Breakdown Strength Research Articles

Design of epoxy composites via molecular orbital modulation and enhanced π-πF interactions achieving synchronous improvement of electrical and mechanical performance

The stacked aromatic rings in bisphenol A epoxy resins provide good mechanical properties and thermal stability while leading to the transport of conjugated delocalized electrons, which dramatically affects the insulation properties of the material. This contradiction leads to performance bottlenecks in epoxy-based encapsulation materials, further limiting the development of high-voltage semiconductor devices. In this study, fluorophenyl-modified epoxy monomers (FPMEPs) are designed to enrich the intermolecular interactions in an aromatic system while inhibiting the charge transport process, thereby solving the contradiction between the electrical and mechanical properties. Firstly, FPMEP with high insulation properties was designed by theoretical calculations and then synthesized by highly selective click chemistry. The fluorophenyl modulates the molecular orbitals of epoxy monomers and acts as a deep trap to inhibit charge injection and transport processes. Further, the π-πF stacking between the aromatic system and fluorophenyl enhances the interaction of the matrix molecules and solves the dispersion problem of fluorinated graphene (FG) fillers. The FPMEP/FG composites thus exhibit a considerable improvement in electrical and mechanical properties (breakdown strength of 39.8 kV/mm, dielectric loss of 0.011@50 Hz, tensile strength of 68.8 MPa, and adhesive strength of 2.15 MPa), and demonstrate good water repellency and aging durability. This matrix-filler synergistic modification strategy provides new insights into the design of insulation material.

Ultrathin natural biotite crystals as a dielectric layer for van der Waals heterostructure applications

Biotite, an iron-rich mineral belonging to the trioctahedral mica group, is a naturally abundant layered material (LM) exhibiting attractive electronic properties for application in nanodevices. Biotite stands out as a non-degradable LM under ambient conditions, featuring high-quality basal cleavage-a significant advantage for van der Waals heterostructure (vdWH) applications. In this work, we present the micro-mechanical exfoliation of biotite down to monolayers (1Ls), yielding ultrathin flakes with large areas and atomically flat surfaces. To identify and characterize the mineral, we conducted a multi-elemental analysis of biotite using energy-dispersive spectroscopy mapping. Additionally, synchrotron x-ray fluorescence and infrared nano-spectroscopy were employed to probe its iron content and vibrational signature in few-layer form, respectively, with sensitivity to the layer number. We have also observed good morphological and structural stability in time (up to 12 months) and no important changes in their physical properties after thermal annealing processes in ultrathin biotite flakes. Conductive atomic force microscopy evaluated its electrical capacity, revealing an electrical breakdown strength of approximately 1 V nm-1. Finally, we explore the use of biotite as a substrate and encapsulating LM in vdWH applications. We have performed optical and magneto-optical measurements at low temperatures. We find that ultrathin biotite flakes work as a good substrate for 1L-MoSe2, comparable to hexagonal boron nitride flakes, but it induces a small change of the 1L-MoSe2g-factor values, most likely due to natural impurities on its crystal structure. Furthermore, our results show that biotite flakes are useful systems to protect sensitive LMs such as black phosphorus from degradation for up to 60 days in ambient air. Our study introduces biotite as a promising, cost-effective LM for the advancement of future ultrathin nanotechnologies.

Roll‐to‐Roll Production of High‐Performance All‐Organic Polymer Nanocomposites for High‐Temperature Capacitive Energy Storage

