Perovskite lead-free dielectrics for energy storage applications

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

Recent development in lead-free perovskite piezoelectric bulk materials

High-Performance Dielectric Ceramic Films for Energy Storage Capacitors: Progress and Outlook

This review provides a detailed overview on the latest developments in the design and control of the interface in polymer based composite dielectrics for energy storage applications. The methods employed for interface design in composite systems are described for a variety of filler types and morphologies, along with novel approaches employed to build hierarchical interfaces for multi-scale control of properties. Efforts to achieve a close control of interfacial properties and geometry are then described, which includes the creation of either flexible or rigid polymer interfaces, the use of liquid crystals and developing ceramic and carbon-based interfaces with tailored electrical properties. The impact of the variety of interface structures on composite polarization and energy storage capability are described, along with an overview of existing models to understand the polarization mechanisms and quantitatively assess the potential benefits of different structures for energy storage. The applications and properties of such interface-controlled materials are then explored, along with an overview of existing challenges and practical limitations. Finally, a summary and future perspectives are provided to highlight future directions of research in this growing and important area.

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Interface design for high energy density polymer nanocomposites

High-performance lead-free piezoelectric materials are in great demand for next-generation electronic devices to meet the requirement of environmentally sustainable society. Here, ultrahigh piezoelectric properties with piezoelectric coefficients (d33 ≈700 pC N-1 , d33 * ≈980 pm V-1 ) and planar electromechanical coupling factor (kp ≈76%) are achieved in highly textured (K,Na)NbO3 (KNN)-based ceramics. The excellent piezoelectric properties can be explained by the strong anisotropic feature, optimized engineered domain configuration in the textured ceramics, and facilitated polarization rotation induced by the intermediate phase. In addition, the nanodomain structures with decreased domain wall energy and increased domain wall mobility also contribute to the ultrahigh piezoelectric properties. This work not only demonstrates the tremendous potential of KNN-based ceramics to replace lead-based piezoelectrics but also provides a good strategy to design high-performance piezoelectrics by controlling appropriate phase and crystallographic orientation.

Ultrahigh Piezoelectric Properties in Textured (K,Na)NbO3-Based Lead-Free Ceramics

Superior energy storage properties and excellent stability achieved in environment-friendly ferroelectrics via composition design strategy

Polarization field engineering of piezoelectric materials is considered as an advisable strategy in fine-tuning photocatalytic performance which has drawn much attention recently. However, the efficient charge separation that determines the photocatalytic reactivities of these materials is quite restricted. Herein, a judicious combination of piezoelectric and photocatalytic performances of BiOX/BaTiO3 (X = Cl, Br, Cl0.166 Br0.834 ) to enable a high piezophotocatalytic activity is demonstrated. Under the synergic advantages of chemical potential difference and piezoelectric potential difference in BiOX/BaTiO3 composites, the photoinduced carriers recombination is largely halted, which directly contributes to the significantly promoted piezophotocatalytic activity of piezoelectric composites. Inspiringly, the BiOBr/BaTiO3 composites under light irradiation with auxiliary ultrasonic activation result in an ultrahigh and stable photocatalytic performance, which is much higher than the total of those by isolated photocatalysis and piezocatalysis, and can rival current excellent photocatalytic system. In fact, the theoretical piezoelectric potential difference of BiOBr/BaTiO3 composites reaches 100 mV, which far exceeds the pure BaTiO3 of 31.21 mV and BiOBr of 30 mV, respectively. First, fabrication of BiOX/BaTiO3 piezoelectric composites and its remarkable piezophoto coupling catalysis behavior lays new ground for developing high-efficiency piezoelectric photocatalysts in purifying wastewater, killing bacteria, and other piezophototronic processes.

Remarkable Piezophoto Coupling Catalysis Behavior of BiOX/BaTiO 3 (X = Cl, Br, Cl 0.166 Br 0.834 ) Piezoelectric Composites

The increasing consumption of compact electronics impels us to design high-performance dielectric energy storage materials. Bi0.5K0.5TiO3-based materials, which have been ignored thus far in energy storage applications, possess an ultrahigh stored energy density (WS = 3.07 J cm−3) and recoverable energy storage density (WR = 2.08 J cm−3), as well as excellent thermal stability (the variation in WR is less than 8% over the range of 25–140 °C) when using a hot-press sintering technique. Moreover, by means of charge–discharge evaluations, the stored energy is released in a very short time (∼0.2 μs), regardless of variations in the temperature. The results presented here strongly indicate that the elaborately designed Bi0.5K0.5TiO3–0.06La(Mg0.5Ti0.5)O3 ceramic is a promising candidate for energy storage applications.

Exploring novel bismuth-based materials for energy storage applications

Electrostatic capacitors with high power density have been demonstrated as efficient power sources in modern electrical and electronic devices. Nevertheless, the low energy density restricted the applications of electrostatic capacitors in the ever-developing electronic world. To improve energy density, herein, one-dimensional (1D) NaNbO3 (NN) nanowires with a high-aspect-ratio are prepared by a simple hydrothermal method and introduced into a poly(vinylidene fluoride) (PVDF) matrix. The NN@PDA nanowires/PVDF nanocomposite films show a high discharge energy density of 12.26 J cm−3 at 410 MV m−1, which is about 107% higher than that of pristine PVDF (5.87 J cm−3 at 350 MV m−1) and 510% higher than that of the best commercial biaxially-oriented-polypropylenes (BOPP) (2 J cm−3 at 640 MV m−1). Moreover, the composite films show a superior power density of 2.01 MW cm−3 and ultra-fast discharge speed of 146 ns. As verified by finite element simulations, 1D NN nanowires incorporation into the polymer matrix could significantly improve the local electric distribution and electric current density distribution in the nanocomposites. Ultimately, it is anticipated that this work will open a new design paradigm to boost the performance of polymer nanocomposites for compact and flexible electrical energy storage applications.

Jiwei Zhai

Papers

Ultrahigh Piezoelectric Properties in Textured (K,Na)NbO3-Based Lead-Free Ceramics

Superior energy storage properties and excellent stability achieved in environment-friendly ferroelectrics via composition design strategy

Remarkable Piezophoto Coupling Catalysis Behavior of BiOX/BaTiO 3 (X = Cl, Br, Cl 0.166 Br 0.834 ) Piezoelectric Composites

Exploring novel bismuth-based materials for energy storage applications

High-performance capacitors based on NaNbO3 nanowires/poly(vinylidene fluoride) nanocomposites