Significantly Enhanced Energy Storage Density by Modulating the Aspect Ratio of BaTiO3 Nanofibers

A BaTiO3/WS2 composite for piezo-photocatalytic persulfate activation and ofloxacin degradation

Piezoelectric fields can decrease the recombination rate of photogenerated electrons and holes in semiconductors and therewith increase their photocatalytic activities. Here, a BaTiO₃/WS₂ composite is synthesized and characterized, which combines piezoelectric BaTiO₃ nanofibers and WS₂ nanosheets. The piezo-photocatalytic effect of the composite on the persulfate activation is studied by monitoring Ofloxacin (OFL) degradation efficiency. Under mechanical forces, LED lamp irradiation, and the addition of 10 mM persulfate, the OFL degradation efficiency reaches ~90% within 75 min, which is higher than efficiencies obtained for individual BaTiO₃, WS₂, or TiO₃, widely used photocatalysts in the field of water treatment. The boosted degradation efficiency can be ascribed to the promotion of charge carrier separation, resulting from the synergetic effect of the heterostructure and the piezoelectric field induced by the vibration. Moreover, the prepared composite displays good stability over five successive cycles of the degradation process. GC-MS analysis is used to survey the degradation pathway of OFL during the degradation process. Our results offer insight into strategies for preparing highly effective piezo-photocatalysts in the field of water purification.

High Energy Storage Performance of PMMA Nanocomposites Utilizing Hierarchically Structured Nanowires Based on Interface Engineering

To overcome the inherent high hysteresis loss of ferroelectric polymer-based nanocomposites, non-ferroelectric linear dielectric poly(methyl methacrylate) (PMMA) is adopted as the polymer matrix for high discharge efficiency. At the same time, slender ferroelectric BaTiO₃ nanowires (BT NWs) with a high dielectric constant are selected as the nanofiller for high energy density. To avoid the agglomeration of BT NWs and enhance the strength of interfaces, dopamine is used as organic coatings to tailor the interface. The BT@dopa NWs/PMMA nanocomposites exhibit excellent interface compatibility between the BT NWs and PMMA matrix and a very good microstructure uniformity. Based on this, hierarchically structured BT@SiO₂@dopa NWs are designed and prepared to overcome the uneven electric field distribution at the interface, resulting from the dielectric constant mismatch. The discharged energy density (U_e) can be largely enhanced from 3.76 J/cm³ for pure PMMA films to 11.78 J/cm³ for PMMA-based nanocomposites by incorporating 5.0 wt % BT@SiO₂@dopa NWs. In addition, a high discharging efficiency (η) of 91% is obtained simultaneously in the nanocomposites. Both experimental and theoretical simulations demonstrate that the double core-shell structure nanowire fillers can effectively alleviate the local field distortion, inhibit leakage current, and suppress remnant electric displacement, leading to the high U_e and η. These findings are significant in facilitating the development of high-performance film dielectric capacitor materials using PMMA-based nanocomposites toward high energy storage density.

Nano-ZnO decorated ZnSnO3 as efficient fillers in PVDF matrixes: toward simultaneous enhancement of energy storage density and efficiency and improved energy harvesting activity

Here, we report the effect of ZnO decoration on ZnSnO3 fillers on the dielectric property, energy storage behaviour and mechanical energy harvesting performance of PVDF matrixes. More enhanced dielectric constant and reduction in dielectric loss were achieved in PVDF-ZnO@ZnSnO3 (PVDF-ZNZS) films than in PVDF-ZnSnO3 (PVDF-ZS) films for the same concentration of filler loading. Similarly, PVDF-ZNZS films showed simultaneous enhancement in electrical energy storage density and storage efficiency compared to PVDF-ZS composites. As all the constituent materials (PVDF, ZnSnO3 and ZnO) were piezoelectric, the resulting composite film showed improved piezoelectric energy harvesting performance too. After rectification, the output ac voltage was used to charge a 10 μF capacitor up to ∼5 V dc which was further used to light up some LEDs. Furthermore, in order to exhibit improved sensitive output, a hybrid piezo-tribo nanogenerator was fabricated which was demonstrated as a motion sensor, a weight sensor and a human body movement sensor as part of a real life application.

