Research on the energy storage performance of laminated composites based on multidimensional co-design in a broad temperature range.

Polymer dielectrics play an irreplaceable role in electronic power systems because of their high power density and fast charge-discharge capability, but it is limited by their low stability in the temperature range of 25-200 °C. Rather than the introduction of one-dimensional fillers in polymers, we used a kind of multidimensional synergistic design to prepare Al2O3-TiO2-Al2O3/PI composites with layered structures by introducing multi-dimensional materials in polyimide (PI). In fact, the composite achieves much higher temperature stability than the pure PI film. The optimally proportioned composite has an energy density of 3.41 J cm-3 (vs. 1.48 J cm-3 for pure PI) even at 200 °C. Additionally, it reaches an impressive energy density retention of up to 90% and maintains an energy efficiency as high as 86% at 400 MV m-1 in the temperature range of 25-200 °C. The multidimensional coordination design is proposed to obtain composite films, and provides a feasible strategy in the study of polymer-based composites with high-temperature performance.

Enhancing Comprehensive Performance via Capturing and Scattering the Carriers inside PESU-Based Nanocomposite Film Capacitors.

Film capacitors have become key electronic components for electrical energy storage installations and high-power electronic systems. Nonetheless, high-temperature and high-electric-field environments would cause a surge of the energy loss, placing a fundamental challenge for film capacitors applied in harsh environments. Here, we constructed a composite film, combining poly(ether sulfone) (PESU) with excellent thermal stability and large-band-gap filler boron nitride nanosheets (BNNSs). The introduction of BNNSs would form deep/shallow traps inside the dielectric polymer matrix, effectively affecting charge migration. Via density functional theory (DFT) calculation, the higher highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the BNNS than the matrix facilitate scattering electrons and attracting holes. The resultant composite obtains the desired discharged energy densities (Ud) of 5.89 and 3.86 J/cm3 accompanied by an efficiency above 90% at 150 and 200 °C, respectively, surpassing those of existing dielectric materials at the high-temperature conditions. The paper provides a promising composite dielectric material for high-performance film capacitors capable of operating in harsh environments.

Tailoring Phase Fraction Induced Saturation Polarization Delay for High-Performance BaTiO3-Based Relaxed Ferroelectric Capacitors.

Electrostatic capacitors based on dielectric materials are essential for enabling technological advances, including miniaturization and integration of electronic devices. However, maintaining a high polarization and breakdown field strength simultaneously in electrostatic capacitors remains a major challenge for industrial applications. Herein, a universal approach to delaying saturation polarization in BaTiO3-based ceramic is reported via tailoring phase fraction to improve capacitive performance. The ceramic of 0.85(0.7BaTiO3-0.3Bi0.5Na0.5TiO3)-0.15Bi0.5Li0.5(Ti0.75Ta0.2)O3 delivers an ultrahigh recoverable energy density (Wrec) of 7.16 J cm-3 along with an efficiency (η) of approximately 90% at a breakdown electric field of 700 kV cm-1, outperforming the current BaTiO3-based ceramics and other lead-free ceramics. Meanwhile, the Wrec and η exhibit wide frequency, temperature, and cycling fatigue stability. Additionally, both an extremely fast discharge time of 115 ns and a large power density of 106.16 MW cm-3 are concurrently attained. This work offers a promising pathway for delaying saturation polarization design in order to create scalable high-energy-density ceramics capacitors and highlight the research prospects of pulse power applications.

Superb Energy Storage Capability for NaNbO3 -Based Ceramics Featuring Labyrinthine Submicro-Domains with Clustered Lattice Distortions.

Designing superb dielectric capacitors is valuable but challenging since achieving simultaneously large energy-storage (ES) density and high efficiency is difficult. Herein, the synergistic effect of grain refining, bandgap widening, and domain engineering is proposed to boost comprehensive ES properties by incorporating CaTiO3 into 0.92NaNbO3 -0.08BiNi0.67 Ta0.33 O3 matrix (as abbreviated NN-BNT-xCT). Apart from grain refining and bandgap widening, multiple local distortions embedded in labyrinthine submicro-domains, as indicated by diffraction-freckle splitting and ½-type superlattices, produce slush-like polar clusters for the NN-BNT-0.2CT ceramic, which should be ascribed to the coexisting P4bm, P21 ma, and Pnma2 phases. Consequently, a high recoverable ES density Wrec of ≈ 7.1 J cm-3 and a high efficiency η of ≈ 90% at 646 kV cm-1 is achieved for the NN-BNT-0.2CT ceramic. Such hierarchically polar structure is favorable to superb comprehensive ES properties, which provide a strategy for developing high-performance dielectric capacitors.

