Environmentally Friendly Bismuth-based Relaxor and Antiferroelectric Ceramics for Energy Storage Applications

In step with the development of energy storage technology and the power electronic industry, dielectric capacitors with high energy density are in high demand. Many modern applications require the dielectric capacitors work under high temperature environment (\u3e 150 °C), which poses challenges for commonly used polymer capacitors. On the other hand, the ceramic capacitors benefited from their inorganic nature, are potential for high-temperature applications. Although lead-based ceramics possess many advantages such as high permittivity, the usage of lead is restricted by some regulations due to its negative effects on the environment and human health. Bismuth ions Bi3+ have a similar 6s2 electronic configuration as Pb2+, and are expected to induce high permittivity and high polarization in bismuth-based ceramics. Among the various dielectrics, relaxors and antiferroelectrics (AFEs) are the most promising candidates for dielectric capacitors with high energy density. The relaxors, which feature high permittivity and slim polarization-electric field (P-E) loop, are expected to deliver a high energy density and a high energy efficiency simultaneously at a relatively low electric field. The AFEs, on the other hand, possess unique double hysteresis loop and can deliver higher energy density than other dielectrics when the polarization and the applied electric field are identical. Therefore, this research focuses on developing bismuth-based relaxors and AFEs with high energy storage properties..

Tunable biodegradability of MnO2 nanoscaffold through an unconventional redox-mechanism.

<b>a,</b> Controlled biodegradation of 2D MnO₂ nanosheets by vitamin C in a dosage-dependent manner in physiological conditions. <b>b,</b> In the structure of thick layered (6 mm) nanoscaffold sandwiched by two cell layers, nanoscaffold has a half-degradation time around 2 weeks. This is achieved under regular cell culture conditions without the addition of any exogenous biochemical or vitamin <b>c,</b> When the thickness of nanoscaffold was significantly reduced to a thin film (<1 mm), the half-degradation time was reduced to less than one week. <b>d,</b> The successful degradation of nanoscaffold thin film was confirmed with SEM and EDX based elemental analysis. <b>e,</b> Micropatterned nanoscaffold assembled from MnO₂ nanosheets using μ-contact printing. Based on the hydrophilic surfaces, nanoscaffold micropatterns with different shapes (line pattern, grid pattern and square pattern) were fabricated using micro-contact printing. These micropatterns were used to visualize the thin nanosheets film as a substrate, and for monitoring the degradation of the scaffold under an optical microscope. In addition, they can also be used as a substrate for controlling cellular geometries for controlled cell adhesion. Scale bars: <b>d,</b> 200 μm; <b>e,</b> 100 μm. Error bars are the standard error of the mean (n=3)

Enhanced neuronal differentiation of rNSCs cultured on MnO2 hybrid nanoscaffold.

<p><b>a,</b> Schematic diagram explaining the enhanced neural differentiation on nanoscaffold for another neural stem cell line from a different source (rats) than human iPSC-NSCs. <b>b,</b> mRNA analysis of neuronal marker (TuJ1) and astrocyte marker (GFAP) of rNSCs cultured on nanoscaffold. Similar to iPSC-NSCs cultured on nanoscaffold, Tuj mRNAs were significantly upregulated by 2.5-fold. Astrocyte markers, on the other hand, was also upregulated by 1.7-fold for rNSCs cultured on nanoscaffold. <b>c-f,</b> Immunostaining of neuronal markers (Tuj, green) and nuclei (DAPI, blue) of rNSCs cultured on glass (<b>c,e</b>) and nanoscaffold (<b>d, f</b>). Consistent with iPSC-NSCs differentiated on nanoscaffold, a higher population of rNSCs was differentiated into neurons compared to glass substrate. All the substrates were coated with laminin with identical concentrations. The differentiation time is 6 days for all the studies.</p

Effects of laminin densities and integrin binding ligand densities on iPSC-NSC adhesion and differentiation.

<b>a,</b> Representative FESEM images of substrates with varying density of pitch and density of gold nanopatterns. These patterns were fabricated using LIL, and by modulating the density of gold nanoarray, we were able to modulate the density of integrin binding molecule (cysteine-RGD, Genescript) and to mimic the varying laminin densities on a glass substrate and nanoscaffold. <b>b,</b> Representative phase images of iPSC-NSCs cultured on nanoarrays with varying RGD densities (50% to 72%, from left to right). <b>c,</b> Increased intensities of integrin binding was found to increase numbers of cell adhered on the substrate as well as percentages of cells expressing neuronal markers (TuJ1, green). Cell nuclei were stained with blue (DAPI) in immunostaining images. Scale bars: <b>a,</b> 2 μm; <b>b-c,</b> 100 μm

