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

Improved Energy Storage Performance of Composite Films Based on Linear/Ferroelectric Polarization Characteristics

The development and integration of high-performance electronic devices are critical in advancing energy storage with dielectric capacitors. Poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (PVTC), as an energy storage polymer, exhibits high-intensity polarization in low electric strength fields. However, a hysteresis effect can result in significant residual polarization, leading to a severe energy loss, which impacts the resultant energy storage density and charge/discharge efficiency. In order to modify the polarization properties of the polymer, a biaxially oriented polypropylene (BOPP) film with linear characteristics has been selected as an insulating layer and combined with the PVTC ferroelectric polarization layer to construct PVTC/BOPP bilayer films. The hetero-structure and polarization characteristics of the bilayer film have been systematically studied. Adjusting the BOPP volume content to 67% resulted in a discharge energy density of 10.1 J/cm3 and an energy storage efficiency of 80.9%. The results of this study have established the mechanism for a composite structure regulation of macroscopic energy storage performance. These findings can provide a basis for the effective application of ferroelectric polymer-based composites in dielectric energy storage.

High-Dielectric PVP@PANI/PDMS Composites Fabricated via an Electric Field-Assisted Approach

Polymer-based composite films with multiple properties, such as low dielectric loss tangent, high dielectric constant, and low cost are promising materials in the area of electronics and electric industries. In this study, flexible dielectric films were fabricated via an electric field-assisted method. Polyaniline (PANI) was modified by polyvinylpyrrolidone (PVP) to form a core–shell structure to serve as functional particles and silicone rubber polydimethylsiloxane (PDMS) served as the matrix. The dielectric constant of the composites prepared under electric fields was improved by the micro-structures formed by external electric fields. With the addition of 2.5 wt% PVP@PANI, the dielectric constant could be significantly enhanced, up to 23; the dielectric loss tangent is only 1, which is lower than that of the aligned PANI samples. This new processing technology provides important insights for aligning fillers in polymer matrix to form composites with enhanced dielectric properties.

High-energy-density polymer dielectrics via compositional and structural tailoring for electrical energy storage

Dielectric capacitors with higher working voltage and power density are favorable candidates for renewable energy systems and pulsed power applications. A polymer with high breakdown strength, low dielectric loss, great scalability, and reliability is a preferred dielectric material for dielectric capacitors. However, their low dielectric constant limits the polymer to achieve satisfying energy density. Therefore, great efforts have been made to get high-energy-density polymer dielectrics. By compositional and structural tailoring, the synergic integrations of the multiple components and optimized structural design effectively improved the energy storage properties. This review presents an overview of recent advancements in the field of high-energy-density polymer dielectrics via compositional and structural tailoring. The surface/interfacial engineering conducted on both microscale and macroscale for polymer dielectrics is the focus of this review. Challenges and the promising opportunities for the development of polymer dielectrics for capacitive energy storage applications are presented at the end of this review.

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A detailed summary of the state-of-the-art polymer dielectrics

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The comparison of polymer nanocomposites with 0D, 1D, and 2D nanofillers

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Analyzing high U_e polymer dielectrics via compositional and structural tailoring

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Summary of micro- or macro-surface and interface engineering

High Conduction Band Inorganic Layers for Distinct Enhancement of Electrical Energy Storage in Polymer Nanocomposites

Dielectric polymer nanocomposites are considered as one of the most promising candidates for high-power-density electrical energy storage applications. Inorganic nanofillers with high insulation property are frequently introduced into fluoropolymer to improve its breakdown strength and energy storage capability. Normally, inorganic nanofillers are thought to introducing traps into polymer matrix to suppress leakage current. However, how these nanofillers effect the leakage current is still unclear. Meanwhile, high dopant (> 5 vol%) is prerequisite for distinctly improved energy storage performance, which severely deteriorates the processing and mechanical property of polymer nanocomposites, hence brings high technical complication and cost. Herein, boron nitride nanosheet (BNNS) layers are utilized for substantially improving the electrical energy storage capability of polyvinylidene fluoride (PVDF) nanocomposite. Results reveal that the high conduction band minimum of BNNS produces energy barrier at the interface of adjacent layers, preventing the electron in PVDF from passing through inorganic layers, leading to suppressed leakage current and superior breakdown strength. Accompanied by improved Young's modulus (from 1.2 GPa of PVDF to 1.6 GPa of nanocomposite), significantly boosted discharged energy density (14.3 J cm^-3) and charge-discharge efficiency (75%) are realized in multilayered nanocomposites, which are 340 and 300% of PVDF (4.2 J cm^-3, 25%). More importantly, thus remarkably boosted energy storage performance is accomplished by marginal BNNS. This work offers a new paradigm for developing dielectric nanocomposites with advanced energy storage performance.

