High Discharge Energy Density Research Articles

Tailored multilayered films of the PVDF/Ba0.8Sr0.2TiO3 nanocomposites with surface-modified nanoparticles for superior dielectric and energy storage performance

The multilayer thick film (~40 μm) of polyvinylidene fluoride-Ba0.8Sr0.2TiO3 (PVDF-BST) have been synthesized by a tape-casting technique. The incorporated BST nanoparticles in the PVDF matrix are functionalized by −PO4−3and −OH−group, which are abbreviated as PBST-P and PBST-H multilayer films. The nature of the functional group attached with the BST nanoparticles is found to strongly influence the dielectric properties, breakdown strength and energy storage behavior of the multilayer films. The dielectric constant (at 1kHz) of PBST-P multilayer film shows a significant increase (~30) as compared to PBST-H film (~22), whereas the tangent loss remains the same. The breakdown strength of PBST-P multilayer film is also high (~381MV/m) as compared to the PBST-H film (~318MV/m). PBST-P film also possesses high discharge energy density (~7.97J/cc at 1800 kV) and ultrahigh energy efficiency (~98%). Enhanced dielectric and energy storage properties of PBST-P film is attributed to the strong bridging interaction between the PVDF matrix and BST-P nanofiller, which creates additional dipoles and a strong local electric field at the interfaces. The study may lead towards the novel ways of developing polymer-ceramic nanocomposites for high-energy density capacitors, where the incorporation of functionalized nanoparticles in the polymer matrix is accompanied by the architectured structure.

Enhanced high-temperature capacitive performance through introduction of polar groups in poly(aryl ether ketone) dielectric polymer

High-temperature poly(aryl ether ketone) dielectrics have attracted application prospects in the field of polymer film capacitors. However, the investigations on improving the capacitive properties of poly(aryl ether ketone) based on molecular structure design strategies were absent. Herein, a series of poly(aryl ether ketone) bearing phthalazinone moiety were synthesized, and the effect of chemical structures on the capacitive properties of the resultant polymers was investigated by experimental data and density functional theory calculation. The introduction of the sulfone group could not only improve the permittivity but also construct deep carrier traps to enhance the breakdown strength, leading to high discharge energy density (Ue) value of the poly(phthalazinone ether sulfone ketone) (PPESK). For the poly(phthalazinone ether nitrile ketone) (PPENK), the introduction of the nitrile group could improve the Ue at room temperature, but reduce the value at elevated temperatures. As a result, at room temperature, the maximum Ue of both the PPESK (4.56 J/cm3) and the PPENK (3.40 J/cm3) was higher than that of the PPEK (3.02 J/cm3). Notably, the maximum Ue of the PPESK reached 3.07 J/cm3 at 150 °C, which is twice that of commercially bi-oriented polypropylene (BOPP) film (1.5 J/cm3 at 70 °C). Additionally, at the electric field of 200 MV/m and 150 °C, the PPESK films exhibited the Ue of 0.72 J/cm3 with charge-discharge efficiency (η) of 97.2 %, which was obviously superior to those of the BOPP (Ue = 0.4 J/cm3 with η of 96 % at 70 °C). This study presents an in-depth analysis regarding the relationship between the sulfone and nitrile groups and the capacitive performance of poly(aryl ether ketone) bearing phthalazinone moiety, which is informative for designing high-temperature dielectric polymers.

Local Isomeric Polar Nanoclusters Enabled Superior Capacitive Energy Storage Under Moderate Fields in NaNbO3-Based Lead-Free Ceramics.