AbstractDielectric materials with significant performance in high temperatures are highly desired, especially in harsh environments. However, the polymer‐based dielectric films have developed so far, the production scale remains at the state of the lab. Here, an all‐organic strategy is proposed by introducing phenyl‐acid‐based polymer nanodots (PAPD) into Polyetherimide (PEI), achieving high capacitive energy storage properties even at 200 °C and mass production by an industrial continuous roll‐to‐roll process. The abundant hydrogen bonding between PAPD and PEI chains ensures uniform distribution for the enhanced interaction between nanofillers and polymer matrix. Under UV irradiation, the electron‐affinity and band gap of the film are further extended, which impede charge transfer and reduction of conductive loss. A low loading (0.3 wt.%) of PAPD renders the membrane significant improvement in breakdown strength and charge–discharge efficiency. An ultrahigh energy storage density of 5.1 J cm−3 with a charge–discharge efficiency of over 90% and charge–discharge cycle stability up to 2 × 104 cycles at 150 °C is observed. Furthermore, a 1000 m long roll of polymeric film is roll‐to‐roll fabricated on an industrial solution‐casting production line and the low cost makes practical commercial scale application possible. Considering the low loading and low cost of nanofiller, this all‐organic design strategy sheds light on the industrial application of high‐temperature dielectric materials.

Roll-to-Roll Manufactured Polyetherimide Nanocomposite With Different Diameters of SiO2 Nanoparticles Exhibiting Improved High-Temperature Dielectric Energy Storage Performance.

To enhance the high-temperature energy storage performance of the polymer-based dielectric film, inorganic nanofillers with large band gaps are much more effective and have been widely adopted. However, the impact of nanoparticle diameters on the dielectric properties of polymer nanocomposites has been less studied. Herein, silicon dioxide nanoparticles (SiO2-NPs)with varying diameters (20, 60, 120, 200nm) prepared by the sol-gel method are incorporated in the PEI matrix to form PEI/SiO2 nanocomposites. The characterization results reveal a distinct correlation between the dielectric properties of polyetherimide (PEI) composites and the diameters of SiO2-NPs. Leakage current density analysis and breakdown strength simulations indicate that SiO2-NPs with smaller diameters generate more deep traps that impede the transport of charge carriers, especially under high temperatures. Notably, PEI/20nm-SiO2 exhibits a high discharged energy density of 4.4 J cm-3 with an efficiency of 90% at 150°C. Furthermore, PEI/SiO2 films with 10µm in thickness are manufactured by a large-scale solution casting process. The continuously prepared PEI/20nm-SiO2 film exhibits a discharged energy density of 3.2 J cm-3 with an efficiency of 90% at 150°C. This study not only provides a strategy for the design of high-performance dielectric polymer composites but also offers a large-scale high-temperature dielectric film for practical use.

Regulating the interfacial structure in percolating graphite nanoplate/PVDF composites via TiO2 as an interlayer towards meliorative dielectric performances

Polymer nanocomposites combining large dielectric permittivity (ε′) but low loss along with high breakdown strength (Eb) have garnered significant attention in the fields of electronic devices and power systems. To concurrently accomplish these desirable performances in pristine graphite nanoplates (GNP)/poly(vinylidene fluoride, PVDF) composites, the GNP were initially encased by a layer of anatase-type titanium dioxide (TiO2) shell, and then incorporated into PVDF to investigate the effect of TiO2 interlayer on the dielectric properties of the nanocomposites, specifically in relation to the thickness of the TiO2 shell and the nanofiller concentration. The TiO2 shell acts as a barrier layer prohibiting the electronic percolating, thus significantly reducing the dielectric loss and leakage conductivity of the GNP@TiO2/PVDF. Moreover, it not only alleviates the strong dielectric mismatch between GNP and PVDF, which restrains local electric field distortion, but also introduces charge traps, raising the energy barrier height for captured charge detrapping and preventing the growth of electric trees and subsequently promoting the Eb. For example, the PVDF with 20 wt% of GNP@TiO2 exhibited good comprehensive dielectric performances: ε′ of 50.63, loss factor of 0.071 (100 Hz) and Eb of 7.89 kV/mm. Additionally, tailoring the TiO2’s thickness can simultaneously modulate the overall dielectric parameters in the GNP@TiO2/PVDF. Theoretical fitting of experimental data via Havriliak-Negami equation uncovers the underlying polarization mechanism and the interlayer’s impact on charge migration. This work provides an efficient method for developing and producing polymeric nanodielectrics that simultaneously incorporate increased Eb with high ε′ but low loss for potential use in power devices and microelectronic devices.

