Post‐Test Characterization of Solid Oxide Fuel‐Cell Stacks

Menzler, Norbert H.; Batfalsky, Peter

doi:10.1002/9783527650248.ch17

Cited by 10 publications

(8 citation statements)

References 13 publications

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“…Detailed information on chromium quantification after fuel cell operation by ICP-OES can be found in the literature. 16 The analysis gave the following results:…”

Section: Resultsmentioning

confidence: 99%

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A Detailed Post Mortem Analysis of Solid Oxide Electrolyzer Cells after Long-Term Stack Operation

Frey

Sebold

Menzler

et al. 2018

J. Electrochem. Soc.

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A long-term test with a two-layer solid oxide electrolyzer stack was carried out for more than 20 000 hours. The stack was mainly operated in a furnace environment in electrolysis mode, with 50% humidification of H2 at 800 °C, a current density of -0.5 Acm -2 and steam conversion rate of 50%. After ~18 000 hours of operation in electrolysis mode, the voltage and area specific resistance degradation rates were ~0.6%/kh and 8.2%/kh, respectively. A detailed post mortem analysis of cells including ICP-OES and microstructural analysis was conducted. Two main degradation phenomena were observed in the cells: In the fuel electrode, the depletion and agglomeration of nickel were visible. At the air electrode, demixing of the air electrode and diffusion of strontium took place. This was observed in the formation of strontium zirconate at the interface between the electrolyte and the GDC barrier layer as well as in the formation of strontium oxide and strontium chromate on top of the cells. Strontium oxide was even found in pores on top of the electrolyte.

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“…Detailed information on chromium quantification after fuel cell operation by ICP-OES can be found in the literature. 16 The analysis gave the following results:…”

Section: Resultsmentioning

confidence: 99%

“…The air electrode and afterwards the complete cells were dissolved and investigated via ICP-OES. Detailed information on chromium quantification after fuel cell operation by ICP-OES can be found in the literature (16). The analysis gave the following results:…”

Section: Stack Dissectionmentioning

confidence: 95%

A Detailed Post Mortem Analysis of Solid Oxide Electrolyzer Cells after Long-Term Stack Operation

Frey

Sebold

Menzler

et al. 2018

J. Electrochem. Soc.

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“…The amount of Cr deposited on the cathode strongly depends on the Cr protection coating applied to the interconnect and the operating temperature (Beez et al, 2017). For stacks with less efficient Cr protection coatings (e.g., porous coatings applied by wet powder spraying), which were operated for up to 17.000 h, we measured a Cr content in the range of 100-200 µg cm −2 on the stack level (Menzler et al, 2011;Menzler and Batfalsky, 2012;Beez et al, 2017). So far a non-linear correlation between the amount of Cr deposited on an LSCF cathode and the operation time of a stack was measured (Menzler and Batfalsky, 2012) and a Cr content in the range of 200 µg cm −2 is the highest value reached for JÜLICH ASC stacks so far.…”

Section: Discussionmentioning

confidence: 99%

“…For stacks with less efficient Cr protection coatings (e.g., porous coatings applied by wet powder spraying), which were operated for up to 17.000 h, we measured a Cr content in the range of 100-200 µg cm −2 on the stack level (Menzler et al, 2011;Menzler and Batfalsky, 2012;Beez et al, 2017). So far a non-linear correlation between the amount of Cr deposited on an LSCF cathode and the operation time of a stack was measured (Menzler and Batfalsky, 2012) and a Cr content in the range of 200 µg cm −2 is the highest value reached for JÜLICH ASC stacks so far. Solid state poisoning by screen printing of Cr 2 O 3 powder enables to deposit the equivalent amount of Cr in <1 day, including preparation of the paste, screen printing and thermal treatment.…”

Section: Discussionmentioning

confidence: 99%

Accelerated Testing of Chromium Poisoning of Sr-Containing Mixed Conducting Solid Oxide Cell Air Electrodes

et al. 2018

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A straightforward method for accelerated testing of Cr poisoning phenomena on mixed ionic and electronic conducting (MIEC) Solid Oxide Cell (SOC) air electrode materials was developed. Cr 2 O 3 -powder is mixed with an organic matrix and screen printed onto anode-supported button cells with (La,Sr)(Co,Fe)O 3−δ (LSCF) cathode. Then, a thermal treatment was conducted to achieve the formation of a well-defined amount of SrCrO 4 on the cathode surface within only a few hours. For the proof of concept, single cell measurements were done to investigate the influence of this new kind of Cr deposition. As reference, a cell poisoned via gas phase diffusion and a cell without any Cr contamination were characterized in the same manner. According to the impedance data, the polarization resistance for both cells, which were contaminated with Cr species, increased. The expected relationship between deposited amount of Cr and increase of polarization resistance was found. ICP-OES analysis proves the high reproducibility of the method as the Cr content is only a function of the Cr paste composition and almost independent of external poisoning conditions. Due to its scalability and reproducibility, this method is proposed to be a new tool for screening of cathode materials and the investigation of different stages of Cr poisoning prior to more sophisticated and time consuming investigations like stack tests.

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“…Stack dissection was performed according to internal standards and protocols (9). Firstly, all planes were removed layer-by-layer, photographed from both sides and stored.…”

Section: Stack Dissection and Post-test Analysismentioning

confidence: 99%

Sol-Gel Thin-Film Electrolyte Anode-Supported SOFC – From Layer Development To Stack Testing

et al. 2013

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One of the current R&D projects on solid oxide fuel cells concerns the reduction of the operation temperature. Nowadays stacks with anode-supported cells and an LSCF-cathode operate typically at a mean temperature of 700°C. The minimum temperature for SOFC using natural gas is approx. 650°C due to reforming limitations. Reducing temperatures below 600°C leads to lower costs, shorter start-up time and thus in-time power delivery by the system (e.g. for auxiliary power units). Forschungszentrum Jülich is also working on the development of an SOFC operating at 400°C for special applications, which can be fueled either with hydrogen (produced by, for example, electrolysis using renewable energy) or with reformate gas based on, for instance, ethanol/methanol. The main challenge for using the SOFC at such low temperatures is, besides electrode activities, overcoming the resistances, especially the ohmic resistance of the electrolyte. This can be achieved in two ways: by introducing materials which show higher oxygen diffusivity or by using the classical materials and minimizing the electrolyte thickness down to values below 2µm.

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Post‐Test Characterization of Solid Oxide Fuel‐Cell Stacks

Cited by 10 publications

References 13 publications

A Detailed Post Mortem Analysis of Solid Oxide Electrolyzer Cells after Long-Term Stack Operation

A Detailed Post Mortem Analysis of Solid Oxide Electrolyzer Cells after Long-Term Stack Operation

Accelerated Testing of Chromium Poisoning of Sr-Containing Mixed Conducting Solid Oxide Cell Air Electrodes

Sol-Gel Thin-Film Electrolyte Anode-Supported SOFC – From Layer Development To Stack Testing

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