Recoverable Energy Research Articles

Effect of rare earth oxides on the energy storage performance of Sr0.7Bi0.2TiO3 ceramics

In this study, Sr0.7Bi0.2TiO3 (SBT) ceramics doped with Y2O3, Dy2O3 and Gd2O3 rare earth oxides were designed and prepared by the conventional solid-state reaction method. The results show that all ceramics exhibit typical relaxor ferroelectric behavior, and the breakdown strength (BDS) of SBT ceramics is improved. Among them, Sr0.7Bi0.15Y0.05TiO3 ceramics demonstrate excellent energy storage performance, with a high recoverable energy density (Wrec ) of 2.4 J/cm3 and an efficiency (η) of 88.1% under 290 kV/cm. Furthermore, Y2O3-doped SBT ceramics exhibit a rapid discharge speed of 0.05 µs and a high power density (PD ) of 144.1 MW/cm3 under 300 kV/cm in charge-discharge tests. These characteristics have significant potential in pulse power applications.

Enhanced energy-storage density in (Pb0.98La0.02)(Zr0.45-xSn0.55Hfx)0.995O3 antiferroelectric ceramics

Antiferroelectric ceramics with unique characteristics of electric-field-induced antiferroelectric to ferroelectric phase transitions and ultra-fast charging-discharging rate, which are demanded in high pulse power devices. In this work, (Pb0.98La0.02)(Zr0.45-xSn0.55Hfx)0.995O3 (PLZSH) antiferroelectric ceramics with x = 0∼0.20 were prepared via a conventional solid-state reaction approach. Incommensurate modulation structure with a 1/n<110> superlattice was observed in AFE at room temperature, which was associated with the unique domain boundaries, contributing the obvious declined AFE-FE phase transition electric field as well as the enhanced energy storage density. It was also observed that the maximum recoverable energy storage density (Wrec) increases from 2.93 J/cm3 (x = 0) to 5.72 J/cm3 (x = 0.15), and the corresponding energy-storage efficiency uprises from 82.4 % to 87.8 % with the increasing x at 280 kV/cm. The superior energy density and efficiency indicate that the obtained PLZSH antiferroelectric ceramics are promising for practical applications in pulse power devices.

High energy storage of PbZrO3 antiferroelectric thin films via constructing phase composition

In this paper, we fabricated PbZrO3 (PZ) thin films by the way of sol–gel spin on LaNiO3 buffered SiO2/Si substrates, and annealed them at different given temperatures by rapid thermal annealing (RTA). By controlling annealing temperature, PZ thin films showed different microstructures and phase compositions, whose impact of electrical properties and energy storage performance were researched. According to the research findings, the phase composition of film presents a general rule with the decrease of annealing temperature: PZ thin films crystallize into perovskite phase, pyrochlore phase, and amorphous phase. The films annealed at 620 °C crystallized into a state of coexistence of pyrochlore phase and perovskite phases, which also show moderate recoverable energy density and the highest energy storage efficiency (8.7 J cm−3 and 93.1%). This energy storage performance can be attributed to the synergistic effect of high electric breakdown strength of dense pyrochlore phase structure and high maximum polarization of perovskite phase. The findings of this paper help to explain the influence of pyrochlore phase on the energy storge performance of thin films. Thus, it is useful way to improve the energy storage performance of thin films.

Quasi-static piezoelectric strain and recoverable energy at a low biased field in Sr2+ substituted electrostrictive BZT ceramic

Quasi-static piezoelectric strain and recoverable energy at a low biased field in Sr2+ substituted electrostrictive BZT ceramic

Achieving high energy storage performance in Na0.5Bi0.5TiO3‒based ceramics via Li+ substitution