Preparation of two–dimensional gradient fillers reinforced polymer nanocomposites for high–performance energy storage of dielectric capacitors

The serious interfacial issue between the inorganic filler and the organic matrix in the dielectric nanocomposite results in a low electric field breakdown strength (Eb) and low energy density (Ue). In this work, novel KxNa1–xNbO3@ZrO2 (KNN@ZO) nanosheets (NSs) were prepared by coating highly insulated ZO on the ferroelectric two–dimensional (2D) KNN NSs via a chemical precipitation method. As fillers, the KNN@ZO significantly improved the energy storage performances of poly (vinylidene fluoride) (PVDF)–polymethyl methacrylate (PMMA) blends. The highly insulated ZO shell restricts the carrier migration at the filler/polymer interface, thereby reducing the local electric field distortion. By sandwich structural design, a high Ue of 19.8 J/cm3, with a large difference of electrical displacement (8.5 μC/cm2), is measured in KNN@ZO/PVDF–PMMA with 5 % filler content at 528 MV/m. According to the finite element simulation, the 2D morphology and gradient structure can enhance the electric field distribution, and therefore effectively increase the Eb of nanocomposites. The results indicate that the 2D core–shell NSs fillers with gradient dielectric constant represent an effective approach to improve energy storage performance of the polymer–based nanocomposites.

Introducing deep trap states for high dielectric strength of aramid‐based composite films

AbstractAramid nanofiber (ANF)‐based composites have drawn tremendous interest in high‐voltage electrical systems due to their superior insulation strength, thermal stability, and mechanical endurance. However, the filler agglomeration and interface compatibility have retarded further improvement of the dielectric performance. Herein, the nano‐titanium dioxide (TiO2) particles treated by aminopropyl triethoxysilane (APTES) serve as the inorganic fillers, which are doped in the ANF to prepare the composite nano‐paper via the blade coating method. The electrostatic interaction between the ANF and fillers highly promotes their uniform distribution. Compared to the pure ANF paper, the composite paper has a denser structure with reduced pores and defects, which significantly improves its dielectric performance with inhibited partial discharge development. At a filler loading of 3 wt% (mass fraction), the breakdown strength is increased by 70.5% to a maximum value of 358.1 kV/mm, while the bulk conductivity is minimised to 5.2 × 10−17 S/m, representing an 88.1% decrease. By analysing the energy band structure of each component, energy barriers at the interface for electrons (1.48 eV) and holes (0.40 eV) are determined. These values indicate deepened trap energy levels, which greatly strengthen the carrier trapping effect for improved dielectric performance.

Enhancing energy storage performance of dielectric capacitors: Tailoring CaO-SrO-Na2O-Nb2O5-SiO2 glass-ceramics through controlled crystallization for pulse power applications

As potential dielectric materials for capacitors, glass-ceramics exhibit significant promise in the realm of pulse power supply. Extensive research has been undertaken to explore the commendable voltage resistance and favorable dielectric properties of glass-ceramics. They exhibit a rapid charge and discharge rate. However, the limited energy storage density of glass-ceramics constrains their practical application. In this study, we focused on the preparation of CaO-SrO-Na2O-Nb2O5-SiO2(CSNNS) glass-ceramics through conventional melting and high-temperature crystallization processes. Our investigation delved into the impact of crystallization temperature on the phase composition, dielectric properties, and energy storage characteristics of the CSNNS glass-ceramics. The results indicate a direct correlation between the dielectric constant and dielectric loss, both exhibiting an upward trend with increasing crystallization temperature. Simultaneously, the microstructure of the glass-ceramics manifests signs of deterioration, characterized by larger grain size and heightened porosity, leading to a reduction in breakdown strength. At a crystallization temperature of 1100 °C, the CSNNS glass-ceramics demonstrated a remarkable combination of a high dielectric constant (∼280) and superior breakdown strength (481 kV/cm). The achieved maximum theoretical energy storage density reached 2.87 J/cm3. At an electric field of 100 kV/cm, the effective energy storage density is 0.23 J/cm3, and the energy storage efficiency is 72 %. These findings demonstrate the broad application potential of the CSNNS glass-ceramics in the domain of pulse power, highlighting their relevance for future developments in this field.

