Ultrahigh Energy Storage Research Articles

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.

Ultrahigh energy storage density in epitaxial AlN/ScN superlattices

Dielectric and antiferroelectric materials are particularly promising for high-power energy-storage applications. However, relatively low energy density greatly hinders their usage in storage technologies. Here, we report first-principles-based calculations predicting that epitaxial and initially non-polar AlN/ScN superlattices can achieve an ultrahigh energy density of up to 200 J/cm$^{\textrm{3}}$, accompanied by an ideal efficiency of 100%. We also show that high energy density requires the system being neither too close nor too far from a ferroelectric phase transition under zero electric field. A phenomenological model is further proposed to rationalize such striking features.

Sandwich structured lead-free ceramics based on Bi0.5Na0.5TiO3 for high energy storage

With the rapid development of electronic information technology and the rising environmental concerns as well as the tendency of electronic devices towards miniaturization and integration, enhancing the energy storage properties of lead-free ceramic capacitors is one of the imperative issues. Although a large number of efforts have been contributed to optimize the energy storage properties of lead-free ceramics, the conflict between the polarization and electric breakdown strength seriously impedes the improvement of energy storage density significantly. Herein, inspired by the layered composites of sandwich, the sandwich structured lead-free ceramics based on Bi0.5Na0.5TiO3 were designed and fabricated to overcome the above challenge effectively. The theoretical simulations and experiment results demonstrate that the polarization and electric breakdown strength can be optimized synchronously via the sandwich structured design. An ultrahigh recoverable energy storage density of ~ 6 J cm−3 and a nearly ideal energy conversion efficiency of ~ 95% can be obtained for the prepared sandwich structured lead-free ceramics. Meanwhile, the maximum applied electric field can be enhanced to more than 500 kV cm−1. The energy storage capabilities also exhibit outstanding stability over a broad temperature range, frequency range and cycle numbers. These results reveal that the Bi0.5Na0.5TiO3-based lead-free ceramics of this study have a great potential for high energy storage capacitors applications.

Ultrahigh energy storage performances derived from the relaxation behaviors and inhibition of the grain growth in La doped Bi5Ti3FeO15 films

Developing environment-friendly film capacitors, which possessing a high energy storage performance, an extra wide working temperature range and a longest lifetime are desirable in applications owning to energy shortage and environmental pollution. Here, lead-free Bi5-xLaxTi3FeO15 films with four-layer Aurivillius structure were fabricated by the sol–gel method. It is revealed that the introduction of lanthanum ions into Bi5Ti3FeO15 films induces relaxation behaviors and inhibits grain growth, thus improving the energy storage performances. Bi4LaTi3FeO15 films achieved a large recoverable energy storage density of 83.2 J/cm3 and a high efficiency of 79.1% under 3460 kV/cm. Moreover, Bi4LaTi3FeO15 films exhibited excellent energy storage performances in fatigue endurance and thermal stability. This work demonstrates that the route through rare-earth doped multilayered perovskite ferroelectric films is an effective approach to enhance energy storage properties.

Ultra-high energy storage density and enhanced dielectric properties in BNT-BT based thin film

In this work, Mn modified 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 thin films (abbreviation for BNT-BT-Mnx) are prepared on Pt/Ti/SiO2/Si substrate via sol-gel and spin-coating. The influences of Mn dopant on the microstructural characteristics, dielectric and energy storage performances are studied systematically. It is found that by incorporating the Mn into BNT-BT, the breakdown strength and maximum polarization are enhanced dramatically, leading to the giant energy storage density of 54 J/cm3, with high permittivity 355 at 1 kHz. Moreover, the dominant leakage conduction mechanisms of the thin films are studied by linear fitting method, revealing that the leakage current mechanism of BNT-BT-Mnx films transforms from space-charge-limited conduction (SCLC) to Schottky emission as the increasing of electric field. The excellent energy storage density as well as dielectric properties suggest that BNT-BT-Mn6 thin film might be an attractive lead-free material for energy storage devices.