In the search for dielectric material with high energy storage density, a ceramic system of 0.8Na0.5Bi0.5TiO3–0.2K1-xLixTaO3 (NBT-KLT-x, x = 0.1–0.5) is proposed in this work. The addition of Li2CO3 is conducive to the decrease of sintering temperature of ceramics. Moreover, the XRD diffraction data of sintered ceramics indicate that pure perovskite phase showing the pseudo-cubic structure can be achieved when x = 0.1–0.3 while the excessive addition of Li2CO3 leads to the formation of pyrochlore phase. Based on the Rietveld refinement and Raman results, the Li+ doping in the NBT-KLT-x solid solutions (x = 0.1–0.3) can improve the phase content of P4bm, induce the lattice expansion and structural change towards a higher-symmetry phase. TEM observation also demonstrates the reduction in the size of polar nanoregions. With increasing x from 0.1 to 0.5, both the oxygen vacancy concentration and grain size display a tendency to decrease first and then increase. For the x = 0.2 ceramics with the lowest oxygen vacancy concentration and grain size, the largest electrical breakdown strength and lowest polarization hysteresis are achieved, giving an excellent recoverable energy storage density of 4.86 J/cm3 under 32 kV/mm, accompanied by a high efficiency of 90.46 %. Additionally, the recoverable energy density achieves a high level of ∼3.5 J/cm3 and energy storage efficiency is larger than 80 % over 28–160 °C, suggesting the outstanding temperature stability.

Concurrent existence of magneto-electric coupling and electro-optic Kerr effect in perovskite-based ternary composites for energy reservoirs

Multiferroics, specifically magneto-electric materials that couple the ferroelectric and ferromagnetic responses, have boosted researchers' interest in fabricating energy storage devices. For this purpose, we synthesized the perovskite-based triphasic composites using sol–gel auto- combustion and solid–state reaction route. The presence of pure perovskite phases and lattice parameters were noted by X-ray diffraction analysis. Further, Rietveld’s refinement confirmed the precision of phase analysis with a high degree of goodness of fit. The homogenous and uniform growth of grains for 0.1BiFeO3 + 0.7BaTiO3 + 0.2Nd0.5Dy0.5MnO3 composite was seen by field emission scanning electron microscope and scanning transmission electron microscope. The perfect match between empirical elemental composition and prepared composites was determined by energy-dispersive X-ray spectroscopy. The highest remanent, maximum polarization, recoverable energy density, and ferroelectric efficiency were observed for the composite mentioned above. Furthermore, mathematical modeling via Python was carried out with ferroelectric data, and a mathematical relation was derived between the electric field and dielectric constant to observe the electro-optic Kerr effect. Similarly, the above-mentioned composite was seen with the highest coercive field, remanent, and maximum magnetization by M–H loops. Finally, the variation in polarization by changing the magnetic field confirmed M-E coupling and declared this 0.1BiFeO3 + 0.7BaTiO3 + 0.2Nd0.5Dy0.5MnO3 triphasic composite as best candidate for energy storage devices.

Outstanding Energy-Storage Density Together with Efficiency of above 90% via Local Structure Design.

Dielectric ceramic capacitors with high recoverable energy density (Wrec) and efficiency (η) are of great significance in advanced electronic devices. However, it remains a challenge to achieve high Wrec and η parameters simultaneously. Herein, based on density functional theory calculations and local structure analysis, the feasibility of developing the aforementioned capacitors is demonstrated by considering Bi0.25Na0.25Ba0.5TiO3 (BNT-50BT) as a matrix material with large local polarization and structural distortion. Remarkable Wrec and η of 16.21 J/cm3 and 90.5% have been achieved in Bi0.25Na0.25Ba0.5Ti0.92Hf0.08O3 via simple chemical modification, which is the highest Wrec value among reported bulk ceramics with η greater than 90%. The examination results of local structures at lattice and atomic scales indicate that the disorderly polarization distribution and small nanoregion (∼3 nm) lead to low hysteresis and high efficiency. In turn, the drastic increase in local polarization activated via the ultrahigh electric field (80 kV/mm) leads to large polarization and superior energy storage density. Therefore, this study emphasizes that chemical design should be established on a clear understanding of the performance-related local structure to enable a targeted regulation of high-performance systems.

Ultrahigh Energy Storage in Tungsten Bronze Dielectric Ceramics Through a Weakly Coupled Relaxor Design.

