Dielectric polymer nanocomposites are rapidly emerging as novel materials for a number of advanced engineering applications. In this Review, we present a comprehensive review of the use of ferroelectric polymers, especially PVDF and PVDF-based copolymers/blends as potential components in dielectric nanocomposite materials for high energy density capacitor applications. Various parameters like dielectric constant, dielectric loss, breakdown strength, energy density, and flexibility of the polymer nanocomposites have been thoroughly investigated. Fillers with different shapes have been found to cause significant variation in the physical and electrical properties. Generally, one-dimensional and two-dimensional nanofillers with large aspect ratios provide enhanced flexibility versus zero-dimensional fillers. Surface modification of nanomaterials as well as polymers adds flavor to the dielectric properties of the resulting nanocomposites. Nowadays, three-phase nanocomposites with either combination of fillers...

Recent Progress on Ferroelectric Polymer-Based Nanocomposites for High Energy Density Capacitors: Synthesis, Dielectric Properties, and Future Aspects.

The demand for dielectric capacitors with higher energy-storage capability is increasing for power electronic devices due to the rapid development of electronic industry. Existing dielectrics for high-energy-storage capacitors and potential new capacitor technologies are reviewed toward realizing these goals. Various dielectric materials with desirable permittivity and dielectric breakdown strength potentially meeting the device requirements are discussed. However, some significant limitations for current dielectrics can be ascribed to their low permittivity, low breakdown strength, and high hysteresis loss, which will decrease their energy density and efficiency. Thus, the implementation of dielectric materials for high-energy-density applications requires the comprehensive understanding of both the materials design and processing. The optimization of high-energy-storage dielectrics will have far-reaching impacts on the sustainable energy and will be an important research topic in the near future.

Homogeneous/Inhomogeneous-Structured Dielectrics and their Energy-Storage Performances.

With the fast development of the power electronics, dielectric materials with high energy-storage density, low loss, and good temperature stability are eagerly desired for the potential application in advanced pulsed capacitors. Based on the physical principals, the materials with higher saturated polarization, smaller remnant polarization, and higher electrical breakdown field are the most promising candidates. According to this rule, so far, four kinds of materials, namely antiferroelectrics, dielectric glass-ceramics, relaxor ferroelectric and polymer-based ferroelectrics are thought to be more likely used in next-generation pulsed capacitors, and have been widely studied. Thus, this review serves to give an overall summary on the state-of-the-art progress on electric energy-storage performance in these materials. Moreover, some general future prospects are also provided from the existed theoretical and experimental results in this work, in order to propel their application in practice.

https://www.worldscientific.com/doi/pdf/10.1142/S2010135X13300016

A review on the dielectric materials for high energy-storage application

High-k polymer nanocomposites have considerable potential in energy storage and dielectric applications because of their ease of processing, flexibility, and low cost. Core-shell nanoarchitecture strategies are versatile and powerful tools for the design and synthesis of advanced high-k polymer nanocomposites. Recent and in-progress state-of-the-art advancements in the application of core-shell nanoarchitecture strategies to design and prepare high-k polymer nanocomposites are summarized. Special focus is directed to emphasizing their advantages over conventional melt-mixing and solution-mixing methods: first, homogeneous nanoparticle dispersion can be easily achieved even in highly loaded nanocomposites; second, the dielectric constant of the nanocomposites can be effectively enhanced and meanwhile the high breakdown strength can be well-preserved; third, for nanocomposites filled with electrically conductive nanoparticles, dielectric loss can be effectively surpressed, and meanwhile a high dielectric constant can be achieved. In addition, fundamental insights into the roles of the interfaces on the dielectric properties of the nanocomposites can be probed. The last part of the article is concluded with current problems and future perspectives of utilizing the core-shell nanoarchitecture strategies for the development of high-k polymer nanocomposites.

Core-shell structured high-k polymer nanocomposites for energy storage and dielectric applications.

Large-aspect-ratio composite nanofibers with interior hierarchical interfaces are employed to break the adverse coupling of electric displacement and breakdown strength in flexible poly(vinylidene fluoride-hexafluoropropylene) nanocomposite films, a small loading of 3 vol% BaTiO3@TiO2 nanofibers gives rise to the highestenergy density (≈31.2 J cm(-3)) ever achieved in polymer nanocomposites dielectrics.

Giant Energy Density and Improved Discharge Efficiency of Solution-Processed Polymer Nanocomposites for Dielectric Energy Storage.

