Giant Energy Storage Density Research Articles

Novel lead-free KNN-based ceramic with giant energy storage density, ultra-high efficiency and excellent thermal stability via relaxor strategy

(1-x)(0.9 K0.5Na0.5NbO3-0.1Ba0.4Sr0.6TiO3)-xBi(Zn0.5Zr0.5)O3 ceramics (abbreviated as (1-x)KNNBST-xBZZ, x = 0, 0.05, 0.10, 0.15, 0.20) were synthesized using the solid-state reaction method and their structure and electrical characteristics, including dielectric and ferroelectric properties, were systematically investigated. The incorporation of Bi/Zn/Zr (BZZ) elements into the KNNBST system results in a substantial increase in volume density, a dominant cubic crystal structure, and enhanced relaxor behaviour. Consequently, these modifications have led to superior energy storage performance. The 0.9KNNBST-0.1BZZ ceramics shows excellent recoverable energy storage density (Wrec = 5.42 J/cm3), and ultra-high energy efficiency (η = 91.09 %) at 470 kV/cm. Moreover, the 0.9KNNBST-0.1BZZ ceramics exhibits favorable frequency stability (1–1000 Hz) and temperature stability (27–190 ℃). The outstanding energy storage characteristics of (1-x)KNNBST-xBZZ ceramics make them highly promising for advanced pulse power capacitors and various energy storage applications.

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 660kV 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.

Fabrication of cellulose-based dielectric nanocomposite film with excellent energy storage performance via codissolution-regeneration method

The extensive use of petroleum-based dielectric composites has caused many environmental problems, which has forced us to turn our attention to biodegradable materials. In this study, cotton cellulose and PVDF were codissolved and regenerated as a matrix film in an elaborate way, and barium titanate (BT) nanoparticles were added to ensure high energy storage performance. Strong hydrogen bonds formed between the fluorine atoms of PVDF and the abundant hydroxyl groups of cellulose molecules, which were more robust than their own intramolecules; these strong hydrogen bonds promoted polarization intensity, thus improving the energy storage density of the matrix (from 6.50 J/cm3 @3.20 MV/cm of pristine PVDF film to 8.29 J/cm3 @3.20 MV/cm). Upon the addition of BT nanofillers, the cellulose/PVDF-BT ternary film exhibited an impressive breakdown strength (3.70 MV/cm) and a giant energy storage density (10.81 J/cm3). In addition, the composite film possessed excellent tensile strength (∼60 MPa). The electrical breakdown behavior was confirmed and visualized by finite element simulation. Significantly, our work has instructive implications for fabricating flexible energy storage devices based on renewable bioresources.

Giant energy-storage density with ultrahigh efficiency in lead-free relaxors via high-entropy design

Next-generation advanced high/pulsed power capacitors rely heavily on dielectric ceramics with high energy storage performance. However, thus far, the huge challenge of realizing ultrahigh recoverable energy storage density (Wrec) accompanied by ultrahigh efficiency (η) still existed and has become a key bottleneck restricting the development of dielectric materials in cutting-edge energy storage applications. Here, we propose a high-entropy strategy to design “local polymorphic distortion” including rhombohedral-orthorhombic-tetragonal-cubic multiphase nanoclusters and random oxygen octahedral tilt, resulting in ultrasmall polar nanoregions, an enhanced breakdown electric field, and delayed polarization saturation. A giant Wrec ~10.06 J cm−3 is realized in lead-free relaxor ferroelectrics, especially with an ultrahigh η ~90.8%, showing breakthrough progress in the comprehensive energy storage performance for lead-free bulk ceramics. This work opens up an effective avenue to design dielectric materials with ultrahigh comprehensive energy storage performance to meet the demanding requirements of advanced energy storage applications.

Giant energy storage density in Ba, La co-doped PbHfO3-based antiferroelectric ceramics by a rolling process

Near-zero remanent polarization, high breakdown electric field, high saturation polarization and low electrical hysteresis are necessary conditions for antiferroelectric ceramics to obtain excellent energy storage performance. Here, Pb0.925BaxLa0.075−x(Hf0.6Sn0.4)0.98125+x/4O3 lead-based antiferroelectric ceramics were prepared by a rolling process. The composition modulations of Ba and La are beneficial to adjust the phase switching field, improve the saturation polarization and reduce the electrical hysteresis, leading to an enhanced energy storage performance. Simultaneously, the Pb0.925Ba0.045La0.03(Hf0.6Sn0.4)0.9925O3 ceramic exhibited a high energy storage density of 7.3 J cm−3 and an energy storage efficiency of 91%, revealing that this composition is an outstanding candidate in pulsed energy storage application and lays a foundation for further study on the energy storage performances of PbHfO3-based antiferroelectric ceramics.

