In this work, we report the successful synthesis of highly dense (1 − x)Ba0.9Sr0.1TiO3 − xNa2/3La1/9NbO3(BST-xNLN) energy storage ceramics. Microstructural analysis confirms the dissolution of the Na2/3La1/9NbO3 component into the Ba0.9Sr0.1TiO3 lattice, and all the ceramics exhibit a single-phase perovskite structure. Upon NLN doping, the crystal structure transforms from a tetragonal to a pseudocubic phase. Electrical properties reveal that the ceramic sample with x = 0.15 exhibits pronounced relaxor behavior, as indicated by a modified Curie–Weiss constant (γ) of 1.96. This composition achieves a superior recoverable energy density (Wrec = 2.01 J/cm3) under 28.68 kV/mm, while also maintaining excellent energy efficiency at η = 90.2

The pulse withstand capability is beyond the structural phase diagram and the electronic structure of lead zirconate titanate family, although it is crucial for the safe and reliable operation. In this work, 15,000 engineering ceramic capacitors of ferroelectric, poled, and rhombohedral Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3, are utilized as an example, to perform the positive and high-voltage pulse withstand test, the impedance analysis and the electric polarization characterization. When the density of state is trap-like in the band gap of the electronic structure, the two energy structures of topological defect states in the gap are developed, to clarify the breakdown probability phenomenon in the test, which are in the quantitative agreement with all of the experiments. The structures highlight the macroscopic quantum nature, offering a failure mechanism for the single capacitor and a strategy of improving device yield rate.

The core‐shell structured nanopowders of Ce 0.9 Y 0.1 O 2‐δ @xBaCe 0.9 Y 0.1 O 3‐δ (YDC@xBCY, x = 0.6, 0.8, 1, 1.2, and 1.4) were synthesized via a co‐precipitation method and then sintered in air atmosphere at 1600 ° C to obtain dense ceramic pellets. XRD, SEM, and EDS analyses confirm that the YDC@BCY core‐shell structure remains in bulk ceramics after sintering. Among all samples, YDC@1BCY exhibits the highest total conductivity in air (1.40 × 10 −4 to 1.05 × 10 −2 S/cm in 350°C–550°C). In a 10% H 2 ‐90% N 2 atmosphere, the proton conductivity of YDC@xBCY peaks at x = 0.8. With the aid of the core‐shell structure design, YDC/BCY heterogeneous interface networks are constructed, and the interconnected high conductive YDC/BCY heterogeneous interface networks facilitate ionic transport within the sample. The core‐shell design offers a promising strategy for improving the ionic conductivity of doped CeO 2 –BaCeO 3 ‐based composite ceramics.

Bi2O3-based high-entropy ceramics of (Bi1-x(Y0.2Er0.2Zr0.2Gd0.2Dy0.2)x)2O3 +/-delta ((Bi1-x(YEZGD)x)2O3 +/-delta, x = 0.1, 0.15, 0.2 and 0.3) were synthesized via solid-state reaction method combined with conventional sintering (in 850-930 degrees C for 10 h). The samples of (Bi1-x(YEZGD)x)2O3 +/-delta (x = 0.15, 0.2, and 0.3) possess a fluorite-structured phase (delta-phase), while 18.50 wt% tetragonal beta-phase coexists with the delta-phase in (Bi0.9(YEZGD)0.1)2O3. All samples exhibit a uniform elemental distribution and a high relative density of 93.01-96.57 %. Among all compositions, (Bi0.8(YEZGD)0.2)2O3 +/-delta demonstrates the highest ionic conductivity (1.32 x 10-4-1.09 x 10-1 S/ cm in 300-550 degrees C), approximately 5.7 times higher than that of the single-doped Bi2O3-based ceramic of (Bi0.8Er0.2)2O3 at 500 degrees C. This enhancement is mainly attributed to the random distribution of multiple cations with various ionic radii, which induces lattice distortions that suppress dopant clustering and enhance oxygen vacancy mobility. The results suggest that the high-entropy design offers an effective strategy for improving the ionic conductivity of Bi2O3-based electrolyte at medium-low temperatures.

Compared with batteries and conventional capacitors, supercapacitors have become a hot research topic in the electrochemically energy -storing domain benefiting from their preponderances. The selection of electrode materials determines the electrochemical performance of supercapacitors. TMSs derived from MOFs show promising potential for the supercapacitors. We have designed a complex of Ni9S8 and Ni17S18 with carbon layers coating by using Ni-MOF as a precursor (Ni9S8/Ni17S18@C). Ni9S8/Ni17S18@C derived from Ni-MOF is obtained by high temperature vulcanization. The presence of the peculiar heterostructure of two-phase metal sulfides in the Ni9S8/ Ni17S18@C can expose ample active sites, which can accelerate the ion diffusion process. The mass specific capacity of Ni9S8/Ni17S18@C can reach 998.5C center dot g(- 1) at 1 A center dot g(-1), and still retains 80.02 % of its original permittance after 5000 charging -discharging cycles. The synergistic effect between metal sulfides and carbon allows more ions to be transported quickly, contributing to improved capacity and excellent magnification performance. Moreover, the asymmetric supercapacitor (ASC) assembled with Ni9S8/Ni17S18@C as the positive pole and porous carbons (PCs) as the negative electrode can achieve an energy density of 58.88 Wh center dot kg(-1) at the power density of 799.63 W center dot kg(-1) and exhibits excellent cycling stability.

