Materials exhibiting high energy/power density are currently needed to meet the growing demand of portable electronics, electric vehicles and large-scale energy storage devices. The highest energy densities are achieved for fuel cells, batteries, and supercapacitors, but conventional dielectric capacitors are receiving increased attention for pulsed power applications due to their high power density and their fast charge-discharge speed. The key to high energy density in dielectric capacitors is a large maximum but small remanent (zero in the case of linear dielectrics) polarization and a high electric breakdown strength. Polymer dielectric capacitors offer high power/energy density for applications at room temperature, but above 100 °C they are unreliable and suffer from dielectric breakdown. For high-temperature applications, therefore, dielectric ceramics are the only feasible alternative. Lead-based ceramics such as La-doped lead zirconate titanate exhibit good energy storage properties, but their toxicity raises concern over their use in consumer applications, where capacitors are exclusively lead free. Lead-free compositions with superior power density are thus required. In this paper, we introduce the fundamental principles of energy storage in dielectrics. We discuss key factors to improve energy storage properties such as the control of local structure, phase assemblage, dielectric layer thickness, microstructure, conductivity, and electrical homogeneity through the choice of base systems, dopants, and alloying additions, followed by a comprehensive review of the state-of-the-art. Finally, we comment on the future requirements for new materials in high power/energy density capacitor applications.

Electroceramics for High-Energy Density Capacitors: Current Status and Future Perspectives

Dielectric materials with high energy densities and efficiencies are greatly required in the field of power electronics to satisfy demand. This study presents a regulating strategy through Zr4+ doping and oxygen treatment for reliably enhancing the energy storage performances of Ca0.5Sr0.5TiO3 ceramics. The introduction of Zr4+ inhibits grain growth, and grain boundary barrier effects are enhanced via oxygen treatment; these outcomes are systemically analyzed using complex impedance data. Exceptional energy storage performance is shown; an energy density of 3.37 J cm−3 and 96% energy efficiency under a breakdown strength of 440 kV cm−1 are obtained simultaneously in Ca0.5Sr0.5Ti0.85Zr0.15O3 ceramics following oxygen treatment, which are better results than for other reported linear dielectric systems. This system also possesses excellent stability, with minimal fluctuations (<10%) over wide frequency (1–1000 Hz) and temperature (20–120 °C) ranges. Furthermore, pulsed charging and discharging tests are carried out, aimed at evaluating the practical performance of the ceramic materials. A prominent CD value of 293.3 A cm−2 and PD value of 17.6 MW cm−3 are achieved, and the stored energy is released sharply (∼20 ns); the ceramics also possess outstanding temperature stability (20–120 °C) and fatigue resistance (300 cycles). These properties verify that these lead-free linear dielectric ceramics have potential for practical energy storage applications, especially in high-temperature and high-pressure environments.

Enhancing the energy storage properties of Ca0.5Sr0.5TiO3-based lead-free linear dielectric ceramics with excellent stability through regulating grain boundary defects

Enhancement of energy storage performance in lead-free barium titanate-based relaxor ferroelectrics through a synergistic two-step strategy design

Enhanced energy storage and fast charge-discharge capability in Ca0.5Sr0.5TiO3-based linear dielectric ceramic

