Tape Casting Research Articles

(Invited) Grain Texture and Transport in Sintered Lithium Cobaltite

Reversible exchange of lithium from lithium cobaltite (LCO) with the layered rock-salt structure was first reported by Goodenough in 1980 [1]. It has since become a critical component in the cathode of lithium-ion batteries that power portable electronics like cell phones, laptop computers, and cordless power tools. The rate of lithium diffusivity in LCO particles ranges from 10-7 to 10-11 cm²/s depending upon the state of charge and the method of measurement [2]. Lithium diffusivity in LCO because of its layered structure is also dependent upon crystallographic direction. In thin-film, micro-batteries (TFMB’s), the crystallographic orientation of LCO is controlled through choice of conditions for deposition and crystallization [3]. The diffusivity of lithium is significantly greater within rather than across the basal plane [4]. Orientations of (104) and (110) are preferred for rate performance.Continuous, roll-to-roll sintering of LCO ribbon with thicknesses down to 10 µm was recently demonstrated [5]. The LCO ribbon because it is sintered and self-supporting can in principle serve as a mechanical support to reduce the proportions of inactive battery components to dramatically increase energy density. A possible way of creating a solid-state battery with LCO ribbon is to capitalize on the LiPON solid electrolyte from TFMB’s. Both composite and dense cathodes can be envisioned. Energy densities greater than 1500 Wh/L are possible. The practicality and design of a cathode-supported battery depends upon lithium diffusion in the LCO and charge transfer resistance at the interface with the separator. Ideally, transport is sufficiently facile that acceptable rate performance in a battery is realized with cathode thickness of greater than 20 µm.In this work, we report on characterization of lithium diffusivity and ohmic losses in sintered LCO with controlled grain textures. LCO cathodes with thicknesses of 15-30 µm with random and (003) grain textures were prepared by tape casting and rapid sintering. The (hk0) texture was made by taking advantage of the (003) textured green tape; approximately 200 layers were stacked and cold-welded to form a block with a thickness of ~8 mm. The sintered block was diced to expose the edge with the favorable (hk0) orientation. Electron backscatter diffraction maps and pole figures that illustrate the grain structure and texture are shown in Fig. 1. The texture is so strong that material is orthotropic in character.Lithium diffusivity and ohmic cell resistances were determined as a function of state of charge by galvanostatic intermittent titration [7]. An average diffusivity to use as a single figure of merit was also determined by fitting of capacities measured as a function of rate of discharge from a cut-off potential of 4.3 V. Rates of lithium diffusion in sintered LCO cathodes with the (hk0) texture is 0.09 µm²/s and approximately twelve-fold greater than for the (003) texture, 0.0076 µm²/s. Ohmic loss was also found to depend upon grain texture. It was approximately 60-100 Ωcm² for (hk0) texture and >500 Ωcm² for (003). A reasonable explanation for the elevated resistance is that charge transfer occurs more easily with the (hk0) texture.[1] K. Mizushima, P.C. Jones, P.J. Wiseman, and J.B. Goodenough, Mat. Res. Bull., 15 (1980) 783-789, https://doi.org/10.1016/0025-5408(80)90012-4.[2] K. Dokko, M. Mohamedi, Y. Fujita, T. Itoh, M. Nishizawa, M. Umeda, and I. Uchida, J. Electrochem. Soc., 148 (2001) A422-A426, https://doi.org/10.1149/1.1359197.[3] J. Trask, A. Anapolsky, B. Cardozo, E. Januar, K. Kumar, M. Miller, R. Brown, and R. Bhardwaj, J. Power Sources, 350 (2017) 56-64, https://dx.doi.org/10.1016/j.jpowsour.2017.03.017.[4] J. Xie, N. Imanishi, T. Matsumura, A. Hirano, Y. Takeda, and O. Yamamoto, Solid State Ionics, 179 2008) 362-370, https://doi.org/10.1016/j.ssi.2008.02.051.[5] C. Tanner and J. Lorenzo, ECS Meet. Abstr. MA2022-02 (2022) 2482, https://doi.org/10.1149/MA2022-0272482mtgabs.[6]J.B. Bates, N.J. Dudney, G.R. Gruzalski, R.A. Zuhr, A. Choudhury, C.F. Luck, and J.D. Robertson, Solid State Ionics, 53-56 (1992) 647-654, https://doi.org/10.1016/0167-2738(92)90442-R.[7] C.J. Wen, B.A. Boukamp, R.A. Huggins, and W. Weppner, J. Electrochem. Soc., 126 (1979) 2258-2266, https://doi.org/10.1149/1.2128939. Figure 1