Enhanced Energy Storage Performance of PVDF-Based Composites Using BN@PDA Sheets and Titania Nanosheets

With the rapid development of modern electrical and electronic applications, the demand for high-performance film capacitors is becoming increasingly urgent. The energy density of a capacitor is dependent on permittivity and breakdown strength. However, the development of polymer-based composites with both high permittivity (εr) and breakdown strength (Eb) remains a huge challenge. In this work, a strategy of doping synergistic dual-fillers with complementary functionalities into polymer is demonstrated, by which high εr and Eb are obtained simultaneously. Small-sized titania nanosheets (STNSs) with high εr and high-insulating boron nitride sheets coated with polydopamine on the surface (BN@PDA) were introduced into poly(vinylidene fluoride) (PVDF) to prepare a ternary composite. Remarkably, a PVDF-based composite with 1 wt% BN@PDA and 0.5 wt% STNSs (1 wt% PVDF/BN@PDA-STNSs) shows an excellent energy storage performance, including a high εr of ~13.9 at 1 Hz, a superior Eb of ~440 kV/mm, and a high discharged energy density Ue of ~12.1 J/cm3. Moreover, the simulation results confirm that BN@PDA sheets improve breakdown strength and STNSs boost polarization, which is consistent with the experimental results. This contribution provides a new design paradigm for energy storage dielectrics.

Achieving Concurrent High Energy Density and Efficiency in All-Polymer Layered Paraelectric/Ferroelectric Composites via Introducing a Moderate Layer

Dielectric polymer capacitors are extensively applied in advanced electronics by virtue of their extremely high power density. However, it remains a challenge to concurrently realize high energy density and high discharge efficiency. In order to solve this conundrum, we herein design a novel all-polymer trilayer structure, where the paraelectric poly(methyl methacrylate) (PMMA) is used as the top layer to obtain a high discharge efficiency, and ferroelectric P(VDF-HFP) is employed as the bottom layer to obtain a high energy density. Particularly, the PMMA/poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) blend composite is used as the middle layer to homogenize the electric field inside the trilayer composites, turning out an obviously boosted breakdown strength and elevated energy density. Consequently, an efficiency as high as 85% and an energy density up to 7.5 J/cm³ along with excellent cycling stability are simultaneously realized at an ultrahigh electric field of 490 kV/mm. These attractive characteristics of the all-polymer trilayer structure suggest that the feasible pathway presented herein is significant to realize concurrently a high energy density and discharge efficiency.

Nonthermal plasma catalysis for toluene decomposition over BaTiO3-based catalysts by Ce doping at A-sites: The role of surface-reactive oxygen species

The insights on the primary surface-reactive oxygen species and their relation with lattice defects is essential for designing catalysts for plasma-catalytic reactions. Herein, a series of Ba_1-xCe_xTiO₃ perovskite catalysts with high specific surface areas (68.6-85.6 m² g^-1) were prepared by a facile in-situ Ce-doping strategy and investigated to catalytically decompose toluene. Combining the catalysts with a nonthermal plasma produced a significant synergy effect. The highest decomposition efficiency (100%), CO_x selectivity (98.1%), CO₂ selectivity (63.9%), and the lowest O₃ production (0 ppm) were obtained when BC₄T (Ce/Ti molar ratio = 4:100) was packed in a coaxial dielectric barrier discharge reactor at a specific input energy of 508.8 J L^-1. The H₂-TPR, temperature-programmed Raman spectra, EPR and OSC results suggested that superoxides (^•O₂^-) were the primary reactive oxygen species and were reversibly generated on the perovskite surface. Molecular O₂ was adsorbed and activated at the active sites (Ti³⁺-V_O) via an electron transfer process to form ^•O₂^-. Surface-adsorbed ^•O₂^- had a greater effect on the heterogeneous surface plasma reactions than the dielectric constant, and enhanced the toluene decomposition and intermediate oxidation. A possible reaction path of toluene decomposition was also proposed.

Morphogenesis mechanisms in the hydrothermal growth of lead-free BCZT nanostructured multipods

The nanostructuring approach may offer a new route to tailor lead-free ferroelectrics with superior energy storage performance for ceramic actuators and capacitors.

