TiO3 Nanoparticles Research Articles

The Role of Silanization of Barium Strontium Titanate Nanopowders on the Dielectric Constant and Thermal Stability of Epoxy Nanocomposites

AbstractThis paper reports polymer composites′ microstructure and dielectric properties based on an epoxy resin matrix containing different amounts (from 2–10 wt. %) of barium strontium titanate nanoparticles. (Ba,Sr)TiO3 was prepared using the hydrothermal method, showing an average particle size of 100 nm. The composites′ thermal properties and morphology were characterized using thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Our studies show that the (Ba,Sr)TiO3 nanoparticles were well dispersed in the epoxy resin matrix thanks to controlled silane functionalization. Accordingly, the glass transition temperature (Tg) value of the nanocomposites was found to be 159.0 °C at 10 wt. % (Ba,Sr)TiO3 loading and is higher than the neat epoxy resin Tg (Tg=154.7 °C). Moreover, the dielectric composite properties were investigated comprehensively via a wide range of frequencies from 10 Hz to 100 kHz. The results indicate that (Ba,Sr)TiO3 nanopowders and the surface modifying filler play a crucial role in the significant increase of the dielectric constants, approximately 1.5 times at the optimum added amount (Ba,Sr)TiO3. The limited functionalization of (Ba,Sr)TiO3 nanoparticles by the silane affords to control the nanocomposite dielectric loss. Furthermore, the nanocomposites also exhibited good thermal stability.

Mechanically induced built-in electric field in BCTZ nanostructures for piezocatalysis: Experiments and modeling

Ba(Ti0.80Zr0.20)O3–0.5(Ba0.7Ca0.3)TiO3 (BCTZ) piezoelectric nanofibers (NFs) and nanoparticles (NPs) were fabricated using electrospinning and sol-gel methods, respectively. The impact of BCTZ nanostructure on piezocatalysis was investigated, revealing that both poled NFs and NPs exhibit a piezocatalytic degradation rate of 2.8 × 10–2 min-1, which is significantly higher than their unpoled counterparts at 2.3 × 10–2 min-1 and 1.9 × 10–2 min-1, respectively. The enhanced piezocatalytic degradation rates of the poled BCTZ nanostructures are attributed to their superior piezoelectricity, resulting in larger built-in electric fields under external strain. Moreover, BCTZ NFs provide numerous active piezocatalytic reaction sites confined to the one-dimensional (1D) fibrous boundaries. Simulation results indicate that BCTZ NFs exhibit greater displacement and higher piezoresponse compared to nanoparticles, due to the electromechanical coupling effect facilitated by the 1D nanostructure. This study provides an efficient pathway to understanding the coupling mechanism between the poled built-in electric field and piezotronics.

Significantly enhanced catalytic performance of solid-state-synthesized Na0.5Bi0.5TiO3 nanoparticles by piezo-phototronic coupling effect

Significantly enhanced catalytic performance of solid-state-synthesized Na0.5Bi0.5TiO3 nanoparticles by piezo-phototronic coupling effect

Transformed construction from type-II WO3/BaTiO3 heterojunction to Z-scheme WO3/Ba0.5Sr0.5TiO3 and WO3/SrTiO3 photocatalytic systems: Enhanced photocatalytic activity and mechanism insight