Hypothesis: Metal -organic frameworks (MOFs) are highly suitable precursors for supercapacitor electrode materials owing to their high porosity and stable backbone structures that offer several advantages for redox reactions and rapid ion transport. Experiments: In this study, a carbon -coated Ni 9 S 8 composite (Ni 9 S 8 @C-5) was prepared via sulfuration at 500 degree celsius using a spherical Ni-MOF as the sacrificial template. Finding: The stable carbon skeleton derived from Ni-MOF and positive structure-activity relationship due to the multinuclear Ni 9 S 8 components resulted in a specific capacity of 278.06 mAh center dot g - 1 at 1 A center dot g - 1 . Additionally, the hybrid supercapacitor (HSC) constructed using Ni 9 S 8 @C-5 as the positive electrode and the laboratory -prepared coal pitch -based activated carbon (CTP-AC) as the negative electrode achieved an energy density of 69.32 Wh center dot kg - 1 at a power density of 800.06 W center dot kg - 1 , and capacity retention of 83.06 % after 5000 cycles of charging and discharging at 5 A center dot g - 1 . The Ni-MOF sacrificial template method proposed in this study effectively addresses the challenges associated with structural collapse and agglomeration of Ni 9 S 8 during electrochemical reactions, thus improving its electrochemical performance. Hence, a simple preparation method is demonstrated, with broad application prospects in supercapacitor electrodes.

Tailoring relaxor phase is an effective strategy to enhance energy-storage properties (ESP) for Bi0.5Na0.5TiO3 (BNT)-based ceramics. Herein, we incorporate Na0.91Bi0.09Nb0.94Mg0.06O3 (NBNM) into BNT matrix to form a solid solution of BNT-xNBNM with x = 0.1-0.4. Rietveld refinements reveal that the composition with x = 0.3 has 46% relaxor tetragonal P4bm phase and 54% relaxor orthorhombic P21ma one, thus exhibiting a large normalized energy-storage density (Wrec/E = 0.015 J kV-1 cm- 2) and a high efficiency (eta = 87%) at 370 kV cm-1. The optimized composition also presents superior temperature stability with a variation of <+/- 5% in the range of 20 C-150 degrees C, outstanding frequency reliability with a variation of <+/- 4% in the range of 5 Hz-500 Hz and excellent charge-discharge properties (discharge rate of 76 ns, current density of 1032 A cm-2 and power density of 129 MW cm-3 at 250 kV cm-1). The results demonstrate a successful strategy to design high per-formance Pb-free relaxor ferroelectrics for pulsed power capacitor applications.

Electrostatic capacitors are fundamental components in electronics and electric power systems because of their inherent superiorities of charging/discharging speed and power density. However, energy storage properties (ESPs) of the top promising relaxor ferroelectric (RFE) are intimately entwined symmetry of local lattice and dynamics of nano-scaled polar structure. Herein, hierarchically polar structure and oxygen octahedral tilting can be induced in the 0.7Bi0.5Na0.5TiO3-0.3Na0.91Bi0.09Nb0.94Mg0.06O3 (BNT-NBNM) matrix with the addition of CaZrO3 (CZ) to achieve outstanding comprehensive ESPs. The chemically induced coexisting triple phases of tetragonal P4bm, orthorhombic P21ma and Pnma2 bring forth hierarchically polar structure, featuring nano domains and slush-like polar clusters embedded in stripe submicro-domains, as indicated by morphological observations, splitting of diffraction spots and polar state distributions. Accordingly, an ultrahigh recoverable energy storage density Wrec = 7.5 J cm -3 concurrent with a high-efficiency & eta; = 94.5 % at a breakdown electric field of 510 kV cm-1 can be attained in BNT-NBNM-0.05CZ RFE ceramic. In addition, the optimal composition also displays excellent stability (Wrec = 5.1 & PLUSMN; 0.1 J cm-3, & eta; = 92.7% & PLUSMN; 1%, 20-170 degrees C and Wrec = 5.2 & PLUSMN; 0.2 J cm-3, & eta; = 92.1% & PLUSMN; 1.3%, 5-500 Hz) at 410 kV cm-1. The present work provides a new perspective for designing lead-free RFE ceramics with ultra-high ESPs that benefit from hierarchically polar structures.

