Owing to the current global scenario of environmental pollution and the energy crisis, the development of new dielectrics using lead-free ceramics for application in advanced electronic and energy storage systems is essential because of the high power density and excellent stability of such ceramics. Unfortunately, most of them have low breakdown strength and/or low maximum polarization, resulting in low energy density and efficiency. To overcome this limitation here, lead-free ceramics comprising a layered structure are designed and fabricated. By optimizing the distribution of the layered structure, a large maximum polarization and high applied electric field (>500 kV cm-1 ) can be achieved; these result in an ultrahigh recoverable energy storage density (≈7 J cm-3 ) and near ideal energy storage efficiency (≈95%). Furthermore, the energy storage performance without obvious deterioration over a broad range of operating frequencies (1-100 Hz), working temperatures (30-160 °C), and fatigue cycles (1-104 ). In addition, the prepared ceramics exhibit extremely high discharge energy density (4.52 J cm-3 ) and power density (405.50 MW cm-3 ). Here, the results demonstrate that the strategy of layered structure design and optimization is promising for enhancing the energy storage performance of lead-free ceramics.

Boosting Energy Storage Performance of Lead-Free Ceramics via Layered Structure Optimization Strategy.

Passive electronic components are an indispensable part of integrated circuits, which are key to the miniaturization and integration of electronic components. As an important branch of passive devices, the relatively low energy-storage capacity of ceramic capacitors limits their miniaturization. To solve this problem, this study adopts the strategy of doping linear materials, specifically CT, into 0.95NaNbO3-0.05Bi(Mg0.5Sn0.5)O3 (0.95NN-0.05BMS) ceramics to increase the disorder of the system through the nonequivalent substitution of A and B sites to achieve the sintering temperature and the residual polarization. Meanwhile, the breakdown electric field strength (Eb) is improved by adjusting the activation energy of the material and the relative density of the sample. Thus, an ultrahigh Wrec of 6.35 J/cm3 and a η of 80% are obtained at an Eb of 646 kV/cm. Additionally, through the analysis of the dielectric temperature spectrum, it is found that the 0.88(0.95NN-0.05BMS)-0.12CT sample can satisfy the technical standards of general ceramic Z5U and patch ceramic X6R. The performance of the ceramics also remains stable within a temperature range of 20-200 °C, a frequency range of 1-100 Hz, and 104 cycles. The charge and discharge tests of the ceramics show that the t0.9 of the sample floats between 1.02 and 1.04 μs, which illustrates its potential application in the field of pulsed power components.

Adjusting the Energy-Storage Characteristics of 0.95NaNbO3-0.05Bi(Mg0.5Sn0.5)O3 Ceramics by Doping Linear Perovskite Materials.

Enhanced energy storage performance in Sr0.7La0.2Zr0.15Ti0.85O3-modified Bi0.5Na0.5TiO3 ceramics via constructing local phase coexistence

Lead-free antiferroelectric ceramics have drawn widespread interest recently on account of their environmentally friendly components and potential applications in high-power systems. However, their relatively low recoverable energy storage density (Wrec < 10 J/cm3), limited by the electric breakdown strength (Eb < 60 kV/mm), and low efficiency (η < 80%), generated by large hysteresis during the antiferroelectric–ferroelectric phase transition, have seriously restricted their application in portable and compact electronic devices. In this study, the relaxor antiferroelectric (1–x)NaNbO3–x(0.55BiFeO3-0.45SrTiO3) ceramics were elaborately designed and systematically explored. With the help of composition regulation, the ceramics not only exhibited a stable antiferroelectric phase but also underwent a structural transformation from an antiferroelectric P (Pbma) phase to R (Pnma) phase, as confirmed by the temperature-dependent dielectric constants, Raman spectra, X-ray diffraction (XRD) refinement, pinched polarization-electric field (P–E) curves, and four-peak current-electric field (I–E) curves. In addition, the relaxor characteristic was demonstrated by the diffuse dielectric peaks, slim P–E curves, flattened Raman peaks, and I–E curves. Consequently, novel relaxor antiferroelectric ceramics were successfully obtained, which simultaneously revealed the features of relaxor and antiferroelectricity. Specifically, the Eb was significantly improved because of the reduced grain size, small sample thickness, exceptionally low dielectric loss, and a moderate dielectric constant. Finally, the sample with x = 0.12 showed an ultrahigh Wrec value of 16.2 J/cm3 and satisfactory η of 82.3% at 97 kV/mm, outperforming most state-of-the-art counterparts. Furthermore, the ceramic also exhibited a large current density (CD) of 1268.4 A/cm2 and power density (PD) of 177.6 MW/cm3 at 28 kV/mm, offering prospective applications in high-power capacitors. This work not only achieved outstanding comprehensive energy storage performance in sodium niobate-based ceramics by modulating the antiferroelectric structure but also provided a feasible route to developing high-performance dielectric capacitors from the viewpoint of structure–property relationship. 