In this study, type-II heterojunction WO3/BaTiO3 and Z-scheme WO3/SrTiO3 or WO3/Ba0.5Sr0.5TiO3 nanocomposite photocatalysts were constructed for photodegradation of organic pollutants in wastewater under visible light. The photocatalytic performance of three WO3/titanate systems were estimated. Some influencing factors such as molar ratio of WO3 and titanates, light irradiation time, catalyst dose, and initial concentration of organic pollutants on the photocatalytic activity were investigated. The stability and reusability of three WO3/titanates systems were examined. Moreover, the production of some radicals in the three WO3/titanates photocatalytic systems was demonstrated, and the three WO3/titanates photocatalytic reaction mechanisms were compared. The results reveal that the configurations of WO3/titanates photocatalytic systems are transformed from type-II heterojunction WO3/BaTiO3 with lower activity to Z-scheme WO3/SrTiO3 and WO3/Ba0.5Sr0.5TiO3 with higher activity via the change of titanates. The WO3/titanate nanocomposites show higher photocatalytic activity at 3.0:1.0 M ratio of WO3 and titanates, and WO3/Ba0.5Sr0.5TiO3 nanoparticles have superior photocatalytic activity. The order of photocatalytic activity is as follows: WO3/Ba0.5Sr0.5TiO3 > WO3/SrTiO3 > WO3/BaTiO3. Several organic pollutants, such as rhodamine B, methyl parathion, direct brilliant yellow-4R, and methylene blue, can be efficiently degraded using WO3/Ba0.5Sr0.5TiO3 under visible light, and the RhB has higher degradation rate. After four cycles, WO3/titanate nanocomposites still have relatively high stability and reusability. •OH plays a major role in three WO3/titanates photocatalytic degradation. It is expected that the Z-scheme WO3/Ba0.5Sr0.5TiO3 photocatalytic technology creates a good foreground for disposing of dyes and pesticides in water and wastewater.

Effective degradation of harmful ciprofloxacin using Sr1-xNixTiO3 nanoparticles as a catalyst under UV light irradiation

Antibiotics that are present in aquatic environments are causing serious health issues these days. This work utilizes pristine SrTiO3 and Sr1-xNixTiO3 (x = 0 < x < 0.20) nanoparticles which are prepared by hydrothermal synthesis for photocatalytic degradation of antibiotics. In order to confirm the successful development of Sr1-xNixTiO3 (x = 0 < x < 0.20) nanoparticles the structural, morphological, and optical properties were characterized using advanced analytical tools such as the X-Ray Diffractometer (XRD), Field Emission Scanning Electron Microscopy (FESEM), UV–Visible Spectroscopy (UV–Vis), and Photoluminescence (PL). A simple and safe technique was used to synthesize Sr1-xNixTiO3 (x = 0 < x < 0.20) nanoparticles for breaking down the ciprofloxacin (CFX) found in the environment, which was not reported previously. The enhanced photocatalytic activity in Sr1-xNixTiO3 (x = 0 < x < 0.20) for the degradation of antibiotic ciprofloxacin (CFX) was demonstrated. The best photocatalytic degradation performance was obtained from Sr0.91Ni0.09TiO3 nanoparticles. 9 % concentration of Ni − doping shows much higher catalytic activity than other concentrations. These results, suggest that Sr0.91Ni0.09TiO3 nanoparticles can be applied to the aquatic environment to remediate the contaminated antibiotics.

Improved photocatalytic degradation of Rhodamine B dye using Bi0.5Na0.5TiO3 ferroelectric nanoparticles: Optimization of pH and poling

We report the optimization of the photocatalytic parameters (pH and corona-poling) for Rhodamine B (RhB) dye degradation over Bi0.5Na0.5TiO3 (BNT) nanoparticles under UV–vis light. The BNT nanoparticles were synthesized by the sol-gel method and the XRD analysis confirmed the monoclinic phase structure with Cc space group. No structural distortions were induced by corona-poling, which was confirmed by Raman Spectroscopy. The average size of the nanoparticles was 152 ​nm with irregular morphology as observed by SEM. The optical bandgap of the sample was 3.23 ​eV, as derived from the absorbance spectra of the sample. The optimized conditions achieved for photocatalytic degradation were at a catalyst dosage of 50 ​mg BNT/50 ​mL of 10 ​ppm RhB dye solution and pH value 2. The degradation efficiency of the poled BNT sample for RhB dye at pH value 2 was found to be 96.19 % in just 60 ​min. Complete decolorization was attained after 90 ​min of irradiation. In this process, degradation followed the pseudo-first order kinetics, with a kinetic rate constant of approximately 0.08804 min−1, which is around 27 times higher than the rate constant of BNT nanoparticles with dye. A detailed mechanism for the degradation of dye molecules based on pH and poling effect has also been proposed. Based on these results, BNT photocatalyst can be a promising candidate for the treatment of organic dyes.

