Dielectric capacitors as a physical power are critical components in advanced electronics and pulse power systems. However, achieving a high energy efficiency without sacrificing recoverable energy density remains a challenge for most dielectric materials. Taking advantage of aliovalent Sm³⁺ dope Ba_0.12Na_0.3Bi_0.3Sr_0.28TiO₃ (BNBST) relaxor ferroelectric at A-site, in this work, to design defect-induced phase/domain structure to improve polarization switching. A high energy efficiency of 91% together with a recoverable energy density of 2.1 J/cm³ has been achieved in Sm_0.07-BNBST ceramics at a low electric field of 114 kV/cm, exceeding other dielectric materials under the same electric field. Besides, Sm_0.07-BNBST ceramics exhibits good energy storage stability, endurance, and fast charging-discharging speed, demonstrating its great potential in electrostatic capacitor applications. This work provides an approach to achieving high-performance dielectrics through aliovalent rare earth doping and builds a close relationship between defect-engineered phase/domain structure and polarization switching for energy storage.

Relaxor ferroelectric ceramics have very high dielectric constant (ε_r) but relatively low electrical breakdown strength (E_b), while glass–ceramics exhibit higher E_b due to the more uniformly dispersed amorphous phases and submicrocrystals/nanocrystals inside. How to effectively combine the advantages of both relaxor ferroelectric ceramics and glass–ceramics is of great significance for the development of new dielectric materials with high energy storage performance. In this work, we firstly prepared BaO–SrO–Bi₂O₃–Na₂O–TiO₂–Al₂O₃–SiO₂ (abbreviated as GS) glass powders, and then fabricated (Ba_0.3Sr_0.7)_0.5(Bi_0.5Na_0.5)_0.5TiO₃ + x wt% GS ceramic composites (abbreviated as BS_0.5BNT–xGS, x = 0, 2, 6, 10, 14, 16, and 18). Submicrocrystals/nanocrystals with a similar composition to BS_0.5BNT were crystalized from the glass, ensuring the formation of uniform core–shell structure in BS_0.5BNT–xGS relaxor ferroelectric ceramic/glass–ceramic composites. When the addition amount of GS was 14 wt%, the composite possessed both high ε_r (> 3200 at 1 kHz) and high E_b (≈ 170 kV/cm) at room temperature, and their recoverable energy storage density and efficiency were W_rec = 2.1 J/cm³ and η = 65.2%, respectively. The BS_0.5BNT–14GS composite also had several attractive properties such as good temperature, frequency, cycle stability, and fast charge–discharge speed. This work provides insights into the relaxor ceramic/glass–ceramic composites for pulsed power capacitors and sheds light on the utilization of the hybrid systems.

Lead-free bulk ceramics for advanced pulsed power capacitors show relatively low recoverable energy storage density (W_rec) especially at low electric field condition. To address this challenge, we propose an A-site defect engineering to optimize the electric polarization behavior by disrupting the orderly arrangement of A-site ions, in which Ba_0.105Na_0.325Sr_0.245-1.5x▯_0.5xBi_0.325+xTiO₃ (BNS_0.245-1.5x▯_0.5xB_0.325+xT, x = 0, 0.02, 0.04, 0.06, and 0.08) lead-free ceramics are selected as the representative. The BNS_0.245-1.5x▯_0.5xB_0.325+xT ceramics are prepared by using pressureless solid-state sintering and achieve large W_rec (1.8 J/cm³) at a low electric field (@110 kV/cm) when x = 0.06. The value of 1.8 J/cm³ is super high as compared to all other W_rec in lead-free bulk ceramics under a relatively low electric field (< 160 kV/cm). Furthermore, a high dielectric constant of 2930 within 15% fluctuation in a wide temperature range of 40-350 ℃ is also obtained in BNS_0.245-1.5x▯_0.5xB_0.325+xT (x = 0.06) ceramics. The excellent performances can be attributed to the A-site defect engineering, which can reduce remnant polarization (P_r) and improve the thermal evolution of polar nanoregions (PNRs). This work confirms that the BNS_0.245-1.5x▯_0.5xB_0.325+xT (x = 0.06) ceramics are desirable for advanced pulsed power capacitors, and will push the development of a series of Bi_0.5Na_0.5TiO₃ (BNT)-based ceramics with high W_rec and high-temperature stability.