Dielectric energy-storage capacitors, known for their ultrafast discharge time and high-power density, find widespread applications in high-power pulse devices. However, ceramics featuring a tetragonal tungsten bronze structure (TTBs) have received limited attention due to their lower energy-storage capacity compared to perovskite counterparts. Herein, a TTBs relaxor ferroelectric ceramic based on the Gd0.03 Ba0.47 Sr0.485-1.5 x Smx Nb2 O6 composition, exhibiting an ultrahigh recoverable energy density of 9 J cm-3 and an efficiency of 84% under an electric field of 660kV cm-1 is reported. Notably, the energy storage performance of this ceramic shows remarkable stability against frequency, temperature, and cycling electric field. The introduction of Sm3+ doping is found to create weakly coupled polar nanoregions in the Gd0.03 Ba0.47 Sr0.485 Nb2 O6 ceramic. Structural characterizations reveal that the incommensurability parameter increases with higher Sm3+ content, indicative of a highly disordered A-site structure. Simultaneously, the breakdown strength is also enhanced by raising the conduction activation energy, widening the bandgap, and reducing the electric field-induced strain. This work presents a significant improvement on the energy storage capabilities of TTBs-based capacitors, expanding the material choice for high-power pulse device applications.

Novel lead-free KNN-based ceramic with giant energy storage density, ultra-high efficiency and excellent thermal stability via relaxor strategy

(1-x)(0.9 K0.5Na0.5NbO3-0.1Ba0.4Sr0.6TiO3)-xBi(Zn0.5Zr0.5)O3 ceramics (abbreviated as (1-x)KNNBST-xBZZ, x = 0, 0.05, 0.10, 0.15, 0.20) were synthesized using the solid-state reaction method and their structure and electrical characteristics, including dielectric and ferroelectric properties, were systematically investigated. The incorporation of Bi/Zn/Zr (BZZ) elements into the KNNBST system results in a substantial increase in volume density, a dominant cubic crystal structure, and enhanced relaxor behaviour. Consequently, these modifications have led to superior energy storage performance. The 0.9KNNBST-0.1BZZ ceramics shows excellent recoverable energy storage density (Wrec = 5.42 J/cm3), and ultra-high energy efficiency (η = 91.09 %) at 470 kV/cm. Moreover, the 0.9KNNBST-0.1BZZ ceramics exhibits favorable frequency stability (1–1000 Hz) and temperature stability (27–190 ℃). The outstanding energy storage characteristics of (1-x)KNNBST-xBZZ ceramics make them highly promising for advanced pulse power capacitors and various energy storage applications.

Energy storage performance of lead-free Ba0.7Sr0.3TiO3 ceramics with doping Bi(Mg0.5Ti0.5)O3

Despite extensive research into lead-free ceramics to achieve excellent dielectric properties and good energy storage performance, the primary challenge of low energy density remains unresolved. Here, a relaxor ferroelectric (1-x)Ba0.7Sr0.3TiO3-xBi(Mg0.5Ti0.5)O3 [(1-x)BST-xBMT] was designed and prepared using a solid-state method, where x = 0.05, 0.15, 0.20, 0.25. It revealed that the introduction of BMT reduces the average grain size, resulting in a decrease and broadening of the dielectric constant peaks. This modification enhanced the breakdown field strength (Eb) of BST ceramics. An effective energy storage density of 2.44 J/cm³ and an energy storage efficiency of 76.25 % ware achieved in 0.80BST-0.20BMT ceramic at an electric field of 300 kV/cm. Furthermore, the recoverable energy density and energy efficiency of the 0.80BST-0.20BMT ceramic exhibited excellent frequency stability over a frequency from 5 Hz to 500 Hz. A power density (PD∼16.06 MW/cm³) and a short discharge time (t0.9∼0.95 μs) were demonstrated in 0.80BST-0.20BMT ceramic at 200 kV/cm.

The enhanced energy storage properties of (1-x)(0.94BNT-0.06BT)-x(Bi0.2Na0.2K0.2La0.2Sr0.2)TiO3 solid solutions

A strategy is developed to enhance the energy storage properties of lead-free Bi0.5Na0.5TiO3-based solid solutions, which is implemented through coupling the lattice instability in 0.94(Bi0.5Na0.5)TiO3-0.06BaTiO3 (0.94BNT-0.06BT) ferroelectric with a composition at its morphotropic phase boundary with the chemical disorder in (Bi0.2Na0.2K0.2La0.2Sr0.2)TiO3 (BNKLST) high-entropy ceramic (HEC). The addition of BNKLST in 0.94BNT-0.06BT could suppress the relaxor behaviors in the resulting solid solutions (1-x)(0.94BNT-0.06BT)-xBNKLST. With increasing content x, BNKLST may triggers more polar nano-regions which are in ergodic states at elevated temperatures. As a result, the thermal stability for energy storage properties is increased. In particular, the solid solution with x = 0.3 not only possesses large dielectric constants but also has a low content of oxygen vacancies, beneficial to its dielectric properties; It exhibits an excellent recoverable energy storage density of 2.24 J/cm3 under an electric field of 140 kV/cm, and a good thermal stability at 50 kV/cm with energy storage efficiency η >80 % up to 200 °C. The results demonstrate that the synergy effect of lattice instability and chemical disorder in the solid solutions is effective in enhancing energy storage properties of HECs, facilitating the design and optimization of dielectric energy storage devices.