Ultrahigh energy storage capacity with superfast discharge rate achieved in Mg-modified Ca0.5Sr0.5TiO3-based lead-free linear ceramics for dielectric capacitor applications

For the urgent demand of environmental protection and energy conservation, it is of great significance to develop environmentally-friendly dielectric ceramics with outstanding characteristic of energy storage and quick charge discharge capacity. For this study, we applied a strategy to achieve the enhancement of energy storage performance in (Ca0.5Sr0.5)1-xMgxTiO3 (abbreviate as CSMTx, x = 0.005, 0.010, 0.020, 0.040) linear ceramics based on the introduction of Mg2+ ion. Scanning electron microscopy and complex impedance measurement reveal that Mg2+ ion doping can refine grain size and increase grain boundary density, which results in grain boundary barrier strengthening owing to high-resistance grain boundaries. As a result, the marvellous energy storage properties, including an ultrahigh recoverable energy density of 2.88 J/cm3 combined with a giant energy efficiency of 90% are concurrently obtained in (Ca0.5Sr0.5)0.99Mg0.01TiO3 ceramic at an enhanced breakdown field (460 kV/cm). Meanwhile, this composition ceramic also exhibits the superior stability of frequency (1–1000 Hz) and temperature (20–100 °C) with minimal variation. In addition, the actual performance of ceramic capacitors in operation can be evaluated via the pulsed charge-discharge process. Delightedly, the superfast discharge speed (t0.9 = 20.4 ns), large current density (CD) of 421.23 A/cm2 and ultrahigh power density (PD) of 25.27 MW/cm3, as well as prominent thermal stability (20–100 °C) are synchronously produced in the CSMT2 ceramic. These merits qualify the unleaded linear ceramic as a competitive candidate for high-power capacitor applications, which offers a practicable approach for exploration on high-performance dielectric materials.

Ultra-high energy storage density and ultra-wide operating temperature range in Bi2Zn2/3Nb4/3O7 thin film as a novel lead-free capacitor

Capacitor with high energy density, wide operating temperature range, large power density and environmental friendliness is strongly demanded in modern electrical and electronic devices. In this work, Bi2Zn2/3Nb4/3O7 (BZN) thin film as a novel lead-free material with ultra-high energy storage density and ultra-wide operating temperature range, is prepared by magnetron sputtering. Dielectric properties and electric breakdown strength depend on the substrate temperature, resulting in the change of energy storage performance. The dielectric constant and breakdown strength reach respectively 182 and 3.81 MV/cm for the BZN thin film prepared at 700 °C, while the maximum recoverable energy storage density (63.5 J/cm3) at 100 Hz is achieved. Moreover, the BZN thin films possess excellent thermal stability of energy storage properties in an ultra-wide temperature range (-150- 250 °C) and strong fatigue endurance after 1 × 106 charge–discharge cycles. These results reveal that the BZN thin film can be a promising candidate for lead-free energy storage application in equipment working in harsh environment.

Achieving ultrahigh energy storage efficiency in local-composition gradient-structured ferroelectric ceramics

Although relaxor dielectric ceramic capacitors possess attractive features for high-power energy storage, their low energy storage efficiency (η) induces the dissipation of energy in the ceramics, thus significantly increasing their temperature and deteriorating their breakdown strength and lifetime in practical applications. Here, a new strategy for designing local-composition gradient-structured grains was proposed to improve the energy storage efficiency performance under a high-intensity electric field. To verify the applicability of the proposed strategy, the 0.9(K0.5Na0.5)NbO3–0.1Bi(Zn2/3Nb1/3)O3 relaxor-ferroelectric solid solution was employed for the experimental procedure. The gradient distribution of Zn from the grain interior to the grain boundary was achieved through the meticulous manipulation of different element diffusion behaviors. The resulting local-composition gradient structure could improve the relaxation behavior, while enhancing their dynamic response to external electric fields, thus decreasing dielectric nonlinearity and remarkably improving η performance under a high-intensity electric field. As a result, the η value of the ceramics decreased by a marginal extent until the electric field reached 326 kV cm−1, with a minimal variation of <±1.5%, demonstrating substantially higher performance than that of the well-studied lead-free nonlinear dielectric ceramics. Furthermore, by alleviating the local electric field concentration near the grain boundary, the unique structure could enhance the intrinsic breakdown of the dielectric material. Finally, through the proposed strategy, the optimum energy storage properties were obtained, namely, a high recoverable energy density of 4.01 J/cm3 and an ultrahigh energy efficiency of 97.1% at 326 kV cm−1. The proposed highly effective local-composition gradient-structured design offers a new paradigm for improving the energy storage efficiency of dielectric ceramic capacitors.

