A novel route to produce BaTiO3 glass-ceramics with nanosized cubic BaTiO3 phase precipitating for high energy-storage applications

To meet requirements of miniaturization devices in high pulsed power technology, super dielectric energy storage performance, such as high dielectric breakdown strength (DBS), large energy storage density with high power density, is extremely important in dielectric materials. However, for BaTiO₃ based ceramics and glass ceramics, there is still a critical challenge to achieve high DBS and large energy storage density. Herein, a novel route was proposed to precipitate nanocrystals with cubic BaTiO₃ phase from glass matrix, which can elevate dielectric constant and meanwhile maintain high DBS compared to parent glass. A high recoverable energy storage density of ∼ 3.66 J cm⁻³ at 1000 kV cm⁻¹ and high discharge energy density of ∼3.57 J cm⁻³ with good thermal stability and ultra-high peak power density of ∼ 910 MW cm⁻³ can be achieved in BaTiO₃ glass ceramic, which implies this type of glass ceramics is suitable for high pulsed power technology application.     

Ordered domain engineering and physical property modification of Ba(Co1/3Nb2/3)O3 complex perovskite ceramics

In the present work, the physical properties modification by ordered domain engineering has been systematically investigated in Ba(Co_1/3Nb_2/3)O₃ ceramics. The 1:2 ordered structure with an ordering degree up to 0.92 with uniform ordered domain size distribution is achieved in Ba(Co_1/3Nb_2/3)O₃ ceramics after post-densification annealing, where the significantly enhanced electric resistivity, thermal conductivity, and dielectric strength, and subsequently the superior energy storage characteristics are achieved. The dielectric strength increases from 618 kV cm^–1 to 972 kV cm^–1 in the present ceramics by such means of ordered domain engineering, while the energy storage density increases from 0.65 J cm^–3 to 1.42 J cm^–3. There are three primary parameters in ordered domain engineering: ordering degree, ordered domain size and its distribution, and ordered domain boundary type. The final physical properties are determined by these three parameters.     

Enhancements of dielectric and energy storage performances in lead-free films with sandwich architecture

High-performance film dielectrics are crucial for capacitive energy storage applications and electronic industries. In this work, improvements of dielectric and energy performance in BiFeO₃-based films are realized by constructing sandwich architectures, which integrates complementary features of spatially organized dielectric layers in a synergistic manner to realize concurrently high permittivity/polarization and low loss/leakage. Moreover, by rationally modifying the sandwich configuration, ie, with insulating layers on the outside, the interfacial Schottky emission is suppressed, leading to further reductions of leakage and conduction loss. Large energy density of ~44 J cm⁻³ (superior to that of either single layer) along with high efficiency of ~76% is thus achieved in the sandwich film. This work proves the feasibility and effectiveness of sandwich architecture in improving dielectric, leakage, and energy storage performances, providing a new paradigm for the development of high-energy-density dielectrics.     

Combustion synthesis of high-performance high-entropy dielectric ceramics for energy storage applications

High-entropy dielectric ceramics have demonstrated a promising prospect for applications in energy storage recently. However, most high-entropy dielectrics synthesized by conventional solid-state reaction (SSR) method demonstrated unsatisfactory performance for energy storage. Therefore, it is meaningful to develop a feasible way to fabricate high-performance high-entropy dielectric ceramics. Herein, high-entropy (Sr_0.6Bi_0.2Na_0.2)(Ti_1-xZr_x/2Al_x/4Nb_x/4)O₃ ceramics are prepared by a solution combustion synthesis (SCS) method. The SCS fabricated ceramics (x = 0.25) demonstrate a high recoverable energy density of ∼4.46 J/cm³ at a high critical electric field of 520 kV/cm, a high energy efficiency ∼88.52%, a large power density of ∼176.65 MW/cm³ (at 400 kV/cm), an ultrafast discharge time of ∼48 ns, and a high Vikers hardness of ∼7.09 GPa. The key energy storage parameters are much better than those of the samples prepared by the SSR method owing to the absence of unexpected impurity phases, and the refined grain size at the submicrometer scale in our SCS fabricated high-entropy ceramics. The study provides a facile way to fabricate high-performance high-entropy dielectric ceramics for energy storage, indicating that the SCS routine is notably advantageous for preparing high-entropy dielectric energy ceramics.     