Giant energy storage density in lead-free dielectric thin films deposited on Si wafers with an artificial dead-layer

High-performance lead-free thin-film capacitors deposited on the silicon (Si) wafers with large energy storage density ( W ) and high reliability are strongly attractive in the modern electrical and electronic devices. Here, an ultrahigh W was achieved in the Ba 0.3 Sr 0.7 Zr 0.18 Ti 0.82 O 3 (BSZT) relaxor ferroelectric thin films deposited on the Si wafers with the help of an ultrathin Ca 0.2 Zr 0.8 O 1.8 (CSZ) artificial “dead-layer” simultaneously possessing high resistivity, wide band gap and high permittivity among linear dielectrics. As the CSZ was implanted, the W of the Ba 0.3 Sr 0.7 Zr 0.18 Ti 0.82 O 3 (BSZT) thin films was greatly increased from 64.9 J/cm 3 to 89.4 J/cm 3 , which is comparable to the best W of thin film deposited on expensive single crystal substrates, and is the largest one reported so far than those of lead-free thin films deposited on the Si wafers, and even for lead thin films. Due to the formation of ultrahigh electrons injection barrier (3.92 eV) between the interface of the CSZ dead layer and the Au top electrode, the Schottky emission of the BSZT thin films under high electric field and at high temperatures was effective suppressed, which is responsible for the greatly improved dielectric breakdown strength and thermal stability. Moreover, the fatigue endurance was also enhanced. It is concluded that the implantation of the CSZ artificial dead-layer could be used as a universal-simple-effective strategy to improve the electrical performances of ferroelectric materials working in the harsh environment of high electric field. With the help of an ultrathin Ca 0.2 Zr 0.8 O 1.8 artificial “dead-layer”, the energy storage properties of the BSZT thin films was greatly improved. The implantation of the new artificial dead-layer could be used as a universal-simple-effective strategy to improve the electrical performances of ferroelectric materials working in the high electric field. • High quality lead-free thin films deposited on Si wafers were obtained. • An ultrahigh energy storage density ( W ) on Si wafers ~ 89 J/cm 3 was achieved. • Artificial Dead-layer implantation benefits the enhancement of W and DBS. • Artificial Dead-layer implantation benefits the improvement of thermal stability and fatigue endurance. • High electrons injection barrier can suppress Schottky Emission.

Giant energy storage density in PVDF with internal stress engineered polar nanostructures

Abstract High power dielectric capacitors with high energy density are needed in order to develop modern electronic and electrical systems, including hybrid vehicles, telecommunication infrastructures and portable electronic devices. Relaxor ferroelectric polymers (RFP) are considered to be the most promising candidates for the next generation of capacitors owing to their relatively high energy storage density. However, the commercialization of RFP capacitors in power systems is hindered by their high cost and low dielectric breakdown strength. In this study, inexpensive, free-standing nano-crystalline (~3.3 nm) poly (vinylidene fluoride) (PVDF) films with high β phase content (~98%), “relaxor-like” ferroelectric behaviour and high breakdown strength (880 kV/mm) were fabricated using the facile Press & Folding (P&F) technique. An internal stress dominated polarization switching model is proposed to explain the origin of the relaxor-like ferroelectric behaviour. The internal stress generated during pressing alters the intermolecular chain distance of the (200) plane of β-PVDF from 4.24 A in internal stress free films to 4.54 A in P&F films, corresponding to a tensile strain and residual stress of 7.11% and 142 MPa, respectively. The internal stress acts to partially reverse the polarization on reversal of the applied electric field. This, combined with preferred in-plane orientation of the crystallites, results in a polar nanostructure with high polarization reversibility at high electric fields. A giant discharged energy storage density of 39.8 J/cm3 at 880 kV/mm was achieved for P&F films, which surpasses all previously reported polymer-based materials.

Optical and dielectric properties of PbZrO3 thin films prepared by a sol–gel process for energy-storage application

PbZrO3 thin films with (100) and (111) orientation were prepared by a simple sol–gel method. X-ray diffraction results revealed that post-annealing temperatures played an important role on the orientation of PbZrO3 films. The frequency dependence of dielectric properties and the ferroelectric characteristics were measured. Giant energy-storage density and energy-storage efficiency calculated from hysteresis loops achieved about 25.25J/cm3 and 62% for PbZrO3 film with thickness of 292nm, respectively, results indicated that PbZrO3 thin films had a potential application in energy-storage device. Optical properties of PbZrO3 thin films were analyzed by a spectroscopic ellipsometer, results revealed that (111)-orientated PbZrO3 thin films exhibited higher refractive index than that of the (100)-orientated PbZrO3 thin films.