Enhanced Breakdown Strength Research Articles

Improving the comprehensive energy storage performance of composite materials through the coupling effect of AgNbO3/PVDF nanocomposite

AbstractCeramic‐polymer nanocomposites with high energy storage density can achieve excellent energy storage performance and have a wide range of application prospects. Currently, it has been shown that the coupling effects have a great impact on improving the performance of dielectric composites, but increasing the breakdown strength of polymer nanocomposite is still a tremendous challenge to the achievement of high energy density under high voltages. The aim of this paper is to further investigate this problem and obtain AgNbO3/PVDF flexible composites by introducing a small amount of AgNbO3 ultrafine powder prepared by hydrothermal method into poly(vinylidene fluoride) (PVDF). The interfacial coupling effect within this nanocomposite with the coupling effects of nonlinear dielectric materials improves its energy storage capacity and electrical strength resistance. The energy density of the 2 wt% AgNbO3/PVDF composite film was raised to 16.5 J/cm3 at the electric breakdown strength of 391.7 MV/m, and its energy storage capacity is two to three times that of AgNbO3 lead‐free antiferroelectric ceramics. Finite element simulations showed the further enhancement of breakdown strength was ascribed to the local electric field and to the AgNbO3 ultrafine powder which blocked the breakdown path in the nanocomposites and coupling effects occurred with PVDF. Hence, the AgNbO3 ultrafine powder has a positive effect on improving the energy storage performance of flexible composites. The effects of nonlinear dielectric material coupling effects and interfacial coupling effects on the dielectric properties of composite dielectric materials are further investigated, which are important for the development of flexible high energy storage capacitors.

High Energy Storage Performance of All-Inorganic Flexible Antiferroelectric-Insulator Multilayered Thin Films.

With the increasingly high requirements for wearable and flexible devices, traditional inorganic capacitors cannot meet the flexible demand of next-generation electronic devices. In this work, the energy storage property of all-inorganic flexible films has been systematically studied. PbZrO3 (PZO) and Al2O3 (AO) are selected as the antiferroelectric layer and insulating layer, respectively. The heterostructured films are prepared on the fluorphlogopite (F-Mica) substrate by chemical solution deposition. The microstructure, polarization behavior, and energy storage performances are investigated. The results demonstrate that the AO/PZO/AO/PZO/AO (APAPA) multilayered thin film possesses a greatly improved energy storage density (Wrec) of 28.1 J/cm3 with an excellent energy storage efficiency (η) of 80.1%, which is ascribed to the enhanced breakdown strength and large difference in polarization. Furthermore, the capacitive films exhibit good stability under a wide working temperature range of 25-140 °C and an electric fatigue endurance of 107 cycles. Besides, the energy storage performances are almost unchanged after 104 bending cycles, demonstrating an excellent mechanical bending endurance. This work sheds light on the preparation technology and improvement of the dielectric energy storage performance for all-inorganic flexible multilayered thin films.

Enhanced breakdown strength and energy density by introducing low-loading poly(1,5-anthraquinone) into poly(vinylidene fluoride)

Enhanced breakdown strength and energy density by introducing low-loading poly(1,5-anthraquinone) into poly(vinylidene fluoride)

Enhancing high-temperature capacitor performance of polymer nanocomposites by adjusting the energy level structure in the micro-/meso-scopic interface region

The interface plays a major role in the conduction and breakdown behaviors of dielectric materials. Enhancing interface compatibility and Schottky barrier to reduce conduction loss and enhance breakdown strength of nanocomposites has been widely studied. Nevertheless, there are few reports on the effect of the energy level structure in filler/polymer and electrode/dielectric interface region on the breakdown strength and high-temperature energy storage performances. Herein, the polyimide (PI) films sandwiched by Al2O3 layers and filled with SiO2 shell-coated high-K BaTiO3 nanofibers were prepared. Our results reveal that the wide bandgap oxide layer can regulate the energy level structure of the interface region, introduce deep traps in the nanocomposites and increase the Schottky barrier at the electrode/dielectric interface to impede charge injection and transport. Moreover, the nanocomposites combine the advantages of anisotropic dielectric properties from the Al2O3 layer, SiO2 shell, and BaTiO3 core, enhancing dielectric constants of the nanocomposites. The optimal nanocomposites show greatly enhanced discharge energy density and breakdown strength at 150 °C, which are 370% and 38% higher than those of PI, respectively. This work provides more insight into the mechanism of electrical conduction and breakdown in polymer nanocomposites and offers an effective strategy for developing polymer nanocomposites with superior capacitive performance at elevated temperatures.