CaTiO3 linear dielectric ceramics with greatly enhanced dielectric strength and energy storage density

CaTiO₃ is a typical linear dielectric material with high dielectric constant, low dielectric loss, and high resistivity, which is expected as a promising candidate for the high energy storage density applications. In the previous work, an energy density of 1.5 J/cm³ was obtained in CaTiO₃ ceramics, where the dielectric strength was only 435 kV/cm. In fact, the intrinsic dielectric strength of CaTiO₃ is predicted as high as 4.2 MV/cm. Therefore, it should be a challenge issue to enhance the dielectric strength and energy storage density of CaTiO₃ ceramics by optimizing the microstructures. In the present work, dense CaTiO₃ ceramics with fine and uniform microstructures are prepared by spark plasma sintering, and the greatly enhanced dielectric strength (910 kV/cm) and energy storage density (6.9 J/cm³) are obtained. This can be ascribed to the improved resistivity and thermal conductivity, associated with the fine and uniform microstructures. The different post‐breakdown features of CaTiO₃ ceramics prepared by different process well interpret why the enhanced dielectric strength is achieved in the SPS sample. The energy storage density can be further improved to 11.8 J/cm³ by introducing the amorphous alumina thin films as the charge blocking layer, where the dielectric strength is 1188 kV/cm.     

Improved dielectric strength and energy storage density in Ba6−3xLa8+2xTi18O54 (x = 0.5, 2/3, and 0.75) ceramics

Dielectric strength and energy storage density in Ba_6−3xLa_8+2xTi₁₈O₅₄ (x = 0.5, 2/3, and 0.75) ceramics were investigated as functions of composition and microstructure. With increasing x, although the dielectric constant decreased from 113 to 102, the energy storage density increased from 2.3 J/cm³ to 3.2 J/cm³ due to the increased dielectric strength for ceramics prepared by conventional sintering. The energy storage was further improved to 4.2 J/cm³ in ceramics prepared by spark plasma sintering under an electric field of 1058 kV/cm. Both dielectric strength and energy storage density in the present ceramics indicated the strong processing and microstructure dependence. The optimum dielectric strength and energy storage density were achieved in the dense ceramics with fine grains, while both dielectric strength and energy storage density decreased in the ceramics with coarse columnar grains.     

Simultaneously achieved high-energy storage density and efficiency in (K,Na)NbO3-based lead-free ferroelectric films

With the development of advanced electrical and electronic devices and the requirement of environmental protection, lead-free dielectric capacitors with excellent energy storage performance have aroused great attention. However, it is a great challenge to achieve both large energy storage density and high efficiency simultaneously in dielectric capacitors. This work investigates the energy storage performance of sol-gel-processed (K,Na)NbO₃-based lead-free ferroelectric films on silicon substrates with compositions of 0.95(K_0.49Na_0.49Li_0.02)(Nb_0.8Ta_0.2)O₃-0.05CaZrO₃-x mol% Mn (KNN-LT-CZ5-x mol% Mn). The appropriate amount of Mn-doping facilitates the coexistence of orthorhombic and tetragonal phases, suppresses the leakage current, and considerably enhances the breakdown strengths of KNN-LT-CZ5 films. Consequently, large recoverable energy storage density up to 64.6 J cm⁻³ with a high efficiency of 84.6% under an electric field of 3080 kV cm⁻¹ are achieved in KNN-LT-CZ5-5 mol% Mn film. This, to the best of our knowledge, is superior to the majority of both the lead-based and lead-free films on silicon substrates and thus demonstrates great potentials of (K,Na)NbO₃-based lead-free films as dielectric energy storage materials.     

