrate that AgNbO3‐based antiferroelectric ceramics are competitive with other lead‐based and lead‐free dielectric capacitors, which are promising candidates for dielectric energy storage applications.

Lead-free antiferroelectric AgNbO3: Phase transitions and structure engineering for dielectric energy storage applications

The development of electronic materials for storing electrical energy is a thriving research field, where the materials used in batteries, supercapacitors, and dielectric capacitors have attracted extensive interest in last decades. The dielectric capacitors showing unique characteristics such as high power density and large charge/discharge rate have been actively studied, where the antiferroelectrics demonstrate great potentials for dielectric energy storage applications by storing and releasing energy upon a reversible electric-field induced antiferroelectric–ferroelectric phase transition. Recently, lead-free antiferroelectric AgNbO3 has emerged as a promising candidate to substitute conventional lead-based antiferroelectrics (such as PbZrO3) in energy storage applications. The phase transition dynamics of AgNbO3 is driven by a complex sequence of oxygen octahedron tilting orders in addition to cation displacement, which can be effectively engineered by a doping strategy. In this article, we present a succinct overview of the phase transition mechanisms in AgNbO3-based ceramics and describe how the phase transition characteristics are affected by the dopants. By exploring the composition related average structure and local structural evolutions, we provide a view toward the goal of establishing a link between the phase transition and physical properties tailored for dielectric energy storage applications.

Enhanced Energy Storage Performance of Sodium Niobate-Based Relaxor Dielectrics by a Ramp-to-Spike Sintering Profile.

Sodium niobate (NaNbO3)-based lead-free ceramics have been actively studied for energy storage applications because of their antiferroelectric and/or relaxor features achieved in modified systems. The P-E loops of NaNbO3-based ceramics are usually hysteretic because of the existence of a metastable ferroelectric phase at room temperature. In this study, by introducing aliovalent cations and A-site vacancies, the relaxor characteristics are greatly enhanced in (Na1-2xBix)(Nb1-xZrx)O3 ceramics, leading to a high energy storage efficiency of above 90%. In addition, sintering aid CuO and a special ramp-to-spike sintering profile were employed to decrease the sintering temperature and reduce the grain size. The modified ceramic exhibits improved insulating properties and hence a higher breakdown strength, leading to a high recoverable energy density of 4.9 J/cm3 and a high energy efficiency of 88% at 430 kV/cm. The ceramic also exhibits satisfactory temperature stability over a wide temperature range from 25 to 125 °C and charge-discharge performance, making it a promising candidate for high-power dielectric energy storage applications.

Novel Ca doped Sr0.7Bi0.2TiO3 lead-free relaxor ferroelectrics with high energy density and efficiency

Sr0.7Bi0.2TiO3 with high relaxor behavior and energy storage efficiency (η) is expected to be applied in power energy storage capacitors. However, its energy storage density is limited by the relatively low dielectric breakdown strength (DBS). Herein, Sr0.7Bi0.2CaxTiO3 (SBT-xC, x = 0 ∼ 0.15) was prepared to decrease the average grain size of Sr0.7Bi0.2TiO3. This can effectively eliminate the oxygen vacancy and decrease the electrical conductivity and leakage current, which result in the enhanced DBS. Meanwhile, Ca doping increases the relaxor behavior and dielectric constant. When x = 0.1, the composition exhibits high DBS of 480.2 kV/cm and excellent energy storage properties, such as high energy storage density of 2.1 J/cm3 with high η of 97.6 % at 290 kV/cm, considerable thermal stability and great frequency stability. Moreover, SBT-0.1C shows high power density of 50.1 MW/cm3. These results suggest that SBT-0.1C is a potential candidate for high performance dielectric energy storage applications.

Optimizing electric field distribution via tuning cross-linked point size for improving the dielectric properties of polymer nanocomposites.

Polymer nanocomposites containing high K ceramics have been developed for boosting the energy density of dielectric capacitors. However, there are numerous challenges in the research about how to optimize the electric field distribution and improve the interfacial structure of nanocomposites for overcoming dielectric mismatches between high K nanofillers and low K polymers. Herein, all-chemical bonding cross-linked nanocomposites were designed and nano-BT with different sizes were regarded as cross-linked points rather than a free dispersed phase in polymers. In addition, the cross-linking degree could be controlled by changing the nano-BT sizes. 60 nm BT-BCB@DPAES nanocomposites possess the most excellent mechanical and thermal properties as well as the highest theoretical breakdown strength. In fact, 100 nm BT-BCB@DPAES nanocomposites have the most perfect dielectric performance combined with the experimental data and finite element simulation, particularly at 150 °C, the highest breakdown strength of 442 MV m-1 and greatest discharged energy density of 3.1 J cm-3 were obtained. This is attributed to the proper cross-linking degree and uniform electric field distribution. Overall, this kind of cross-linked structure can effectively enhance dielectric performance, particularly at elevated temperatures. This provides an idea for developing high temperature polymer nanocomposites for dielectric energy storage applications.