Enhanced breakdown strength of ferroelectric–dielectric multilayered thin films by blocking oxygen vacancies through linear dielectric layer

Enhanced breakdown strength of ferroelectric–dielectric multilayered thin films by blocking oxygen vacancies through linear dielectric layer

Enhancement of breakdown strength and electromigration reliability for cobalt lines lightly doped with boron

Conventional copper interconnect is facing a considerable rise in electrical resistivity for applications in nanoscale devices due mainly to its significant-high electron mean free path. Cobalt, a metal with a shorter electron mean free path, has been suggested as the most promising interconnecting material for the next-generation device. Thus, this work studies alloying cobalt film with a small amount of boron as an electromigration retarder without sacrificing its electrical conductivity through evaluating its electrical properties, electromigration resistance, bonding structure, and thermal stability. Examining composition of the boron lightly-doped cobalt films shows that it can be intentionally controlled by the deposition power, yielding the incorporating boron not significantly increasing its electrical resistivity. Additionally, boron incorporation strongly intensifies the breakdown strength and electromigration reliability of the cobalt film. However, boron addition leads to a higher surface energy, and thus causes a degradation of the thermal stability. Nevertheless, the studied boron lightly-doped cobalt film is still thermally stable up to 600 °C, making it a promising interconnecting material for application in nanoscale devices.

Nanocrystalline Engineering Induced High Energy Storage Performances of Fatigue-Free Ba2Bi3.9Pr0.1Ti5O18 Ferroelectric Thin Films.

Electrostatic capacitors, though presenting faster rate capability and higher power density, are hindered in applications because of their low energy density. Accordingly, many efforts in electrostatic capacitors, for electronics and electrical power systems, have mainly concentrated on the development of dielectric materials with high-energy density (Ud) and charge-discharge efficiency (η) as well as good stability performances of thermal and fatigue endurance. Herein, we demonstrate that an excellent Ud (∼90 J/cm3) and high η (∼84.2%), as well as outstanding fatigue cycles (1 × 108 st), frequency stability (20-2000 Hz), and a wide temperature range (RT ∼ 160 °C), can be attained in Ba2Bi3.9Pr0.1Ti5O18 (BBPT) ferroelectric thin films via nanocrystalline engineering. It is revealed that nanocrystalline engineering of the BBPT ferroelectric thin films could be controlled via the heat-treatment temperature, which could effectively regulate the breakdown strength and polarization. The enhanced breakdown strength and polarization of the nanocrystalline engineering is further verified through the theoretical phase-field simulations along with experimental results. These results indicate that this is a feasible and scalable route to develop dielectric thin film materials with a high energy storage capability.

Synergy of a Stabilized Antiferroelectric Phase and Domain Engineering Boosting the Energy Storage Performance of NaNbO3-Based Relaxor Antiferroelectric Ceramics.

Relaxor antiferroelectric (AFE) ceramic capacitors have drawn growing attention in future advanced pulsed power devices for their superior energy storage performance. However, state of the art dielectric materials are restricted by desirable comprehensive energy-storage features, which have become a longstanding hurdle for actual capacitor applications. Here, we report that a large energy density Wrec of 5.52 J/cm3, high efficiency η of 83.3% at 560 kV/cm, high power density PD of 114.8 MW/cm3, ultrafast discharge rate t0.9 of 45 ns, and remarkable stability against temperature (30-140 °C)/frequency (5-200 Hz)/cycles (1-105) are simultaneously achieved in 0.7 NaNbO3-0.3 CaTiO3 relaxor AFE ceramics via the synergy of stabilized AFE R phase and domain engineering in combination with breakdown strength enhancement. The structural origin for these achievements is disclosed by probing the in situ microstructure evolution by means of the first-order reversal curve method, piezoelectric force microscopy, and Raman spectroscopy. The highly dynamic polar nanoregions and stabilized AFE R phase synergistically generate a linear-like and highly stable polarization field response over a wide temperature and field scope with concurrently improved energy density and efficiency. This work offers a new solution for designing high-performance next-generation pulsed power capacitors.