High discharge energy density in novel K1/2Bi1/2TiO3-BiFeO3 based relaxor ferroelectrics

An increasing number of new dielectrics are being reported for the development of next-generation ceramic capacitors for power electronics used in clean energy technologies. Here, high discharge energy density (W_dis) ~6.1 J cm^?3 with efficiency (η)~72% under a pulsed field (E_max) of 410 kV cm^?1 is reported along with temperature stability up to 150 °C (E_max = 200 kV cm^?1) for 0.5 K_0.5Bi_0.5TiO₃-0.42BiFeO₃-0.08Sm(Mg_2/3Nb_1/3)O₃ (KBT-BF-SMN) bulk ceramics. The optimised composition is chemically heterogeneous but electrically homogenous, similar to several BiFeO₃-based dielectrics reported previously and adding to the growing body of evidence that electrical (measured at weak-field) not chemical homogeneity is the best guide to increased E_max and enhanced energy density. KBT-BF-SMN ceramics are therefore considered as promising candidates for pulsed power and power electronics applications.     

Novel NaNbO3–Sr0.7Bi0·2TiO3 lead-free dielectric ceramics with excellent energy storage properties

NaNbO₃ (NN) is considered to be one of the most prospective lead-free antiferroelectric energy storage materials due to the merits of low cost, nontoxicity, and low density. Nevertheless, the electric field-induced ferroelectric phase remains dominant after the removal of the electric field, resulting in large residual polarization, which prevents NN ceramics from obtaining superior energy storage performance. In this work, the relaxor ferroelectric Sr_0·7Bi_0·2TiO₃ (SBT) was chosen to partially replace the NN ceramics, and the introduction of the nanodomain of the relaxor ferroelectric hinders the generation of field-induced ferroelectric phases, allowing the material to combine the large polarization strength of the relaxor ferroelectric with the near-zero residual polarization of the antiferroelectric. Large recoverable energy storage density (4.5 J cm^?3) and ultra-high energy storage efficiency (90.3%) were gained in NN-20SBT under an electric field of 288 kV cm^?1. Furthermore, superior temperature (25–120 °C) and frequency (1–500 Hz) stabilities were acquired. These performances demonstrate that NN-20SBT ceramics are potential candidates as dielectric materials for high energy storage density pulsed power capacitors.     

PLZST antiferroelectric ceramics with promising energy storage and discharge performance for high power applications

Capacitors are widely used as energy storage elements in electric vehicles (EVs) and pulsed power. At present, it is still challenging to develop capacitor dielectrics with good energy storage and discharge performance. In this work, antiferroelectric (AFE) ceramics (Pb_0.94La_0.04)[(Zr_0.6Sn_0.4)_0.92Ti_0.08]O₃ with enhanced antiferroelectricity were fabricated by a rolling process. The obtained ceramics have a high recoverable energy density of 5.2 J/cm³ and an extremely high efficiency of 91.2% at 327 kV/cm. The ceramics have good energy storage and discharge performance in the temperature range from −40°C to 100°C due to the existence of AFE phase. An energy density of 3.7 J/cm³ can be released at 200 kV/cm in less than 500 ns and the discharge current keeps stable after 1000 charge-discharge cycles. By direct short experiment, a current density of 1657 A/cm², which is the highest result in recently developed AFE ceramics, and a power density of 228 MW/cm³ were achieved. The possibility of using AFEs at low temperature was confirmed. The excellent energy storage and discharge performance prove the great potential of the obtained ceramics in high energy and power density applications.     