Solid Oxide Electrochemical Cells for Nitrogen and Oxygen Production

Nitrogen and oxygen are both very important commodities with a wide variety of applications in industries, such as chemical, food and metallurgical plants as well as in the medical sector. Nowadays most of the nitrogen and oxygen are produced via air separation technologies such as cryogenic distillation (ASU) or pressure swing adsorption (PSA). Both ASU and PSA offer economical and mature ways for nitrogen and oxygen production at large (>100 ton/day) or medium scales (20-100 tons/day). If one can develop a technology for providing these gases in an energy efficient and cost effective way also at small scale, preferably driven by electricity only, this would enable new applications of the gases. Such a technology would match characteristics of the future green electricity system relying on small scale (few MWs) power generation and fluctuating production..In this work we present an efficient electrochemical process for N2 and O2 production based on a solid oxide electrochemical cell technology by oxygen extraction from air. Cells with a 53 × 53 mm2 size were produced by a conventional tape casting method. They consist of a ca.10 μm CGO (Ce0.9Gd0.1O2-δ) electrolyte sandwiched between composite electrodes made from either LSCF (La0.6Sr0.4Co0.2Fe0.8O3-δ) - CGO, or LSF (La0.6Sr0.4FeO3-δ) - CGO. To boost performance at low temperature, the electrodes were infiltrated with Pr-oxide. The electrochemical performance with the different supports were characterized by obtaining current-voltage (iV) characteristics at different temperatures as well as through electrochemical impedance spectroscopy(EIS) with or without infiltration. For characterization, air was used as feed stock to the cathode compartment and air, or oxygen was used as sweep gas to the anode compartment. A voltage below 200 mV is needed to drive a current of 1 A/cm2 through the cell, which can provide a purity of 90% of N2 out at an operation temperature of 650 °C (see Figure 1a). The cells were demonstrated to operate for producing a 98% pure N2 stream without degradation over a 1500 h period (see Figure 1b).Further analysis show that the specific power consumption calculated based on the power input and outlet gas flow rate for 90% N2 production is ca. 0.1 kWh/m3 and the specific power consumption for 96% and 98% N2 production is 0.21 and 0.31 kWh/m3, respectively. A 3-fold increase in required power is observed when going from a N2 purity from 90% to 98%.Detailed electrochemical analysis and the electrochemical performance comparison between LSCF and LSF based mixed ionic electronic conductor (MIEC) electrodes will be presented. Factors limiting cell performance will as well as analysis of optimal point of operation in terms of energy consumption and reliability will also be discussed. Acknowledgment This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 862482. Figure 1

Pressureless sintering of large sized fully ceramic microencapsulated fuel pellets

Large-sized fully ceramic microencapsulated (FCM) nuclear fuel pellets were fabricated by a novel tape casting process in this study. The process involved producing a single layer of FCM fuel green tapes embracing TRISO particles by tape casting with silicon carbide ceramic as the matrix. The resulting tapes were stacked vertically and made into green bodies through cold isostatic pressing. Large-sized FCM fuel pellet with diameters over 86 mm was then successfully prepared by pressure-less sintering with AlN-Y2O3-Sc2O3−MgO as sintering additives. The FCM fuel pellets obtained through this method exhibited a dense structure, flat surface, and no cracks. Thus, the integrated formation of the fuel-free zone and fuel-filled zone could be realized by precisely controlling the fuel-free zone thickness. The TRISO particles were regularly and uniformly distributed in a triangular shape and remained structurally intact. By adjusting the spacing of the TRISO particles in the FCM fuel pellets to a range of 500 to 1500 μm, the volume fraction of fuel particles in the FCM fuels was controlled between 12.8 and 31.7 vol.%.