Effect of synthesis methodologies upon the photocatalytic performance of Bi0.5Na0.5TiO3 for pollutant degradation.

In the face of mounting environmental concerns, we must seek out innovative solutions for remediation. Using nanomaterials to degrade organic pollutants in water under ambient visible light holds great promise as a safe, cost-efficient, and effective approach to addressing pollution in our water bodies. The development of novel materials capable of such pollution degradation is desired to preserve the environment. In this study, Bi0.5Na0.5TiO3 (BNT) nanoparticles are synthesized through hydrothermal and solid-state routes, and their physicochemical properties are compared to assess their photocatalytic performance. The results of the characterization studies indicate that the hydrothermally synthesized nanoparticles outperformed the solid-state synthesized counterparts in terms of photocatalytic performance. The photocatalytic degradation of Rhodamine blue dye under ambient light exposure is examined at various dye concentrations and catalyst dosages. BNT nanoparticles demonstrated excellent photocatalytic properties, stability, and recyclability, making them a promising candidate for various photocatalytic applications. The findings of this study could pave the way for the development of sustainable and environmentally friendly photocatalytic technologies for water remediation.

A dual optimization approach for photo-electric catalysis: Heterojunction of BiOBr/Ba0.7Sr0.3TiO3 system construction and ferroelectric polarization

The spontaneous polarization of ferroelectrics is used to promote the separation of photogenerated electrons and holes, showing the great potential of solar-driven photo-electric catalysis. However, the rapid recombination of photogenerated electrons and holes seriously restricts the photo-electric catalysis efficiency. In this study, Ba0.7Sr0.3TiO3 nanoparticles combined with BiOBr nanosheets are synthesized by hydrothermal method to prepare BiOBr/Ba0.7Sr0.3TiO3 composite photoelectrodes. Under different Curie temperature(Tc) conditions and visible light irradiation, the photocurrent density of ferroelectric Ba0.7Sr0.3TiO3 (≤Tc) (0.54 mA∙cm−2) is superior to that of cis-electric Ba0.7Sr0.3TiO3 (≥Tc) (0.46 mA∙cm−2).The potential difference at the interface of BiOBr/Ba0.7Sr0.3TiO3 can effectively promote the separation of photogenerated carriers, while the internal polarization electric field of ferroelectric Ba0.7Sr0.3TiO3 further promotes the separation and transfer of photogenerated electrons and holes in the photoelectrodes, allowing more charges to be injected into the heterojunction interface to participate in the surface redox reaction, which significantly improves the photo-electric catalysis performance of BiOBr/Ba0.7Sr0.3TiO3. We believe that this work may open up new avenues for the research and development of highly efficient polarized ferroelectric material photoelectrodes for photo-electric catalysis.

Synthesis, Structural, Optical, and Electrical Characterization of Biochitosan/Na0.5Bi0.5TiO3 Composite Thin-Film Materials.

The purpose of this research work was to synthesis bioderived nanocomposite films by incorporating Na0.5Bi0.5TiO3 (NBTO) nanoparticles into a chitosan matrix. The NBTO nanoparticles were synthesized using a traditional solid-state technique. Then, through a solution-casting approach, flexible composite films were fabricated using chitosan polymer. The study presents a range of compelling findings. For structural and morphological insights, scanning electron microscopy (SEM) reveals a fascinating morphology where NBTO nanoparticles are uniformly dispersed and interlocked with other particles, forming interconnected grains with significant interspaces within the chitosan matrix. For the optical properties, the spectral response within the 300-800 nm range is primarily governed by light scattering attributed to NBTO particles with diameter sizes ranging from 100 to 400 nm, as well as the distinctive bandgap exhibited by the NBTO phase. The investigation of dielectric properties demonstrates that composite films exhibit markedly higher dielectric values in comparison to pure chitosan films. It is noteworthy that an increase in the NBTO content results in a corresponding increase in dielectric values, enhancing the versatility of these materials. Local piezoelectric measurements utilizing piezoresponse force microscopy confirm the expected piezoelectric and ferroelectric behavior of NBTO particles when dispersed within the chitosan matrix. This research introduces a novel class of biocompatible nanocomposite materials, combining impressive structural attributes, enhanced dielectric properties, and piezoelectric capabilities. The outcomes of this study hold substantial promise for advanced applications in opto- and piezoelectric technologies, marking a significant advancement in biologically sourced materials with multifunctional properties.