Realizing ultra-high energy storage density of lead-free 0.76Bi0.5Na0.5TiO3-0.24SrTiO3-Bi(Ni2/3Nb1/3)O3 ceramics under low electric fields

• 0.90(BNT-ST)-0.10BNN ceramic possesses a desired W rec of 4.1 J/cm 3 and η of 83.15% at 250 kV/cm. • W rec and η are both insensitive to thermal stimulus over 25–120 °C. • 0.90(BNT-ST)-0.10BNN ceramic exhibits a fast discharge speed ( t 0.9 = 62.4 ns). • The improved properties are explained by first order reversal curve distribution. The electrical and electronic devices become more and more integrated and miniaturized. It is necessary to develop high performance lead-free energy storage ceramics. In this work, new relaxor ferroelectric (1-x)(0.76Bi 0.5 Na 0.5 TiO 3 -0.24SrTiO 3 )-xBi(Ni 2/3 Nb 1/3 )O 3 ceramics were prepared by the traditional solid-state reaction method. Particularly, the 0.90(BNT-ST)-0.10BNN ceramic exhibits the excellent recoverable energy storage density ( W rec = 4.1 J/cm 3 ) and efficiency ( η = 83.15%) under a low electric field (250 kV/cm). The 0.90(BNT-ST)-0.10BNN ceramic has excellent stability between 25 °C and 120 °C. In addition, an ultrahigh power density of 49.8 WM/cm 3 and a fast charge-discharge rate ( t 0.9 = 62.4 ns) can be obtained simultaneously. These properties indubitably reflect that the (1-x)(BNT-ST)-xBNN ceramics have a great potential for the applications of high energy storage capacitors.

Enhanced dielectric, thermal stability, and energy storage properties in compositionally engineered lead-free ceramics at morphotropic phase boundary

Structural inhomogeneity at morphotropic phase boundary (MPB) offers a novel paradigm to explore and modulate the physical properties of dielectric materials to design next-generation multifunctional devices. In this work, two lead free materials at MPB; Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) and (Bi0.5Na0.5)TiO3-0.06BaTiO3 (BNTBT), are combined together to synthesize polycrystalline composite samples of (1-x) BCZT-xBNTBT with x = 0.0, 0.25, 0.50, 0.75, and 1.0. Structural investigations using XRD show the coexistence of double phases for pristine BCZT (tetragonal (P4mm) + rhombohedral (R3m)), and for pristine BNTBT (tetragonal (P4bm) + rhombohedral (R3c)). However, all the doped samples with x = 0.25, 0.5, and 0.75 display a coexistence of triple phases with P4mm, P4bm, and R3c symmetries. Detailed dielectric study reveals a normal ferroelectric to macroscopic ergodic relaxor crossover for samples with x = 0.25 and 0.75. Intriguingly, sample x = 0.25 displays a coexistence of high dielectric constant (4050), ultralow dielectric loss (≤0.02), high temperature thermal stability of permittivity (variation ≤ ±15%) in a temperature range 135 °C–450 °C, large recoverable energy density (Wrec = 423 mJ/cm3) with ultrahigh energy storage efficiency (η = 95.4%) at low applied electric field - 23 kV/cm. Nevertheless, at similar applied field strength, the obtained values of Wrec and η exceed most of the selected lead-free energy storage materials. This work may pave a new path to design superior high-temperature dielectrics, through intermixing of MPBs, for energy storage applications.

Ultrahigh energy storage density of Ca2+-modified PLZST antiferroelectric ceramics prepared by the tape-casting method

High energy density is the goal pursued by energy storage dielectric capacitors. Lead-based antiferroelectric ceramics are the most promising material system. Herein, the improved recoverable energy storage of 14.5 J/cm3 and efficiency of 77.1 % are obtained at x = 0.02 in Ca2+-modified Pb0.97-xCaxLa0.02(Zr0.93Sn0.05Ti0.02)O3 (PCLZST) antiferroelectric ceramics, which are fabricated by the tape-casting method. It is proved that the partial substitution of Ca2+ to Pb2+ at A-site can effectively strengthen the antiferroelectricity due to the reduced tolerance factor. Besides, the addition of Ca2+ can refine the grains and increase the breakdown strength, up to 448 kV/cm vs 376 kV/cm for PLZST ceramics. In addition, the discharge energy density and time are 11.6 J/cm3 and 5.09 μs, respectively. These characteristics indicate that Pb0.95Ca0.02La0.02(Zr0.93Sn0.05Ti0.02)O3 ceramic is a potential energy storage material for pulsed power systems.