Catalyst‐free epoxy resins with high‐performance and excellent healing efficiency via interpenetrating networks

AbstractThe difficult recycling and degradation in cured epoxy resins can be solved by introducing dynamic covalent bonds. However, the introduction of dynamic bonds degrades the properties of epoxy resins. In this paper, the dual‐cured epoxy resin with high mechanical properties and high healing efficiency were obtained by constructing interpenetrating networks (IPNs). The effect of IPNs on the recyclability of epoxy resins was investigated. The performance is as follows, the flexural and tensile strengths is 89 and 54.2 MPa, respectively, and the breakdown strength is 32.5 kV/mm. In addition, the recyclability and high healing efficiency of the dual‐cured epoxy resin were verified, and the effect of the hot‐pressing temperature and time on the properties of the recycled samples were investigated. Under certain hot‐pressing conditions, the flexural and tensile strengths of the recycled samples were recovered to 95.06% and 85.28%, respectively, and the breakdown strength was recovered to 83.6%.

Remarkable energy storage performance of BiFeO3-based high-entropy lead-free ceramics and multilayers

Electrostatic energy storage capacitors featuring fast charge–discharge capability play an indispensable role in pulsed power capacitors. However, the inverse correlation between polarization and dielectric breakdown strength (Eb) is the main obstacle limiting the access to high recoverable energy storage density (Wrec) and high efficiency (η). In this work, we designed a series of novel (1-x)BiFeO3-x(Ba0.2Sr0.2Ca0.2Bi0.2Na0.2)TiO3 (BF-xBSCBNT, x = 0.4–1.0) high-entropy lead-free relaxor ferroelectric ceramics. The synergy of refined grain size, broadened band gap, and core–shell microstructure is well-investigated by experimental results and phase-field simulations. High polarization difference is achieved by the strengthened relaxation behavior and the dominated polar nanoregions (PNRs). Both high Wrec of 6.0 J/cm3 and η of 81.1 % are achieved in the BF–0.8BSCBNT ceramics. In particular, a remarkable Wrec of 12.1 J/cm3 with a η of 86.1 % are obtained in the multilayer ceramic capacitors (MLCCs) fabricated from the x = 0.8 composition. Excellent temperature stability (<4.0 % in the range of 25–140 °C) and frequency stability (<6.2 % in the range of 1–500 Hz) are also achieved in MLCCs. The excellent energy storage performance demonstrates that high-entropy strategy is effective to develop novel lead-fee ceramics and devices for energy storage applications.

Synergistic optimization of delayed polarization saturation and enhanced breakdown strength in lead-free capacitors for superior energy storage characteristics

High-performance dielectric energy-storage ceramics are indispensable core components in pulsed power systems. Despite progress in enhancing energy storage performance, there are still significant constraints among various macroscopic performance parameters, hindering their miniaturization and integration into devices. Herein, we propose a novel weakly coupled relaxor ferroelectric ceramic system that delays premature polarization saturation of BaTiO3-based ceramics to achieve the desirable energy storage characteristics. The ceramic exhibits a high energy storage density (Wrec) of ∼4.58 J cm−3 and high energy efficiency (η) of ∼95.2 % under an electric field of 540 kV cm−1, along with good performance stability in the range of 40–160 °C and 1–120 Hz. Furthermore, the enhanced insulation properties and refined average grain size contribute to the high breakdown field strength (Eb) of the system. These findings provide a viable framework for the design of dielectric ceramic capacitors with high energy-storage characteristics.

Simultaneous Improvement of Energy Storage Characteristics and Temperature Stability in K0.5Na0.5NbO3-Based Ceramics via LiF Modification.

