Recent fabrication techniques for micro-tubular solid oxide fuel cell support: A review

Jamil, Siti Munira; Othman, Mohd Hafiz Dzarfan; Rahman, Mukhlis A.; Ismail, Ahmad Fauzi; Li, Kang

doi:10.1016/j.jeurceramsoc.2014.08.034

Cited by 159 publications

(39 citation statements)

References 91 publications

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“…Different materials can be used in the different layers to increase the functionality of the membranes. Duallayered polymeric membranes have found use in applications such as pervaporation and membrane distillation and triple-layered membranes in solid oxide fuel cells [19,20]. However, the multi-layered membranes in literature are mostly entirely organic, or inorganic, and the fingerlike structures in these membranes are still enclosed inside the membranes.…”

Section: Introductionmentioning

confidence: 99%

New designs of ceramic hollow fibres toward broadened applications

Lee

Wang

2016

Journal of Membrane Science

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Three structural designs for ceramic membranes have been achieved for the first time through the co-extrusion of polymeric and ceramic layers. During co-extrusion, micro-channels are initiated due to the Rayleigh-Taylor instability and they propagate through the different layers.The polymeric layer(s) is then calcined off during the heat treatment step, which opens the microchannels and following sintering a ceramic membrane with open micro-channels ranging from a few to a few tens of micrometres in diameter can be formed. These long, straight and nontortuous micro-channels can be controlled to be open at any or all of the surfaces. Design 1 has open micro-channels passing through the entire membrane wall, Design 2 has a separation layer at the lumen and open micro-channels at the shell side, and Design 3 has open micro-channels from both lumen and shell sides sandwiching a separation layer of sponge-like structure. Aside from having much improved mass transfer property due to the reduced effective membrane thickness, they can be easily incorporated into hybrid systems with anticipated improvements in unit compactness and performance. The pure water permeation of Design 2 reached up to 159, 000 L/m 2 h bar with pore sizes in the micro-filtration range. The micro-channels are easily accessible from the shell/lumen side; therefore catalysts or adsorbents can be easily deposited into the micro-channels. Examples of possible applications include a high-efficiency dispersing device realised with Design 1; a gas chromatography column for gas separation with very low pressure drop realised with Design 2 and a highly compact membrane micro-reactor for consecutive reactions proposed with Design 3.

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Section: Introductionmentioning

confidence: 99%

New designs of ceramic hollow fibres toward broadened applications

Lee

Wang

2016

Journal of Membrane Science

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“…4,5,11 Within this context, Powder Extrusion Moulding (PEM) is highlighted a fast near-net-shape and cost-effective manufacturing method to produce tubular geometries. Similarly to Powder Injection Moulding techniques (PIM), PEM forming technology combines the advantages of plastic extrusion moulding and conventional powder metallurgy.…”

Section: Introductionmentioning

confidence: 99%

High-performance Ni–YSZ thin-walled microtubes for anode-supported solid oxide fuel cells obtained by powder extrusion moulding

et al. 2016

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Aiming at the fabrication of microtubular anode-supports for Solid Oxide Fuel Cells (SOFCs) applications, this contribution deals with the production of Ni-YSZ thin-walled tubes (<1 mm thickness) via Powder Extrusion Moulding (PEM). The overall method has been optimized with an emphasis on the effect of NiO particle size using two commercial NiO powders with mean sizes of 0.7 and 8 μm. A thermoplastic binder system based on polypropylene (PP), paraffin wax (PW) and stearic acid (SA) in a volume ratio of 50, 46 and 4, respectively, was used along with corn starch as a pore forming agent. Different feedstocks with solid loadings varying from 45 to 65 vol.% were processed and characterized to determine the optimal formulation. Typically, the mixtures exhibited a pseudoplastic behaviour from 100 to 1000 s-1. Feedstocks with finer NiO particles had the most balanced properties for PEM purpose and an optimal powder volume content of 65 vol.% was established. After extrusion and debinding steps, defect-free and constant cross-section tubes with 15 mm of length and 4 mm of nominal diameter were obtained. Final microstructure and DC conductivity were found to be closely linked to the NiO particle size, yielding a higher amount of open porosity and a better performance when using finer NiO powder. Based on this study, packing mechanism was found to be likely limited by the contribution of steric hindrances when dissimilar and coarse powder are mixed, which may play a decisive role in order to set tailored formulations. IntroductionSolid Oxide Fuel Cells (SOFCs) have emerged as an alternative to conventional power generators because of their high conversion efficiency and environmentally friendly performance while operating between 700 and 1000 °C. The most common configuration consists of a Ni-YSZ anode, a YSZ electrolyte and a lanthanum strontium-doped manganite (LSM) cathode.1,2 Among the different geometric designs of SOFCs, there is an increasing tendency to develop tubular devices because of their better thermo-mechanical properties, sealing simplicity, good thermal shock resistance, rapid start-up/shut-down time and excellent power cycling.3 Additionally, current technology is progressing towards microtubular stacks (MT-SOCF) owing to the enhanced volumetric power density, inversely proportional to diameter.4,5 On this matter, majority of recent works are heading for electrode-supported designs with thinner electrolytes to reduce the operation temperature, and thereby extending the range of SOFCs applications into mobile and portable fields.3 Specifically, anode-supported configurations have been on particular interest to overcome the issues associated with the consolidation of a dense electrolyte layer on the traditionally used cathodesupports.6-10 Nevertheless, in order to expedite the commercialization of MT-SOFCs systems, cell costs need to be remarkably reduced. In this way, the fabrication method of the support still remains as one of the major challenges, as well as the improvement of overall cell efficiency ...