Double enhanced energy storage density via polarization gradient design in ferroelectric poly(vinylidene fluoride)-based nanocomposites

Encapsulating ferroelectric ceramic nanofillers into polymer matrix with various architectures has been demonstrated as an effective strategy for ultrahigh energy storage density. Nevertheless, large discrepancy in permittivities between ceramic fillers and polymer requires sophisticated interfacial modification to alleviate local charge concentration. The idea to design graded permittivity from the filler center to surrounding matrix in composites is promising, yet remains a big challenge. Here coaxial electrospinning technique has been employed to control the polarization gradient distribution in TiO2 nanofibers (TOnf) and poly(vinylidene fluoride)/poly(vinylidene fluoride-co-trifluoroethylene) [PVDF/P(VDF-TrFE)] core-shell structured hybrid nanocomposites system where TOnf is fixed at volume fraction 2%, and the polarization gradient of the polymer is adjusted via altering the volume ratios of PVDF and P(VDF-TrFE) in the coaxial electrospun polymer blends in two layers, respectively. Compared with nanocomposites made from mixed solution electrospun randomly and oriented TOnf-PVDF/P(VDF-TrFE) at the same constituent volume fraction, the dielectric losses of coaxial-spun films decrease more than twice, from 0.087 for random nanocomposite film to 0.028, and more intriguingly, the discharged energy storage density (Ue) doubled increasing from 6.5 J cm−3 for random nanocomposite film to 12.7 J cm−3 for coaxial electrospun film with medium polarization gradient. Finite element analyses reveal the polarization and local electric field distribution in the nanocomposites with various polarization gradient design, and the results unambiguously demonstrate that Ue can be significantly boosted via controlled polarization gradient design.

Optimizing the grain size and grain boundary morphology of (K,Na)NbO3-based ceramics: Paving the way for ultrahigh energy storage capacitors

Relaxor dielectric ceramic capacitors are very attractive for high-power energy storage. However, the low breakdown strength severely restricts improvements to the energy storage density and practical application. Here, a strategy of designing small grain sizes and abundant amorphous grain boundaries is proposed to improve the energy storage properties under the guidance of phase field theory. 0.925(K0.5Na0.5)NbO3–0.075Bi(Zn2/3(Ta0.5Nb0.5)1/3)O3 (KNN–BZTN) relaxor ferroelectric ceramic is taken as an example to verify our strategy. The grain sizes and grain boundaries of the KNN–BZTN ceramics are carefully controlled by the high-energy ball milling method and two–step sintering strategy. Impedance analysis and diffusion reflectance spectra demonstrate that KNN–BZTN ceramics with a small grain size and abundant amorphous grain boundary exhibit a lower charge carrier concentration and higher band gap. As a consequence, the breakdown electric field of KNN–BZTN ceramics increases from 222 kV/cm to 317 kV/cm when the grain size is decreased from 410 nm to 200 nm, accompanied by a slightly degraded maximum polarization. KNN–BZTN ceramics with an average grain size of ∼250 nm and abundant amorphous grain boundaries exhibit optimum energy storage properties with a high recoverable energy density of 4.02 J/cm3 and a high energy efficiency of 87.4%. This successful local structural design opens up a new paradigm to improve the energy storage performance of other dielectric ceramic capacitors for electrical energy storage.

High energy storage density with high power density in Bi0.2Sr0.7TiO3/BiFeO3multilayer thin films

A novel Bi0.2Sr0.7TiO3/BiFeO3thin film prepared by sol–gel/spin coating possesses ultrahigh energy storage density, good thermal stability and excellent charge-discharge performance.

Composition and strain engineered AgNbO3-based multilayer capacitors for ultra-high energy storage capacity

With strain engineer and MnO2 addition, an ultra-high energy-storage density Wrec = 7.9 J cm−3 and efficiency η = 71% were achieved in Ag(Nb0.85Ta0.15)O3 + 0.25 wt% MnO2 multilayer capacitors.

Ultrahigh energy storage performance of a polymer-based nanocomposite via interface engineering

Multiscale internal/external interfaces are constructed to break the paradox of a high dielectric constant with decreased breakdown strength for superior energy storage capability. An ultrahigh discharged energy density of ∼25.26 J cm−3 is achieved.