Energy storage performance of PVDF composites enhanced by two-dimensional Na0.5Bi0.5TiO3 with high polarization

With the increasing consumption of non-renewable energy sources such as fossil fuels, human beings are facing the crisis of energy shortage. Therefore, researchers in most regions and countries in the world are actively committed to designing and developing new dielectric energy storage components with high energy storage density and high energy storage efficiency. In this work, 2-dimensional flaky Na0.5Bi0.5TiO3 (NBT) inorganic powders were prepared by the two-step molten salt method and compounded with polymer polyvinylidene fluoride (PVDF). NBT/PVDF monolayer and 'sandwich' structure composites were prepared by the tape casting method, and the flaky NBT powders were arranged in parallel in the PVDF matrix. The phase and microstructure of the prepared NBT powders were analyzed by X-ray diffractometer and scanning electron microscope. The dielectric, conductivity, ferroelectric, and energy storage properties of the prepared composites were tested. The results show that the critical breakdown field strength of the prepared single-layer NBT/PVDF and 'sandwich' structure composites with a volume fraction of 0.75 vol.% NBT inorganic powder is 380 kV/mm and 540 kV/mm, respectively. The energy storage density reaches 13.78 J/cm3 and 21.57 J/cm3, which is about 1.87 and 3.01 times the volume fraction of 0 vol.%.

Design, Fabrication, and Screening of Environmental‐Thermal Barrier Coatings Prepared by Ultrafast High‐Temperature Sintering

AbstractThe demand for more efficient gas turbines relies heavily on the development of new environmental‐thermal barrier coatings (ETBCs). However, there is still uncertainty about which alloys and composites will be used for the next generation of turbine blades, as well as the most promising coating materials. Herein, an ETBCs development strategy is presented by integrating the coating design, synthesis, and screening using an ultrafast high temperature sintering (UHS) technique to accelerate coating improvements. The initial basis for composition selection is their thermal expansion mismatch with the substrate alloys; for which a temperature‐dependent coefficient of thermal expansion database is created. By combining tape casting method with the UHS technique a high‐throughput synthesis of single and multi‐layer coatings are realized with different compositions, layer stacking sequences, and layer thicknesses. To evaluate the coatings, thermal cycling tests from room temperature to 1300 °C are conducted. The approach enabled coatings on objects with complex geometries, multi‐layer ETBCs, and porosity tailoring by using staged UHS that runs with different temperatures and durations. The fast iteration strategy is more cost‐effective for the screening of ETBCs compared to conventional methods and greater throughput which can be further extended for rapid optimization of other materials systems.

ZrC-SiC closed-cell ceramics with low thermal conductivity: Exploiting unique spherical closed-cell structure through tape casting and CVI techniques

Porous ultra-high temperature ceramics (UHTCs) are recognized as novel candidates for fulfilling the requirements of thermal protection systems of hypersonic aircrafts, as they possess excellent high-temperature resistance and low thermal conductivity. Currently, the reported porous UHTCs predominantly exhibit an open pore structure. By contrast, closed-cell UHTCs, formed by employing ceramic hollow microspheres (HMs) as pore-forming agents, hold great potential for achieving superior thermal insulation performance. Unfortunately, the implementation of this strategy has been hindered by the scarcity of raw materials and preparation techniques.In this paper, ZrC-SiC closed-cell ceramics were first successfully prepared through a combination of tape casting and chemical vapor infiltration (CVI) techniques, utilizing the self-developed ZrC HMs as the primary raw material. The morphology, microstructure, and thermal insulation properties of the obtained ZrC-SiC closed-cell ceramics were investigated. The results indicate that when the content of ZrC HMs is 30 vol.%, the density of the prepared porous ceramics is 2.09 g cm–3, with a closed porosity of 14.05% and a thermal conductivity of 1.69 W (m K)–1. The results clearly prove that the CVI process can successfully convert ZrC HMs into closed pore structures within porous ceramics. The introduction of ZrC HMs suppresses the contribution of free electrons to thermal conductivity and brings about a large number of solid-gas interfaces, which increases the interfacial thermal resistance and significantly reduces the phonon thermal conductivity. Consequently, the as-prepared ZrC-SiC closed-cell ceramics show excellent thermal insulation properties. This study provides a new idea and method for the development of porous UHTCs and offers a more reliable material choice for thermal protection systems.