Giant Energy Storage Density with Antiferroelectric-Like Properties in BNT-Based Ceramics via Phase Structure Engineering.

Driven by the information industry, advanced electronic devices require dielectric materials which combine both excellent energy storage properties and high temperature stability. These requirements hold the most promise for ceramic capacitors. Among these, the modulated Bi0.5 Na0.5 TiO3 (BNT)-based ceramics can demonstrate favorable energy storage properties with antiferroelectric-like properties, simultaneously, attaching superior temperature stability resulted from the high Curie temperature. Inspired by the above properties, a strategy is proposed to modulate antiferroelectric-like properties via introducing Ca0.7 La0.2 TiO3 (CLT) into Bi0.395 Na0.325 Sr0.245 TiO3 (BNST) ((1-x)BNST-xCLT, x = 0.10, 0.15, 0.20, 0.25). Combining both orthorhombic phase and defect dipole designs successfully achieve antiferroelectric-like properties in BNST-CLT ceramics. The results illustrate that 0.8BNST-0.2CLT presents superior recoverable energy storage density ≈8.3 J cm-3 with the ideal η ≈ 80% at 660 kV cm-1 . Structural characterizations demonstrate that there is the intermediate modulated phase with the coexistence of the antiferroelectric and ferroelectric phases. In addition, in situ temperature measurements prove that BNST-CLT ceramics exhibit favorable temperature stability over a wide temperature range. The present work illustrates that BNT-based ceramics with antiferroelectric-like properties can effectively enhance the energy storage performance, which provides novel perspectives for the subsequent development of advanced pulsed capacitors.

Delayed Polarization Saturation Induced Superior Energy Storage Capability of BiFeO3 -Based Ceramics Via Introduction of Non-Isovalent Ions.

Electrostatic capacitors are emerging as a highly promising technology for large-scale energy storage applications. However, it remains a significant challenge to improve their energy densities. Here, an effective strategy of introducing non-isovalent ions into the BiFeO3 -based (BFO) ceramic to improve energy storage capability via delaying polarization saturation is demonstrated. Accordingly, an ultra-high energy density of up to 7.4 J cm-3 and high efficiency ≈ 81% at 680 kV m-1 are realized, which is one of the best energy storage performances recorded for BFO-based ceramics. The outstanding comprehensive energy storage performance is attributed to inhibiting the polarization hysteresis resulting from generation ergodic relaxor zone and random field, and generating highly-delayed polarization saturation with continuously-increased polarization magnitudes with the electric field of supercritical evolution. The contributions demonstrate that delaying the polarization saturation is a consideration for designing the next generation of lead-free dielectric materials with ultra-high energy storage performance.

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.

Two-Dimensional Fillers Induced Superior Electrostatic Energy Storage Performance in Trilayered Architecture Nanocomposites.

Dielectric capacitors with ultrahigh power densities and fast charging/discharging rates are of vital relevance in advanced electronic markets. Nevertheless, a tradeoff always exists between breakdown strength and polarization, which are two essential elements determining the energy storage density. Herein, a novel trilayered architecture composite film, which combines outer layers of two-dimensional (2D) BNNS/poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) with high breakdown strength and an intermediate layer made of blended 2D MoS2 nanosheets/P(VDF-HFP) with large polarization, is fabricated using the layer-by-layer casting method. The insulating BNNS with a wide band gap is able to largely alleviate the distortion of the local electric field, thereby suppressing the leakage current and effectively reducing the conductivity loss, while the 2D MoS2 nanosheets act as microcapacitors in the polymer composites, thus significantly increasing the permittivity. A finite element simulation is carried out to further analyze the evolution process of electrical treeing in the experimental breakdown of the polymer nanocomposites. Consequently, the nanocomposites possess an excellent discharged energy density of 25.03 J/cm3 accompanied with a high charging/discharging efficiency of 77.4% at 650 MV/m, which greatly exceeds those of most conventional single-layer films. In addition, the corresponding composites exhibit an outstanding reliability of energy storage performance under continuous cycling. The excellent performances of these polymer-based nanocomposite films could pave a way for widespread applications in advanced capacitors.

Ultrahigh Energy Storage Performance of Layered Polymer Nanocomposites over a Broad Temperature Range.

To reach the full potential of polymer dielectrics in advanced electronics and electrified transportation, it calls for efficient operation of high-energy-density dielectric polymers under high voltages over a wide temperature range. Here, the polymer composites consisting of the boron nitride nanosheet/polyetherimide and TiO2 nanorod arrays/polyetherimide layers are reported. The layered composite exhibits a much higher dielectric constant than the current high-temperature dielectric polymers and composites, while simultaneously retaining low dielectric loss at elevated temperatures and high applied fields. Consequently, the layered polymer composite presents much improved capacitive performance than the current dielectric polymers and composites over a temperature range of 25-150 °C. Moreover, the excellent capacitive performance of the layered composite is achieved at an applied field that is about 40% lower than the typical field strength of the current polymer composites with the discharged energy densities of >3 J cm-3 at 150 °C. Remarkable cyclability and dielectric stability are established in the layered polymer nanocomposites. This work addresses the current challenge in the enhancement of the energy densities of high-temperature dielectric polymers and demonstrates an efficient route to dielectric polymeric materials with high energy densities and low loss over a broad temperature range.