Abstract 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 $${\rm{B}}{{\rm{a}}_{0.105}}{\rm{N}}{{\rm{a}}_{0.325}}{\rm{S}}{{\rm{r}}_{0.245 - 1.5x}}{_{0.5x}}{\rm{B}}{{\rm{i}}_{0.325 + x}}{\rm{Ti}}{{\rm{O}}_3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>Ba</mml:mtext> <mml:mrow> <mml:mn>0.105</mml:mn> </mml:mrow> </mml:msub> <mml:msub> <mml:mtext>Na</mml:mtext> <mml:mrow> <mml:mn>0.325</mml:mn> </mml:mrow> </mml:msub> <mml:msub> <mml:mtext>Sr</mml:mtext> <mml:mrow> <mml:mn>0.245</mml:mn> <mml:mo>−</mml:mo> <mml:mn>1.5</mml:mn> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mo>□</mml:mo> <mml:mrow> <mml:mn>0.5</mml:mn> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mtext>Bi</mml:mtext> <mml:mrow> <mml:mn>0.325</mml:mn> <mml:mo>+</mml:mo> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mtext>TiO</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:math> ( $${\rm{BN}}{{\rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{\rm{B}}_{0.325 + x}}{\rm{T}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>BNS</mml:mtext> <mml:mrow> <mml:mn>0.245</mml:mn> <mml:mo>−</mml:mo> <mml:mn>1.5</mml:mn> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mo>□</mml:mo> <mml:mrow> <mml:mn>0.5</mml:mn> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mtext>B</mml:mtext> <mml:mrow> <mml:mn>0.325</mml:mn> <mml:mo>+</mml:mo> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:mtext>T</mml:mtext> </mml:math> , x = 0, 0.02, 0.04, 0.06, and 0.08) lead-free ceramics are selected as the representative. The $${\rm{BN}}{{\rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{\rm{B}}_{0.325 + x}}{\rm{T}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>BNS</mml:mtext> <mml:mrow> <mml:mn>0.245</mml:mn> <mml:mo>−</mml:mo> <mml:mn>1.5</mml:mn> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mo>□</mml:mo> <mml:mrow> <mml:mn>0.5</mml:mn> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mtext>B</mml:mtext> <mml:mrow> <mml:mn>0.325</mml:mn> <mml:mo>+</mml:mo> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:mtext>T</mml:mtext> </mml:math> ceramics are prepared by using pressureless solid-state sintering and achieve large W rec (1.8 J/cm 3 ) at a low electric field (@110 kV/cm) when x = 0.06. The value of 1.8 J/cm 3 is super high as compared to all other W rec in lead-free bulk ceramics under a relatively low electric field (&lt; 160 kV/cm). Furthermore, a high dielectric constant of 2930 within 15% fluctuation in a wide temperature range of 40–350 °C is also obtained in $${\rm{BN}}{{\rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{\rm{B}}_{0.325 + x}}{\rm{T}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>BNS</mml:mtext> <mml:mrow> <mml:mn>0.245</mml:mn> <mml:mo>−</mml:mo> <mml:mn>1.5</mml:mn> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mo>□</mml:mo> <mml:mrow> <mml:mn>0.5</mml:mn> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mtext>B</mml:mtext> <mml:mrow> <mml:mn>0.325</mml:mn> <mml:mo>+</mml:mo> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:mtext>T</mml:mtext> </mml:math> ( 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 $${\rm{BN}}{{\rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{\rm{B}}_{0.325 + x}}{\rm{T}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>BNS</mml:mtext> <mml:mrow> <mml:mn>0.245</mml:mn> <mml:mo>−</mml:mo> <mml:mn>1.5</mml:mn> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mo>□</mml:mo> <mml:mrow> <mml:mn>0.5</mml:mn> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:msub> <mml:mtext>B</mml:mtext> <mml:mrow> <mml:mn>0.325</mml:mn> <mml:mo>+</mml:mo> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:mtext>T</mml:mtext> </mml:math> ( x = 0.06) ceramics are desirable for advanced pulsed power capacitors, and will push the development of a series of Bi 0.5 Na 0.5 TiO 3 (BNT)-based ceramics with high W rec and high-temperature stability. 

Remarkably enhanced dielectric stability and energy storage properties in BNT—BST relaxor ceramics by A-site defect engineering for pulsed power applications

Glass ceramics composed of Na2O–BaO–Bi2O3–Nb2O5–Al2O3–SiO2 (NBBN-AS) were modified by rare-earth doping and prepared via the melt-quenching process accompanied by controlled crystallization. High-r...

Achieving Superior Energy Storage Properties and Ultrafast Discharge Speed in Environment-Friendly Niobate-Based Glass Ceramics.

