Numerical evaluation of micro-structural parameters of porous supports in metal-supported solid oxide fuel cells

Reiss, Georg; Frandsen, Henrik Lund; Brandstätter, Wilhelm; Weber, André

doi:10.1016/j.jpowsour.2014.09.185

Cited by 22 publications

(17 citation statements)

References 55 publications

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“…That it is reasonable to expect higher tortuosity values with increasing support layer densification has previously been illustrated by studies of a DTU MS-SOFC with a relatively dense support layer. 22 In here high tortuosity values around 5 were found from modelling of 3D microstructural reconstructions. For comparison, AS-SOFCs with the conventional Ni:YSZ cermet anode have typically a tortuosity value of around or slightly below 2.…”

Section: Resultsmentioning

confidence: 59%

Towards High Power Density Metal Supported Solid Oxide Fuel Cell for Mobile Applications

Nielsen

Persson

Muhl

et al. 2018

J. Electrochem. Soc.

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For use of metal supported solid oxide fuel cell (MS-SOFC) in mobile applications it is important to reduce the thermal mass to enable fast startup, increase stack power density in terms of weight and volume and reduce costs. In the present study, we report on the effect of reducing the Technical University of Denmark (DTU) SoA MS-SOFCs support layer thickness from 313 μm gradually to 108 μm. The support layer thickness decrease in the DTU co-sintering MS-SOFC fabrication route results in an increased densification of the support layer and a slight decrease in performance. To mitigate the performance loss, two different routes for increasing the porosity of the support layer and thus performance were explored. The first route is the introduction of gas channels by puncturing of the green tape casted support layer. The second route is modification of the co-sintering profile. In summary, the cell thickness and thus weight and volume was reduced and the cell power density at 0.7 V at 700 • C was increased by 46% to 1.01 Wcm −2 at a fuel utilization of 48%. All modifications were performed on a stack technological relevant cell size of 12 cm × 12 cm. Solid oxide fuel cell (SOFC) is attractive due to the excellent power generation efficiency and fuel flexibility. The conventional ceramic electrolyte and anode supported SOFC (AS-SOFC) is limited to stationary power generation applications as a result of the difficulty of quick startup and the high operating temperatures of 700 to 1000 • C. If quick startup of a SOFC is realized, mobile applications may be considered. To enable this, it is important to shorten the startup time and reduce the heat cycle performance degradation and increase stack power density both in terms of weight and volume. As an approach to solving these problems, metal supported SOFCs (MS-SOFCs) have attracted attention. The development of this new generation of SOFC is currently in progress. DTU Energy's MS-SOFC technology is based on co-sintering of laminated tape casted electrolyte, anode and support layers in a reducing atmosphere. This implies that the sintering shrinkage of the different layers must be matched sufficiently so that the mechanical stresses originating from any mismatch in sintering shrinkage of the individual layers can be absorbed by the cell structure. If the cell structure is unable to absorb the mechanical stresses, the cell will crack. Perfect matching of sintering shrinkage of the layers is practically very difficult as e.g. the electrolyte layer needs to be completely dense and thus gastight, while the anode and support layers in contrast needs to be highly porous to allow sufficient gas transport.An overview and recent progress of MS-SOFCs have been reviewed in Ref. 1. The company Ceres Power founded in 2001 is at present the organization, which most effectively has demonstrated up scaled large cell sized >80 cm 2 MS-SOFC stack technology. This is followed by consortia involving the company Plansee. At last MS-SOFC stacking has been demonstrated within consortia consi...

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Section: Resultsmentioning

confidence: 59%

Towards High Power Density Metal Supported Solid Oxide Fuel Cell for Mobile Applications

Nielsen

Persson

Muhl

et al. 2018

J. Electrochem. Soc.

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“…12 For cells similar to type B in Figure 1 tortuosities around 5 were found along with a relatively low density of percolated pores. For comparison, ASSOFCs with the conventional Ni:YSZ cermet anode have typically a tortuosity of around or slightly below 2.…”

Section: Resultsmentioning

confidence: 86%

Performance Factors and Sulfur Tolerance of Metal Supported Solid Oxide Fuel Cells with Nanostructured Ni:GDC Infiltrated Anodes