The high-field energy-storage performance of dielectric capacitors has been significantly improved in recent years, yet the high voltage risks of device failure and large cost of insulation technology increase the demand for high-performance dielectric capacitors at finite electric fields. Herein, a unique superparaelectric state filled with polar nanoclusters with various local symmetries for lead-free relaxor ferroelectric capacitors is subtly designed through a simple chemical modification method, successfully realizing a collaborative improvement of polarization hysteresis, maximum polarization, and polarization saturation at moderate electric fields of 20-30kVmm-1. Therefore, a giant recoverable energy density of ≈5.0Jcm-3 and a high efficiency of ≈82.1% are simultaneously achieved at 30kVmm-1 in (0.9-x)NaNbO3-0.1BaTiO3-xBiFeO3 lead-free ceramics, showing a breakthrough progress in moderate-field comprehensive energy-storage performances. Moreover, superior charge-discharge performances of high-power density ≈182MWcm-3, high discharge energy density ≈4.3Jcm-3 and ultra-short discharge time <70ns as well as excellent temperature stability demonstrate great application potentials for dielectric energy-storage capacitors in pulsed power devices. This work provides an effective and paradigmatic strategy for developing novel lead-free dielectrics with high energy-storage performance under finite electric fields.

Epoxy fiber derived all‐polymer films for high performance electrostatic energy storage dielectrics

Dielectric films with high discharged energy density are highly desired in electrical and electronic systems. Adding inorganic nanoparticles, especially for 1D inorganic fillers, in polymer films is recognized as one of the most effective methods to improve the electric breakdown strength, which is a key parameter of energy storage. However, 1D inorganic fillers added into thin films will undoubtedly introduce many defects and reduce the electric insulation performance. Herein, homogeneous epoxy fiber derived all‐polymer films were fabricated by electrospinning, laminating, and curing in sequence. The existing 1D structure of the epoxy films significantly enhanced the dielectric constant and electric breakdown strength, resulting in a very high enhancement of 2.7 times the discharged energy storage density at 25 °C, up to 9.6 J/cm3. Assisted by the simulation analysis, the enhanced dipole polarization and reduced current density are found to be the main reasons for the improved energy storage performances. Preparing all‐polymer films with fiber structure has proved to be an effective way to find advanced energy storage dielectric films.This article is protected by copyright. All rights reserved.

High-temperature dielectric with excellent capacitive performance enabled by rationally designed traps in blends

Polymer dielectrics with excellent capacitive performance are urgently needed in advanced electrical and electronic systems. However, due to the dramatic increase in the conduction loss, the energy density and efficiency of polymers degrade severely at elevated temperatures, limiting their application in harsh environments up to 150 °C. Herein, an all-organic polyurea (PU)/polyetherimide (PEI) blend film is designed to prepare high-temperature polymer dielectric. It is found that carrier traps can be introduced by blending, and the hydrogen bond between PU and PEI increases the trap depth, leading to suppressed leakage current and enhanced breakdown strength, thus improving the energy storage performance. PU/30%PEI exhibits a high discharged energy density of ∼3.74 J/cm3 with an efficiency higher than 90% at 150 °C, which is 78% and 70% higher than pristine PU and PEI, respectively. This work provides a facile strategy to improve the energy storage performance of polymer dielectrics by introducing deep traps through blending.

Synthesis and high-temperature energy storage performances of fluorinated polyimides

In light of the increasingly stringent requirements for the applications of light-weight flexible high-temperature-resistant dielectric materials in the fields of aerospace, electronics, and electric vehicles, the imperative lies in the development of dielectric materials with high discharged energy density, enduring temperature resistance and high reliability. This work introduced side-chain trifluoromethyl (–CF3) groups into high-temperature engineering polymer polyimides and conducted comprehensive studies on the breakdown and energy storage capabilities. The introduction of bulky –CF3 substituents reduces the intermolecular interactions, increases the free volume, and suppresses the high-temperature leakage conductance loss by decreasing the formation of intermolecular charge transfer complexes between polymer chains. As a result, the fluorinated polyimides (PFI) with lower dielectric constant exhibit enhanced breakdown strengths (730 MV m−1 at 25 °C; 630 MV m−1 at 150 °C), leading to a high discharged energy density of 3.6 J cm−3 (∼1.7 times of pristine polyimides), alongside a charge-discharge energy efficiency of ∼80% at 150 °C. These findings underscore the great potential of PFI for applications in the field of high-temperature energy storage.