Achieving Ultrahigh Energy Storage Density in Lead-Free Sodium Niobate-Based Ceramics by Modulating the Antiferroelectric Phase

The 0.63(1-x)Bi1.02FeO3-0.37BaTiO3-xBi(Zn2/3(Nb0.85Ta0.15)1/3)O3 (abbreviated BF-BT-xBZNT) high temperature dielectric ceramics were prepared via a two-step sintering (TTS) method. The appropriate medium permittivity achieved in the BF-BT-0.13BZNT ceramic is conducive to mitigating the polarization saturation and improving the breakdown field strength. The domain evolution behavior from piezoresponse force microscopy (PFM) reveals that the introduction of BZNT promotes the formation and switching of more nanodomains of BF-BT ceramics, facilitating the enhancement of energy storage efficiency. The excellent energy storage performance of total energy storage density (Wtot) of 6.06 J/cm3, recoverable energy storage density (Wrec) of 4.85 J/cm3 and a high energy storage efficiency (η) of 80% are simultaneously obtained under 410 kV/cm in the BF-BT-0.13BZNT ceramic. Meanwhile, the ceramic exhibits excellent thermal endurance (10–130 ℃), frequency (1–100 Hz) and fatigue (105 cycles) stability. The current work provides a promising strategy for designing high-performance dielectric energy storage materials which operate in harsh environments. 

Achieving ultrahigh energy storage performance in BiFeO3-BaTiO3 based lead free relaxors via a composition optimization strategy

Developing high-performance dielectric capacitors is essential to meet the growing demands of hybrid electric vehicles and high-power applications. The energy storage efficiency and the temperature-variant energy storage properties should be considered besides the energy density. In this work, we prepared (1 − x)(0.8NaNbO3–0.2SrTiO3) − xBi(Zn0.5Sn0.5)O3 (abbreviated as (1 − x)(NN–ST) − xBZS) lead-free ceramics, where ion disorder is induced in the A–B sites. The experimental results indicate that the antiferroelectric orthorhombic R phase is stabilized, and the breakdown strength is enhanced due to the decreased grain size after BZS modification, which are conducive to optimizing the energy storage performance. The piezoresponse force microscopy (PFM) observation reveals that the incorporated BZS promotes the reversibility of domains, resulting in enhanced energy storage efficiency. Therefore, an energy density of 5.82 J cm−3 and an efficiency of 92.3% are simultaneously obtained in the 0.96(NN–ST) − 0.04BZS composition, and the obtained efficiency in this work reaches a record high in NN-based energy storage ceramics. Especially, the sample displays extraordinary temperature stability, that is, high energy storage density (3.6–4.31 J cm−3) and efficiency (90–95%) are achieved in a wide temperature range from −60 °C to 180 °C. Our work would provide a powerful strategy for designing high-performance energy storage capacitors operating in harsh environments.

Extraordinary energy storage performance and thermal stability in sodium niobate-based ceramics modified by the ion disorder and stabilized antiferroelectric orthorhombic R phase

(Bi0.5Na0.5)TiO3-based relaxor ferroelectrics with enhanced energy-storage density and efficiency under low/moderate - fields via average ionic polarizability design

Weijie Yang

Papers

Extraordinary energy storage performance and thermal stability in sodium niobate-based ceramics modified by the ion disorder and stabilized antiferroelectric orthorhombic R phase

(Bi0.5Na0.5)TiO3-based relaxor ferroelectrics with enhanced energy-storage density and efficiency under low/moderate - fields via average ionic polarizability design