Superior energy storage of sandwiched PVDF films by separate introduction of core-shell Ag@BT nanoparticles and 2D MXene nanosheets

Polymer-based dielectrics exhibit promising applications in energy storage devices due to their enormous power density, good flexibility, and low cost. However, the low energy storage density remains to be the bottleneck. Here, sandwiched polymer-ceramic nanocomposite films are designed by stacking the PVDF middle layer incorporated Ag-decorated BaTiO3 (BT) ceramic nanoparticles (Ag@BT NPs) and the PVDF top/bottom layers embedded 2D layered MXene nanosheets. Interestingly, the optimal performances with a reversible energy storage density (Wre) as high as ∼ 22.3 J/cm3 with an efficiency η ∼ 77% at a low electric field of 270 MV/m are achieved for the film with 5 wt% DA@Ag@BT/PVDF middle layer. Strong interfacial coupling, ionic interaction, and enhanced breakdown strength due to the Coulomb blocking effect in the hierarchical structures with different fillers are responsible for the high energy storage performance. Moreover, the phase-field simulation further proved an appropriate amount of DA@Ag@BT NPs can effectively prevent the formation of the conductive network, inhibit the dielectric loss and improve the breakdown strength. This hierarchical strategy demonstrates an applicable route for fabricating polymer nanocomposites with high performance.

Ultrahigh Energy Density in Continuously Gradient‐Structured All‐Organic Dielectric Polymer Films

AbstractHigh‐performance dielectric capacitors are critical for advanced electronics and electrical power systems. Polymeric dielectrics have been widely investigated for using in dielectric capacitors because of their high dielectric constants, flexibility, low density, and easy processability. However, it is still challenging to achieve simultaneous improvements in both energy density and efficiency in these dielectric polymers. Here, we report ferroelectric polyvinylidene‐fluoride‐based all‐organic dielectric polymer films with continuous compositional gradient structure are reported by modulating the spatial distribution of polymethyl‐methacrylate components, prepared via a facile and scalable additive manufacturing method. The continuous out‐of‐plane composition gradient in the all‐organic dielectric polymer films allows to tune electrical and mechanical behaviors, and thus induces a notably enhanced breakdown strength by modulating the electromechanical breakdown process related to the coupling of local electric field and stress. An ultrahigh discharge energy density of 38.8 J cm−3 along with a high discharge efficiency of >80% is achieved at the electric field of 800 kV mm−1 in the gradient polymer films, which is the highest energy density reported thus far in polymer‐based dielectrics including their nanocomposites and the highest energy efficiency achieved along with an energy density of >30 J cm−3.

Suppressed dielectric loss and enhanced breakdown strength in Ni/PVDF composites through constructing Al2O3 shell as an interlayer

Suppressed dielectric loss and enhanced breakdown strength in Ni/PVDF composites through constructing Al2O3 shell as an interlayer

Fabrication of high-temperature aromatic polyamides with ultra-high breakdown strength via complex-assisted chain arrangement

• Highly orientated polyamides were prepared via complex-assisted chain arrangement. • The breakdown strength of the polyamide increased from 460 to 641 kV/mm. • Cross-linking enhanced breakdown strength to 706 and 572 kV/mm at 25 and 150 °C. • Breakdown strength of the cross-linked polymer is higher than that of commercial film. • The polymer films presented excellent mechanical properties and dimensional stability. Improving the breakdown strength ( Eb ) of high-performance polymer films is critical for their use as high-temperature insulation films. In this study, we demonstrated HCl can complex with the benzimidazole units of heterocyclic aramid polymers, temporarily suppressing the intermolecular hydrogen-bonding interactions. Moreover, the weak interchain interactions led to improved mobility and extended the conformation of the macromolecular chain. Therefore, after HCl decomplexation, the macromolecular chains presented higher orientations and degrees of order during subsequent high temperature annealing, resulting in an increase the Eb of the films from 460 to 641 kV/mm at 25 °C. The Fourier-transform infrared spectroscopy and theoretical calculation results indicated that the hydrogen-bonding interactions were restored and enhanced after HCl decomplexation via annealing. In addition, trace amounts of O 2 were used to catalyze the cross-linking reaction between phenyl groups based on the high electron density of the benzimidazole moieties. Owing to the chemical cross-linking reaction, the Eb of the films further increased to 706 and 572 kV/mm at 25 °C and 150 °C, respectively, whereas the tensile strength of the films reached 337.4 MPa.