Improvement of energy storage properties of NaNbO3-based ceramics through the cooperation of relaxation and oxygen vacancy defects

The development of materials with high energy storage plays a crucial role in solving energy consumption. Traditional dielectric ceramics have the disadvantages of low energy storage and low efficiency. The most effective solution is to reduce the dielectric loss and increase the breakdown strength. In this paper, (Na_0.73Bi_0.08Sm_0.01)(Nb_0.91Ta_0.09)O₃ relaxor ferroelectric ceramics were prepared, which achieved a high energy storage density of 1.66 J cm^?3, high efficiency (83.6%) at 214 kV/cm at room temperature. The addition of Bi₂O₃ makes the A site cations disordered, thereby generating random fields, breaking the long-range order, and forming polar nanodomains. That allows the ceramic to acquire relaxation properties, reducing the dielectric loss. The impedance analysis proves that the breakdown strength is related to the addition of Sm₂O₃. The addition of Sm reduces the oxygen vacancy defect concentration and inhibits the migration of carriers, thereby improving its breakdown strength. Through proper doping of Bi and Sm, the relaxation properties and breakdown field strength of the ceramics are enhanced to obtain excellent energy storage performance. This provides a new idea in terms of relaxation and oxygen vacancy defects for NaNbO₃-based energy storage ceramics.     

Reinforced via the insulative boric oxide in the BaTiO3 amorphous thin film with high energy storage capability and stability

Dielectric film capacitors are considered as a potential candidate for advanced power electronics technology due to their fast charging and discharging rate and stability. However, the further improvement of energy storage density is still a major challenge. Herein, a reasonable amorphous structure is applied to the preparation of dielectric film capacitors to improve the dielectric and energy storage properties. The high breakdown strength and energy storage density in the amorphous film are assigned by the disordered structure and intrinsic high insulative for B₂O₃. As a result, a high discharge energy storage density of 68.64 J cm^?3 and an efficiency of 85% can be achieved in the BaTiO₃-5wt%B₂O₃ amorphous thin film at 7.3 MV cm^?1, together with excellent thermal stability (20–200 °C) and cyclic stability (up to 10⁵ times) This work provides a paradigmatic method to achieve high energy storage density and stability.     

High energy storage performance in BaTiO3-based lead-free relaxors via multi-dimensional collaborative design

The application of advanced pulse power capacitors strongly depends on the fabrication of high-performance energy storage ceramics. However, the low recoverable energy storage density (W_rec) and energy efficiency (η) become the key links limiting the development of energy storage capacitors. In this work, a high W_rec of ～5.57 J cm^?3 and a large η of ～85.6% are simultaneously realized in BaTiO₃-based relaxor ceramics via multi-dimensional collaborative design, which are mainly attributed to the ferroelectric-relaxor transition, enhanced polarization, improved breakdown electric field, and delayed polarization saturation. Furthermore, the excellent temperature stability (ΔW_rec < ± 5%, 25–140 °C), frequency stability (ΔW_rec < ± 5%, 1–200 Hz), and outstanding charge/discharge performance (current density ～1583.3 A cm^?2, power density ～190.0 MW cm^?3) with good thermal stability are also achieved. It is encouraging that this work demonstrates that multi-dimensional collaborative design is a good strategy to develop new high-performance lead-free materials used in advanced dielectric capacitors.     

Energy storage and discharge performance for (1−x)BaSrTiO3−xBi(Zn1/2Ti1/2)O3 ceramics

Although lead-free dielectric ceramics have been widely studied to obtain excellent dielectric properties and good energy storage properties, the primary challenge of low energy storage density has not yet been resolved. Here, we introduce the concept of crossover relaxor ferroelectrics, which represent a state intermediate between normal ferroelectrics and relaxor ferroelectrics, as a solution to address the issue of low energy density. The (1−x)BaSrTiO₃−xBi(Zn_1/2Ti_1/2)O₃ (x = 0,.05, .1, .15, .2) ceramics were prepared by a solid-state method. Remarkably, 0.85BST–0.15BZT ceramics achieved a high recoverable energy density (W_rec) of 2.18 J/cm³ under an electric field of 240 kV/cm. BST–BZT materials exhibit substantial recoverable energy density, high breakdown strength, and superior energy efficiency, positioning them as a promising alternative to meet the diverse demands of high-power applications.     