The splendid energy storage performances with eminent stability of dielectric ceramics utilized in pulsed power devices have been paid more attention by researchers. This scheme can be basically realized through introducing Li+, Bi(Mg2/3Ta1/3)O3, NaNbO3, and LiF into KNN-based ceramics. Under the breakdown strength (BDS) of 460 kV/cm, an outstanding energy storage density (W) of 6.05 J/cm3 with a high energy efficiency (η) of 85.9% is implemented. Within the broad temperature range from 20 to 140 °C, the numerical fluctuations of energy storage characteristics can be maintained at a relatively stable level (ΔWrec ≈ 3.5%, Δη ≈ 2.8%). As for the charging-discharging performances, this component possesses a fast discharging speed (t0.90 ≈ 51 ns) and remarkable temperature stability (the variations are smaller than 3.5%). Additionally, the internal mechanisms of outstanding energy storage properties can be confirmed via crystal structures and domain structures, the content of oxygen vacancies, dielectric and impedance spectra, and phase simulation. Hence, the combination of outstanding energy storage with remarkable thermal stability can be fulfilled in one ceramic system according to this discovery, providing a research thought of developing the materials for dielectric capacitors.

Preparation and study on electrical/thermal properties of epoxy/polyacrylate rubber composite dielectric

AbstractWith the development of power systems and electronic devices, epoxy resin (EP) is facing increasingly severe operating environments, and its performance may not meet expectations. In order to broaden the application of EP, the DE/EP composite films were prepared with EP as matrix, polyacrylic rubber dielectric elastomer (DE) as reinforcement materials. The structure of DE/EP composite films was characterized by XRD, SEM, and other methods, and the electrical and thermal properties of the materials were tested and studied. The study found that with appropriate dissolution and stirring treatment, DE can be evenly dispersed in the EP matrix, and the introduction of DE does not significantly affect the structure of the EP molecular chain, also found the introduction of DE improve the electrical and thermal properties of EP. The breakdown strength of the 4% DE/EP composite film surpasses that of the pure EP film by 15.58%. Additionally, the thermal conductivity of the 8% DE/EP composite film is elevated by 41.6% compared to the pure EP film, while its dielectric constant is also enhanced by 8.2%. This work may provide a theoretical basis for studying the application of EP modified system in electrical engineering, integrated circuit packaging and other fields.

Research Progress in Dielectric Properties of Inorganic Two‐Dimensional Nano‐Fillers Polyvinylidene Fluoride Nano‐Dielectric Materials

Two‐dimensional (2D) nanofillers can effectively improve the performance of nano‐dielectrics by having larger aspect ratios and larger electron‐scattering interfaces than one‐dimensional (1D) nanofillers and zero‐dimensional (0D) nanofillers; the formation of a large interfacial area in the polymer matrix effectively traps or scatters the mobile charges and increases the curvature of the propagation paths of the electric tree, thus effectively increasing the breakdown strength and the energy‐storage density of nanodielectrics. In this article, the intrinsic mechanism of 2D nanodielectrics is elaborated using percolation theory, microcapacitance theory, interfacial model, and ping‐pong racket model. Surface modification, oriented alignment, and multilayer structural design are reviewed to enhance the dielectric properties of nanodielectrics. Additionally, an outlook on the multiple challenges and potential opportunities in the process of preparing energy‐storage capacitors with excellent performance is provided.

Ultra-Low Loading Fillers Induced Excellent Capacitive Performance in Polymer-Based Multilayer Nanocomposites under Harsh Environments.