The unique atom configuration in high-entropy dielectric ceramics gives rise to high P max , small P r . Accordingly, ultrahigh recoverable energy density of 8.8 J cm −3 and high η of 92.5%, as well as excellent thermal stability, are achieved.

Abstract Mesoporous activated carbon acquired from coal pitch was produced by an elementary activation process utilizing coal pitch, a coproduct of coal tar production, as a precursor material. The activated carbon CP-AC-700 with obvious pore characteristics was obtained by carbonizing the pre-carbonized coal pitch at 700°C with KOH as the activator. The CP-AC-700 exhibited excellent double-layer electrochemical performance in the three-electrode electrochemical testing system. After three-electrode testing, the material had a specific capacitance of 356 F·g − 1 at a current density of 1 A·g − 1 . Assembled bilayer supercapacitor was tested in a two-electrode system. At a power density of 500·21 W·kg − 1 , the corresponding energy density reached 10.15 Wh·kg − 1 . Following 5000 charge/discharge cycles conducted under constant current conditions, the symmetric supercapacitor exhibited a capacity retention rate of 93.02%. Porous activated carbon prepared from coal pitch showed excellent electrochemical properties as a supercapacitor electrode material and proved to be a promising electrode material with double-layer capacitance.

Eco-friendly Bi0.5Na0.5TiO3 relaxor ferroelectric has attracted considerable attention for pulsed power ca-pacitor applications due to its large saturation polarization. However, high remnant polarization and low breakdown strength (Eb) restrict its application. Herein, linear dielectric CaTiO3 (CT) is introduced into Bi0.5Na0.5TiO3-Na0.91Bi0.09Nb0.94Mg0.06O3 (BNT-NBNM) ceramic to enhance its Eb. Interestingly, CT additive can stabilize polar orthorhombic P21ma phase. As a result, a high recoverable energy density of 6.4 J/cm3 and a high efficiency of 92% at 400 kV/cm as well as an ultrafast discharge rate of 57 ns are obtained in 0.63BNT-0.27NBNM-0.1CT ceramic. Furthermore, temperature dependent Raman spectra reveal that the superior temperature stability of energy storage properties over the temperature span of 30-150 degrees C is due to insensitive B-O vibration to temperature. The results demonstrate an effective strategy to construct superior and stable BNT-based energy storage materials for pulsed power capacitor applications.(c) 2023 Elsevier B.V. All rights reserved.

Due to high power density, fast charge/discharge speed, and high reliability, dielectric capacitors are widely used in pulsed power systems and power electronic systems. However, compared with other energy storage devices such as batteries and supercapacitors, the energy storage density of dielectric capacitors is low, which results in the huge system volume when applied in pulse systems. Therefore, to meet the needs of device miniaturization and integration, reducing the system volume and increasing the energy storage density have become very key research hot spots in the dielectric energy storage fields. In this paper, we first introduce the research background of dielectric energy storage capacitors and the evaluation parameters of energy storage performance. Then, the research status of ceramics, thin films, organic polymers, and organic–inorganic nanocomposites for energy storage is summarized. Next, the methods of improving the energy storage density of dielectric capacitors are concluded. For ceramic blocks and films, methods, such as element doping, multi-phase solid solution/coexistence structure, “core–shell” structure/laminated structure, and other interface adjustments, are effective to increase the energy storage density. While for organic–inorganic nanocomposites, the energy storage performance can be optimized by the surface modification and distribution of fillers, and multi-layer structure design. Finally, the future development tendency of the energy storage materials is prospected to consolidate the research foundation of dielectric energy storage and provide certain guidance value for their practical applications.

A series of novel Bi0.38Na0.38Sr0.24Ti(1-x)(Mn1/3Nb2/3)(x)O-3 lead-free ceramics (BNST-100xMN) were designed and fabricated. The dielectric, ferroelectric, energy-storage, electrostrain properties, and impedance performance of these materials were systematically investigated. A large strain response under low driving electric field was obtained that benefits from the enhanced relaxor-to-ferroelectric phase transition. The optimum piezoelectric stain coefficient d(33)* of 930 pm/V (under 40 kV/cm) was achieved in BNST-1MN composition. The substitution by MN dopant gave rise to a homogeneous micro-morphology with small grains that gave rise to an enhanced high breakdown strength (BDS). Slim and slanted ferroelectric hysteresis was obtained by introducing a larger amount of MN, and hence the BNST-2MN ceramic exhibits a high energy-storage density of 1.30 J/cm(3) at 110 kV/cm, accompanied with an excellent fatigue-free behavior. The dielectric response exhibited a stable high temperature dielectric property with low dielectric loss. These results indicate that BNST-100xMN ceramics are promising candidates for the actuator and energy storage applications.