Nielsen

Sudireddy

Hagen

et al. 2016

J. Electrochem. Soc.

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Two metal supported solid oxide fuel cells (active area 16 cm 2 ) with nanostructured Ni:GDC infiltrated anodes, possessing different anode and support microstructures were studied in respect to sulfur tolerance at an operating temperature of 650 • C. The studied MS-SOFCs are based on ferretic stainless steel (FeCr) and showed excellent performance characteristics at 650 • C with fuel utilization corrected area specific resistances of 0.35 cm 2 and 0.7 cm 2 respectively. The sulfur tolerance testing was performed by periodic addition of 2, 5, and 10 ppm H 2 S in hydrogen based fuel under galvanostatic operation at a current load of 0.25 Acm −2 . The results were compared with literature on the sulfur tolerance of conventional SOFC Ni/YSZ cermet anode. The comparison in terms of absolute cell resistance increase and relative anode polarization resistance increase indicates, that the nanostructured Ni:GDC MS-SOFC based anode is significantly more sulfur tolerant than the conventional Ni/YSZ cermet anode. Furthermore, it was shown that the believed extension of the electrochemical three-phase-boundary reaction zone in the presence of GDC must be very limited and cannot account for the higher sulfur tolerance of GDC modified SOFC anodes. In recent years, there has been a growing interest in developing metal supported solid oxide fuel cells (MS-SOFCs). MS-SOFCs are interesting as they potentially offer some advantages compared to conventional electrode and electrolyte supported SOFCs, such as low materials cost, better thermal conductivity and ductility of the support. The two later aspects improve the shock resistance and lower internal gradients within the stacks. This enables faster start-up, higher tolerance toward operation under transient conditions and operation at higher fuel utilization.Today's commercially available and relevant SOFC fuels such as natural gas, diesel and biogas etc. all contain trace amounts of sulfur. Thus, tolerance toward sulfur poisoning is desirable. Ceria and gadolinium doped ceria (GDC) have been reported in the literature to have a beneficial effect on the tolerance toward sulfur poisoning. [1][2][3][4] The ceria can be incorporated as a microstructured Ni:GDC cermet anode, but also as non-percolated nanostructuring via infiltration of isolated ceria and doped ceria particles into the conventional microstructured Ni:YSZ cermet anode. Both approaches have been reported to improve the tolerance toward sulfur poisoning. In the present study we report the performance and sulfur tolerance of MS-SOFCs with two different microstructures of the support and the anode functional layer (AFL). The MS-SOFCs of the present study are based on ferritic stainless steel (FeCr) with an aimed operating temperature of 650• C. This lower operating temperature compared to electrode and electrolyte supported SOFC (750• C-850• C) will favor sulfur adsorption and is thus expected to increase the impact of sulfur poisoning. The AFL was infiltrated with Ni-GDC precursor solution and subsequently heat treated r...

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“…A volume of 1.1 mm Â 2.2 mmÂ0.37 mm was scanned with a frame averaging of two and a rotation step of 0.36, such that the entire thickness of the actual metallic support is covered. The scanning data is identical to those used in a previous study [15].…”

Section: Methodsmentioning

confidence: 99%

“…Nevertheless, the outcome of this approach relies on the feasibility of separating the convoluted response of the measurements by a relatively simple and suitable model. It is currently not possible to separate the gas diffusion loss in the metal-supported SOFCs, as the relaxation times overlap with a process related to hydrogen electro-oxidation [15].…”

Section: Introductionmentioning

confidence: 99%

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Numerical evaluation of oxide growth in metallic support microstructures of Solid Oxide Fuel Cells and its influence on mass transport

Reiss¹,

Frandsen

Persson

et al. 2015

Journal of Power Sources

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Numerical evaluation of micro-structural parameters of porous supports in metal-supported solid oxide fuel cells

Cited by 22 publications

References 55 publications

Towards High Power Density Metal Supported Solid Oxide Fuel Cell for Mobile Applications

Towards High Power Density Metal Supported Solid Oxide Fuel Cell for Mobile Applications

Performance Factors and Sulfur Tolerance of Metal Supported Solid Oxide Fuel Cells with Nanostructured Ni:GDC Infiltrated Anodes

Numerical evaluation of oxide growth in metallic support microstructures of Solid Oxide Fuel Cells and its influence on mass transport

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