Design, characterization, fabrication, and performance evaluation of ferroelectric dielectric resonator antenna for high-speed wireless communication applications

The research comprehensively analyzes the structural, electrical, and electrodynamic characteristics of Ba0.7Sr0.3TiO3 nanoparticles synthesized using a sol-gel approach. The formation of a tetragonal perovskite phase and the nano-crystalline nature have been confirmed using X-ray diffraction (XRD) analysis. Fourier transform infrared (FTIR) spectroscopy has been employed to identify characteristic absorption bands correlated with the crystal lattice vibrations of Ba0.7Sr0.3TiO3. The sample’s morphology has been examined using scanning electron microscopy (SEM), revealing a relatively dense and homogeneous composition composed of small spherical particles. The electrical properties of Ba0.7Sr0.3TiO3 nanoparticles have also been investigated using a ferroelectric measurement technique. The soft electric hysteresis loop with a small coercive field value makes the sample suitable for photovoltaic applications. Finally, a compact dielectric resonator antenna (DRA) based on Ba0.7Sr0.3TiO3 nanoparticles has been designed and characterized. The designed DRA demonstrates good impedance matching, broadside radiation pattern, and high antenna gain and efficiency at the frequency band of 5.6–6.15 GHz, making it suitable for sub-6 GHz (5 G) applications.

Tuning the Ferroelectric Response of Sandwich-Structured Nanocomposites with the Coordination of Ba0.6Sr0.4TiO3 Nanoparticles and Boron Nitride Nanosheets to Achieve Excellent Discharge Energy Density and Efficiency.

With the rapid development of new electronic products and sustainable energy systems, there is an increasing demand for electrical energy storage devices such as electrostatic capacitors. In order to comprehensively improve the dielectric, insulating, and energy storage properties of PVDF-based composites, sandwich-structured composites were prepared by layer-by-layer solution casting. The outer layers of the sandwich structure composite are both PVDF/boron nitride nanosheet composites, and the middle layer is a PVDF/Ba0.6Sr0.4TiO3 nanoparticles composite. The structural and electrical properties of the sandwich-structured composites were characterized and analyzed. The results show that when the volume percentage of Ba0.6Sr0.4TiO3 nanoparticles in the middle layer of the sandwich structure composite is 1 vol.%, the dielectric properties are significantly improved. Its dielectric constant is 8.99 at 10 kHz, the dielectric loss factor is 0.025, and it has better insulating properties and resistance to electrical breakdown. Benefiting from the high breakdown electric field strength and the large maximum electrical displacement, the sandwich-structured composites with 1 vol.% and Ba0.6Sr0.4TiO3 nanoparticles in the middle layer show a superior discharge energy density of 8.9 J/cm3, and excellent charge and discharge energy efficiency of 76%. The sandwich structure composite achieves the goal of simultaneous improvement in breakdown electric field strength and dielectric constant.