Synthesis of BaTiO3 nanoparticles as shape modified filler for high dielectric constant ceramic-polymer composite

Coral-like structured barium titanate (BaTiO₃) nanoparticles were synthesized as filler for a high dielectric elastomer. The nanoparticle size, and shape, and the reactivity of the synthesis were modified according to temperature, time, pH, and precursor materials. Dielectric properties of poly(dimethylsiloxane) (PDMS) composites were estimated by volume fractions of BaTiO₃ of 5, 10, and 15 vol% for both sphere and coral-like shapes. As a result, coral-like BaTiO₃–PDMS composites had the highest dielectric constant of 10.97, which was 64% higher than the spherical BaTiO₃–PDMS composites for the 15 vol% fraction. Furthermore, the phase transition process and surface modification were applied to increase the dielectric properties through calcination and improved particle dispersion in the elastomer using polyvinylpyrrolidone (PVP). The dispersion of the PVP coated BaTiO₃–PDMS composite was improved compared to pristine BaTiO₃ as shown by SEM imaging. The coral-like BaTiO₃ embedded composite could be used for electronic devices such as piezoelectric devices or electro-adhesive grippers, which require flexible and high dielectric materials.

Coral-like structured barium titanate (BaTiO₃) nanoparticles were synthesized as filler for a high dielectric elastomer.

Polymer Matrix Nanocomposites with 1D Ceramic Nanofillers for Energy Storage Capacitor Applications

Recent developments in various technologies, such as hybrid electric vehicles and pulsed power systems, have challenged researchers to discover affordable, compact, and super-functioning electric energy storage devices. Among the existing energy storage devices, polymer nanocomposite film capacitors are a preferred choice due to their high power density, fast charge and discharge speed, high operation voltage, and long service lifetime. In the past several years, they have been extensively researched worldwide, with 0D, 1D, and 2D nanofillers being incorporated into various polymer matrixes. However, 1D nanofillers appeared to be the most effective in producing large dipole moments, which leads to a considerably enhanced dielectric permittivity and energy density of the nanocomposite. As such, this Review focuses on recent advances in polymer matrix nanocomposites using various types of 1D nanofillers, i.e., linear, ferroelectric, paraelectric, and relaxor-ferroelectric for energy storage applications. Correspondingly, the latest developments in the nanocomposite dielectrics with highly oriented, surface-coated, and surface-decorated 1D nanofillers are presented. Special attention has been paid to identifying the underlying mechanisms of maximizing dielectric displacement, increasing dielectric breakdown strength, and enhancing the energy density. This Review also presents some suggestions for future research in low-loss, high energy storage devices.

Interface design for high energy density polymer nanocomposites

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.

Flexible piezoelectric energy harvesters using different architectures of ferrite based nanocomposites

Electroactive phase transition in polyvinylidene fluoride (PVDF) can be economically achieved readily by addition of nanofillers.

High Discharge Energy Density at Low Electric Field Using an Aligned Titanium Dioxide/Lead Zirconate Titanate Nanowire Array

Polymer-based capacitors with high energy density have attracted significant attention in recent years due to their wide range of potential applications in electronic devices. However, the obtained high energy density is predominantly dependent on high applied electric field, e.g., 400-600 kV mm-1, which may bring more challenges relating to the failure probability. Here, a simple two-step method for synthesizing titanium dioxide/lead zirconate titanate nanowire arrays is exploited and a demonstration of their ability to achieve high discharge energy density capacitors for low operating voltage applications is provided. A high discharge energy density of 6.9 J cm-3 is achieved at low electric fields, i.e., 143 kV mm-1, which is attributed to the high relative permittivity of 218.9 at 1 kHz and high polarization of 23.35 µC cm-2 at this electric field. The discharge energy density obtained in this work is the highest known for a ceramic/polymer nanocomposite at such a low electric field. The novel nanowire arrays used in this work are applicable to a wide range of fields, such as energy harvesting, energy storage, and photocatalysis.