Excellent energy-storage property and thermal stability of PLZT-based antiferroelectric ceramics

(Pb, La)(Zr, Ti)O₃ antiferroelectric (AFE) materials are promising materials due to their energy-storage density higher than 10 J cm⁻³, but their low energy-storage efficiency and poor temperature stability limit their application. In this paper, the (1 − x)(Pb_0.9175La_0.055)(Zr_0.975Ti_0.025)O₃–xPb(Yb_1/2Nb_1/2)O₃ (PLZTYN100x) AFE ceramics were prepared via two-step sintering method and investigated thoroughly. With the doping of Yb³⁺ and Nb⁵⁺, the phase structure transforms from the orthorhombic phase (AFE_O) to the coexistence of the orthorhombic-and-tetragonal phases. This structure reduces the free energy difference between the AFE and ferroelectric phases and reduces the fluctuation of energy with temperature, improving the energy storage efficiency and temperature stability. When the x = 0.05 (PLZTYN5), the AFE ceramic exhibits excellent temperature stability and ultrahigh energy storage performance, whose recoverable energy density (W_rec) is 6.8–8.2 J cm⁻³ at 30 kV mm⁻¹ in the temperature range from −55 to 75°C, and efficiency (ƞ) is 78%–86.7%. In addition, the change of W_rec is less than 15%, exceeding the performance of most AFE ceramics. The results demonstrate that the PLZTYN5 ceramic has great potential in pulse power capacitors.     

Improved energy storage performance of Bi(Mg0.5Ti0.5)O3 modified Ba0.55Sr0.45TiO3 lead-free ceramics for pulsed power capacitors

(1–x)Ba_0.55Sr_0.45TiO₃–xBi(Mg_0.5Ti_0.5)O₃ (x = 0, 0.08, 0.1, 0.12, 0.15, 0.2) ceramics were fabricated via a solid-state reaction route. The ultrahigh recoverable energy density (W_rec = 4.05 J cm^?3), efficiency (η = 78%), maximum polarization (P_max = 51.40 μC cm^?2), and high dielectric breakdown strength (BDS = 230 kV cm^?1) were achieved for the 0.9BST?0.1BMT ceramic. The fast discharge rate (t_0.9～0.14 μs), current density (C_D～637.02 A cm^?2), high power density (P_D～38.70 MW cm^?3), good temperature stability (20?180 °C), frequency stability (10?500 Hz), and fatigue endurance for cycling (10⁵) of 0.9BST?0.1BMT ceramic make it suitable for the development of energy-storage devices. The relaxor behavior with a high W_rec (3.06 J cm^?3) and η (93%) at BDS (220 kV cm^?1) was also achieved for the 0.8BST?0.2BMT ceramic. This study systematically investigates the correlation among the structural, dielectric, impedance, and energy storage properties of BMT-doped BST ceramics.     

High energy storage density and efficiency in nanostructured (Bi0.2Na0.2K0.2La0.2Sr0.2)TiO3 high-entropy ceramics

High-entropy ceramics (HECs) (Bi_0.2Na_0.2K_0.2La_0.2Sr_0.2)TiO₃ (BNKLST) with single-phase perovskite structure have been successfully prepared by a modified citrate acid method. In comparison to (Bi_0.5Na_0.5)TiO₃ (BNT) ceramics prepared by the same synthesis route, the BNKLST HECs exhibit dense nanostructures with grain sizes as small as 45 nm, which are suggested to be responsible for the significantly improved electric breakdown fields and reduced leakage currents in the ceramics, and they have much enhanced elastic modulus owing to the entropy-stabilized perovskite structure. The electrical and dielectric characterizations reveal that BNKLST has high electrical resistances and dielectric constants at elevated temperatures, and, in particular, a recoverable energy storage density of 0.959 J/cm³ can be achieved under an applied electric field of 180 kV/cm. Moreover, the energy storage efficiency in BNKLST can be maintained to be larger than 90% at 40–200°C. These excellent properties suggest that entropy-stabilized BNT-based ceramics are promising dielectrics for electrical energy storage applications.     