Preparation and properties of lignin-based polyurethane materials

In this paper, lignin-based polyurethane (LPU) films were successfully prepared by tape casting using modified alkaline lignin instead of partial polycarbonate diol (PCDL) in reaction with isophorone diisocyanate (IPDI), with diethylene glycol (DEG) as chain extender and dibutyltin dilaurate (DBTDL) as catalyst. The factors influencing the hydroxylation modification of alkali lignin were discussed, and the optimal reaction conditions were determined: reaction temperature of 50 °C, reaction time of 60 min, hydrogen peroxide to lignin mass ratio of 1.2:1, and iron hydroxide to alkali lignin mass ratio of 2 %. The lignin-based polyurethane films with different R values were also prepared by changing the ratio of isocyanate groups to hydroxyl groups (R-value), and the effects of different R values on the polyurethane properties were investigated. It was characterized by Fourier transform infrared spectroscopy (FTIR), mechanical property tests, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), moisture and oxygen permeability property tests, and UV spectroscopy tests. The results show that changing the R-value can improve the mechanical properties, thermal stability, barrier properties, and UV shielding properties of polyurethane materials. When the R-value is 1.8, the lignin-based polyurethane film material has the best performance.

Aqueous tape casting phosphate ceramic electrolyte membrane for high performance all solid-state lithium metal battery

Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolyte has caused great attention because of its low cost, high ionic conductivity, and superior air stability. In this work, high quality LATP ceramic electrolyte membranes are fabricated by an aqueous tape casting technique in the air, in contrast to traditional fabrication methods that are usually inefficient and noncontinuous, this technique provides an environment-friendly, scalable, continuous fabrication route for mass production of ceramic electrolyte membranes. The as-prepared LATP ceramic membrane with a relative density of 95.6 % shows a total Li ionic conductivity of 3.8 × 10−4 S cm−1. Simply coated with a flexible polymer electrolyte film on the surface of the LATP ceramic membrane, the solid-solid interfacial polarization between the LATP ceramic membrane and the electrodes can be well controlled under a reasonable level, leading to excellent battery performance. Discharge capacities of 160.6, 157.6, 151.2, 138.9 and 123.9 mAh g−1 at 0.05, 0.1, 0.2, 0.5 and 1 C rates are achieved, respectively. This study demonstrates a promising strategy for commercializing all-solid-state batteries with a cost-effective and scalable manufacturing technique.

Features of forming a low-temperature cubic Li7La3Zr2O12 film by tape casting

Currently, interest to lithium and lithium-ion all-solid-state power sources is rapidly growing all over the world. However, several issues should be addressed before all-solid-state batteries production: high resistance values of the solid electrolyte membrane and poor contact between electrolyte and electrode materials. The transition to thin-film technologies is one of the promising ways to solve these problems. Tape casting can be proposed to obtain thin-film solid electrolytes. In this research, the features of the structure formation, morphology and lithium-ion conductivity of Li7La3Zr2O12 films were investigated. Li7La3Zr2O12 films with the thickness of 35 µm were obtained by tape casting on Ni substrate. The influence of organic components’ content on homogeneous coatings formation was established. Heat treatment conditions for dried films were chosen based on differential scanning calorimetry and optical dilatometry. Phase change from tetragonal to low-temperature cubic modification occurs after annealing the Li7La3Zr2O12 films at 700 °C and higher. The annealed Li7La3Zr2O12 films have developed surface, which can lead to improved contact between the solid electrolyte and an electrode in an electrochemical cell. Li7La3Zr2O12 films annealed at 800 °C have the highest lithium-ion conductivity values (2.5·10–7 and 1.5·10–5 S·cm–1 at 90 and 215 °С, respectively). The technology of Li7La3Zr2O12 films formation with the thickness of ~23 µm by tape casting was developed.