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“…The tubular anode support was fabricated via a phase inversion assisted extrusion process. [43][44][45][46][47] A sintering step was then undertaken at 1450…”

Section: Methodsmentioning

confidence: 99%

3D Characterization of Diffusivities and Its Impact on Mass Flux and Concentration Overpotential in SOFC Anode

Tjaden

Bertei

et al. 2017

J. Electrochem. Soc.

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In recent years great effort has been taken to understand the effect of gas transport on the performance of electrochemical devices. This study aims to characterize the diffusion regimes and the possible inaccuracies of the mass transport calculation in Solid Oxide Fuel Cell (SOFC) anodes when a volume-averaged pore diameter is used. 3D pore size distribution is measured based on the extracted pore phase from an X-ray CT scan, which is further used for the calculation of a Knudsen number (K n ) map in the porous medium, followed by the voxel-based distribution of the effective diffusion coefficients for different fuel gases. Diffusion fluxes in a binary gas mixture using the lower boundary, upper boundary and average effective coefficients are compared, and the impact on overpotential is analyzed. The results show that pore diameters from tens to hundreds of nanometers result in a broad range of Knudsen number (1.1 ∼ 4.8 and 0.6 ∼ 3 for H 2 and CH 4 respectively), indicative of the transitional diffusion regime. The results highlight that for a porous material, such as an SOFC anode where Knudsen effects are non-negligible, using a volume-averaged pore size can overestimate the mass flux by ±200% compared to the actual value. The characteristic pore size should be chosen sensibly in order to improve the reliability of the mass transport and electrochemical performance evaluation. Mass transport can significantly limit the reaction rate and lead to concentration polarization in electrochemical devices such as fuel cells, electrolysers and oxygen transport membranes, especially under the conditions of high operating current density and fuel conversion ratios.1 Besides the material-specific transport properties of chemical species (e.g., diffusivity, viscosity, etc.), mass transport is mainly dependent on microstructural parameters of the electrode such as porosity, tortuosity and pore size. [2][3][4] In recent years great effort has been taken to understand the effect of gas transport on the performance of electrochemical devices in terms of electrochemical impedance, 5 concentration polarization loss, 4,6 and electrochemical simulation. 7-10Concentration polarization is caused by the consumption of the fuel gas resulting in a reduction of concentration at the anode/electrolyte interface. In solid oxide fuel cell (SOFC) anodes, concentration polarization is governed by the diffusion of fuel gas (e.g. H 2 ) from the gas inlet to the triple phase boundary. A faster diffusion rate can contribute to a larger partial pressure of the fuel gas within the pores and thus a larger limiting current density, which in turn mitigates the polarization loss. 11The effective diffusivity is closely related to the temperature, pressure, gas species as well as to the microstructure of the porous material.12 A considerable amount of work has been reported to measure the diffusivity, such as the experimental methods including diffusion cells, 13 gas chromatography, 14 thermo-gravimetric analysis, 15 as well as theoretical calculations ...

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Recent fabrication techniques for micro-tubular solid oxide fuel cell support: A review

Cited by 159 publications

References 91 publications

New designs of ceramic hollow fibres toward broadened applications

New designs of ceramic hollow fibres toward broadened applications

High-performance Ni–YSZ thin-walled microtubes for anode-supported solid oxide fuel cells obtained by powder extrusion moulding

3D Characterization of Diffusivities and Its Impact on Mass Flux and Concentration Overpotential in SOFC Anode

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