Chromium deposition and poisoning in dry and humidified air at (La0.8Sr0.2)0.9MnO3+ cathodes of solid oxide fuel cells

Chen, Xinbing; Zhen, Yongda; Li, Jian; Jiang, San Ping

doi:10.1016/j.ijhydene.2009.12.185

Cited by 94 publications

(67 citation statements)

References 34 publications

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“…Numerous studies (e.g. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]) have considered the severity of chromium poisoning of (La,Sr)MnO 3 -based cathodes depending on whether the SOFC is operated under load or is held at open-circuit, whether the air supplied to the cathode is dry or humidified, and depending on the interconnect metallic alloy used (Inconel 600, Cr5Fe1Y 2 O 3 , Crofer22APU, RA446, 17-4 stainless steel, AISI 441, SUS430, ITM or ZMG232).…”

Section: Introductionmentioning

confidence: 99%

Conductivity and oxygen reduction activity changes in lanthanum strontium manganite upon low-level chromium substitution

Tsekouras

Braun

2014

Solid State Ionics

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On the timescale of solid oxide fuel cell (SOFC) system lifetime requirements, the thermodynamically predicted low-level substitution of chromium on the B-site of (La,Sr)MnO 3 could be a source of cathode degradation underlying more overt and well-known chromium poisoning mechanisms. To study this phenomenon in isolation, electronic conductivity (σ) and electrochemical oxygen reduction activity of the (La 0.8 Sr 0.2 ) 0.98 Cr x Mn 1−x O 3 model series (x = 0, 0.02, 0.05 or 0.1) were measured in air between 850 and 650 °C. Depending on the extent of chromium substitution and the measurement temperature, electrochemical impedance spectroscopy (EIS) results could be deconvoluted into a maximum of three contributions reflecting possible limiting processes such as oxide ion transport and dissociative adsorption. Chromium substitution resulted in lowered σ (from 174 S cm − 1 (x = 0) to 89 S cm − 1 (x = 0.1) at 850 °C) and a steady rise in associated activation energy (E a ) (from 0.105 ± 0.001 eV (x = 0) to 0.139 ± 0.001 eV (x = 0.1)). From EIS analyses, ohmic and polarisation resistances increased, whilst Ea for the overall oxygen reduction reaction also increased from 1.39 ± 0.04 eV (x = 0) to 1.48-1.54 ± 0.04 eV upon chromium substitution.Keywords level, conductivity, oxygen, reduction, activity, changes, chromium, lanthanum, substitution, strontium, manganite, upon, low Depending on the extent of chromium substitution and the measurement temperature, electrochemical impedance spectroscopy (EIS) results could be deconvoluted into a maximum of three contributions 2 reflecting possible limiting processes such as oxide ion transport and dissociative adsorption. Chromium substitution resulted in lowered  (from 174 S cm -1 (x = 0) to 89 S cm -1 (x = 0.1) at 850 °C) and a steady rise in associated activation energy (E a ) (from 0.105 ± 0.001 eV (x = 0) to 0.139 ± 0.001 eV (x = 0.1)). From EIS analysis, ohmic and polarisation resistances increased, whilst E a for the overall oxygen reduction reaction also increased from 1.39 ± 0.04 eV (x = 0) to 1.48-1.54 ± 0.04 eV upon chromium substitution.

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Section: Introductionmentioning

confidence: 99%

Conductivity and oxygen reduction activity changes in lanthanum strontium manganite upon low-level chromium substitution

Tsekouras

Braun

2014

Solid State Ionics

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“…Strontium-doped lanthanum manganite perovskite oxides (La 1-x Sr x MnO 3±δ , LSM) have been widely studied in recent years due to their interesting applications in solid oxide fuel cells (SOFC), oxi-reduction catalysts (automotive catalysis), sensors and memories [1][2][3][4][5][6] . These latter applications are due to the outstanding magnetotransport properties of these oxides [7][8][9] .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of La1-xSr xMnO3±δ powders obtained by the polymeric precursor route

et al. 2011

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Polycrystalline strontium-doped lanthanum manganite (LSM) powders with 0.15, 0.22, and 0.30 mol % Sr were synthesized by the polymeric precursor route using a molar ratio of 3:1 citric acid and metal cations. The powders were characterized by Fourier transform infrared spectroscopy, thermal analysis, high-temperature X-ray diffraction to determine the crystalline perovskite phase and crystallite sizes, scanning electron microscopy for the morphological analysis, nitrogen adsorption to determine the specific surface area, and laser scattering to evaluate the particle size distribution. The LSM perovskite-type oxides containing intermediate 0.22 mol % Sr were found to exhibit a tendency to decrease in crystallite size and increase in specific surface area and, when calcined at 700-900 °C exhibited a pure phase of perovskite, had a crystallite size of about 17-20 nm and a specific surface area for 900 °C of 34.3 m 2 .g -1.