Achieving high energy storage density and excellent stability in BiScO3 modified BaTiO3-based ceramics

High-performance dielectric energy storage ceramics has been brought to the fore by data as a result of the rapid rise in new energy development. The dielectric energy storage materials that can withstand harsh environments while having excellent energy storage performance, large breakdown strength, and maximum polarization is highly demanding. Herein, we fabricated the BiScO3 (BS) modified 0.88(Ba0.6Ca0.4)TiO3-0.12Bi[Mg2/3(Nb0.85Ta0.15)1/3O3] (BCT-BMNT) ceramics with excellent energy storage performance. The experimental results revealed that the breakdown strength of BCT-BMNT-xBS ceramics can be substantially increased by careful engineering of the grain uniformity induced by the incorporation of the BS. The BCT-BMNT-0.2BS ceramic exhibited a considerably optimal recoverable energy storage density of 5.75 J/cm3 along with a high energy efficiency of 89.63 % at 650 kV/cm. Moreover, this sample showed good stability in the temperature range of 20–160 °C and frequency range of 1–500 Hz and excellent fatigue resistance up to 105 cycles. Regarding the pulsed performance, as-prepared sample exhibited excellent power density of 145.30 MW/cm3 and current density of 937.43 A/cm2. Meanwhile, it showed a fast discharge time (t0.9) of 50.20 ns under the electric field of 460 kV/cm. This study demonstrates the crucial role that BS doping plays in improving the energy storage capabilities of BT-based lead-free ceramics, which pave the way for the use of BT-based ceramics in the field of energy storage.

Energy storage density of tailored relaxor-antiferroelectric state in Gd-doped Ag(Nb0.8Ta0.2)O3 ceramics

Antiferroelectric state AgNb0.8Ta0.2O3 ceramics can be adjusted by doping with Gd to form the relaxor-antiferroelectric state (Ag1-3xGdx)(Nb0.8Ta0.2)O3 ceramics (x = 0, 0.01, 0.02, 0.03, 0.04) for energy storage applications. The superb recoverable energy density (Wrec) of ∼9.47 J cm−3 at x = 0.01 and energy storage efficiency (η) of ∼68 % at x = 0.02 can be achieved at 375 kV cm−1. The superb Wrec can be attributed to phase evolution modulated with optimal fractions of ferroelectric Pmc21, antiferroelectric Pnma, and nonpolar cubic Pm-3m symmetries. Polarization-electric field (P-E) hysteresis loop, dielectric permittivity, atomic vibration, and electron diffraction pattern were used to probe the mechanism of superb recoverable energy density.

Achieving ultrahigh energy storage density under low electric field in (Na0.5Bi0.5)TiO3-based relaxor ferroelectric ceramics via a synergistic optimization strategy

Lead-free dielectric ceramic capacitors are attracting much interest in pulse power systems owing to their fast charge/discharge rate and high power density. However, their development towards integration and miniaturization in electronic devices has been severely impeded by low energy storage performance (ESP) under low electric field (E). Herein, a synergistic optimization strategy of composition design and domain engineering was proposed in the Bi(Mg0.5Hf0.5)O3-modified Na0.5Bi0.5TiO3-Sr0.7Bi0.2Ca0.1TiO3 ceramics [(1-x)(NBT-SBCT)-xBMH], aiming to improve ESP at low E. As a result, an ultrahigh recoverable energy density (Wrec) of ∼5.9 J/cm3 and a high efficiency (η) of ∼85 % can be obtained in x = 0.20 ceramics under a low E of 260 kV/cm, which is superior to previously reported lead-free materials under the equivalent E. The outstanding Wrec is mainly ascribed to the ultrahigh polarization discrepancy (ΔP) of ∼50.8 μC/cm2 since the rich hybridization of Bi 6 s and O 2p orbitals maintains a maximum polarization and the addition of Mg2+ and Hf4+ transforms the long-range ferroelectric order into polar nanoregions (PNRs) with good relaxation characteristics. Moreover, a fast discharge time (∼62 ns), good temperature (20–120 °C) and frequency (1–103 Hz) stabilities, and excellent fatigue resistance (×105 cycles) can be concurrently realized in x = 0.20 ceramics. These results demonstrate the promising strategy of developing low E lead-free ceramics for dielectric energy storage.