Dielectric ceramic capacitors, with the advantages of high power density, fast charge- discharge capability, excellent fatigue endurance, and good high temperature stability, have been acknowledged to be promising candidates for solid-state pulse power systems. This review investigates the energy storage performances of linear dielectric, relaxor ferroelectric, and antiferroelectric from the viewpoint of chemical modification, macro/microstructural design, and electrical property optimization. Research progress of ceramic bulks and films for Pb-based and/or Pb-free systems is summarized. Finally, we propose the perspectives on the development of energy storage ceramics for pulse power capacitors in the future.

Supercapacitors (SCs) are one of the most promising electrical energy storage technologies systems due to their fast storage capability, long cycle stability, high power density, and environmental friendliness. Enormous research has focused on the design of nanomaterials to achieve low cost, highly efficient, and stable electrodes. Ceramic materials provide promising candidates for SCs electrodes. However, the low specific surface area and relatively low surface activity severely hinder the SCs performance of ceramic materials. Therefore, the basic understanding of ceramic materials, the optimization strategy, and the research progress of ceramic electrodes are the key steps to enable good electrical conductivity and excellent electron transport capabilities, and realize economically feasible ceramic electrodes in industry. Herein, we review recent achievements in manufacturing the ceramic electrodes for SCs, including metal oxide ceramics, multi-elemental oxide ceramics, metal hydroxide ceramics, metal sulfide ceramics, carbon-based ceramics, carbide and nitride ceramics, and other special ceramics (MXene). We focus on the unique and key factors in the component and structural design of ceramic electrodes, which correlate them with SCs performance. In addition, the current technical challenges and perspectives of ceramic electrodes for SCs are also discussed.

(Ba_0.3Sr_0.7)_x(Bi_0.5Na_0.5)_1-xTiO₃ (BS_xBNT, x = 0.3–0.8) ceramics were prepared to investigate their structure, dielectric and ferroelectric properties. BS_xBNT ceramics possess pure perovskite structure accompanied from a tetragonal symmetry to pseudo-cubic one with the increase of x value, being confirmed by X-ray diffraction (XRD) and Raman results. The T_m corresponding to a temperature in the vicinity of maximum dielectric constant gradually decreases from 110 ℃ (x = 0.3) to –45 ℃ (x = 0.8), across T_m = 36 ℃ (x = 0.5) with a maximum dielectric constant (ɛ_r = 5920 @1 kHz) around room temperature. The saturated polarization P_s gradually while the remnant polarization P_r sharply decreases with the increase of x value, making the P–E hysteresis loop of BS_xBNT ceramics goes slim. A maximum difference between P_s and P_r (P_s–P_r) is obtained for BS_xBNT ceramics with x = 0.5, at which a high recoverable energy density (W_rec = 1.04 J/cm³) is achieved under an applied electric field of 100 kV/cm with an efficiency of η = 77%. Meanwhile, the varied temperature P–E loops, fatigue measurements, and electric breakdown characteristics for the sample with x = 0.5 indicate that it is promising for pulsed power energy storage capacitor candidate materials.

A glass with composition of B₂O₃-Bi₂O₃-SiO₂-CaO-BaO-Al₂O₃-ZrO₂ (BBSZ) modified Ba_xSr_1-xTiO₃ (BST, x = 0.3 and 0.4) ceramics were prepared by a conventional solid state reaction method abided by a formula of BST + y%BBSZ (y = 0, 2, 4, 7, and 10, in mass). The effect of BBSZ glass content on the structure, dielectric properties and energy storage characteristics of the ceramics was investigated. The dielectric constant reduced but the endurable electrical strength enhanced due to the BBSZ glass addition in BST ceramics. In particular, the dielectric loss of the ceramics at elevated temperature (e.g. 200 ℃) can be strongly suppressed from tanδ>20% to tanδ<3% after BBSZ glass modification. For Ba_0.3Sr_0.7TiO₃+2% BBSZ ceramics, an optimized energy storage density (γ = 0.63 J/cm3) and efficiency (η = 91.6%) under an applied electric field of 160 kV/cm was obtained at room temperature. Meanwhile, the temperature dependent polarization-electric field (P-E) hysteresis loops were measured to evaluate the energy storage characteristics of the ceramics potential for high voltage capacitor application at elevated temperatures.