High energy storage performance induced by the introduction of BiScO3 into (Bi0.5Na0.5)TiO3–BaTiO3 lead-free ferroelectric ceramics

In this work, ternary 0.25(Bi0.5Na0.5)TiO3-(0.75-x)BaTiO3-xBiScO3(abbreviated as 0.25BNT-(0.75-x)BT-xBS, x = 0.19, 0.21, 0.23, 0.25, 0.27) lead-free ferroelectric ceramics were synthesized using the solid-state reaction method. The introduction of BiScO3 into (Bi0.5Na0.5)TiO3–BaTiO3 ceramics had a significant impact on changing the phase structures, and microstructures, as well as the dielectric and ferroelectric properties. All ceramics exhibited a coexistence of tetragonal(P4bm) and rhombohedral(R3c) perovskite phases, while the influence of the BiScO3(BS) content on the average grain size was not significant. Slim polarization-electric field hysteresis loops were recorded for the 0.25BNT-(0.75-x)BT-xBS ceramics, with low remnant polarization (Pr) and large maximum polarization(Pmax). 0.25BNT-0.50BT-0.25BS ceramic had the largest Pmax, which induced a high energy storage density of 2.93 J/cm3 and energy storage efficiency of 91 % under a low electric field of 230 kV/cm 0.25BNT-0.50BT-0.25BS ceramic not only yielded excellent fatigue resistance, but also maintained good energy storage performance at high temperature and high frequency, which are considered of great importance since they can be leveraged for the potential development of high temperature and frequency capacitors. In addition, an excellent pulse performance was measured, with a high discharge energy density of 3.42 J/cm3 and a fast discharging rate t0.9 of 130 ns. This good pulse performance was maintained at high temperatures, suggesting that the proposed material is also highly competitive for applications where high-temperature pulse devices are required.

Engineering Phase Separation in Niobate Glass through Ab Initio Molecular Dynamics for Enhanced Energy Storage Performance and Unprecedented Thermal Stability in Niobate-Based Glass Ceramics.

The advancement of lead-free glass ceramics (GCs) possessing appropriate energy storage characteristics is crucial for the renewable energy and electronics industry. In this study, we synthesized lead-free GCs predominantly composed of the tungsten bronze phase, Ba3.3Nb10O28.3. Ab initio molecular dynamics initially reveal nonuniform distribution within the Ba/Nb-O regions in niobite glassy melts, offering valuable insights for the subsequent crystallization process. The proposal of a B-site engineering strategy is suggested, which entails the concurrent reduction of grain size and augmentation of the band gap in tungsten bronze GCs doped with Ta. This approach results in a substantial enhancement of the dielectric breakdown strength (BDS). Phase-field simulations have indicated that the refinement of grain sizes plays a pivotal role in augmenting the local electric field distribution and breakdown path, thereby contributing to the enhancement of BDS. As a consequence of these modifications, a notably high recoverable energy density (Wrec) of 5.23 J/cm3 can be achieved, accompanied by an ultrahigh efficiency (η) of 94%, and superior thermal stability in energy storage. These outcomes are particularly evident in the case of 2 mol % Ta2O5-doped P2O5-K2O-BaO-Bi2O3-TeO2-Nb2O5 (PKBBTN-T) GCs, where the Wrec and η can be determined to be 2.87 ± 3% J/cm3 and 95.46 ± 4%, respectively, over a temperature range spanning from 20 to 150 °C. Additionally, this specimen exhibits an exceptionally high discharge energy density (Wdis) of 4.01 J/cm3. This comprehensive investigation, comprising experimental and theoretical analyses, establishes an effective pathway and paradigm for the development of dielectric materials with ultrahigh energy storage properties.

Samarium-modified PLZST-based antiferroelectric energy storage ceramics for low-temperature sintering in reducing atmosphere

The energy storage properties of pure PLZST-based antiferroelectric ceramics are excellent; however, the high sintering temperature renders them unsuitable for co-firing with copper inner electrodes as MLCC dielectric materials. The proven BASK glass additive was employed in this study to lower the sintering temperature of PLSZT ceramics, while simultaneously doping Sm3+ ions to enhance their sintering performance under reducing atmospheres. The precise evaluation process confirmed that the addition of glass effectively reduced the sintering temperature to 1040 °C. Furthermore, the defect association of Sm3+ doping hindered the formation of oxygen vacancies, facilitated ceramic grain growth, and significantly enhanced insulation resistivity. Consequently, an ultrahigh recoverable energy density (Wrec) of 5.19 J/cm3 with a high energy storage efficiency (η) of 94.5% are achieved at an electric field of 430 kV/cm. Moreover, the AFE ceramics possess excellent discharge energy storage properties with a high discharge energy density (Wd) of 4.26 J/cm3 and a large power density (Pd) of 139 MW/cm3.