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“…16 Cr deposition decreases significantly with the decrease of temperature, most likely due to the reduced Sr segregation as well as the decrease of the partial pressure of gaseous Cr species at reduced temperatures.…”

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“…14,15 Both the humidity in the air stream and operation temperature have a significant effect on the Cr deposition. 16 Cr deposition decreases significantly with the decrease of temperature, most likely due to the reduced Sr segregation as well as the decrease of the partial pressure of gaseous Cr species at reduced temperatures. 17 The sulfur in the form of SO 2 or H 2 S in the air stream is another important contaminant affecting the performance stability of SOFC cathodes.…”

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Co-Deposition and Poisoning of Chromium and Sulfur Contaminants on La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δCathodes of Solid Oxide Fuel Cells

Wang

O’Donnell

et al. 2015

J. Electrochem. Soc.

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The presence of both chromium and sulfur (Cr/S) contaminants on the microstructure and electrocatalytic activity properties of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) electrodes of solid oxide fuel cells (SOFCs) is studied, using Confocal laser Raman spectroscopy, XRD, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and electrical conductivity relaxation (ECR) methods. LSCF dense bar samples were heat treated in the presence of Cr 2 O 3 and 20 ppm SO 2 and in the temperature range of 600-900 • C. The deposition and reaction products between LSCF and Cr/S depend on the temperature: SrCrO 4 only forms on LSCF samples at 900 • C and 800 • C, while formation of SrSO 4 phase occurs at all temperatures studied. The results indicate that sulfur shows a higher activity with LSCF, as compared to gaseous Cr species. Segregated SrO is more likely to react with gaseous Cr species at higher temperatures, however, reaction with SO 2 is more pronounced at lower temperatures, forming SrSO 4 . ECR results indicate that co-deposition of Cr and sulfur significantly deteriorates the surface exchange and diffusion processes for the O 2 reduction reaction on LSCF electrodes. The durability of a solid oxide fuel cell (SOFC) is critically related to the degradation behavior of its cathodes such as La 0.8 Sr 0.2 MnO 3 (LSM) and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) in the presence of impurity species such as chromium from the chromia-forming interconnect, silica, boron and volatile alkaline elements from the glass seals sealant and sulfur from air.1-8 Among them, gaseous chromium species vaporized from the chromium oxide scale of chromia-forming metallic interconnect are probably the most investigated contaminants affecting the performance of SOFCs' cathodes. The mechanism and process of the deposition and poisoning of chromium species at the cathodes of SOFCs have been extensively investigated, including LSM, 9-11 LSCF 12 and Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF). 13 In the case of LSCF electrodes, deposition of Cr species preferentially take place on the surface of the LSCF electrode, resulted from the interaction between the segregated SrO and gaseous Cr species.14,15 Both the humidity in the air stream and operation temperature have a significant effect on the Cr deposition. 16 Cr deposition decreases significantly with the decrease of temperature, most likely due to the reduced Sr segregation as well as the decrease of the partial pressure of gaseous Cr species at reduced temperatures. 17The sulfur in the form of SO 2 or H 2 S in the air stream is another important contaminant affecting the performance stability of SOFC cathodes. SO 2 content in air can be in the range of 10-340 μg m −3 (3.5 × 10 −3 -0.12 ppm) in cities. 18 Despite the low concentration of SO 2 , sulfur in the air stream can accumulate at the cathodes of SOFC cells, degrading the performance.5 Wang et al. 19 studied the polarization performance behavior of LSCF in the presence of 0.1 ppm SO 2 and observed two-stages of performance degrad...

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Chromium deposition and poisoning in dry and humidified air at (La0.8Sr0.2)0.9MnO3+ cathodes of solid oxide fuel cells

Cited by 94 publications

References 34 publications

Conductivity and oxygen reduction activity changes in lanthanum strontium manganite upon low-level chromium substitution

Conductivity and oxygen reduction activity changes in lanthanum strontium manganite upon low-level chromium substitution

Synthesis and characterization of La1-xSr xMnO3±δ powders obtained by the polymeric precursor route

Co-Deposition and Poisoning of Chromium and Sulfur Contaminants on La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δCathodes of Solid Oxide Fuel Cells

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Chromium deposition and poisoning in dry and humidified air at (La0.8Sr0.2)0.9MnO3+ cathodes of solid oxide fuel cells

Cited by 94 publications

References 34 publications

Conductivity and oxygen reduction activity changes in lanthanum strontium manganite upon low-level chromium substitution

Conductivity and oxygen reduction activity changes in lanthanum strontium manganite upon low-level chromium substitution

Synthesis and characterization of La1-xSr xMnO3±δ powders obtained by the polymeric precursor route

Co-Deposition and Poisoning of Chromium and Sulfur Contaminants on La0.6Sr0.4Co0.2Fe0.8O3-δCathodes of Solid Oxide Fuel Cells

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Co-Deposition and Poisoning of Chromium and Sulfur Contaminants on La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δCathodes of Solid Oxide Fuel Cells