Multilayer-structured nanocomposites are recognized as a prominent strategy for overcoming the paradox between the breakdown strength (Eb) and polarization (P) to achieve superior energy storage performance. However, current multilayer-structured nanocomposites involving substantial quantities of nanofillers (>10vol.%) for high dielectric constant as polarization layer will inevitably deteriorate mechanical properties and breakdown strength. Herein, an innovative approach is reported to breaking conventional rules by designing a multilayered polymer composite with ultralow loading of Al2O3 nanoparticles, i.e., 0.3vol.% for polarization layers and 2vol.% for insulation layers. By modulating the spatial distribution of Al2O3 nanoparticles in polymer, a significantly increased interfacial dipole response is induced, and deep interfacial traps are constructed to capture the mobile charges, thereby suppressing high-temperature conduction loss. The resulting multilayered polymer composite exhibits an unparalleled discharged energy density of 7.8 Jcm-3 with a charging/discharging efficiency exceeding 90% at 150°C. This work provides valuable insights into achieving superior capacitive performance in multilayer composite films operating under extreme conditions.

Improving the electromechanical deformability of MWCNT/silicone composites via encapsulating MWCNT with polyphenols and multilayered structure regulation

AbstractSilicone rubber (SR) is an ideal dielectric elastomer substrate due to its excellent flexibility and fast response speed. However, the innate low dielectric permittivity (ε) of SR generally requires a rather high driving voltage that restricts its widespread application. Typical attempts to increase ε of SR usually deteriorate either its flexibility or electrical stability. Herein, conductive multi‐walled carbon nanotube (MWCNT) were first surface modified with polyphenols (PNs) (MWCNT@PNs), aiming to facilitate its well dispersion within SR matrix, which may maintain the softness and electrical stability of SR via suppressing concentrated physical crosslinking and local leakage current flow. Then, five‐layered MWCNT@PNs/SR composites were prepared with the outer two insulating layers of SR while middle three dielectric layers of MWCNT@PNs filled SR. The multilayered structure further hindered the formation of conductive pathways through the composites, promising a high breakdown strength of the composites. Therefore, the multilayered MWCNT@PNs/SR composites exhibited increased ε, maintained low Young's modulus and electrical breakdown strength compared with pure SR of the same five‐layered structure. Among them, the composite with uniformly distributed MWCNT@PNs (m‐1: 1: 1) showed a highest actuation strain of 11.9% (at 19.6 kV mm−1), which was 4.1 times higher than that of SR (2.9% at 19.1 kV mm−1).

Achieving Significantly Boosted Dielectric Energy Density of Polymer Film via Introducing a Bumpy Gold/Polymethylsilsesquioxane Granular Blocking Layer.

Polymer dielectrics are the key materials for pulsed energy storage systems, but their low energy densities greatly restrict the applications in integrated electronic devices. Herein, a unique bumpy granular interlayer consisting of gold nanoparticles (Au NPs) and polymethyksesquioxane (PMSQ) microspheres is introduced into a poly(vinylidene fluoride) (PVDF) film, forming trilayered PVDF-Au/PMSQ-PVDF films. Interestingly, the Au/PMSQ interlayer arouses a dielectric enhancement of 47% and an ultrahigh breakdown strength of 704MVm-1, which reaches 153% of pure PVDF. It is revealed that the greatly enhanced breakdown strength originated from the Coulomb-blockade effect of Au NPs and the excellent insulating properties of PMSQ microspheres with a special molecular-scale organic-inorganic hybrid structure. Benefiting from the concurrently enhanced dielectric and breakdown performances, an outstanding energy density of 22.42Jcm-3 with an efficiency of 67.1%, which reaches 249% of that of the pure PVDF, is achieved. It is further confirmed that this design strategy is also applicable to linear dielectric polymer polyethyleneimine. The composites exhibit an energy density of 8.91Jcm-3 with a high efficiency of ≈95%. This work offers a novel and efficient strategy for concurrently enhancing the dielectric and breakdown performances of polymers toward pulsed power applications.