A newly designed glass-ceramic system consisting of 15Bi2O3-15Nb2O5-40SiO2-30Al2O3 was successfully prepared, which was followed by its controlled crystallization at different heating temperatures. The effects of crystallization temperature on the microstructure, phase evolution and the energy storage behaviors of the novel material were systematically investigated. A maximum theoretical energy storage density of up to 15.3 J/cm3 was found in the samples heated at 800 °C. The polarization-electric (PE) hysteresis loops of this material exhibited very good linear character and high energy efficiency. In addition, an approximate value of 25 ns for discharged period T has been obtained, which demonstrated that most of the energy stored in dielectric was released over a very short time. The maximum powder density exceeds a high value of 90 MW/cc in a 390 kV/cm electric field. Therefore, the new developed Bi2O3-Nb2O5-SiO2-Al2O3 glass-ceramic can be used as an alternative, promising high-performance electrostatic capacitor material.

Dielectric characterization of a novel Bi2O3-Nb2O5-SiO2-Al2O3 glass-ceramic with excellent charge-discharge properties

Excellent energy storage and charge-discharge performances in sodium-barium-niobium based glass ceramics

The BaO-Na2O-Bi2O3-Nb2O5-Al2O3-SiO2 (BNBN-AS) glass-ceramics were prepared by technics of melt-quenching accompanied with process of controlled crystallization. According to the X-ray diffraction results, NaNbO3 with perovskite structure and Ba2NaNb5O15 with tungsten bronze structure were all precipitated at four different crystalline temperatures. With the increasing of crystalline temperature, the relative dielectric constant kept increasing, while breakdown strength (BDS) increased first and then decreased. The highest relative dielectric constant of 123 at 1000 °C as well as optimal breakdown strength of 1878.75 ± 63.2 kV/cm at 950 °C were acquired in this system. The theoretical energy-storage density was markedly enhanced up to the maximum value of 18.4 ± 1.3 J/cm3 at 950 °C, which is approximately twice than that at 850 °C. The discharged energy density reached to 0.48 J/cm3 at the applied electric field of 600 kV/cm for the sample crystallized at 950 °C, which promises a broad application prospect.

Effects of crystalline temperature on microstructures and dielectric properties in BaO-Na2O-Bi2O3-Nb2O5-Al2O3-SiO2 glass-ceramics

The barium sodium niobate (BNN) glass-ceramics with different amount of CaF2 addition were fabricated by melting-crystallization method. Effects of CaF2 on microstructure, phase compositions, interface polarization, dielectric, energy-storage and charge–discharge properties of the BNN-glass-ceramics were comprehensively studied. Results indicate a suitable amount of CaF2 (from 1.0 to 3.0 mol%) is helpful to improve both relative permittivity and breakdown strength (BDS) of the BNN-glass-ceramics. The theoretical energy-storage density is up to 14.3 J/cm3 when the amount of CaF2 reaches 3.0 mol%. The optimal composition of 3.0 mol% CaF2 addition was further evaluated by a pulsed charged–discharged circuit and P–E hysteresis loops, from which we can conclude BNN-glass-ceramic is an excellent linear dielectric material. And the stored energy could be released within 50 ns and discharge power density reaches 75.6 MW/cm3. It’s for such results that the glass-ceremics with CaF2 addition are promising materials for pulse power applications.

Kaikai Chen

Papers

Achieving Superior Energy Storage Properties and Ultrafast Discharge Speed in Environment-Friendly Niobate-Based Glass Ceramics.

Dielectric characterization of a novel Bi2O3-Nb2O5-SiO2-Al2O3 glass-ceramic with excellent charge-discharge properties

Excellent energy storage and charge-discharge performances in sodium-barium-niobium based glass ceramics

Effects of crystalline temperature on microstructures and dielectric properties in BaO-Na2O-Bi2O3-Nb2O5-Al2O3-SiO2 glass-ceramics

Enhanced energy-storage density in sodium-barium-niobate based glass-ceramics realized by doping CaF 2 nucleating agent