Electric Energy Storage Properties Research Articles

Enhanced Energy Storage Performance and Efficiency in Bi0.5(Na0.8K0.2)0.5TiO3-Bi0.2Sr0.7TiO3 Relaxor Ferroelectric Ceramics via Domain Engineering.

Dielectric materials are highly desired for pulsed power capacitors due to their ultra-fast charge-discharge rate and excellent fatigue behavior. Nevertheless, the low energy storage density caused by the low breakdown strength has been the main challenge for practical applications. Herein, we report the electric energy storage properties of (1 - x) Bi0.5(Na0.8K0.2)0.5TiO3-xBi0.2Sr0.7TiO3 (BNKT-BST; x = 0.15-0.50) relaxor ferroelectric ceramics that are enhanced via a domain engineering method. A rhombohedral-tetragonal phase, the formation of highly dynamic PNRs, and a dense microstructure are confirmed from XRD, Raman vibrational spectra, and microscopic investigations. The relative dielectric permittivity (2664 at 1 kHz) and loss factor (0.058) were gradually improved with BST (x = 0.45). The incorporation of BST into BNKT can disturb the long-range ferroelectric order, lowering the dielectric maximum temperature Tm and inducing the formation of highly dynamic polar nano-regions. In addition, the Tm shifts toward a high temperature with frequency and a diffuse phase transition, indicating relaxor ferroelectric characteristics of BNKT-BST ceramics, which is confirmed by the modified Curie-Weiss law. The rhombohedral-tetragonal phase, fine grain size, and lowered Tm with relaxor properties synergistically contribute to a high Pmax and low Pr, improving the breakdown strength with BST and resulting in a high recoverable energy density Wrec of 0.81 J/cm3 and a high energy efficiency η of 86.95% at 90 kV/cm for x = 0.45.

The enhanced electrical energy storage properties of (Bi0.5Na0.5)TiO3–BaTiO3/graphene oxide heterogeneous structures

The enhanced electrical energy storage properties of (Bi0.5Na0.5)TiO3–BaTiO3/graphene oxide heterogeneous structures

Synergistic effect enhances energy storage properties of BNT-based relaxor ferroelectric thin films

Lead-free thin film capacitors with high energy density and efficiency are promising candidates for pulse power systems in advanced electronic industries due to their low cost, lightweight, and integration development. In this study, 0.6Bi0.5Na0.5TiO3-0.4Sr0.7Bi0.2TiO3+x mol Mn (BNT-SBT-xMn) thin films are fabricated on Pt/Ti/SiO2/Si substrates via sol-gel method. The BNT-SBT-xMn films with perovskite phase possess uniform grain size, well density, and low roughness. The introduction of Mn ions compensates for valence unbalances of A-site vacancy of BNT-based films and forms defective dipoles. Their synergism hinders the transmission of carriers, reduces the leakage current density, and improves polarization and breakdown behavior. Therefore, the BNT-SBT-2% Mn film achieves a high recoverable energy density of 85.35 J/cm3 together with an enhanced energy efficiency of 73.17% under an electric field of 3114 kV/cm. Meanwhile, the BNT-SBT-2% Mn film displays a good frequency (10 Hz-2k Hz), temperature (20–200 °C), and fatigue (1-105 cycles) stability in electrical energy storage properties, suggesting that it would be a promising candidate for the advanced power systems.

Electrical energy storage properties of AgNbO3-based antiferroelectric ceramics prepared without an oxygen atmosphere by using hydrothermally synthesized powders

AgNbO3 based ceramics are commonly sintered with an O2 atmosphere. In this work, after synthesizing AgNbO3, Na-doped AgNbO3, and Ta-doped AgNbO3 powders by a hydrothermal method, the ceramics were sintered in the air atmosphere by using the synthesized powders. The novel process with the absence of an O2 atmosphere is practical and facile. The structural, dielectric, antiferroelectric, and electrical energy storage properties of fabricated ceramics were studied. Na doping has a weak influence on the structure but can significantly improve the electrical breakdown field. Ta doping induces a pure antiferroelectric phase and the electrical energy storage efficiency is improved greatly.