Cost-effective production of Titania nanoparticles for the modification of transformer insulating oil

Nanofluids are prospective solutions for improving the transformer dielectric strengthby adding nanoparticles to the standard oils used in transformers.Oil-based titania nanofluids are becoming increasingly popular due to their superior insulating qualities and distinctive thermal performance, and they areconsideredas possible replacements in the domains of transformer insulating oils.This paper describes the industrial synthesis of titania nanoparticles for improving the insulating characteristics of virgin oil used in transformers.The titania nanoparticles were analyzed using an X-ray diffractogram (XRD), which revealed a prominent peak at Bragg angle 25O, indicating that the titania nanoparticles were generated in the anatase phase. Fourier transform infrared (FTIR) spectroscopy study endorsed the formation of Ti-O-Ti, Ti-OH, C-H and O-H stretching vibrations at 760 cm−1, 1345 cm−1, 2475 cm−1, and 3646 cm−1 wavenumbers respectively. Field emission scanning electron microscopy (FESEM) and Atomic Force Microscopy (AFM) examinations on the produced titania nanoparticles revealed that the particles had a circular shape with a diameter of 55 nm and an average roughness value of roughly 3.6 nm respectively.The viscosity of the host virgin oil and the nanoparticles-filled nanofluid were examined, and higher viscosity values were found as particle concentration increased.The effective conductivity study with the zeta potential and thermal conductivity fluctuation with temperature variation also revealed that at higher temperatures, conductivity with the zeta potential increased and thermal conductivity dropped. Furthermore, the breakdown strength of the titania nanoparticles-based virgin oil was observed to be effectively increased with the particle concentration.

Remarkable Dielectric Breakdown Strength of Printable Polyelectrolyte Photopolymer Complexes.

Polymer-based dielectrics are struggling to keep pace with the increasing demands of modern electronics. This lag in dielectric performance has spurred significant interest in the production of advanced dielectrics via novel chemistries and processing techniques. Polyelectrolyte complexes (PECs) have recently shown great promise as dielectric insulation, but processing challenges presented by these ionically bound networks limit their use to conformal thin films. Recent advances have enabled the additive manufacturing of PECs with vat photopolymerization, allowing the creation of a polyelectrolyte complex of arbitrary shape. Herein, multiple polyelectrolyte resin formulations, comprised of polyethylenimine and methacrylic acid (with varying amounts of 2-hydroxyethyl methacrylate and/or N,N-dimethylacrylamide), are investigated for the production of additively manufactured dielectric insulators. These dielectrics not only possess high dielectric breakdown strengths (>300 kV/mm), but their dielectric behavior can also be readily tailored through resin formulation and post-processing conditions. The presented vat photopolymerization of PECs allows for the creation of bulk dielectrics with arbitrary geometry, while the novel chemistry provides a practical route forward to produce dielectrics with precisely tailored properties for specific applications.

Magnetic-assisted alignment of nanofibers in a polymer nanocomposite for high-temperature capacitive energy storage applications.

Flexible polymer-based dielectrics with high energy storage characteristics over a wide temperature range are crucial for advanced electrical and electronic systems. However, the intrinsic low dielectric constant and drastically degraded breakdown strength hinder the development of polymer-based dielectrics at elevated temperatures. Here, we propose a magnetic-assisted approach for fabricating a polyethyleneimine (PEI)-based nanocomposite with precisely aligned nanofibers within the polymer matrix, and with Al2O3 deposition layers applied on the surface. The resulting polymer nanocomposite exhibits simultaneously increased dielectric constant and enhanced breakdown strength at high temperatures compared to pristine PEI. The enhanced dielectric constant is contributed by the depolarization effect of out-of-plane orientated nanofibers in composite films, while the surficial Al2O3 layers, with a wide bandgap, effectively prevent charge injection and transport at the electrode/dielectric interface. The optimally aligned composite films exhibit a significantly enhanced discharged energy density of 6.5 J cm-3 at 150 °C, with approximately 41% and 132% enhancement compared to random films and pristine PEI films, respectively. Additionally, a metalized multilayer polymer-based capacitor utilizing this composite film produces a high capacitance of 88 nF, while demonstrating excellent cyclability and flexibility at 150 °C. This work offers an effective strategy for developing polymer-based composite dielectrics with superior capacitive performance at elevated temperatures and demonstrates the potential of fabricating high-quality flexible capacitors.