Perovskite lead-free dielectrics for energy storage applications

Due to the nature of domains, ferroics, including ferromagnetic, ferroelectric, and ferroelastic materials, exhibit hysteresis phenomena with respect to external driving fields (magnetic field, electric field, or stress). In principle, every ferroic material has its own hysteresis loop, like a fingerprint, which contains information related to its properties and structures. For ferroelectrics, many characteristic parameters, such as coercive field, spontaneous, and remnant polarizations can be directly extracted from the hysteresis loops. Furthermore, many impact factors, including the effect of materials (grain size and grain boundary, phase and phase boundary, doping, anisotropy, thickness), aging (with and without poling), and measurement conditions (applied field amplitude, fatigue, frequency, temperature, stress), can affect the hysteretic behaviors of the ferroelectrics. In this feature article, we will first give the background of the ferroic materials and multiferroics, with an emphasis on ferroelectrics. Then it is followed by an introduction of the characterizing techniques for the loops, including the polarization–electric field loops and strain–electric field curves. A caution is made to avoid misinterpretation of the loops due to the existence of conductivity. Based on their morphologic features, the hysteresis loops are categorized to four groups and the corresponding material usages are introduced. The impact factors on the hysteresis loops are discussed based on recent developments in ferroelectric and related materials. It is suggested that decoding the fingerprint of loops in ferroelectrics is feasible and the comprehension of the material properties and structures through the hysteresis loops is established.

Decoding the Fingerprint of Ferroelectric Loops: Comprehension of the Material Properties and Structures

Dramatic changes in the physical properties of composites occur when filler particles form a percolating network through the composite, particularly when the difference between the properties of the constitutive phases is large. By use of electric conductivity and dielectric properties as examples, recent studies on the physical properties of composites near percolation are reviewed. The effects of geometric factors and intrinsic properties of the fillers and the matrix, and especially of the interface between fillers and matrix, on electric and dielectric properties near percolation are discussed. Contact resistivity at the interface is less desirable for enhancing electrical conductivity. By contrast, an interface with high resistivity suppresses tunneling between adjacent fillers and leads to percolative composites with higher dielectric constant but lower dielectric loss. This review concludes with an outlook on the future possibilities and scientific challenges in the field.

Physical Properties of Composites Near Percolation

We present a critical review that encompasses the fundamentals and state-of-the-art knowledge of barium titanate-based piezoelectrics. First, the essential crystallography, thermodynamic relations, and concepts necessary to understand piezoelectricity and ferroelectricity in barium titanate are discussed. Strategies to optimize piezoelectric properties through microstructure control and chemical modification are also introduced. Thereafter, we systematically review the synthesis, microstructure, and phase diagrams of barium titanate-based piezoelectrics and provide a detailed compilation of their functional and mechanical properties. The most salient materials treated include the (Ba,Ca)(Zr,Ti)O3, (Ba,Ca)(Sn,Ti)O3, and (Ba,Ca)(Hf,Ti)O3 solid solution systems. The technological relevance of barium titanate-based piezoelectrics is also discussed and some potential market indicators are outlined. Finally, perspectives on productive lines of future research and promising areas for the applications of these ma...

BaTiO3-based piezoelectrics: Fundamentals, current status, and perspectives

High strain piezoelectric ceramics are the state-of-the-art materials for high precision, positioning devices. A comprehensive review of the latest developments of the various types of perovskite piezoelectric ceramic systems is presented herein, with special attention given to three promising families of lead-free perovskite ferroelectrics: the barium titanate, alkaline niobate and bismuth perovskites. Included in this review are details of phase transition behavior, strain enhancement approaches, material reliabilities as well as the status of some promising applications. This current review describes both compositional and structural engineering approaches that are intended to achieve enhanced strain properties in perovskite piezoelectric ceramics. The factors that affect the strain behavior of high-strain perovskite piezoelectric ceramics are addressed. The reliability characteristics of these high-strain ferroelectrics as well as the recent approaches to the long-term electrical, thermal and time-stability enhancement are summarized. Several promising applications of high-strain perovskite materials are introduced, which take advantages of their characteristics; examples include high-energy storage, pyroelectric and electro-caloric effect and luminescent properties.