Simultaneously enhanced discharge energy density and efficiency in nanocomposite film capacitors utilizing two-dimensional NaNbO3@Al2O3 platelets.

With rapid developments in the consumer electronics market, electrostatic capacitors need to store as much energy as possible within a rather restricted space. In this work, nanocomposite films combining two-dimensional core-shell NaNbO3@Al2O3 platelets (2D NN@AO Ps) and poly(vinylidene-fluoride hexafluoropropylene) (P(VDF-HFP)), featuring excellent energy storage capability, high efficiency, and ultrafast discharge performance, are designed and fabricated. Both the experimental results and finite element simulations confirm the superiority of these 2D NN@AO Ps nanocomposite films in improving the breakdown strength (Eb) and energy storage capability. In particular, the introduction of 3 vol% 2D NN@AO Ps results in much enhanced discharge energy density of 14.59 J cm-3 and outstanding discharge efficiency of 70.1% in NN@AO Ps/P(VDF-HFP) nanocomposite films, which is much greater than that of pure P(VDF-HFP) (7.74 J cm-3). The corresponding nanocomposite films exhibit excellent reliability in energy storage performance under consecutive cycling. Therefore, this research could reveal a new chapter in the study and application of polymer nanocomposites in energy-storage dielectric capacitors.

Largely enhanced energy storage capability of a polymer nanocomposite utilizing a core-satellite strategy.

The development of new generation dielectric materials toward capacitive energy storage has been driven by the rise of high-power applications such as electric vehicles, aircraft, and pulsed power systems. Here we demonstrate remarkable improvements in the energy density and charge-discharge efficiency of poly(vinylidene fluoride) (PVDF) upon the incorporation of core-satellite structures, namely NaNbO3(NN)@polydopamine (PDA)@Ag nanowires. As compared to the NN NWs/PVDF and NN@PDA NWs/PVDF nanocomposites, the NN@PDA@Ag NWs/PVDF nanocomposites exhibit greatly enhanced energy density and significantly suppressed energy loss. As a result, the NN@PDA@Ag NWs/PVDF nanocomposite films with optimized filler content exhibit an excellent discharge energy density of 16.04 J cm-3 at 485 MV m-1, and maintain a high discharge efficiency of 62.8%. Moreover, the corresponding nanocomposite films exhibit a superior power density of 2.1 MW cm-3 and ultra-fast discharge speed of 153 ns. Ultimately, the excellent dielectric and capacitive properties of the polymer nanocomposites could pave the way for widespread applications in modern electronics and power modules.

Interfacial Coupling Effect in Organic/Inorganic Nanocomposites with High Energy Density.

Organic/inorganic nanocomposites (OINs) can be potentially used as high-performance capacitors due to their rapid charge-discharge capability along with respectable power density. The coupling effect of the filler/matrix interface plays a prominent role in the dielectric and electric properties of OINs. Along with a review of contemporary theoretical models, recent advances in interfacial optimization to improve energy density through careful interface control and design are also presented. Possible mechanisms that may improve energy density and potential applications for high-energy-density capacitors are also highlighted.

Ultrafast Discharge and Enhanced Energy Density of Polymer Nanocomposites Loaded with 0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Zr0.2Ti0.8)O3 One-Dimensional Nanofibers.

One-dimensional (1D) materials as fillers introduced into polymer matrixes have shown great potential in achieving high energy storage capacity because of their large dipole moments. In this article, 1D lead-free 0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Zr0.2Ti0.8)O3 nanofibers (BCZT NFs) were prepared via electrospinning, and their formation mechanism was systematically studied. Polypropylene acyl tetraethylene pentamine (PATP) grafted into the surface of BCZT NFs was embedded in the polymer matrixes, which effectively improved the distribution and compatibility of the fillers via chemical bonding and confined the movement of the charge carriers in the interface filler-matrix. The energy density at a relatively low electric field 380 MV m-1 was increased to 8.23 J cm-3 by small loading of fillers, far more than that of biaxially oriented polypropylene (BOPP) (≈ 1.2 J cm-3 at 640 MV m-1). Moreover, the nanocomposite loaded with 2.1 vol % BCZT@PATP NFs exhibits a superior discharge speed of ≈0.189 µs, which indicates the potential application in practice. The finite element simulation of electric potential and electric current density distribution revealed that the PATP grafted into the BCZT NFs surface could significantly improve the dielectric performances. This work could provide a new design strategy for high-performance dielectric polymer nanocomposite capacitors.