Study on energy and information storage properities of 2D-MXene/polyimide composites

The memristor is a basic unit of advanced information storage devices. As a passive device, it needs additional bias voltage to drive, which brings great challenges to the development of highly integrated of memristors. Therefore, it is urgent to develop highly reliable functional materials with both resistance memory and electric energy storage properties. Herein, with the introduction of Ti3C2TX nanosheets (TCTNs) into a polyimide matrix, we take the lead in realizing synchronous resistance memory characteristics and energy storage performance in one material system. With the addition of only 0.5 wt% TCTNs, the charge-discharge energy storage density of the polyimide (PI)-based composite increased by approximately 30%, and showed the memristor characteristics. More encouragingly, the composites also exhibited a massive increase in mechanical flexibility and electrical reliability. The slightly ordered arrangement of TCTNs in the PI matrix was confirmed by synchrotron radiation SAXS and HR-TEM. Finite element analysis was used to simulate the redistribution of the stress field and electric field of these composites in the presence of different distribution states of TCTNs. The chemical valence state and the atomic structure of TCTNs in the PI matrix were investigated by synchrotron radiation XAFS technology. DFT calculation models were established to calculate the evolution of the energy band structure of TCTNs during the synthesis process of the composites, determining the synergistic enhancement mechanism of energy storage and information storage properties in TCTNs/PI composites. This study is expected to provide a material candidate of highly integrated and reliable self-powered information storage devices.

Dielectric and electrical energy storage properties of BiFeO3–BaTiO3–SrTiO3 ternary bulk ceramics

Dielectric and electrical energy storage properties of BiFeO3–BaTiO3–SrTiO3 ternary bulk ceramics

Relaxor Ferroelectric Polymers: Insight into High Electrical Energy Storage Properties from a Molecular Perspective

Relaxor ferroelectric polymers exhibit both high dielectric constants and low remnant polarization and thus deliver much higher energy densities and greater charge–discharge efficiencies than normal ferroelectrics for capacitive energy storage applications. Herein, dielectric energy storage behavior of several newly discovered relaxor ferroelectric polymers is studied from a molecular perspective. It is observed that the homopolymers exhibit very slim polarization–electric field loops and the highest charge–discharge efficiencies among ferroelectric polymers, which are attributed to the highly disordered chain conformation as evidenced from the scanning probe microscopy results. Based on the findings on the relaxor homopolymers, the benchmark relaxor ferroelectric terpolymers is revisited and insights into their outstanding capacitive performance are provided. Moreover, it is found that the disordered chain conformation in relaxor ferroelectric polymers remains as the ground state at varied temperatures and applied electric fields, which is in stark contrast to relaxor perovskites whose ground state is strongly dependent on temperatures and external electric fields. The discovery of the absence of thermal‐ and field‐induced phase transition in relaxor ferroelectric polymers makes this class of ferroelectric materials more attractive for advanced electronic and energy applications.

A novel highly dispersed tetra-metal nano heterogeneous ozone catalyst derived from microbial adsorption and in situ pyrolysis

In recent years, the pyrolysis of microbial biomasses that adsorb various metal ions has enabled the preparation of carbon-based polymetallic nanomaterials with excellent electrocatalytic and electrical energy storage properties. However, the preparation of ozone catalysts by this technique and the corresponding catalytic oxidation mechanism are still unclear. In this study, an Escherichia coli strain (BL21) was used for tetra-metal (Cu, Fe, Mn and Al) absorption and the obtained microbial biomass was pyrolyzed under the protection of a nitrogen flow at 700 °C and activated at 900 °C to prepare a microbial-char-based tetra-metal ozone catalyst (MCOC). This was used to degrade phenol and coking wastewater and exhibited a strong catalytic capability for coking wastewater, whose chemical oxygen demand removal efficiency of 70.86% is 16.7% higher than that of pure ozone and 14.67%, 7.21% and 3.58% higher than that of three commercial catalysts, respectively. It also improved the efficiency of ozonation for phenol by 33%. The MCOC was characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy–energy-dispersive spectroscopy, transmission electron microscopy and other methods. The results demonstrated that the spherical metal nanoparticles had sizes ranging from 3 nm to 7 nm and that crystals of Fe2O3 and Fe3P were observed. The study showed that the MCOC promoted the production of more hydroxyl radicals and superoxides from ozone, which attack organics. The oxygen vacancies of the catalyst were also investigated. It was proved that the Lewis acid sites on the surface of metal oxides are the active centers of ozone decomposition. Therefore, this work provides a new method for the synthesis of multi-metal nanocomposites and expands the application of biosynthetic nanomaterials.

