The effect of anode support on the electrochemical performance of microtubular solid oxide fuel cells fabricated by gel-casting

Morales, M.; Laguna‐Bercero, M. A.; Navarro, María Elena; Espiell, F.; Segarra, M.

doi:10.1039/c5ra02304a

Cited by 21 publications

(23 citation statements)

References 40 publications

(47 reference statements)

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“…40 Current densities at 0.5 V and 650 C for the cells with different amounts of pore former in the support are also presented in Fig. 3a.…”

Section: Electrochemical Characterizationmentioning

confidence: 99%

“…This is also consistent with EIS analysis, as concentration polarization increases when increasing wall thickness. 40 In conclusion, the reduction of wall thickness and outer diameter in a mT-SOFC signicantly increases the volumetric and area power density keeping almost constant both the MOR and the microstructural properties.…”

Section: à2mentioning

confidence: 99%

“…The current density, as an electrochemical parameter, clearly shows the gas transport limitations on cell performances, especially working at high current densities. The effect of gas transport limitation was conrmed by EIS experiments, 40 where the low frequency Warburg response (hydrogen transport through the Ni-SDC support) increases when reducing the porosity of the support. Therefore, the large variation in porosity and pore size distribution between the cells with different amounts of pore former in the support would explain the signicant differences in cell performance.…”

Section: Electrochemical Characterizationmentioning

confidence: 99%

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Microtubular solid oxide fuel cells fabricated by gel-casting: the role of supporting microstructure on the mechanical properties

Morales

Laguna‐Bercero

2017

RSC Adv.

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Different cell configurations of anode-supported microtubular solid oxide fuel cells (mT-SOFCs) using samaria-doped ceria (SDC) as the electrolyte were fabricated. Several cells were processed varying the porosity and wall thickness (outer diameter) of NiO-SDC tubular supports. Suitable aqueous slurry formulations of NiO-SDC for gel-casting were prepared using agarose, as a gelling agent, and sucrose, as a pore former. The subsequent NiO-SDC anode functional layer (AFL), the SDC electrolyte and the La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3Àd -SDC cathode were deposited by spray-coating. Afterwards, the electrochemical performance of different single cells was tested under humidified hydrogen as the fuel and air as the oxidant. The mechanical strength of the supporting tubes at different processing stages (green, pre-/ post-sintering, post-reduction, post-redox cycle conditions) were also determined to study the macromechanical failure behaviour of the cells. In addition, the mechanical strength of half-cells with different porosity, sintering temperature and wall thickness in the tubular supports was also determined. For this purpose, the modulus of rupture was measured by a three point bending test. This study shows that the electrochemical properties and mechanical strength are feasible for further development of anodesupported mT-SOFCs fabricated by gel-casting.

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“…40 Current densities at 0.5 V and 650 C for the cells with different amounts of pore former in the support are also presented in Fig. 3a.…”

Section: Electrochemical Characterizationmentioning

confidence: 99%

Section: à2mentioning

confidence: 99%

Section: Electrochemical Characterizationmentioning

confidence: 99%

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Microtubular solid oxide fuel cells fabricated by gel-casting: the role of supporting microstructure on the mechanical properties

Morales

Laguna‐Bercero

2017

RSC Adv.

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“…Typically, highly porous Ni-YSZ cermets with porosity levels around 40-50 vol.% are required to ensure an efficient three-phase-boundary (TPB) among electrode, electrolyte and gas phase.17 Commonly, carbon black, flake graphite, spherical polymethyl methacrylate, rice starch or sucrose have been used to produce similar porous structures. [18][19][20][21][22] In this work, the use of corn starch as a pore forming agent in an extrusion process is addressed for the first time. The planned research work entails the mixture of dissimilar powders in a relatively wide range of sizes and shapes, which constitutes a particular issue not very common in conventional PEM.…”

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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“…One of the key parameters is to achieve strong interfaces between the different components and thus reducing polarization losses of the cells. For that purpose, different fabrication methods for the tubular supports were reported, such as cold isostatic pressing [4,5], powder extrusion moulding (PEM) [6,7,8], powder injection moulding (PIM) [9], gel-casting [10,11], slip-casting [12,13] or the immersion-induced inversion method [14,15]. Currently, the state of the art configuration for microtubular cells is the use on anode supported cells, and the most used composition is nickel-YSZ [2,3].…”

Section: Introductionmentioning

confidence: 99%

Highly stable microtubular cells for portable solid oxide fuel cell applications

Monzón

Laguna‐Bercero

2016

Electrochimica Acta

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The effect of anode support on the electrochemical performance of microtubular solid oxide fuel cells fabricated by gel-casting

Abstract: Different cell configurations of anode-supported microtubular solid oxide fuel cells (mT-SOFCs) using samaria-doped ceria (SDC) as the electrolyte were fabricated.

Cited by 21 publications

References 40 publications

Microtubular solid oxide fuel cells fabricated by gel-casting: the role of supporting microstructure on the mechanical properties

Microtubular solid oxide fuel cells fabricated by gel-casting: the role of supporting microstructure on the mechanical properties

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

Highly stable microtubular cells for portable solid oxide fuel cell applications

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