Novel design of highly [110]-oriented barium titanate nanorod array and its application in nanocomposite capacitors.

Nanocomposites in capacitors combining highly aligned one dimension ferroelectric nanowires with polymer would be more desirable for achieving higher energy density. However, the synthesis of the well-isolated ferroelectric oxide nanorod arrays with a high orientation has been rather scant, especially using glass-made substrates. In this study, a novel design that is capable of fabricating a highly [110]-oriented BaTiO3 (BT) nanorod array was proposed first, using a three-step hydrothermal reaction on glass-made substrates. The details for controlling the dispersion of the nanorod array, the orientation and the aspect ratio are also discussed. It is found that the alkaline treatment of the TiO2 (TO) nanorod array, rather than the completing transformation into sodium titanate, favors the transformation of the TO into the BT nanorod array, as well as protecting the glass-made substrate. The dispersity of the nanorod array can be controlled by the introduction of a glycol ether-deionized water mixed solvent and soluble salts. Moreover, the orientation of the nanorod arrays could be tuned by the ionic strength of the solution. This novel BT nanorod array was used as a filler in a nanocomposite capacitor, demonstrating that a large energy density (11.82 J cm-3) can be achieved even at a low applied electric field (3200 kV cm-1), which opens us a new application in nanocomposite capacitors.

High-Energy-Density Polymer Nanocomposites Composed of Newly Structured One-Dimensional BaTiO3@Al2O3 Nanofibers.

Flexible electrostatic capacitors are potentially applicable in modern electrical and electric power systems. In this study, flexible nanocomposites containing newly structured one-dimensional (1D) BaTiO3@Al2O3 nanofibers (BT@AO NFs) and the ferroelectric polymer poly(vinylidene fluoride) (PVDF) matrix were prepared and systematically studied. The 1D BT@AO NFs, where BaTiO3 nanoparticles (BT NPs) were embedded and homogeneously dispersed into the AO nanofibers, were successfully synthesized via an improved electrospinning technique. The additional AO layer, which has moderating dielectric constant, was introduced between BT NPs and PVDF matrixes. To improve the compatibility and distributional homogeneity of the nanofiller/matrix, dopamine was coated onto the nanofiller. The results show that the energy density due to high dielectric polarization is about 10.58 J cm-3 at 420 MV m-1 and the fast charge-discharge time is 0.126 µs of 3.6 vol % BT@AO-DA NFs/PVDF nanocomposite. A finite element simulation of the electric-field and electric current density distribution revealed that the novel-structured 1D BT@AO-DA NFs significantly improved the dielectric performance of the nanocomposites. The large extractable energy density and high dielectric breakdown strength suggest the potential applications of the BT@AO-DA NFs/PVDF nanocomposite films in electrostatic capacitors and embedded devices.

Significantly Enhanced Energy Density in Nanocomposite Capacitors Combining the TiO2 Nanorod Array with Poly(vinylidene fluoride).

A novel inorganic/polymer nanocomposite, using 1-dimensional TiO2 nanorod array as fillers (TNA) and poly(vinylidene fluoride) (PVDF) as matrix, has been successfully synthesized for the first time. A carefully designed process sequence includes several steps with the initial epitaxial growth of highly oriented TNA on the fluorine-doped tin oxide (FTO) conductive glass. Subsequently, PVDF is embedded into the nanorods by the spin-coating method followed by annealing and quenching processes. This novel structure with dispersive fillers demonstrates a successful compromise between the electric displacement and breakdown strength, resulting in a dramatic increase in the electric polarization which leads to a significant improvement on the energy density and discharge efficiency. The nanocomposites with various height ratios of fillers between the TNA and total film thickness were investigated by us. The results show that nanocomposite with 18% height ratio fillers obtains maximum increase in the energy density (10.62 J cm-3) at a lower applied electric field of 340 MV m-1, and it also illustrates a higher efficiency (>85%) under the electric field less than 100 MV m-1. Even when the electric field reached 340 MV m-1, the efficiency of nanocomposites can still maintained at ∼70%. This energy density exceeds most of the previously reported TiO2-based nanocomposite values at such a breakdown strength, which provides another promising design for the next generation of dielectric nanocomposite material, by using the highly oriented nanorod array as fillers for the higher energy density capacitors. Additionally, the finite element simulation has been employed to analyze the distribution of electric fields and electric flux density to explore the inherent mechanism of the higher performance of the TNA/PVDF nanocomposites.