Energy storage and ferroelectric properties of flexible 1-x(Na0.5Bi0.5TiO3)-xBaTiO3 thin films on Pt/mica substrates

We investigated the energy storage and ferroelectric properties of flexible 1-x(Na0.5Bi0.5TiO3)-xBaTiO3 (NBT) thin films with BaTiO3 (BT) concentrations ranging from 0 to 6 mol% on Pt/mica substrates depending on the BT concentration. The NBT thin films exhibiting preferentially a-oriented crystallinity on the (111) Pt/mica substrates showed improved leakage current characteristics by increasing the BT concentration. In particular, the NBT thin films with zero BT concentration showed a high remanent polarization of about 28.4 μC/cm2. On the other hand, the NBT thin films with a BT concentration of 6 mol% significantly reduced the remanent polarization to about 4.7 μC/cm2 due to the characteristics of the relaxor. As a result, the NBT thin films with a BT concentration of 6 mol% showed a high energy storage efficiency of 89.5 % with a high recoverable energy storage density of 54.3 J/cm3 and a low loss energy density of 6.3 J/cm3.

Dielectric, energy storage, and charge–discharge properties of Yb‐modified Sr0.7Bi0.2TiO3 relaxor ferroelectric ceramic

AbstractDielectric capacitors have been widely studied in advanced electronics systems due to their rapid discharge rate and high‐power density. Among them, relaxor ferroelectrics characterized by nanodomains possess broad application prospects as dielectric materials with high energy density and high efficiency. In this paper, the dielectric characteristics, energy storage performance, and charge–discharge behavior of rare‐earth Yb‐doped Sr0.7Bi0.2TiO3 ceramics are systematically investigated. The Yb‐doped SBT ceramics reduced the grain size, improved the insulation and thermal conductivity, and significantly improved the dielectric breakdown strength. Finally, a high recoverable energy density of 2.32 J/cm3 and an excellent energy storage efficiency of 92.2% were obtained at 300 kV/cm. In addition, pulsed charge–discharge tests show that Sr0.7Bi0.15Yb0.05TiO3 possesses a rapid discharge rate and high‐power density with superior thermal stability. Based on these outstanding characteristics, Sr0.7Bi0.15Yb0.05TiO3 exhibits promising applications in pulsed power systems.

Effects of phase transition on the dynamic discharge energy density of antiferroelectric ceramics

AbstractAntiferroelectrics (AFEs) are widely used for energy storage capacitors. At present, there are two methods to evaluate the energy density of AFE: the recoverable energy density Wre calculated by the low‐frequency P–E loop and the dynamic discharge energy density Wdis calculated by the fast discharge current. It has been widely observed that the value of Wdis is lower than Wre but less attention was paid to how to increase Wdis. Compared with Wre, the value of Wdis is closer to the energy density of AFE pulse capacitors in practical applications. In this work, the effects of phase transition properties on the dynamic discharge energy density were studied from the aspect of domain switching mobility. Compositions with P–E loop varying from “square” to “slant” were fabricated. It was found that in AFEs with “square” P–E loops, the recoverable energy density Wre was remarkably higher than Wdis. By modifying the P–E loops to long slim, the value of Wdis tended to be close to Wre, resulting in higher dynamic discharge energy efficiency. This indicates that by adjusting the P–E loop, higher Wdis can be achieved in AFE with lower Wre. The AFEs with long slim P–E loops also have faster discharge speeds, leading to higher power density. The outstanding fast discharge performance of AFEs with long slim P–E loops originated from their faster domain mobility and less viscous force during domain switching. This work provides a new approach to designing the AFEs energy storage materials by tuning their dynamic phase‐transition properties and domain mobility.