Electrocaloric behaviour of tape cast and grain oriented NBT-KBT ceramics

We have investigated the effects of grain orientation and tape casting process on the electrocaloric properties of 0.82Na0.5Bi0.5TiO3-0.18 K0.5Bi0.5TiO3 (0.82NBT-0.18KBT) ceramics at the Morphotropic Phase Boundary (MPB), using direct and indirect measurements. We observe a larger electrocaloric response for the template-free ceramics compared to 7 and 10 wt% template containing ones, suggesting that grain orientation along rhombohedral < 100 > does not improve the electrocaloric response. Indirect measurements yielded a large adiabatic temperature change of around 3 K under an electric field of 50 kV/cm, which is significantly higher than 0.9 K reached at a lower electric field of 40 kV/cm using the direct measurement.

UV photodetector study based on Ce: ZnO nanostructures with different concentration of Ce dopant

UV photodetectors (PDs) find pivotal roles across diverse domains like space exploration, radiation monitoring, and electronics. Zinc oxide (ZnO), an n-type semiconductor with a wide bandgap, stands out as an attractive material for photodetection due to its remarkable UV responsivity. This study centers on assessing the role of Ce doping in enhancing the UV sensitivity of ZnO-based photodetectors when subjected to laser illumination (excitation wavelength: 374 nm). Synthesized through a hydrothermal approach, Zn1-xCexO nanostructures with varying concentrations (x = 1.5, 3.5, 5.5, and 7.5 wt%) were subsequently deposited onto ZnO nanorods (NRs) via tape casting. A comprehensive array of characterization techniques was employed to analyze the structural, morphological, and optoelectrical properties of Ce:ZnO. Incorporating Ce to ZnO lattice induced a reduction in the density of oxygen vacancies, culminating in an enhancement of optoelectronic performance. This improvement encompassed aspects such as photocurrent and responsivity within a p-n heterojunction Ce: ZnO–Cu2O (CZC) UV-PD setup. The introduction of cerium led to a slight shift in the band gap energies, from 3.18 eV for pristine ZnO to 3.23–3.19 eV for the CZ samples. Impressively, Ce-doped ZnO (5.5 wt%) nanostructures exhibited enhanced performance in UV detection, showcasing a detectivity of approximately ∼42 × 109 (Jones), an expedient rise time of under 0.1 s, and a desirable decay time of 8.7 s for the CZC-3%.

Dehydroxylation of Kaolinite and Halloysite-Rich Samples: An In Situ Study of the Texture and Structural Evolutions

Halloysite and kaolinite are dioctahedral TO phyllosilicates that drive the interest of scientists for formulating environmentally friendly materials, and consequently in the field of ceramics. The main scope of this study was the understanding of the texture evolution upon the dehydroxylation reaction and the influence of the presence of halloysite. In situ synchrotron (002) and (111) poles figures were recorded on the DiffAbs beamline at SOLEIL Synchrotron, from room temperature to 1000 °C, on kaolinite and/or halloysite-rich samples shaped by tape casting. Commercial kaolins and halloysite provided by Imerys company were used. The samples were labeled KRG100, KCS100, H100, KRG50H50 and KRG59H50 in relation with the wt. % of kaolin (KRG, KCS) or halloysite (H) clays. In samples KCS100 and KRG100, a strong texture was observed until in situ annealing at 700 °C, with respect to the c-axis of kaolinite. On the contrary, the texture with respect to the c-axis of halloysite for the sample H100 was weak whatever the temperature was. Moreover, this weak texture disappeared before the complete dehydroxylation of halloysite. This is due to the opening of some halloysite tubes. When considering the samples KRG50H50 and KCS50H50, a significant texture was observed with the c-axis preferentially oriented perpendicular to the sample surface. The presence of kaolinite platelets predominated onto the alignment of halloysites tubes. Furthermore, it was noted that the halloysite influenced the (002) diffracted intensity into the temperature range 20 °C to 400 °C. Above 400 °C, the behavior obtained for the (002) reflection in samples KRG50H50 and KCS50H50 was similar to the behavior noticed for pure kaolins KRG100 and KCS100, respectively. The dehydroxylation temperature range appeared to be relevant with combined effect of kaolinite and halloysite transformations arising from KRG100 or KCS100 and H100 samples. Therefore, the onset point of dehydroxylation is 550 °C ± 25 °C for KRG100, KCS100, KRG50H50 and KCS50H50. For the pure halloysite H100 sample, the dehydroxylation starts at the lower temperature 475 °C. It was also noted that during the dehydroxylation of kaolinite, the characteristic portion of ring related to the diffracted intensity of the (111) reflection located at χ = 45° tended to disappear above 550 °C and led to the formation of a new transitory phase with a (111) reflection with perpendicular alignment to the c-axis. Indeed, an epitaxial relationship with the (111) kaolinite reflection could be assumed. Further X-ray scattering experiments allowed highlighting the effective offset temperature of the dehydroxylation, which was identified as close to 720 °C. The metakaolinite achieved structural transformation to another transitory phase at 1000 °C.