Improved electric energy storage properties of BT-SBT lead-free ceramics incorporating with A-site substitution with Na & Bi ions and liquid sintering generated by Na0.5Bi0.5TiO3

Due to the merits of high safety and easy preparation, dielectric ceramics have become key engineering materials for capacitors. Within this article, different contents of Na0.5Bi0.5TiO3 were introduced into Ba0.65Sr0.245Bi0.07TiO3 relaxor ferroelectric ceramics in order to increase the disorder degree of A-site ions in perovskite structure and modify the relaxation, which could generate liquid sintering promoting densification, then finally enhancing the dielectric energy store performance of ceramics. The research results show that all the bulk samples prepared through traditional processing route are exhibiting pseudocubic perovskite structure, and their surfaces are with Na0.5Bi0.5TiO3 (NBT)-rich phase formed during densification due to a relatively low sintering temperature of NBT. The relaxation coefficient of BT-SBT-0.01NBT ceramic is 1.8. Because of the existence of liquid phase formation during sintering, the dielectric breakdown strength (BDS) of BT-SBT-0.01NBT ceramic is increased to 230 kV/cm, and the recoverable energy density (Wrec) reached 2.22 J/cm3. The introduction of NBT can hence enhance the relaxation and BDS, finally elevate the energy storage performances.

Investigation of electrical and electric energy storage properties of La -doped Na0.3 Sr0.4Bi0.3TiO3 based Pb-free ceramics

Na0.3Sr0.4Bi0.3TiO3 with various concentrations in La modified ceramic specimens were fabricated using a traditional die-press process. All the obtained NBT-ST-xLa ceramics exhibited a typical perovskite structure with a single phase, and the grain sizes were found to be uniform and fine. The electric breakdown strength of the sample after La doping increased significantly. In particular, the ceramic electric breakdown strength of x = 0.02 component reached 190 kV/cm, the stored energy density reached 1.67 J/cm3, and the efficiency was stable and greater than 80%. In addition, the ceramic with x = 0.02 La also exhibited an excellent temperature, frequency stability, and good fatigue resistance. More specific and detailed analysis were conducted in this study.

High Energy Storage Properties and Electrical Field Stability of Energy Efficiency of (Pb0.89La0.11)(Zr0.70Ti0.30)0.9725O3 Relaxor Ferroelectric Ceramics

In this study, electric energy storage properties of (Pb0.89La0.11)(Zr0.70Ti0.30)0.9725O3 (PLZT 11/70/30) relaxor ceramics were investigated. XRD pattern and SEM image confirms the perovskite phase and dense structure without any secondary phases and pores, respectively. Room temperature dielectric constant was found to be high (~ 3520) with low dielectric loss (~ 0.03). Dielectric constant changes with temperature confirm the relaxor ferroelectric behaviour of PLZT ceramics. Different parameters such as degree of deviation (ΔTm) from the Curie–Weiss law, the diffuseness of the phase transition (ΔTdiff) and degree of diffuseness (γ), which are related to the relaxor nature of ferroelectrics were calculated. With the remarkably slim polarization versus electric field hysteresis loops even at high applied electric field, high energy storage of 0.85 J/cm3 and very high energy storage efficiency of 92.9% were obtained from the PLZT ceramics. These values suggest that the PLZT 11/70/30 composition can be used for the pulse driving energy storage applications.