High energy storage density and power density achieved simultaneously in NaNbO3-based lead-free ceramics via antiferroelectricity enhancement

High-performance lead-free dielectric ceramics with simultaneously high energy storage density and power density are in high demanded for pulse power systems. To realize excellent energy-storage characteristics, a strategy to enhance antiferroelectricity and construct a local random field simultaneously was proposed in this study. Based on the above strategy, a series of (1-x)NaNbO3-xBi(Ni1/2Sn1/2)O3 [xBNS, x = 0.05, 0.10, 0.15, 0.20, and 0.22] solid solutions were designed and fabricated. An ultrahigh energy storage density (Utotal) of 7.35 J/cm3, and recoverable energy density (Urec) of 5.00 J/cm3 were achieved in the 0.10BNS ceramics. In addition, an adequate stability of energy storage properties at a range of temperatures (20–140 °C), frequencies (1–100 Hz), and fatigue test durations (1–104 cycles) were realized in 0.10BNS ceramics. 0.10BNS ceramics displayed a high current density of 1005 A/cm2, an ultrahigh power density of 100.5 MW/cm3, and an ultrashort discharge time of 46.5 ns? This remarkable performance not only justified our strategy but also confirmed 0.10BNS ceramics as a promising candidate for energy storage.

Ultrahigh energy storage performance in gradient textured composites of plate-like Na0.5Bi4.5Ti4O15/PVDF through interface engineering

The gradient textured plate-like Na0.5Bi4.5Ti4O15 (P-NBT4)/PVDF composites have been realized through tape casting process of layer by layer, which loadings are gradually decreased from bottom layer to top layer. The micro-capacitance formed by P-NBT4 particles and interfacial polarization between layers enables the composites to obtain a high permittivity. In addition, the different electric field of gradient composites will weaken the growth of electric tree between layers, as well as the P-NBT4 ceramic particles in composite films can extend the breakdown path, so that the composites will undergo premature breakdown. By comparing, the large energy storage density (16.41 J/cm3) at the relative low electric field of 350 kV/mm is obtained in the gradient textured composites.

Ultra-High Capacitive Energy Storage Device Designed By Wooden Biomass Derived Lignin Based Hierarchically Porous Carbon

On the field of carbon-based material, researches about biomass conversion have steadily investigated owing to their specific characteristics such as abundance, ease of handling and environmental-friendly. Here is an outline for a kind of biomass, lignin which in a main composition of lignocellulosic structure of lignum and also the second abundant aromatic biopolymer in nature. In this research, lignin was used as a carbon precursor to manufacture hierarchically porous carbonaceous material for energy storage. Hydrothermal carbonization and chemical activation were operated to convert the biomass precursor to object porous carbon which possessed high specific surface area over 2800 m2 g-1. The hierarchical pore structure of as-obtained material could support increasing electron percolation properties in the electrochemical performance test. Due to their high specific surface area and hierarchical porous architecture, the as-obtained porous carbon showed excellent ion and electron transport properties, which can be a benefit for high performance in supercapacitor application.

Ultrahigh energy storage density at low operating field strength achieved in multicomponent polymer dielectrics with hierarchical structure

Dielectric composites with excellent capacitive energy storage capabilities have great potential applications in energy storage capacitors operating efficiently at relatively low field strengths. Herein, unlike the traditional methods via the introduction of fillers including randomly distributed ceramic nanofibers and aligned nanowires arrays into the monolayer films are simply to increase the energy storage density (Ue), both Ue and charge–discharge efficiency (η) at low electric field strengths have been improved in tri-layered all-polymer films owing to the synergistic effect of multiple interbedded interfaces and deliberately modulation of linear dielectric poly(methyl methacrylate) (PMMA) contents. The effects of film structure on the energy storage capabilities have been comparatively discussed. Consequently, an ultrahigh Ue of 15 J cm−3 accompanied with great η of 76.5% has been delivered in the resulting tri-layered film via optimizing the PMMA content (30 wt%) of out layers at 350 MV m−1, surpassing the energy storage upper limits of the reported polymer dielectrics that show the Ue of ~12 J cm−3 and η of ~70% at comparable electric fields of 310–380 MV m−1. Along with high pulsed power density, multicomponent polymer dielectrics with hierarchically structure provide an effective paradigm for achieving the low operating field strength applications of capacitive energy storage devices with excellent energy storage capability.