Progress in high-strain perovskite piezoelectric ceramics

The development of energy storage devices with a high energy storage density, high power density, and excellent stability has always been a long-cherished goal for many researchers as they tackle issues concerning energy conservation and environmental protection. In this work, we report a novel BaTiO3-based lead-free composition (0.85BaTiO3–0.15Bi(Zn1/2Sn1/2)O3) with an ultrahigh energy storage density (2.41 J cm−3) and a high energy storage efficiency of 91.6%, which is superior to other lead-free systems reported recently. The energy storage properties of 0.85BT–0.15BZS ceramic manifest excellent frequency stability (5–1000 Hz) and fatigue endurance (cycle number: 105). The pulsed charging–discharging process is measured to elucidate the actual operation performance in the 0.85BT–0.15BZS ceramic. Delightfully, the 0.85BT–0.15BZS ceramic also possesses an ultrahigh current density of 551 A cm−2 and a giant power density of 30.3 MW cm−3, and the stored energy is released in sub-microseconds. Moreover, the 0.85BT–0.15BZS ceramic exhibits outstanding temperature stability of its dielectric properties, energy storage properties, and charging–discharging performance over a broad temperature range (20–160 °C) due to the weakly-coupled relaxor behavior. These results not only indicate the superior potential of environment-friendly BaTiO3-based relaxor ferroelectric ceramics for the design of ceramic capacitors of both high energy storage and power applications, but they also show the merit of the weakly-coupled relaxor behavior to improve the thermal stability of energy storage properties.

Novel BaTiO3-based lead-free ceramic capacitors featuring high energy storage density, high power density, and excellent stability

This study presents an innovative strategy to improve the energy storage properties of NaNbO3 lead-free ceramics by the addition of Bi2O3. The introduction of Bi2O3 can effectively increase the breakdown strength and decrease the remnant polarization of NaNbO3 ceramics. Meanwhile, hybridization between the O2− 2p and Bi3+ 6p orbitals can enhance the polarization. The novel NaNbO3-based (Na0.7Bi0.1NbO3) ceramics demonstrate ultrahigh energy storage efficiency of 85.4% and remarkably high energy storage density (4.03 J cm−3) at 250 kV cm−1 simultaneously, which are superior to the results of almost all recently reported lead-free alternatives. The outstanding stability of energy storage characteristics in terms of frequency (1–1000 Hz), temperature (20–120 °C) and fatigue (cycle number: 105) is also observed in Na0.7Bi0.1NbO3 ceramics. Furthermore, additional pulsed charge–discharge measurements for Na0.7Bi0.1NbO3 ceramics are also carried out to evaluate actual operation performance. The Na0.7Bi0.1NbO3 ceramics exhibit extremely high power density (62.5 MW cm−3) and current density (1250 A cm−2) and release all stored energy rapidly (∼155 ns) under various electric fields and temperatures. These properties qualify these environment-friendly Na0.7Bi0.1NbO3 ceramics as innovative and most promising alternatives for energy storage applications, especially for high power and pulsed power system applications.

Superior energy storage properties and excellent stability of novel NaNbO3-based lead-free ceramics with A-site vacancy obtained via a Bi2O3 substitution strategy

Recently, ceramic capacitors with fast charge–discharge performance and excellent energy storage characteristics have received considerable attention. Novel NaNbO3-based lead-free ceramics (0.80NaN...

Novel Sodium Niobate-Based Lead-Free Ceramics as New Environment-Friendly Energy Storage Materials with High Energy Density, High Power Density, and Excellent Stability

Bismuth ferrite (BiFeO3, BFO) possesses very large spontaneous polarization, which provides a great potential in dielectric energy-storage capacitors. However, the presence of large remanent polarization heavily restricts the achievement of excellent performance in the energy storage field. Herein we designed local compositional disorder and constructed quenched random fields to maximize the discrepancy between the maximum polarization and the remanent polarization by means of introducing Zn2+ and Ta5+ at B-sites together in BiFeO3-based solution. Interestingly, pinched-hysteresis loops were observed in this Ba(Zn1/2Ta2/3)O3-modified BFO-based solution. Ultrahigh recoverable energy density (2.56 J cm−3) was first reported under low electric field (16 kV mm−1), which is much superior to the previous results regarding BFO-based bulk ceramics. In addition, an excellent recoverable energy density (>2 J cm−3) and a high efficiency (>80%) were obtained simultaneously in this BZT-modified BFO-based bulk material under low electric field (<20 kV mm−1). These results demonstrate that the strategy of constructing weakly coupled polar structures is feasible and effective to boost the energy density and efficiency for BiFeO3-based bulk ceramics, which may pave a significant step towards utilizing energy-storage applications for BiFeO3-based materials.

Designing lead-free bismuth ferrite-based ceramics learning from relaxor ferroelectric behavior for simultaneous high energy density and efficiency under low electric field

Ruihong Liang

Papers

Novel BaTiO3-based lead-free ceramic capacitors featuring high energy storage density, high power density, and excellent stability

Superior energy storage properties and excellent stability of novel NaNbO3-based lead-free ceramics with A-site vacancy obtained via a Bi2O3 substitution strategy

Novel Sodium Niobate-Based Lead-Free Ceramics as New Environment-Friendly Energy Storage Materials with High Energy Density, High Power Density, and Excellent Stability

Designing lead-free bismuth ferrite-based ceramics learning from relaxor ferroelectric behavior for simultaneous high energy density and efficiency under low electric field

Combining high energy efficiency and fast charge-discharge capability in novel BaTiO3-based relaxor ferroelectric ceramic for energy-storage