Investigation of structure, thermal and dielectric study of Dy0.05Ba0.7Sr0.25TiO3/polystyrene nanocomposites

In the present study, Dy0.05Ba0.7Sr0.25TiO3 (Dy-BST) nanoparticles were prepared using the conventional solid-state reaction technique. Different volume fractions of Dy-BST (0, 5, 10, 15 & 20) were immersed in the polystyrene (PS) matrix, forming PS/Dy-BST nanocomposites, then their crystal structure, morphology, topography, thermal properties, electrical properties, breakdown voltage, and energy storage were investigated. X-ray diffraction (XRD) validates the cubic phase of Dy-BST nanoparticles incorporated in PS/Dy-BST nanocomposites. The size of Dy-BST nanoparticles was in the range (8–18 nm) using HRTEM. Incorporating Dy-BST NPs into the polymer matrix improved the thermal stability and limited the thermal degradation of the nanocomposite. The loading of Dy-BST in PS has a positive effect on dielectric properties and breakdown strength. The permittivity (ε′) enhanced from 2 to 10 at a constant frequency of 105 Hz while a relatively high loss (tanδ) decreased from 0.0015 to 0.0011 with the increase of Dy-BST content in the PS matrix. Finally, dielectric strengths of PS/Dy-BST nanocomposites were evaluated using high voltage testing; then their corresponding energy densities were obtained. The energy density increased to 133% at a 10 vol.% loading of Dy-BST compared to pure polystyrene.

Cycling of block copolymer composites with lithium-conducting ceramic nanoparticles.

Solid polymer and perovskite-type ceramic electrolytes have both shown promise in advancing solid-state lithium metal batteries. Despite their favorable interfacial stability against lithium metal, polymer electrolytes face issues due to their low ionic conductivity and poor mechanical strength. Highly conductive and mechanically robust ceramics, on the other hand, cannot physically remain in contact with redox-active particles that expand and contract during charge-discharge cycles unless excessive pressures are used. To overcome the disadvantages of each material, polymer-ceramic composites can be formed; however, depletion interactions will always lead to aggregation of the ceramic particles if a homopolymer above its melting temperature is used. In this study, we incorporate Li0.33La0.56TiO3 (LLTO) nanoparticles into a block copolymer, polystyrene-b-poly (ethylene oxide) (SEO), to develop a polymer-composite electrolyte (SEO-LLTO). TEMs of the same nanoparticles in polyethylene oxide (PEO) show highly aggregated particles whereas a significant fraction of the nanoparticles are dispersed within the PEO-rich lamellae of the SEO-LLTO electrolyte. We use synchrotron hard x-ray microtomography to study the cell failure and interfacial stability of SEO-LLTO in cycled lithium-lithium symmetric cells. Three-dimensional tomograms reveal the formation of large globular lithium structures in the vicinity of the LLTO aggregates. Encasing the SEO-LLTO between layers of SEO to form a "sandwich" electrolyte, we prevent direct contact of LLTO with lithium metal, which allows for the passage of seven-fold higher current densities without signatures of lithium deposition around LLTO. We posit that eliminating particle clustering and direct contact of LLTO and lithium metal through dry processing techniques is crucial to enabling composite electrolytes.

Core-shell structure strategy and oxygen vacancy engineering of 0.1LaMnO3@0.9(Ba0.5Sr0.5)TiO3 ceramics towards tuning electrical properties

In recent years, core-shell structures have attracted much attention for their potential in tuning the functional properties of materials and have become an effective method for preparing high-performance materials. In this work, core-shell structured 0.1LaMnO3@0.9(Ba0.5Sr0.5)TiO3 nanoparticles were fabricated by sol-gel method and dense ceramics were prepared at different sintering temperatures. The phase composition, morphology, chemical state and electrical properties were systematically investigated. Structural analysis confirmed the formation of 0.1LaMnO3@0.9(Ba0.5Sr0.5)TiO3 core-shell nanostructures. The results show that the prepared samples exhibit typical negative temperature coefficient characteristics in the range of 50–1000 °C, which is derived from the effect of carrier pairs and oxygen vacancies on the electrical properties. This study provides new insights from structure to material into guiding the development and design of advanced thermistor materials for temperature sensing applications.