Al2O3 dielectric ceramic tapes containing hBN for applications on high-frequency substrates

In this study, we manufactured dielectric alumina (Al2O3) ceramic tapes incorporated with hexagonal boron nitride (hBN) for applications on high-frequency substrates. The ceramic tapes were produced using the tape casting technique. Structural and morphological analyzes show the presence of hBN nanoplatelets dispersed in the Al2O3 matrix, confirming the efficiency of the tape-casting technique and the sintering process. We verified that the crystalline structure of hBN is essential in the dielectric response, showing a reduction in dielectric losses with the incorporation of hBN into the Al2O3 ceramic matrix, making ceramic tapes attractive in dielectric applications. Furthermore, the mechanical properties of the tapes show satisfactory results, reinforcing our findings. Thus, our results become fascinating for applications in high-frequency substrates for electronic transmission devices.

Free-standing TiNb6O17/rGO composites as a superior anode host for high-performance Li-ion capacitor

Li-ion capacitors are very enticing power sources having high energy and power density as they exemplify the benefits of both Lithium-ion battery (LIB) and supercapacitors (SCs) together. However, the high performance of LIC is limited due to low specific capacity and slow reaction kinetics of electrodes. Herein, pseudo-capacitive titanium niobium oxide (TiNb6O17: TNO) and reduced graphene oxide (rGO) composite material was fabricated and investigated as a unique anode material for LIC. The application of TNO-rGO composite electrode (R-TNO) as insertion anode material in LIC has been investigated due to its excellent electrochemical performance, intrinsic fast pseudo-capacitive behavior along with good reversibility and cyclability. A novel LIC was fabricated using R-TNO electrode as an innovative insertion type anode and activated carbon (AC) as cathode for the first time. Compared to conventional method (with binder), here the electrodes are prepared using binder-free and current-collector tape casting method to further enhance the energy and power density. As a result, the flexible and free-standing electrodes were acquired and used as anode for flexible LIC application. Comprehensive electrochemical analysis elucidates the improved storage behavior of composite electrode with rapid reaction kinetics, high reversibility and excellent cyclic stability. Novel R-TNO/AC LIC exhibited maximum energy density of 142.10 Wh/kg and power density of 18.75 kW/kg. The LIC device illustrated 88% cyclic stability even after 10,000 cycles, confirming its good electrochemical stability during electrochemical process. The extraordinary performance of LIC device is ascribed to collective effect of pseudo-capacitive behavior of TiNb6O17 particles and the buffering effect provided by rGO sheets. The results obtained are encouraging and propose the utilization of fabricated intercalation anode materials for the development of safe and high performance LICs.