Ultrahigh Energy Efficiency and Large Discharge Energy Density in Flexible Dielectric Nanocomposites with Pb0.97La0.02(Zr0.5SnxTi0.5-x)O3 Antiferroelectric Nanofillers

Flexible dielectric capacitors have been widely studied recently on account of their fast charge-discharge speed, high power density, and superior wearable characteristics. Inorganic ferroelectric fillers/polymer matrix composites combining large maximum electric displacement (D_max) of ferroelectric materials with good flexibility and high electric breakdown strength (E_b) of the polymer are regarded as the most promising materials for preparing flexible dielectric capacitors with superior energy storage properties. However, simultaneously achieving large discharge energy density (W_d) and high energy efficiency (η) in these composites remains challenging on account of a large remnant electric displacement (D_r) and low D_max - D_r values of ferroelectric fillers. In contrast, antiferroelectrics (AFEs) exhibit near zero D_r and larger D_max - D_r values and are thus attractive composite fillers to simultaneously achieve large W_d and high η. On the basis of these factors, in this report, we design and prepare Pb_0.97La_0.02(Zr_0.5Sn_xTi_0.5-x)O₃ (PLZST) AFE nanoparticles (NPs)/poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) nanocomposites and investigate the effects of the Sn and AFE NPs contents on the energy storage capacity of the nanocomposites. Through reasonable adjustment of the Sn content and the PLZST AFE fillers content, because of the large D_max - D_r value of 7.75 μC/cm² and small D_r value of 0.26 μC/cm² at the E_b as high as 3162 kV/cm, the Pb_0.97La_0.02(Zr_0.5Sn_0.38Ti_0.12)O₃ AFE NPs/P(VDF-HFP) polymer nanocomposite with 7 wt % fillers exhibits the most superior energy storage properties with an ultrahigh η of 93.4% and a large W_d of 12.5 J/cm³. These values are superior to those of the recently reported dielectric nanocomposites with a single-layer structure containing ferroelectric nanowires, nanofibers, nanobelts, nanotubes, and nanosheets or core-shell structure fillers, which are prepared via a very complicated method. This work not only shows that, in principle, the polarization characteristics of the composites depend mainly on those of the inorganic fillers but also demonstrates a convenient, effective, and scalable way to fabricate dielectric capacitors with superior flexibility and energy storage capacities.

Polymer Matrix Nanocomposites with 1D Ceramic Nanofillers for Energy Storage Capacitor Applications

Recent developments in various technologies, such as hybrid electric vehicles and pulsed power systems, have challenged researchers to discover affordable, compact, and super-functioning electric energy storage devices. Among the existing energy storage devices, polymer nanocomposite film capacitors are a preferred choice due to their high power density, fast charge and discharge speed, high operation voltage, and long service lifetime. In the past several years, they have been extensively researched worldwide, with 0D, 1D, and 2D nanofillers being incorporated into various polymer matrixes. However, 1D nanofillers appeared to be the most effective in producing large dipole moments, which leads to a considerably enhanced dielectric permittivity and energy density of the nanocomposite. As such, this Review focuses on recent advances in polymer matrix nanocomposites using various types of 1D nanofillers, i.e., linear, ferroelectric, paraelectric, and relaxor-ferroelectric for energy storage applications. Correspondingly, the latest developments in the nanocomposite dielectrics with highly oriented, surface-coated, and surface-decorated 1D nanofillers are presented. Special attention has been paid to identifying the underlying mechanisms of maximizing dielectric displacement, increasing dielectric breakdown strength, and enhancing the energy density. This Review also presents some suggestions for future research in low-loss, high energy storage devices.

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.

Boosting the Recoverable Energy Density of Lead-Free Ferroelectric Ceramic Thick Films through Artificially Induced Quasi-Relaxor Behavior

Dielectric ceramic film capacitors, which store energy in the form of electric polarization, are promising for miniature pulsed power electronic device applications. For a superior energy storage performance of the capacitors, large recoverable energy density, along with high efficiency, high power density, fast charge/discharge rate, and good thermal/fatigue stability, is desired. Herein, we present highly dense lead-free 0.942[Na_0.535K_0.480NbO₃]-0.058LiNbO₃ (KNNLN) ferroelectric ceramic thick films (∼5 μm) demonstrating remarkable energy storage performance. The nanocrystalline KNNLN thick film fabricated by aerosol deposition (AD) process and annealed at 600 °C displayed a quasi-relaxor ferroelectric behavior, which is in contrast to the typical ferroelectric nature of the KNNLN ceramic in its bulk form. The AD film exhibited a large recoverable energy density of 23.4 J/cm³, with an efficiency of over 70% under the electric field of 1400 kV/cm. Besides, an ultrahigh power density of 38.8 MW/cm³ together with a fast discharge speed of 0.45 μs, good fatigue endurance (up to 10⁶ cycles), and thermal stability in a wide temperature range of 20-160 °C was also observed. Using the AD process, we could make a highly dense microstructure of the film containing nano-sized grains, which gave rise to the quasi-relaxor ferroelectric characteristics and the remarkable energy storage properties.

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.

Effect of the coverage level of carboxylic acids as a modifier for barium titanate nanoparticles on the performance of poly(vinylidene fluoride)-based nanocomposites for energy storage applications

Changes in the breakdown strength of nanocomposites show diversity as the modifier content increases for different modifiers.