γ-Ray Irradiation Significantly Enhances Capacitive Energy Storage Performance of Polymer Dielectric Films.

Polymer dielectric capacitors are fundamental in advanced electronics and power grids but suffer from low energy density, hindering miniaturization of compact electrical systems. It is shown that high-energy and strong penetrating γ-irradiation significantly enhances capacitive energy storage performance of polymer dielectrics. γ-irradiated biaxially oriented polypropylene (BOPP) films exhibit an extraordinarily high energy density of 10.4 J cm-3 at 968 MV m-1 with an efficiency of 97.3%. In particular, an energy density of 4.06 J cm-3 with an ultrahigh efficiency of 98% is reliably maintained through 20000 charge-discharge cycles under 600 MV m-1. At 125°C, the γ-irradiated BOPP film still delivers a high discharged energy density of 5.88 J cm-3 with an efficiency of 90% at 770 MV m-1. Substantial improvements are also achieved for γ-irradiated cycloolefin copolymers at a high temperature of 150°C, verifying the strategy generalizability. Experimental and theoretical analyses reveal that the excellent performance should be related to the γ-irradiation induced polar functional groups with high electron affinity in the molecular chain, which offer deep energy traps to impede charge transport. This work provides a simple and generally applicable strategy for developing high-performance polymer dielectrics.

Ultrahigh efficiency and enhanced discharge energy density at low loading of nanofiller in trilayered polyvinylidene fluoride‐Ba0.8Sr0.2TiO3 nanocomposites

AbstractPoly(vinylidene)fluoride‐Ba0.8Sr0.2TiO3 (PVDF‐BST) trilayered nanocomposites (with different vol% loading of BST nanoparticles, i.e. 0.75%, 1.50%, 2.25% and 3.00%) has been processed by the tape casting technique. The upper and lower layers of the nanocomposites are casted in the same direction, whereas the middle layer is casted in the opposite direction. The trilayered PVDF‐BST nanocomposite consisting of 3.00 vol% of BST nanoparticles exhibited high dielectric permittivity (~25), low tangent loss (~0.03) and moderately high breakdown strength (BDS ~282 MV/m). Moreover, it also possesses a high discharge energy density (~7.8 J/cc at 1400 kV/cm) and efficiency (~93%). A mechanism for the excellent energy storage behavior and dielectric properties has been proposed. Where, moderately high BDS and low tangent loss are associated with the spatial distribution of the local electric field at interlayer interfaces of PVDF‐BST trilayered nanocomposites, which restricts the conduction of charge carriers at high electric field. The ultrahigh efficiency and enhanced discharge energy density is attributed to the formation of interfacial dipoles at various interfaces such as interlayer, intralayer (PVDF/PVDF), and PVDF/BST interfaces. These investigations would be adopted as a futuristic strategy for developing excellently efficient polymer‐ceramic nanocomposites for the high energy density capacitors used in pulsed power applications.Highlights PVDF‐BST trilayered nanocomposites exhibit high ε′ ~25 and low tanδ ~0.03. Nanocomposite shows ultra‐high energy efficiency ~93% and enhanced UD ~ 7.8 J/cc. Mechanism for the excellent energy storage and dielectric properties Relies on the interfacial dipoles and distribution of the local electric field.