Ultrahigh Energy Storage Properties in (Sr0.7Bi0.2)TiO3-Bi(Mg0.5Zr0.5)O3 Lead-Free Ceramics and Potential for High-Temperature Capacitors

2020 by the authors. Due to the enhanced demand for numerous electrical energy storage applications, including applications at elevated temperatures, dielectric capacitors with optimized energy storage properties have attracted extensive attention. In this study, a series of lead-free strontium bismuth titanate based relaxor ferroelectric ceramics have been successfully synthesized by high temperature solid-state reaction. The ultrahigh recoverable energy storage density of 4.2 J/cm3 under 380 kV/cm, with the high efficiency of 88%, was obtained in the sample with x = 0.06. Of particular importance is that this ceramic composition exhibits excellent energy storage performance over a wide work temperature up to 150 °C, with strong fatigue endurance and fast discharge speed. All these merits demonstrate the studied ceramic system is a potential candidate for high-temperature capacitors as energy storage devices

Enhanced energy density and electric cycling reliability via MnO2modification in sodium niobate-based relaxor dielectric capacitors

© 2020 World Scientific Publishing Co. Pte Ltd. All rights reserved. Sodium niobate (NaNbO3)-based dielectrics have received much attention for energy storage applications due to their low-cost, lightweight, and nontoxic nature. The field-induced metastable ferroelectric phase in NaNbO3-based dielectrics, however, leads to a large hysteresis of the polarization-electric field (P-E) loops and hence deteriorate the energy storage performance. In this study, the hysteresis was successfully reduced by introducing Bi3+and Ti4+into A-site and B-site of NaNbO3, respectively. MnO2addition was added to further increase the ceramic density and enhance the cycling reliability. As a result, a high recoverable energy density of 4.3 J/cm3and a high energy efficiency of 90% were simultaneously achieved in the ceramic capacitor at an applied electric field of 360 kV/cm. Of particular importance is that the ceramic capacitor exhibits a stable energy storage properties over a wide temperature range of -70 to 170 °C, with much improved electric cycling reliability up to 105cycles

Enhanced Energy Storage Performance of Sodium Niobate-Based Relaxor Dielectrics by a Ramp-to-Spike Sintering Profile

Sodium niobate (NaNbO3)-based lead-free ceramics have been actively studied for energy storage applications because of their antiferroelectric and/or relaxor features achieved in modified systems. The P-E loops of NaNbO3-based ceramics are usually hysteretic because of the existence of a metastable ferroelectric phase at room temperature. In this study, by introducing aliovalent cations and A-site vacancies, the relaxor characteristics are greatly enhanced in (Na1-2xBix)(Nb1-xZrx)O3 ceramics, leading to a high energy storage efficiency of above 90%. In addition, sintering aid CuO and a special ramp-to-spike sintering profile were employed to decrease the sintering temperature and reduce the grain size. The modified ceramic exhibits improved insulating properties and hence a higher breakdown strength, leading to a high recoverable energy density of 4.9 J/cm3 and a high energy efficiency of 88% at 430 kV/cm. The ceramic also exhibits satisfactory temperature stability over a wide temperature range from 25 to 125 °C and charge-discharge performance, making it a promising candidate for high-power dielectric energy storage applications

Bi-modified SrTiO3-based ceramics for high-temperature energy storage applications

2019 The American Ceramic Society Dielectric capacitors with high energy storage performance are in great demand for emerging advanced energy storage applications. Relaxor ferroelectrics are one type dielectric materials possessing high energy storage density and energy efficiency simultaneously. In this study, 0.9(Sr0.7Bi0.2)TiO3-0.1Bi(Mg0.5Me0.5)O3 (Me = Ti, Zr, and Hf) dielectric relaxors are designed and the corresponding energy storage properties are investigated. The excellent recoverable energy density of 3.1 J/cm3 with a high energy efficiency of 93% is achieved at applied electric field of 360 kV/cm for 0.9(Sr0.7Bi0.2)TiO3-0.1Bi(Mg0.5Hf0.5)O3 (0.9SBT-0.1BMH) ceramic. High breakdown strength of 460 kV/cm in 0.9SBT-0.1BMH ceramic is obtained by Weibull distribution with satisfied reliability. In addition, 0.9SBT-0.1BMH shows outstanding thermal stability of energy storage performance up to 200°C, with the variation being less than 5%, together with satisfying cycling stability and high charge-discharge rate, making the 0.9SBT-0.1BMH ceramic a potential lead-free candidate for high power energy storage applications at elevated temperature