Effect of Inorganic Nanoparticles on Energy‐Storage Properties of P(VDF–HFP)‐Based Nanocomposites

Polyvinylidene fluoride (PVDF) and its copolymers have been widely used in polymer‐based film capacitors due to their relatively high permittivity and electrical displacement compared with other polymers. Herein, poly(vinylidene fluoride‐hexafluoropropylene) (P(VDF–HFP)) is selected as the polymer matrix, and 0.5 (Bi0.5Na0.5)TiO3–0.5(Sr0.85Sm0.1)TiO3 (BNT–SST) nanoparticles are added as the filler into the polymer to prepare BNT–SST/P(VDF–HFP) nanocomposites. The microstructure, electrical properties, mechanical properties, and energy‐storage properties of the nanocomposites are investigated. The addition of BNT–SST nanoparticles improves the dielectric characteristics and breakdown strength of the nanocomposites. Particularly, when the BNT–SST filler content is 0.7 vol%, the highest breakdown strength reaches 545 MV m−1, which is 1.3 times higher than pure P(VDF–HFP). In addition, the insulation and mechanical properties of BNT–SST/P(VDF–HFP) composite films are improved. The highest direct current resistivity and Young's modulus obtained by 0.7 vol% BNT–SST/P(VDF–HFP) nanocomposites are 6.8 × 1013 Ω cm and 1.94 GPa, respectively. More importantly, at 545 MV m−1, the energy‐storage density and efficiency of 0.7 vol% BNT–SST/P(VDF–HFP) composites are 19.07 J cm−2 and 67.01%, respectively, which are better than other polymer matrix composites. These findings suggest that the addition of inorganic nanoparticles has important research implications for improving the energy‐storage performance of polymer‐based film capacitors.

Pyro-photocatalytic Coupled Effect in Ferroelectric Bi0.5Na0.5TiO3 Nanoparticles for Enhanced Dye Degradation

Advanced oxidation processes (AOPs), achieved through the continuous attack of reactive oxygen species (ROS), are considered the most efficient way to mineralize organic pollutants. Among them, photocatalysis is the most environmentally friendly strategy for pollution mitigation but is hampered by low conversion efficiency. By exploiting the coupling effect without changing the properties of the semiconductor, the application of pyroelectric fields can significantly improve the catalytic performance. The degradation rate of rhodamine B by Bi0.5Na0.5TiO3 (BNT) nanoparticles under temperature fluctuations and visible light irradiation was up to 98%. The performance was enhanced by 216.54% and 31.48% compared to the pyroelectric catalysis and photocatalysis alone, respectively. The improved performance is due to the introduced pyroelectric potential with the imposition of temperature fluctuations, which can make the domains enhance the polarization of ferroelectrics, thus promoting the charge separation. This method can significantly advance the coupled pyro-photocatalytic reaction of ferroelectric semiconductors and also can enable the synergistic utilization of multiple energy sources such as solar and thermal energy, which is a promising strategy for environmental remediation.

Multifunctional sensors for respiration monitoring and antibacterial activity based on piezoelectric PVDF/BZT-0.5BCT nanoparticle composite nanofibers

In clinical practice, combining sensitive and efficient sensors that have antibacterial properties with masks is a convenient way to monitor vital signs. Therefore, developing flexible pressure sensors with high sensitivity and antibacterial properties is the key for such smart devices. In our work, poly (vinylidene fluoride) (PVDF) nanofibers (NFs) with a high piezoelectric phase were fabricated by electrospinning with an optimized spinning voltage and collecting roller speed. Ba(Ti0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-0.5BCT) nanoparticles (NPs) synthesized by the hydrothermal method were introduced into PVDF NFs to improve their piezoelectric response to external strain. With 20 wt% 0.5BZT-BCT NPs, the PVDF/BZT-BCT fiber composite sensor showed an output voltage up to 6.37 V with superior sensitivity (0.24 V Kpa−1), a short response time (∼50 ms), good durability over a wide time range and a low detection limit (2.50 mg). The sensor was built in a mask that demonstrated high sensitivity in monitoring the respiratory rate as well as antimicrobial resistance to Echerichia coli (E. coli) and Staphylococcus aureus (S. aureus). Furthermore, this composite fiber sensor can also be applied for the detection of body movement. The multifunctional 0.5BZT-BCT/PVDF fiber composite sensor may find clinical applications.