Fabrication of flat stainless steel substrates with improved oxidation behavior for metal-supported solid oxide cells using aqueous tape casting

An aqueous tape casting procedure was developed and optimized to fabricate thick, flat tapes for use as porous stainless-steel substrates for metal-supported solid oxide cells (MS-SOCs). Curling tape is one of the main challenges when using aqueous based slurry formation. This work demonstrated that the sedimentation problem can be solved by increasing solid loading rather than adding excessive binder to raise viscosity. The effect of various casting surfaces on tape curling was also investigated. Materials that allow easy tape release resulted in flatter tapes once the water was evaporated. In addition, substrate oxidation resistance at high temperature was evaluated with respect to starting powder size, sintering extent, and pore former types. High sintering extent that removes or encloses the porosity between steel particles while retaining porosity left by pore formers can effectively prevent breakaway oxidation due to local chromium depletion. Carbon residue in the steel substrates from the slurry organic content can be decreased when formulating the slurry to prevent Cr-rich phase formation in the steel, which severely compromises the substrate oxidation resistance and ductility. By dwelling the substrate in high purity hydrogen, the sensitization can be reversed, but more detailed investigation of the reaction dynamics is needed. By combining the strategies described, this work produced crack-free, flat, 400–500 μm thick stainless steel substrates with 28.7 vol% porosity and improved oxidation resistance compared to previous substrates fabricated by dry pressing of fine powders.

Microstructural and electrochemical properties of Ni-impregnated GDC10 and 8YSZ freeze tape cast scaffolds as fuel electrodes for solid oxide cells

Ni-impregnated Gd0.1Ce0.9O2 and Y0.08Zr0.92O2 fuel electrodes for solid oxide cells are manufactured by the combination of the freeze tape casting and infiltration techniques. Their morphological properties are investigated by scanning electron microscope and X-Ray microtomography while their electrochemical performance is evaluated in symmetrical Y0.08Zr0.92O2-supported button cells by electrochemical impedance spectroscopy. The microstructural analysis of the manufactured scaffolds highlights the characteristic anisotropy of porosity provided by the freeze tape casting method. The average tortuosity factor across the out of plane direction has been calculated equal to 1.38, being considerably lower than the average values of the other components, (τx = 10.2) and (τy = 6.87). The contribution provided by gas diffusion to the overall polarization resistance of the freeze tape cast electrodes has been estimated around 6·10−4 Ω cm2 in the 600–750 °C temperature range, thus lower than the best reported values for the state-of-the-art electrodes featuring sponge-like porosity. The measured impedance data highlighted the higher electrochemical performance of the Ni-impregnated Gd0.1Ce0.9O2 architecture, holding a polarization resistance of 0.823 Ω cm2 at 750 °C, which is regarded as a very promising result for a ∼600 μm thick electrode. The interpretation of the impedance data was supported by the distribution of relaxation times analysis and the complex non-linear least square fit. In particular, the electrochemical investigation highlighted the presence of two major resistive contributions which have been ascribed to the occurrence of a chemical capacitance within the GDC10 lattice (low frequency contribution) and to the multi-layered architecture of the tested symmetrical cells which increases the contact losses (high frequency contribution).

Spectrum regulation of YAG:Ce/YAG:Cr/YAG:Pr phosphor ceramics with barcode structure prepared by tape casting

AbstractYAG:Ce/YAG:Cr/YAG:Pr composite phosphor ceramics with barcode structure were prepared by tape casting combined with the solid‐state reaction method. This structure provides a convenient and effective method for regulating the optical parameters such as luminous efficacy (LE), color rendering, and correlated color temperature (CCT) of white light‐emitting diodes/laser diodes (LEDs/LDs). For the sample with a thickness ratio of 6:6:6 for YAG:Ce, YAG:Cr, and YAG:Pr, the in‐line transmittance reaches 60% at 800 nm, and it shows a good optical performance with the LE of 106 lm/W, the color gamut (Rg) of 77, the color fidelity index (Rf) of 86, and the CCT of 7642 K. The electroluminescence spectra and color coordinates can be adjusted by changing the ratio of each component in the composite ceramic and the thickness of the ceramic because the tape casting method allows precise control of the thickness of each ceramic layer. The high tunability provides more freedom in the performance design of composite phosphor ceramics and makes them the most promising candidate for high brightness white LEDs/LDs.