Giant electrocaloric and energy storage performance of [(K0.5Na0.5)NbO3](1\u2212x)-[LiSbO3]x nanocrystalline ceramics

Electrocaloric (EC) refrigeration, an EC effect based technology has been accepted as an auspicious way in the development of next generation refrigeration due to high efficiency and compact size. Here, we report the results of our experimental investigations on electrocaloric response and electrical energy storage properties in lead-free nanocrystalline (1 − x)K0.5Na0.5NbO3-xLiSbO3 (KNN-xLS) ceramics in the range of 0.015 ≤ x ≤ 0.06 by the indirect EC measurements. Doping of LiSbO3 has lowered both the transitions (TC and TO–T) of KNN to the room temperature side effectively. A maximal value of EC temperature change, ΔT = 3.33 K was obtained for the composition with x = 0.03 at 345 K under an external electric field of 40 kV/cm. The higher value of EC responsivity, ζ = 8.32 × 10−7 K.m/V is found with COP of 8.14 and recoverable energy storage of 0.128 J/cm3 with 46% efficiency for the composition of x = 0.03. Our investigations show that this material is a very promising candidate for electrocaloric refrigeration and energy storage near room temperature.

Enhanced electrical energy storage properties in La-doped (Bi0.5Na0.5)0.93Ba0.07TiO3 lead-free ceramics by addition of La2O3 and La(NO3)3

Lead-free [(Bi0.5Na0.5)0.93Ba0.07]1−x La x TiO3 (BNBLT) ceramics for energy storage application were prepared by traditional solid-state reaction technique, and the La3+ ions doping content was varied at 0 ≤ x ≤ 0.04. The BNBLT ceramics showed single-phase perovskite structure without impurity phase. Compact and uniform microstructure with fine grain size was obtained. The remanent polarization and coercive field decreased with the increase in La3+ ions doping content, and the energy storage density increased drastically. The maximum energy storage density of the BNBLT ceramics at x = 0.04 was 1.09 J/cm3 by using La2O3 powders and can be further increased to 1.21 J/cm3 using La(NO3)3 powders, and meanwhile, the breakdown field strength increased obviously. Anti-ferroelectric-like behavior with a double pinched P–E hysteresis loop was observed in La3+-doped BNBLT ceramics at room temperature, which is promising candidate for energy storage dielectric ceramic.

Energy storage density and tunable dielectric properties of BaTi0.85Sn0.15O3/MgO composite ceramics prepared by SPS

(100-x) wt.% BaTi0.85Sn0.15O3–x wt.% MgO (BTS/MgO) composite ceramics were prepared by spark plasma sintering (SPS) technology. Phase constitution, microstructure, dielectric and electrical energy storage properties of BTS/MgO composite ceramics were investigated. The samples prepared by SPS had smaller grain size and presented layer-plate substructure. Dielectric permittivity and dielectric loss of BTS/MgO composite ceramics decreased significantly with the content of MgO increasing, and dielectric tunability maintained a relatively high value (>45%). Meanwhile, the dielectric breakdown strength was improved when addition of MgO in BTS matrix, which resulted in a significant improvement of energy storage density. The high dielectric breakdown strength of 190kV/cm, energy storage density of 0.5107J/cm3 and energy storage efficiency of 92.11% were obtained in 90wt.% BaTi0.85Sn0.15O3–10wt.% MgO composite ceramics. Therefore, BTS/MgO composites with good tunable dielectric properties and electrical energy storage properties could be exploited for energy storage and phase shifter device applications.

Bifacial carbon nanofoam-fibrous PEDOT composite supercapacitor in the 3-electrode configuration for electrical energy storage

Electrical energy storage properties of supercapacitors based on carbon nanofoam-fibrous PEDOT composite and microporous PEDOT film/graphite electrodes formed by the pulsed current electropolymerization technique are investigated. The 3-dimensional nano-architecture of the composite carbon nanofoam -fibrous PEDOT electrode exhibits high pore connectivity and electrolyte ion diffusivity. By utilizing its bifacial ion transportation ability and reduced ion diffusion impedance, a supercapacitor device in the 3-electrode configuration has been tested which shows high specific capacitance of 210.8Fg−1 as compared to 142.5Fg−1 observed for the supercapacitor in the conventional 2-electrode design. The voltage scan rate dependence shows high efficacy of the bifacial carbon nanofoam electrode in faster ion transport in the 3-electrode supercapacitor configuration. The 3-electrode supercapacitor cell shows energy density of 8.53Whkg−1 which is nearly 1.7 times higher than the energy density of the 2-electrode supercapacitor cell. The power density of ∼19.7kWkg−1 for the 3-electrode supercapacitor cell is also superior as the 2-electrode supercapacitor exhibit a typical value of 11.8kWkg−1.

