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To improve the interface compatibility, dielectric properties and energy storage density of polyimide(PI)-based composite materials, the core@dual-shell nanoparticles, BT@TiO2@PDA were obtained via facile solution method using the dopamine to coat on the BT@TiO2 nanoparticles, which is barium titanate (BT) coated with amorphous-TiO2, hydrolyzed from tetra-n-butyl titanate (TBT). A series of modified BaTiO3/PI (BT@TiO2@PDA/PI) composites with different contents of BT@TiO2@PDA were prepared through a solution casting film formation method. The results show that the dispersion of nanofillers in the polymer matrix and the interface compatibility between them can be improved by utilizing core@dual-shell nano-structured BaTiO3. The permittivity κ of BT@TiO2@PDA/PI composite films with 40%(mass fraction) filler loading increase to 8.8 (1 kHz), which is about 2.7 times higher than that of pristine polyimide, 1.4 times higher than that of pristine BaTiO3/PI composite films. Temperature-dependent and frequency-dependent dielectric performance tests confirm that BT@TiO2@PDA/PI composites possess good temperature and frequency stability. In the frequency range of 100 kHz, the dielectric loss of the composites is less than 0.010; when the filler loadings are under 40%, the permittivity of the composites decreases by less than 0.6 (1 kHz) from 25 ℃ to 160 ℃.

Barium titanate (BT) nanoparticles were surface coated by a silane coupling agent (KH550) and core–shell structured nanoparticles (named KH550@BT) were obtained. Similarly, BT nanoparticles coated by polydopamine (PDA) were named as PDA@BT. Meanwhile, boron nitride (BN) nanosheets (BNNS) were successfully unstripped from block BN. Then, two kinds of ternary poly(arylene ether nitrile) (PEN)‐based composites are prepared using the solution casting method. Composites with 30 wt% KH550@BT and 12 wt% BNNS were named as KH550@BT/BNNS/PEN. Composites with 30 wt% PDA@BT and 12 wt% BNNS were named as PDA@BT/BNNS/PEN. The microstructure, dielectric properties, and energy storage properties of the ternary composites were studied in detail. PEN embedded with either BNNS or BT were prepared and studied for comparison. As a result, the introduction of BT will improve the dielectric constant (εr) and energy storage density (W), but it will reduce the breakdown strength (Eb) and charge–discharge efficiency (η) of composites. BNNS not only improves Eb and W but also improves η of composites. Although the introduction of BT and BNNS simultaneously may reduce η, it will improve εr, Eb, and W of composites. Most importantly, the fast discharge speed and high power density demonstrate that the BT/BNNS/PEN composites are potential candidates to be used in high power pulsed capacitors fields. Highlights: Boron nitride nanosheets improve the breakdown strength of composites.The composites achieve simultaneous increment of εr and Eb.The power density of the BT/BNNS/PEN composites was higher than 70 MW cm−3. [ABSTRACT FROM AUTHOR]

Firstly, the BaTiO3 nanoparticles were coated with a layer of paraffin, forming a core shell structure. Then, as‐prepared paraffin@BaTiO3 nanofillers were directly blended with polyimide (PI) prepolymer to fabricate paraffin@BaTiO3/PI composite films. The microstructure, thermal, and dielectric properties were investigated in detail. The surface‐modified paraffin@BaTiO3 nanoparticles exhibited a typical core shell structure with uniform and complete coverage. The char yield of the composite film with 10 wt% paraffin@BaTiO3 increased from 56.40% to 70.73%. It is obvious that the paraffin@BaTiO3 nanofillers have a positive effect on ablative performance of the composite film. Compared with pure PI, the εr of paraffin@BaTiO3/PI composites with 40% mass fraction increased from 3.41 to 9.35 (1 kHz). The tanδ of paraffin@BaTiO3/PI composites was just 0.0065 (1 kHz) when the filler loading was 40 wt%. Temperature dependency of the permittivity of the composites reveals a zero‐temperature‐coefficient from 80°C to 180°C. [ABSTRACT FROM AUTHOR]

Owing to their excellent dielectric properties and energy storage performance, polymer‐based composites have shown great potential in the application of pulse energy storage capacitors and electrostatic capacitors. In this study, BaTiO3 (BT) particles with different sizes were modified with dopamine to prepare core–shell structured BT particles (PDA@BT), and then the poly(arylene ether nitrile) (PEN)‐based PDA@BT/PEN composites were prepared. As a common biological material, dopamine has a variety of functional groups which can be used to improve the compatibility between the fillers and the matrix. Moreover, the movement of the carriers at the interface of the composites is limited and the loss is reduced. The composites with an optimized filler size illustrate a high energy density of 1.37 J/cm3 at 160 kV/mm, which nearly reaches up to the energy density of biaxially oriented polypropylene (BOPP) at low electric field. In addition, the composites have the superior power density of 1.88 MW/cm3 with a fast discharge time of 0.138 μs. [ABSTRACT FROM AUTHOR]

It is well known that the intelligent hybridization of active materials and the controllable recombination of nanostructures can significantly improve the electrochemical performance of pseudocapacitor electrodes. In this work, a NiO/NiCo2O4 needle/sphere nanostructure was synthesized on the hydrochloric acid-activated Nickel foam by a simple hydrothermal method and measured the performance of it as an electrode material for supercapacitors. Field emission scanning electron microscope, transmission electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy were used to characterize the morphology and composition of the samples. The electrodes display a prominent specific capacitance (2447 F/g at the ampere density of 2 A/g) and remarkable cycling stability (85.2% capacity remained after 3000 cycles), owing to the unique needle/sphere composite architecture and the rational combination of active materials. The results demonstrate that the three-dimensional composite structure of NiO/NiCo2O4 nanomaterials provides a large specific surface area for the electrode, which promotes the penetration of electrolyte ions and the transmission of electrons. This novel structured material will be promising in the application of supercapacitor electrode materials. [ABSTRACT FROM AUTHOR]

Nickel niobate (NiNb2O6) was used to modify the barium titanate (BaTiO3) ceramics, the obtained NiNb2O6‐BaTiO3 ceramics possess better dielectric performances than that of raw BaTiO3. By adding NiNb2O6‐BaTiO3 into poly(arylene ether nitriles) (PEN) polymer, a series of NiNb2O6‐BaTiO3/PEN composite films with different NiNb2O6‐BaTiO3 contents were prepared via solution casting method. The morphology, thermal, mechanical, dielectric properties, and flexibility of the obtained NiNb2O6‐BaTiO3/PEN composite films were investigated detailedly. As the filler content increases, the tensile modulus of NiNb2O6‐BaTiO3/PEN composite films increases gradually, while the tensile strength decreases. Thermal and flexibility analysis shows that the addition of the NiNb2O6‐BaTiO3 fillers does not affect the thermal and flexibility properties endowed by the PEN matrix. The dielectric constant of the composites almost linearly increases from 3.7 (1 kHz) to 15.3 (1 kHz) as the filler content increases from 0 to 40 wt%. Besides, results show that NiNb2O6‐BaTiO3/PEN composites exhibit higher dielectric constant than that of BaTiO3/PEN. The as‐prepared NiNb2O6‐BaTiO3 will be a more promising filler to prepare polymer‐ceramic composites for organic film capacitors. [ABSTRACT FROM AUTHOR]