Low-temperature co-fired PZNN-PZT multilayer piezoelectric ceramics with excellent electrical and bending properties

A 0.65 Pb(Zr0.47Ti0.53)O3–0.35[Pb(Zn0.1Ni0.9)1/3Nb2/3]O3 (PZNN-PZT) piezoceramic with sintering aids of Li2CO3, Bi2O3, CuO and Sm2O3 was prepared via a traditional solid reaction to achieve a high-performance multilayer actuator. The microstructure and electrical properties of ceramic bulks were systematically explored. The piezoceramics sintered at various temperatures show multi-phase co-existence. The sintering aids are beneficial for grain growth and microstructure densification. The piezoceramic sintered at 960 °C possesses relatively desirable electrical properties, including d33 ∼ 550 pC/N, kp ∼0.7 εr ∼2200, tan δ ∼0.021, Qm ∼71, Tc ∼240.5 °C, Pr ∼24.44 μC/cm2 and Ec ∼823.7 V/cm. Furthermore, we employed the tape casting and low-temperature co-fire methods to fabricate a PZT-PZNN/Ag–Pd multilayer piezoceramic of 7 × 7 × 36 mm3 in dimension with a single ceramic film of about 80 μm in thickness. The Ag–Pd electrode is effectively bonded with the ceramic layer, especially chemical binding induced by oxygen diffusion at some partial areas, which plays a crucial role in high binding strength (∼9.2 MPa). The multilayer piezoceramic exhibits outstanding actuating characteristics of high Smax ∼55.53 μm @ 150 V, and low H ∼19.8% @ 150 V together with outstanding stiffness of 70.87 N/μm @ 150 V.

Silicon infused Molybedenum di-selinide (MoSe2) nanosheets for enhanced hydrogen evolution reaction (HER) and lithium-ion battery (LIB) applications

The systematized design of two-dimensional (2D) nanocatalysts for sensible energy-efficient reactions is quite a puzzling prospective aspect in energy-related applications. In this current work, we used a top-down strategy to synthesize silicon (Si) nanoparticles using a high-energy mechanical ball milling technique. In hydrothermal reaction, these Si nanoparticles were introduced into the 2D MoSe2 matrix sequence based on varying the percentages of silicon (0–15%) vs Selinium content. The high crystalline phases of the synthesized 10% Si:MoSe2 exhibited the sheet-like morphology and silicon inserted layered structure. The pristine MoSe2@CC & Si:MoSe2@CC electrodes were prepared by tape casting method. During HER reaction, the miniscule insertion of Si into MoSe2 matrix amplified the current density until 10% addition and moved the reduction curves towards lower onset overpotential (76.23 mV) in addition to the significant Tafel value (112.3 mV/decade). The potential of the better performed electrode in HER was explored as an anode for Lithium-ion battery (LIB) applications. The electrode delivered a discharge capacity of 406.7 mAh g−1 at a current density of 100 mA/g after 100 charge-discharge cycles. Furthermore, the rationally constructed bifunctional electrode (Si:MoSe2@CC) showed strong physicochemical stability, which can be used in future sustainable energy generation and storage devices.

Tape Casting and Characterization of h-BN/PU Composite Coatings for Corrosion Resistance Applications

In the present work, a slurry of polyurethane (PU) was prepared by adding various contents (3 and 8 wt.%) of hexagonal boron nitride (h-BN). Ethanol was utilized as a solvent to reduce the viscosity and sticking effect of the PU. The mixture was then applied as polymer matrix composite (PMC) coating on steel substrates via tape casting. The prepared coatings were characterized for their structure, adhesion and thermal properties, and corrosion resistance characteristics. The structural and morphological features of the h-BN/PU composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Rockwell-C adhesion tests were conducted to examine the adhesion between the substrate and composite coating. The potentiodynamic polarization tests were utilized to assess the anti-corrosion performance of composite coatings when applied and steel substrates. The results exhibited that the inclusion of h-BN filler (3 wt.%) could effectively enhance the anti-corrosion performance of the h-BN/PU composite. The reason for the improvement in corrosion properties was attributed to lower surface roughness, uniform distribution and great adhesion strength of PU/3 wt.% h-BN composite. Furthermore, the PU/3 wt.% h-BN composites showed relatively improved thermal stability and higher glass transition temperature (Tg). However, further loading of h-BN contents (8 wt.%) deteriorates the thermal and corrosion resistance properties of the composite due to the clustering of h-BN, which creates localized areas of increased corrosive activity.