Enhanced energy storage density of Ba0.4Sr0.6TiO3–MgO composite prepared by spark plasma sintering

(100−x) wt%Ba0.4Sr0.6TiO3–xwt%MgO composite (x=3, 5, 10) were prepared by spark plasma sintering (SPS) and their phase constitutions, microstructure and electrical energy storage properties were investigated. It was found that the reaction between Ba0.4Sr0.6TiO3 and MgO was suppressed due to low sintering temperature and short sintering period. The Curie temperature of BST/MgO composite is independent of the MgO content, which confirms the absence of chemical interdiffusion between BST and MgO. Diffuse phase transition was observed due to the reduced grain size and lack of sufficient chemical diffusion during SPS process. The dielectric breakdown strength of Ba0.4Sr0.6TiO3/MgO composite was greatly improved, which results in a significant improvement of maximum energy storage density. The high dielectric breakdown strength of 300kV/cm, highest maximum energy storage density of 1.50J/cm3 and high energy storage efficiency of 88.5% were obtained in 95wt%Ba0.4Sr0.6TiO3–5wt%MgO composite.

Electrical energy discharging performance of poly(vinylidene fluoride‐co‐trifluoroethylene) by tuning its ferroelectric relaxation with polymethyl methacrylate

ABSTRACTPoly(methyl methacrylate) (PMMA) was introduced into ferroelectric Poly(vinylidene fluoride‐co‐trifluoroethylene) P(VDF‐co‐TrFE) via a simple solution blending process and a series of P(VDF‐co‐TrFE)/PMMA blends with varied PMMA content was obtained in an effort to investigate the confinement effect of PMMA on the crystalline, dielectric, and electric energy storage properties of P(VDF‐co‐TrFE). PMMA addition could reduce the crystallinity dramatically as well as the crystal size due to its dilution effect and impediment effect on the crystallization of P(VDF‐co‐TrFE). PMMA introduction is also responsible for the phase transition of P(VDF‐co‐TrFE) from α phase into γ phase. As expected, both the dielectric constant and loss of the blends are reduced as PMMA addition increases for the dilute, decoupling, and confinement effect of PMMA on the relaxation behavior of crystal phases of P(VDF‐co‐TrFE) under external electric field. As a result, both the maximum and remnant polarization of the blends are significantly depressed. The irreversible polarization of P(VDF‐co‐TrFE) is effectively restricted by the addition of PMMA due to its impeding effect on the crystallization of P(VDF‐co‐TrFE) and restricting effect on the switch of the polar crystal domains. Therefore, the energy loss induced by the ferroelectric relaxation of P(VDF‐co‐TrFE) is significantly reduced to less than 25% at an electric field of 450 MV/m while the energy storage density is well maintained at about 10 J/cm−3 in the blend with 30 wt % PMMA. The results may help to understand how the ferroelectric relaxation affects the energy loss of ferroelectrics fundamentally and design more desirable materials for high energy storage capacitors. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40114.

Electric energy storage properties of poly(vinylidene fluoride)

High discharged energy density observed in poly(vinylidene fluoride) (PVDF) based copolymers has attracted considerable research interests in the past years. Crystalline properties exhibit great influence on their dielectric and energy storage properties. To understand how crystalline properties influence the energy storage properties of PVDF, PVDF films with three different crystal forms are investigated in this paper. It is shown that γ-PVDF is allowed to work under higher electric fields than α- and β-PVDF in the absence of phase transition in α-PVDF and early polarization saturation in β-PVDF. Consequently, γ-PVDF exhibits the highest energy density of 14 J/cm3 under 500 MV/m electric field.