Nonpolar sub-10 nm TiO2 nanocrystal for high energy density polypropylene nanocomposites

Film capacitors have shown great potential in high-power energy storage devices due to their high breakdown strength and low dielectric loss. However, the state-of-the-art commercial capacitor dielectric, biaxially oriented polypropylene (BOPP), exhibits limited energy storage density below 2 J cm−3 because of its low dielectric constant (approximately 2.2 at 103 Hz). In this work, we present a novel PP-based nanocomposites by incorporating nonpolar sub-10 nm sized TiO2 nanoparticles into the PP matrix for the first time. The nonpolar TiO2 nanoparticles are functionalized with Trioctylphosphine oxide (TOPO) ligands, ensuring excellent compatibility and dispersion of the TiO2 fillers in the PP matrix, resulting in a homogeneous dielectric PP nanocomposite. Moreover, the TOPO ligand, with lower LUMO energy level and higher HOMO level than that of PP matrix, serves as an energy trap to capture carriers upon their occurrence. Furthermore, the well-dispersed sub-10 nm sized TiO2 nanoparticles enlarges the interfacial area, thereby increasing the interfacial polarization and the dielectric constant. The resultant PP nanocomposites exhibit a high discharged energy density of 4.19 J cm−3 at 600 MV m−1, representing a remarkable 74.9% increase compared to that of the pure PP films. This work provides a brand-new strategy for constructing homogeneous PP nanocomposite dielectrics by incorporating nonpolar sub-10 nm sized TiO2 nanoparticles as fillers. And this approach is critical for the design of high energy density PP-based nanocomposites.

High discharge energy density in rationally designed graphene oxide@zinc oxide/polymer blend-polyetherimide heterostructured bilayer nanocomposites

The advancement of new dielectric materials exhibiting greater discharge energy density is crucial for current power systems and electronic devices. In this work, various weight percentages of graphene oxide@zinc oxide (GO@ZO) nanofillers were incorporated inside a polymer blend of poly(vinylidene fluoride-hexafluoropropylene)/polyetherimide (P(VDF-HFP)/PEI; shortened as BP) and used as a high dielectric top layer. In contrast, linear-type PEI (L) was used as a bottom insulation layer to achieve a high breakdown strength (Eb) in bilayer nanocomposites. As a result, the 2BP-L composite demonstrated a high discharged energy density of 12.63 J/cm3 at an electric field of 527 MV/m with only 2 wt% GO@ZO nanofillers addition in the top layer. Such a high discharge energy density with minimal nanofiller loading is attributed to the utilization of novel surface-decorated GO@ZO nanofillers and new bilayer-heterostructured linear/ferroelectric-linear polymer. In comparison to its counterparts (i.e., PEI, P(VDF-HFP) and 0BP-L), the 2BP-L nanocomposite showed ∼426.3 %, 92.5 %, and 9.8 % enhancement in discharge energy density, respectively. The discharge rate and stability analysis revealed a significantly higher power density of 0.55 MW/cm3, indicating its high potential to be used as a pulsed power system. Finite element simulation revealed that the effective internal electric field distribution and higher dielectric displacement in 2BP-L resulted in such enhancement over its counterparts. This study presents a new model to maximize the energy storage capability of flexible energy storage devices and advances knowledge of the polarization mechanisms and breakdown of bilayer nanocomposite dielectric materials.

Design and preparation of ternary polymer nanocomposites for high energy density film capacitors

High discharge energy density (Ue) film capacitors are important for miniaturization and integration in power electronic applications. The Ue of a polymer film is mainly dependent on Weibull's breakdown strength (Eb) and dielectric constant (εr). This work aims to develop ternary nanocomposites composed of polycarbonate (PC), Al2O3 nanoparticles (Al2O3 NPs) and BaTiO3 nanowires (BT NWs) for capacitive energy-storage. Al2O3 NPs have a wide bandgap and are expected to enhance Eb owing to their insulating nature, while BaTiO3 nanowires (BT NWs) are ferroelectric and are expected to provide a high εr. To overcome local electric-field distortion at the interface due to the mismatch in εr, core-shell structured BT@SiO2 NWs are prepared. The Eb of the composite containing 1.0 wt% Al2O3 NPs and 6.0 wt% BT@SiO2 NWs can reach 626 MV/m while that of the pure PC is 465 MV/m. As a result, its Ue reaches 12.12 J/cm3, which is improved by 211% that of the pure PC. Its discharge efficiency is 83.5%. A finite element analysis corroborates the superiority of the ternary polymer nanocomposites for dielectric energy-storage.