Enhanced electrostatic energy storage achieved in BiFeO3-driven (Sr,Bi)TiO3 ceramics for high-voltage pulsed applications

The paradoxical relationship between ferroelectric polarization and dielectric breakdown to a great extent hinders the increase in energy storage properties of dielectric materials. A strategy of combining large polarization and high dielectric breakdown by composition optimization was designed in (Sr_0.7Bi_0.2)TiO₃–BiFeO₃ system. All ceramics show dense microstructures with fine grain sizes. A promising energy density of 3.67 J/cm³ with an efficiency of 89.1% can be obtained in 0.93(Sr_0.7Bi_0.2)TiO₃-0.07BiFeO₃ at 340 kV/cm. The energy density shows excellent temperature reliability in a wide temperature range till 160 °C and reliable fatigue endurance till 10⁵ cycles. This research expands the strategy of combing large polarization and dielectric breakdown for developing novel dielectrics used in pulse power electronics.     

Improving energy density of crystalline–amorphous multilayer films deposited on Ti foils by structural modulation

Dielectric capacitors are one of the most important energy-storage components specifically used for various high-power pulse applications. However, the low energy-storage density (U_e) of dielectrics used today limits their application. In this study, crystalline–amorphous multilayer films of crystalline Sr_0.85Bi_0.1TiO₃ (SBT)/amorphous SBT/amorphous Al₂O₃ (S_c–(8−n)S_a–nA_a) were fabricated on flexible Ti foils using the sol–gel method. An enhancement in energy density was achieved by adjusting the thicknesses of the amorphous SBT and Al₂O₃ (AO) layers. The crystalline SBT layer contributes to an increase in the dielectric constant and the amorphous AO layer to an increase in the breakdown strength. Moreover, the AO layers that are inserted are capable of suppressing the leakage current by eliminating the space charge limited conductance mechanism and thereby effectively decreasing the probability of breakdown of the SBT layers. A lower leakage current and higher breakdown strength can be further achieved using an Al electrode instead of the Au electrode. A large energy density of 27.2 J cm⁻³ can be realized via the crystalline–amorphous multilayer films with the Al electrode, which represents an enhancement of ~234% over that of the amorphous SBT film (8.14 J cm⁻³). In addition to the high energy-storage enhancement, this study also presents a promising method that can be used to fabricate flexible multilayer films for lightweight and high energy density applications and for devices used to service high-temperature conditions.     

High energy storage efficiency of NBT-SBT lead-free ferroelectric ceramics

Ceramic-based dielectrics have been widely used in pulsed power capacitors owing to their good mechanical and thermal properties. Bi_0.5Na_0.5TiO₃-based (NBT-based) solid solutions exhibit relatively high polarization, which is considered as a promising dielectric energy storage material. However, the high remnant polarization and low energy efficiency limit their application in dielectric capacitors. Herein, a typical relaxor ferroelectric Sr_0·7Bi_0·2TiO₃ (SBT) was introduced into the NBT system to strengthen the overall relaxor behavior, resulting in reduced remnant polarization. We prepared (1-x)NBT-xSBT (x = 0.35, 0.45, 0.55, and 0.65) ceramics by the conventional solid-phase reaction method and further investigated their microstructures, dielectric and energy storage properties. With the increase of SBT content, the size of the grains and the maximum dielectric constant gradually decreased, simultaneously. Furthermore, the dielectric shoulder corresponding to the maximum dielectric constant shifted to a lower temperature, indicating that the enhancement of polarization dynamics was a consequence of the domain refinement. As a result, the optimum property was identified in the 0.45NBT-0.55SBT sample with a high recoverable energy density of 1.34 J/cm³ and an outstanding energy efficiency of 96% at a low electric field of 100 kV/cm.