Enhanced piezo-photocatalysis in Bi0.5Na0.5TiO3@Ag composite to efficiently degrade multiple organic pollutants

The synergistic piezo-photocatalysis with enhanced efficiency for degrading obstinate pollutants in wastewater is considered as an advanced way to ameliorate the global water contamination. In this work, we report a facile route to construct the Bi0.5Na0.5TiO3@Ag composite by photoreduction of AgNO3 to obtain Ag on Bi0.5Na0.5TiO3 nanoparticles. And the composite was used to degrade three representative pollutants, i.e. ciprofloxacin, methyl orange and mitoxantrone hydrochloride. Remarkably, for methyl orange solution with the initial concentration of 10 mg/L, the degradation rate constant of the composite reached 0.051 min−1. H+ and •O2− play a major role in this degradation process, verified by the radical quenching experiments. The absorption platform of Bi0.5Na0.5TiO3 was located in the UV region, after introducing Ag in the composite, the absorption region broadened to both UV and visible light, greatly promoting the response to light. Simultaneously, the induced piezo-potential by mechanical energy in Bi0.5Na0.5TiO3 hindered the carrier recombination, resulting in high-efficiency synergistic piezo-photocatalytic process. This work provides a paradigm to innovate both material and catalytic way for degrading multiple organic pollutants.

Tunable BaxSr1-xTiO3 nanoparticles induced high energy storage density in layer-structured asymmetric polymer-based nanocomposites

In order to solve the problem of low charging and discharging energy density of dielectric capacitors, the structure design of layered polymer matrix composites is carried out in this paper. Ba0.7Sr0.3TiO3, Ba0.8Sr0.2TiO3 and Ba0.9Sr0.1TiO3 nanoparticles were successfully prepared by the oxalate coprecipitation method. The surface of BaxSr1-xTiO3 was successfully coated with dopamine, which promoted the dispersion of the polymer matrix of the ceramic powder. Monolayer BaxSr1-xTiO3/PVDF composites containing BaxSr1-xTiO3 with different Ba/Sr ratios were successfully prepared by the casting method. Three-layer asymmetric composites with different fillers were successfully prepared by layer-by-layer casting. The phase and microstructure of the as-prepared materials were analyzed by XRD and SEM. The dielectric, electrical conductivity, ferroelectric and energy storage properties of the composites were tested. The effects and laws of the design of the three-layer asymmetric structure on the dielectric properties and energy storage properties of the layered composites are mainly studied. When the structure of the three-layer asymmetric composite is 1-2-3, the breakdown field strength reaches 330 kV/mm, the discharge energy density reaches 8.51 J/cm3, and the charge-discharge efficiency is 67%. This work demonstrates that layered composites with asymmetric properties can facilitate the development of electrical energy storage.

Flexible mixed ion-electron conductor fabric for stable and dendrite-free Li-metal anodes

Li-metal batteries are promising candidates for next generation rechargeable batteries. However, the hazards caused by the growth of Li-dendrite and enormous volume fluctuations during cycling hinder its practical applications. Here, to solve these problems, a flexible mixed ion-electron conducting fabric scaffold is constructed by uniformly incorporating Li0.33La0.56TiO3 nanoparticles into a 3D carbon nanofiber skeleton. The mixed conductor fabric cannot only homogenize the distribution of electric filed and alleviate volume changes, but also can accelerate the migration and distribution of Li+, thus achieving uniform Li plating/stripping behavior by balanced ion/electron transport. Consequently, the obtained stable and dendrite-free Li-metal anode has a notable cycling stability and rate performance. This work provides a promising direction for the design of practical composite Li-metal anodes.