High Energy Storage and Excellent Thermal Stability in Ternary (1−x)[0.94(Bi0.5Na0.5)TiO3‐0.06BaTiO3]‐xCa(Mg1/3Nb2/3)O3 Lead‐Free Ferroelectric Ceramics

AbstractIn this work, a new type of ternary lead‐free ferroelectric ceramics (1−x)[0.94(Bi0.5Na0.5)TiO3‐0.06BaTiO3]‐xCa(Mg1/3Nb2/3)O3 is synthesized by traditional solid‐state reaction method (x = 0.02, 0.04, 0.06, 0.07, 0.08, 0.10, and 0.15). No phase transition is detected and all ceramics exhibited the perovskite structure consisting of the rhombohedral (R3c) and tetragonal (P4bm) phases. By increasing the Ca(Mg1/3Nb2/3)O3(CMN) content, the average grain size shows a slight change. More specifically, the grain size is 1.00 µm when x &lt; 0.10 and then increases to 1.20 µm in x = 0.10 and 0.15. When x = 0.07, an optimum energy storage performance with recoverable energy density (Wrec) of 4.13 J cm−3 is achieved under an electric field of 340 kV cm−1. At the same time, it exhibits excellent pulse performance at 25 °C, with an effective discharging time (t0.9) of 3.2 ns and a discharge energy density (WD) of 0.61 J cm−3, suggesting a fast charging–discharging rate. In addition, the current density (CD) and power density (PD) are 92.31 A cm−2 and 6.46 MW cm−3, respectively. Overall, the 0.93[0.94(Bi0.5Na0.5)TiO3‐0.06BaTiO3]‐0.07Ca(Mg1/3Nb2/3)O3 ceramics is considered a competitive candidate for the development of high‐energy storage capacitors and pulse‐power devices.

Stereo‐Active Lone Pairs Induced Giant Polarization in a 2D Ge‐Based Halide Perovskite Antiferroelectric

AbstractAntiferroelectrics, characterized by electrically controlled antipolar‐polar phase transformation, have attracted tremendous attention as a class of promising electroactive materials for assembling electronic devices. The emerging two‐dimensional (2D) halide perovskites with superior compositional diversity offer an ideal platform for exploring electroactive materials, whereas lead‐free antiferroelectric counterparts are still scarcely reported. Herein, for the first time, a new lead‐free 2D germanium iodide perovskite antiferroelectric (i‐BA)2CsGe2I7 (1, i‐BA is iso‐butylammonium) has been presented, which exhibits a high Curie temperature (Tc) up to 403 K. Remarkably, benefiting from the lone pair stereochemical activity in Ge2+ induced large structural distortion and Cs+ ion off‐center displacement, 1 shows well‐defined double P–E hysteresis loops in a wide temperature range with a giant maximum polarization up to 18.8 µC cm−2, which achieves a new high record among molecular antiferroelectrics. Moreover, under a low external electric field of 22.5 kV cm−1, the antipolar‐polar phase transformation in 1 affords a recoverable energy storage density Wrec of 0.27 J cm−3 and high storage efficiency up to 79.76%. Such lead‐free halide perovskite antiferroelectric with intriguing antiferroelectric behaviors, including high Tc, large polarization and remarkable energy storage properties, is exciting, which provides an alternative candidate for high‐performance antiferroelectrics for environmentally friendly electronic devices.

Boosting Energy Storage Performance of Glass Ceramics via Modulating Defect Formation During Crystallization.

Along with the demand for further miniaturization of high and pulsed power devices, it becomes more and more important to realize ultrahigh recoverable energy storage density (Wrec ) with high energy storage efficiency (η) and ultrahigh discharge energy storage density (Wd ) accompanied by high power density (Pd ) in dielectrics. To date, it remains, however, a big challenge to achieve high Wrec or Wd in glass ceramics compared to other dielectric energy storage materials. Herein, a strategy of defect formation modulation is applied to form "amorphous-disordered-ordered" microstructure in BaTiO3 -based glass ceramics so as to achieve a high Wrec of 12.04 J cm-3 with a high η of 81.1% and an ultrahigh Wd of 11.98 J cm-3 with a superb Pd of 973 MW cm-3 . This work demonstrates a feasible route to obtain glass ceramics with an outstanding energy storage performance and proves the enormous potential of glass ceramics in high and pulsed power applications.