Polyamideimide dielectric with montmorillonite nanosheets coating for high-temperature energy storage

To meet the ever-increasing demand for electric power storage and conversion under harsh environment, polymer dielectrics, as the functional component in electrostatic capacitors, are required to serve at high temperatures. However, it is challenging to maintain favorable electrical insulation in polymer dielectrics with the temperature rise because of the high conduction loss at elevated temperature, which will lead to reduced breakdown strength, energy density, and service life. Here, a versatile surface engineering method is presented to enhance the high-temperature electrical insulation and energy storage performance of polymer dielectric via dip-coating montmorillonite (MMT) nanosheets. At 150 °C, a significantly enhanced breakdown strength of 551MV/m is achieved in a MMT coated polyamideimide (PAI) with optimized coating thickness and MMT content, resulting in a high energy density of 2.9 J cm−3 and a charge-discharge efficiency >80% that outperform existing high-temperature polymers and polyimide-based composites. Finite element simulation demonstrates that this superior performance is attributed to the anisotropic electrical properties of MMT nanosheets, which not only blocks charges injected from electrodes but also regulates the transport of charges to dissipate along the in-plane direction. This work offers a versatile and scalable approach for enabling high-temperature electrostatic energy storage and high-temperature insulation of a wide range of polymer dielectrics.

Enhanced breakdown strength of PVDF textile composites by BiFeO3 fibers in low loading

Enhanced breakdown strength of PVDF textile composites by BiFeO3 fibers in low loading

Ultrahigh energy efficiency of (1-x)Ba0.85Ca0.15Zr0.1Ti0.9O3-xBi(Mg0.5Sn0.5)O3 lead-free ceramics

Relaxor ferroelectrics (RFEs) with superior energy storage properties are the commonly selected materials for energy storage capacitors. In this work, a relaxor end-member of Bi(Mg0.5Sn0.5)O3 (BMS) was introduced into ferroelectric (FE) Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics, which remarkably inhibited grain growth and triggered a FE-to-RFE phase transition, as well as improved breakdown strength. An ultrahigh energy efficiency (η) of 97.6% with a high recoverable energy density (Wrec) of 1.703 J/cm3, and excellent temperature stability (30–130 °C) have been achieved in (1-x)Ba0.85Ca0.15Zr0.1Ti0.9O3-xBi(Mg0.5Sn0.5)O3 with x = 0.08 (BCZT-BMS8) ceramic, which is mainly due to the slim P-E loop and enhanced breakdown strength. It should be noted that the ultrahigh η of 97.6% for BCZT-BMS8 is quite attractive for further applications. Electron paramagnetic resonance signal of oxygen vacancies (g ~ 1.955) was detected in BCZT-based ceramics for the first time, which could be helpful to explore novel lead-free ceramics for energy storage capacitors.

Study on structural and functional properties of porous SiO2 core‐shell construction/polyethylene nanocomposites with enhanced interfacial interaction

AbstractThe addition of inorganic particles can endow polymer matrices with different new features, thereby realizing an optimization to the structural and functional properties of composite. The overall properties of composites are greatly influenced by both fillers dispersion and fillers‐polymer interfacial interaction. However, to simultaneously improve these mentioned two issues is still a critical challenge in the field of polymer‐based nanocomposite. Herein, a typical core‐shell structured mesoporous silica‐coated silica (SiO2@mSiO2) construction was successfully synthesized by using a bi‐phase method. The SiO2@mSiO2 filled polyethylene (PE) nanocomposite was fabricated through a precisely controlled melt‐mixing approach. Benefiting from the additional mesoporous SiO2 shell, both the dispersion of SiO2@mSiO2 and the SiO2@mSiO2‐PE matrix interfacial interaction are improved. Moreover, the stress–strain behavior, temperature‐dependent mechanical property, thermal stability, and electrical insulating property of SiO2@mSiO2/PE composite were studied in detail. It is found that SiO2@mSiO2 core‐shell nanoparticles are capable of not only making a balance between the strength and toughness of the PE‐based composite, but also improving the thermal stability of the composite. In addition, the SiO2@mSiO2/PE composite exhibited an enhanced breakdown strength (256.4 MV·m−1) when filled with as small as 1 wt% SiO2@mSiO2, which is 108% higher than neat PE. All these optimized features are attributed to the well‐designed core‐shell structure. These experimental results provide a promising way to design and fabricate future advanced composite with excellent structural and functional properties in the future.