Multilayer BOPET dielectric film with internal double electron barrier for high temperature applications

With the continuous development of modern electronic and power equipment, practical applications in harsher environment call for film capacitors with higher temperature resistance. Here, we designed a multilayer film including two outer layers of biaxially oriented polyethylene terephthalate (BOPET), two inorganic layers of boron nitride nanosheets (BNNSs), and an intermediate epoxy layer. Due to the blocking effect of the BNNSs layer, the propagation of the breakdown path is hindered, which improves the breakdown strength of the film. Meanwhile, the carrier transport in the medium is effectively hindered, reducing the conduction loss of the composite film. As a result, the optimized multilayer composite film had a high discharged energy density of 8.76 J/cm3, maintaining a high charge-discharge efficiency of 95% at 25 °C, while remarkable values of 7.04 J/cm3 and 73% were obtained even at 150 °C, which showed prominent improvements compared with BOPET. Thus, it turns out to be a promising strategy of fabricating high temperature dielectric films.

Chemical and physical synergism between PAF-54 and SFPEEKK for effective shuttle effect inhibition of lithium–sulfur battery

Lithium-sulfur batteries (LSBs) have garnered considerable interest due to their high theoretical discharge specific capacity and energy density. However, the formation of lithium polysulfides during the electrochemical redox process leads to the loss of active material and undesirable electrochemical properties. In this study, we developed a novel Janus separator (FSP-PAF) prepared by coating PAF-54 compounded sulfonated poly (ether ether ketone ketone) and Super P onto the PE separator to effectively mitigate the shuttle effects. The FSP-PAF exhibited a high ionic conductivity of 6.4 × 10−4 S/cm and a Li+ transfer number (tLi+) of 0.72. Lithium-sulfur batteries assembled with FSP-PAF demonstrated a capacity of 1112 mA h/g at 0.2 °C, and a remarkable capacity retention rate of 65 % after 500 cycles, and maintained a capacity of 720 mA h/g even at a high rate of 3 °C. This synergistic effect involving PAF-54, sulfonated poly (ether ether ketone ketone), and Super P held great promise for the application of LSBs.

Improving energy storage performance of BLLMT ceramic by doping BZT combining with defect engineering and film scraping process

The (1-x)(Ba0.94Li0.02La0.04)(Mg0.04Ti0.96)O3-xBi(Zn1/2Ti1/2)O3 ((1-x)BLLMT-xBZT, x = 0.02, 0.04, 0.06, 0.08, 0.10, 0.12) ceramic thick films were prepared by traditional solid-state sintering method combined with film scraping process. Li+ and La3+ ions doping at A-site, and Mg2+ and Zn2+ ions doping at B-site of the perovskite structure, and adding BZT component enhance charge compensation, enlarge polarization difference, increase breakdown strength, and enhance relaxation degree, leading to the improved pulse charging and discharging energy storage performance of the BaTiO3-based ceramic films. The 0.92BLLMT-0.08BZT ceramic film has high discharge energy density of 4.61 J/cm3, high pulse power density PD = 224.14 MW/cm3, high current density CD = 896.58 A/cm2, high discharge speed of 234 ns, and high pulse discharge density Wd = 4.61 J/cm3 under 500 kV/cm combined with high breakdown strength of 500 kV/cm, relating to charge compensation, multiple ferroelectric phases coexistence, and formation of polar nanoregions. The strategy by equivalent and heterovalent ions doping at A-site and B-site of the perovskite structure and introducing Bi-based component combined with film scraping process strengthens charge compensation, enhances relaxation characteristic, and reduces grain size, providing an efficient route to develop prospect BT-based dielectric ceramic capacitors for potential application in high-power pulse energy storage such as 0.92BLLMT-0.08BZT.

