TEM investigation on zirconate formation and chromium poisoning in LSM/YSZ cathode

Hessler-Wyser, Aïcha; Wuillemin, Zacharie; Schuler, J. Andreas; Faes, Antonin; herle, Jan Van

doi:10.1007/s10853-011-5347-5

Cited by 14 publications

(5 citation statements)

References 30 publications

(51 reference statements)

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“…The degradation in the current density for both cases is due to the increase in the polarization resistance, , corresponding to the increasingly enlarged Nyquist arcs over time (Figure a,b). The degradation mechanism is inferred from the Bode plots in Figure a,b, given that the impedance at low (≤30 Hz) and high (≤3 kHz) frequencies are responses to the transfer of O 2– ions along the surface and across the bulk, respectively. ,− The electrode performance degradation by Cr poisoning is due to the preferential Cr deposition at the triple phase boundary (TPB) between air, electrode, and electrolyte via the following electrochemical reduction. − In contrast, the degradation by S poisoning is due to the chemisorption of SO 2 on the LSM surface, resulting in SrSO 4 precipitation and nonstoichiometric, Sr-depleted LSM. ,, …”

Section: Resultsmentioning

confidence: 99%

Strontium Manganese Oxide Getter for Capturing Airborne Cr and S Contaminants in High-Temperature Electrochemical Systems

Hong

Aphale

Heo

et al. 2019

ACS Appl. Mater. Interfaces

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Traces (ppm to ppb level) of airborne contaminants such as CrO2(OH)2 and SO2 irreversibly degrade the electrochemical activity of air electrodes in high-temperature electrochemical devices such as solid oxide fuel cells by retarding oxygen reduction reactions. The use of getter has been proposed as a cost-effective strategy to mitigate the electrode poisoning. However, owing to the harsh operating conditions (i.e., exposure to heat and moisture), the long-term durability of getter materials remains a considerable challenge. In this study, we report our findings on strontium manganese oxide (SMO) as a robust getter material for cocapture of airborne Cr and S contaminants. The SMO getter with a 3D honeycomb architecture, fabricated via slurry dip-coating, successfully maintains the electrochemical activity of solid oxide cells under the flow of gaseous Cr and S species, validating the getter’s capability of capturing traces of Cr and S contaminants. Investigations found that both Sr and Mn cations contribute to the absorption reaction and that the reaction processes are accompanied by morphological elongation in the form of SrSO4 nanorods and SrCrO4 whiskers, which favors continued absorption and reaction of incoming S and Cr contaminants. The SMO getter also displays robust stability at high temperatures and in humid environments without phase transformation and hydrolysis. These results demonstrate the feasibility of the use of SMO getter under severe operating conditions representative of high-temperature electrochemical systems.

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Section: Resultsmentioning

confidence: 99%

Strontium Manganese Oxide Getter for Capturing Airborne Cr and S Contaminants in High-Temperature Electrochemical Systems

Hong

Aphale

Heo

et al. 2019

ACS Appl. Mater. Interfaces

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“…In another study by the authors, 36 Si was identified in TEM investigations at LSM/YSZ and zirconate/LSM interfaces, where Si was possibly combined with Zr and/or La as a silicate phase. As these phases were only sparsely observed within other TEM samples from this same repeat-element and as their formation is more likely linked to the reaction of endogenous Si with cathode material during sintering, the here-observed glass-forming exogenous Si contamination is suggested to have significantly contributed to cathode degradation.…”

Section: Resultsmentioning

confidence: 92%

Glass-Forming Exogenous Silicon Contamination in Solid Oxide Fuel Cell Cathodes

Schuler

Wuillemin

Hessler-Wyser

et al. 2011

Electrochem. Solid-State Lett.

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Spatially resolved analyses, by energy-dispersive X-ray spectroscopy ͑EDS͒ and scanning electron microscopy, allowed the quantification of exogenous Si contamination in a solid oxide fuel cell ͑SOFC͒ cathode after operation. The Si quantification, taking into account the endogenous Si impurity level, correlated well with the expectation from the condensation of Si͑OH͒ 4 vapor, originating from upstream alloy components and saturated in the hot inlet air. At higher resolution, EDS-transmission electron microscopy pointed out the deposition of Si vapor in the form of amorphous SiO 2 , blocking oxygen incorporation into the electrolyte phase within a composite SOFC cathode.In solid oxide fuel cell ͑SOFC͒ technology, silicon ͑Si͒ is, by its insulating and glass-forming properties, a major limitation for electrochemical performance. 1,2 As endogenous impurity in SOFC ceramics, Si is present in raw materials and is introduced by costcutting exercises during powder preparation. 3 Besides bulk impurity, exogenous Si contamination is vehicled in SOFC operation by the reactants, stemming from oils and greases as well as mineral dust. 2,4-6 In particular, cell-proximal system components such as furnace materials 7-9 or the common use of quartz reactors can lead to Si contamination. [10][11][12] Although the presence of Si is ubiquitous and influences both the electrolyte and cathode resistivities, 13 the understanding of its effect on electrochemical cathode processes, by a deleterious poisoning of the active catalytic sites for oxygen reduction, is lacking. 14 Moreover, it is suggested that different Si contamination levels are at least partially responsible for disagreements in the literature related to cathode performance and degradation, 13 as well as for the laboratory specific behavior of SOFC electrodes. 2,15 To enable data correlation from different researches, quantification methods for Si contamination are needed; 16 an area where this study aims to contribute. Energy-dispersive X-ray spectroscopy ͑EDS͒ is employed here as an identification and quantification tool for both endogenous Si impurity levels and Si contamination stemming from exogenous sources.

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“…The reactive trapping of volatile Cr species within the LSC CCL, as previously reported in (17), is suggested to lower the Cr concentration on the cathode surface decreasing both the Cr amounts at the interface and their distribution in the cathode thickness. Regarding the nature of the Cr accumulations, analyses of composition and phase identification is already reported elsewhere (18) and beyond the scope of the present work.…”

Section: Cr Profilingmentioning

confidence: 95%

Multi-Scale Assessment of Cr Contamination Levels in SOFC Cathode Environment

Schuler

Wuillemin

et al. 2011

ECS Trans.

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This study aims to quantify in a holistic approach chromium (Cr) contamination in solid oxide fuel cell (SOFC) stack testing using adapted tools: i) a hot gas sampling method to analyze volatile Cr species in the air flux at the cathode inlet location; and ii) a rapid quantification method for Cr as condensed matter in cathode material of post-test samples. The hot air sampling method reveals itself as a reproducible and time-resolved quantification technique for Cr trace amounts in a gas flow; this technique is seen as a promising evaluation tool for Cr contamination issues in SOFC systems. The quantification method reveals severe Cr-poisoning in a cell. The combined findings indicate that Cr contamination generated by system components located upstream the cell must be suppressed by hindering the access of Cr pollutants to the cathode compartment.

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TEM investigation on zirconate formation and chromium poisoning in LSM/YSZ cathode

Abstract: Cell durability is a crucial technological issue for SOFC commercialization, and considerable progress has been made

Cited by 14 publications

References 30 publications

Strontium Manganese Oxide Getter for Capturing Airborne Cr and S Contaminants in High-Temperature Electrochemical Systems

Strontium Manganese Oxide Getter for Capturing Airborne Cr and S Contaminants in High-Temperature Electrochemical Systems

Glass-Forming Exogenous Silicon Contamination in Solid Oxide Fuel Cell Cathodes

Multi-Scale Assessment of Cr Contamination Levels in SOFC Cathode Environment

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