Optimizing nanostructures to achieve enhanced breakdown strength and improved energy storage performances in dipolar polymers.

Polymer dielectrics have attracted ever-increasing attention for electrical energy storage applications in recent years. Typically, polymer-based nanocomposite films are adopted to obtain polymer dielectrics with high energy density but sometime suffer from the inhomogeneous distribution of fillers. In this work, enhanced breakdown strength, suppressed dielectric loss and improved energy storage performances of PVDF film are concurrently achieved via the regulation of the sub-nano free volume, without introduction of any kinds of fillers and also minimizing the uneven distribution of the local electric field. The most improved breakdown strength is up to 488 MV m-1, with an enhancement of 60% compared with that of pristine PVDF, which enables the irradiated PVDF film to exhibit an improved polarization strength and charged energy density, giving rise to a maximum polarization strength of 3.55 μC cm-2 and a charged energy density of 9.75 J cm-3. More importantly, the irradiated PVDF film exhibits a superior discharged energy density of 7.91 J cm-3 which is 261% that of the pristine PVDF film, while maintaining the charge-discharge efficiency above 80%. In addition, the alteration of experimental breakdown strength with the increase of irradiation dose is found to be inversely correlated with the size variation of free volume holes, and the theoretical simulation of local electric field distribution further proves that the breakdown strength enhancement originates from the size shrinkage of free volume holes. The adjustment of free volume provides a potentially effective way to regulate the dielectric properties and energy storage performances of dipolar polymers.

Enhanced Breakdown Strength and Energy Density at High Temperature of Polymer Nanocomposite Films Realized by Inorganic Semiconductor Heterostructures

Enhanced Breakdown Strength and Energy Density at High Temperature of Polymer Nanocomposite Films Realized by Inorganic Semiconductor Heterostructures

Enhancing breakdown strength and lifetime of multilayer dielectric films by using high temperature polycarbonate skin layers

Polymer multilayer films (MLFs) hold a potential to achieve high energy density, high temperature rating, and high breakdown strength simultaneously for next-generation film capacitors. Under extreme conditions such as high AC electric fields and high temperatures, an important dielectric loss mechanism is the homocharge injection from metal electrodes and subsequent charge recombination (i.e., AC electronic conduction) at the electrode/dielectric interfaces. In this work, the mechanism of the AC electronic conduction loss is studied for high-temperature polycarbonate (HTPC)/poly(vinylidene fluoride) (PVDF) MLFs with either HTPC (MLF@HTPC) or PVDF skin layers (MLF@PVDF). Based on the DC/AC breakdown strength and lifetime measurements, it is observed that homocharge injection was more significant for MLF@PVDF than MLF@HTPC. Using the electric displacement-electric field loop analysis, dielectric losses from both AC electronic conduction and ferroelectric switching (PVDF) are quantified. A dipolar electric double layer model at the electrode/PVDF interfaces is proposed to explain the more significant ferroelectric switching and charge injection in MLF@PVDF. From these experimental results, it is concluded that enhanced breakdown strength and lifetime can be achieved for MLF@HTPC because of the reduced homocharge injection and AC electronic conduction at high electric fields and high temperatures.

Regulation of electron depletion layer in polymer-based nanocomposites for superior energy storage capability

Polymer-based dielectrics trigger great interests in advanced electric systems due to their high breakdown strength and power density. However, a major drawback is that excessive addition of high-εr ceramic nanofillers may deteriorate their breakdown strength and further reduce energy density. Herein, a general strategy is provided to dramatically enhance the breakdown strength by introducing a small amount of core–shell structured Al2O3@BiFeO3 nanofibers into PVDF/PMMA polymer matrix. The thickness of BiFeO3 shell is regulated by controlling its molar concentration. A significantly enhanced breakdown strength (759 kV mm−1) and an ultrahigh energy density (22.7 J cm−3) with an energy efficiency of 72% are observed. The greatly improved breakdown strength is ascribed to the regulation of electron depletion layer. When the width of heterojunction region gradually approaches to the scale of electron depletion layer, more annihilation of electrons happens and thus contributes to the enhancement of the breakdown strength. The results suggest that our designed structure can help to address the issue of both enhancing the breakdown strength and energy density for diverse nanocomposites over a broad application.