Polyetherimide nanocomposites filled with in‐situ synthesised bismaleimide‐DDE@CCTO hybrid nanofibers enabling improved dielectric and interfacial performance

AbstractMost current research of nanocomposite dielectrics for modern electronic devices and electric equipment usually focuses more on dielectric properties while in some extent ignoring the interfacial adhesion characteristics. However, the poor interfacial adhesion frequently results in serious dielectric field distortion, which would in return impair the dielectric performance enhancement. As such, how to simultaneously achieve the excellent dielectric properties and interfacial adhesion performance in organic‐inorganic nanocomposite system is worth in‐depth investigation. To realise this aim, novel hybrid nanofibers are neatly fabricated using in situ copolymerisation reaction of bismaleimide and diamino‐diphenyl ether monomers on the CCTO nanofiller surface via covalent bond connections. The resulting nanocomposites achieve high dielectric constant (9.3) and low dielectric loss (0.0185) at 1 kHz. The BMI‐DDE@CCTO/PEI yields a high discharge energy density (3.09 J/cm3) at moderate electric field (200 MV/m). Noticeably, the nanocomposites enable stable dielectric performance over a wide temperature range from room temperature to 150°C. Moreover, the binding energy for BMI‐DDE and PEI is 1052 kJ/mol according to DFT calculation. As such, the authors speculate this interesting study would inspire the broad researchers devoting to investigating bismaleimide‐coated high‐aspect‐ratio nanofillers and their dielectric materials for collaboratively improved dielectric and interfacial performance.

Boosting capacitive performance of lead-free relaxor ferroelectrics by introducing a linear dielectric

As an important core component used in high-power pulse electronic systems, dielectric ceramic capacitors have gained great interest because of their ultrahigh powder density (PD) and fast discharge speed (t0.9). However, inferior energy storage performance (ESP) greatly limits the development of energy storage devices with the requirement of miniaturization and integration. Herein, we propose a feasible approach to introduce linear dielectric CaTiO3 (CT) into (Bi0.5Na0.5)TiO3 (BNT) for the design of engineered relaxor ferroelectrics to tune ESP at the grain, domain, and macroscopic scales. The results demonstrate that introducing CT generates enhanced relaxor behavior with highly dynamic polar nanoregions, refines grain size, and suppresses dielectric loss, synergistically yielding increased breakdown strength, negligible remnant polarization, and a nearly linear polarization hysteresis loop. Consequently, superior ESP is achieved in BNT-0.3CT relaxor ferroelectric ceramics with a large energy density (∼5.65 J/cm3) and a high efficiency (∼88.1 %). Based on CT-induced merits, the excellent temperature/frequency/cycling stabilities and remarkable charge-discharge properties featuring a high PD of 200.4 MW/cm3, high discharge energy density of 2.27 J/cm3 and ultrashort t0.9 of 58 ns of the designed ceramics broaden the actual application prospects. This work demonstrates that introducing linear dielectric CT holds great promise for developing high-performance energy storage dielectrics.

Realizing high energy density and discharge energy density in high hardness Ba1.938Bi0.375Nb5O15-based glass ceramics

The practical utility of glass-ceramics-based (GCs) energy storage materials is limited due to their low energy density. In this work, we synthesized the unleaded GCs containing two crystalline phases: Ba1.938Bi0.375Nb5O15 and BaNb2O6. An increase in crystallization time at a specific temperature initially leads to a decrease and then an increase in the dielectric permittivity (εr) and breakdown strength (BDS) due to changes in crystallinity. Specifically, at a crystallization temperature of 750 °C for 4 h, the BDS reaches approximately 1422 kV/cm, driven by a lower oxygen density, higher activation energy, and the formation of a fine-grained structure in the compact GCs. Numerical simulation was employed to uncover the underlying mechanism behind the enhanced BDS achieved through changing crystallization time. As a result of the enhanced BDS and polarization, this study achieved remarkable and comprehensive outcomes: a high efficiency (η) of 85.89%, a high energy density (Wrec) of 3.79 J/cm3, an ultrahigh discharge energy density (Wdis) of 3.26 J/cm3 and a high Vickers hardness (Hv) of 6.85 GPa. Meanwhile, this sample crystallized for 4 h demonstrates excellent thermal stability and frequency stability. These results show that these GCs could be highly competitive as lead-free materials for energy storage capacitors.