Dielectric materials with high electric energy densities and low dielectric losses are of critical importance in a number of applications in modern electronic and electrical power systems. An organic–inorganic 0–3 nanocomposite, in which nanoparticles (0-dimensional) are embedded in a 3-dimensionally connected polymer matrix, has the potential to combine the high breakdown strength and low dielectric loss of the polymer with the high dielectric constant of the ceramic fillers, representing a promising approach to realize high energy densities. However, one significant drawback of the composites explored up to now is that the increased dielectric constant of the composites is at the expense of the breakdown strength, limiting the energy density and dielectric reliability. In this study, by expanding the traditional 0–3 nanocomposite approach to a multilayered structure which combines the complementary properties of the constituent layers, one can realize both greater dielectric displacement and a higher breakdown field than that of the polymer matrix. In a typical 3-layer structure, for example, a central nanocomposite layer of higher breakdown strength is introduced to substantially improve the overall breakdown strength of the multilayer-structured composite film, and the outer composite layers filled with large amount of high dielectric constant nanofillers can then be polarized up to higher electric fields, hence enhancing the electric displacement. As a result, the topological-structure modulated nanocomposites, with an optimally tailored nanomorphology and composite structure, yield a discharged energy density of 10 J/cm3 with a dielectric breakdown strength of 450 kV mm–1, much higher than those reported from all earlier studies of nanocomposites.

Topological‐Structure Modulated Polymer Nanocomposites Exhibiting Highly Enhanced Dielectric Strength and Energy Density

Physiological electric potential is well-known for its indispensable role in maintaining bone volume and quality. Although implanted biomaterials simulating structural, morphological, mechanical, and chemical properties of natural tissue or organ has been introduced in the field of bone regeneration, the concept of restoring physiological electric microenvironment remains ignored in biomaterials design. In this work, a flexible nanocomposite membrane mimicking the endogenous electric potential is fabricated to explore its bone defect repair efficiency. BaTiO3 nanoparticles (BTO NPs) were first coated with polydopamine. Then the composite membranes are fabricated with homogeneous distribution of Dopa@BTO NPs in poly(vinylidene fluoridetrifluoroethylene) (P(VDF-TrFE)) matrix. The surface potential of the nanocomposite membranes could be tuned up to −76.8 mV by optimizing the composition ratio and corona poling treatment, which conform to the level of endogenous biopotential. Remarkably, the surface potentia...

Nanocomposite Membranes Enhance Bone Regeneration Through Restoring Physiological Electric Microenvironment

PbTiO3−Bi(Zn1/2Ti1/2)O3 and related solid solutions exhibit an unusually negative thermal expansion with considerably enhanced tetragonality and Curie temperature. A zero thermal expansion is found over a wide temperature range of room temperature to 500 °C. Direct experimental evidence is given for the fact that the negative thermal expansion of PbTiO3-based solid solutions is strongly correlated with the temperature dependence of the ferroelectricity, which is a new negative thermal expansion mechanism.

Zero Thermal Expansion in PbTiO3-Based Perovskites

By using Bi2O3-doped Ba0.3Sr0.7TiO3 (BSBT) fibers prepared via electrospinning and modified by dopamine as dielectric fillers, BSBT/P(VDF-TrFE) flexible nanocomposites are fabricated by solution casting. A low loading of BSBT nanofibers leads to a large increase in the dielectric constant and breakdown strength. In particular, the discharged energy density of the nanocomposites is significantly enhanced several times in comparison with the pure polymer matrix. The enhanced breakdown strength and discharged energy density could be attributed to the combined effects of the surface modification, large aspect ratio and paraelectric polarization behavior of the BSBT fibers. The present work indicates the enhancing potential of energy density on the polymer–ceramic composite by the paraelectric nanofiber fillers.

Largely enhanced energy density in flexible P(VDF-TrFE) nanocomposites by surface-modified electrospun BaSrTiO3 fibers

Ba0.6Sr0.4TiO3 (BST) nanofibers prepared via electrospinning and modified by dopamine are used as dielectric fillers in polyvinylidene fluoride (PVDF)-based composites. With 4.4 vol. % of BST nanofibers, the extractable energy density of the BST/PVDF composites is more than doubled as compared with pure PVDF matrix. Such significant enhancement is attributed to the combined effect of both surface modification by dopamine and large aspect ratio of the BST nanofibers. Paraelectric or anti-ferroelectric fillers of large aspect ratio may serve as a general strategy for enhanced electric energy density in polymer composites.

Penghao Hu

Papers

Topological‐Structure Modulated Polymer Nanocomposites Exhibiting Highly Enhanced Dielectric Strength and Energy Density

Nanocomposite Membranes Enhance Bone Regeneration Through Restoring Physiological Electric Microenvironment

Zero Thermal Expansion in PbTiO3-Based Perovskites

Largely enhanced energy density in flexible P(VDF-TrFE) nanocomposites by surface-modified electrospun BaSrTiO3 fibers

Significant enhancement in energy density of polymer composites induced by dopamine-modified Ba0.6Sr0.4TiO3 nanofibers