Effect of strontium concentration on sulfur poisoning of LSCF cathodes

Wang, Fangfang; Yamaji, Katsuhiko; Cho, Do-Hyung; Shimonosono, Taro; Kishimoto, Haruo; Brito, Manuel E.; Horita, Teruhisa; Yokokawa, Harumi

doi:10.1016/j.ssi.2012.05.026

Cited by 42 publications

(35 citation statements)

References 13 publications

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“…15,16,[18][19][20]35 The interaction between LSCF and SO 2 leads to the formation of SrSO 4 at temperatures ≥700 • C and SrS at temperatures below 700 • C. Madarasz et al studied the oxidation behavior of SrS in air and showed that oxidation of SrS starts slowly at 700 • C, forming SrSO 4 . 15,16,[18][19][20]35 The interaction between LSCF and SO 2 leads to the formation of SrSO 4 at temperatures ≥700 • C and SrS at temperatures below 700 • C. Madarasz et al studied the oxidation behavior of SrS in air and showed that oxidation of SrS starts slowly at 700 • C, forming SrSO 4 .…”

Section: Discussionmentioning

confidence: 99%

Sulfur Deposition and Poisoning of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δCathode Materials of Solid Oxide Fuel Cells

Wang

Chen

Jiang

2014

J. Electrochem. Soc.

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Sulfur in the air stream is one of the major contaminants affecting the performance stability of cathodes of solid oxide fuel cells (SOFCs) such as La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) perovskite. Here sulfur deposition and poisoning was investigated on LSCF bar samples in the presence of 20 ppm SO 2 and temperature range of 400-900 • C, using scanning electron microscopy, confocal laser Raman spectroscopy and electrical conductivity relaxation (ECR) methods. Sulfur (SO 2 ) reacts with LSCF, primarily forming SrSO 4 at high temperatures (i.e., ≥ 700 • C) and SrS at low temperatures (i.e. <700 • C). Surface segregated SrO plays an important role in the sulfur deposition. The most important observation of this study is that sulfur deposition shows a distinct volcano-type dependency on the heat-treatment temperature and is most pronounced at temperatures around 700 • C, indicating that the reaction rate between the segregated SrO and SO 2 is highest at ∼700 • C. The ECR results indicate that the surface exchange coefficient of LSCF after the exposure to 20 ppm SO 2 at 700, 800 and 900 • C for 48 h is two orders of magnitude lower than that of the sample tested in the absence of SO 2 , indicating that sulfur poisoning deteriorates significantly the surface exchange and diffusion processes for the O 2 reduction reaction on LSCF electrodes.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252 Downloaded on 2014-12-11 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252 Downloaded on 2014-12-11 to IP

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Section: Discussionmentioning

confidence: 99%

Sulfur Deposition and Poisoning of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δCathode Materials of Solid Oxide Fuel Cells

Wang

Chen

Jiang

2014

J. Electrochem. Soc.

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“…The three main disadvantages of Srcontaining materials are a) their high values of thermal expansion coefficients (TECs) [12,13], b) they react with zirconia to form SrZrO 3 insulating phase [14] and c) they easily form SrSO 4 insulating phase in the presence of sulfur [15], leading to a degradation of the cell performances.…”

Section: Introductionmentioning

confidence: 99%

La2−Pr NiO4+ as suitable cathodes for metal supported SOFCs

et al. 2015

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Aiming at a tradeoff between the chemical stability of La 2 NiO 4+ δ (LNO) and the high electrochemical performances of Pr 2 NiO 4+ δ (PNO), La 2 − x Pr x NiO 4+ δ mixed nickelates, further referred as LPNO, were studied as possible oxygen electrodes for solid oxide fuel cells (SOFCs). LPNO phases were synthesized using the modified citrate-nitrate route followed by a heat treatment at 1200°C for 12 h under air. Structural characterizations of those K 2 NiF 4 -type compounds show the existence of two solid solutions with orthorhombic structure, namely a La-rich one from x = 0 to 0.5 with Fmmm space group, and a Pr-rich one from x = 1.0 to 2.0 with Bmab space group. The mixed ionic and electronic conducting (MIEC) properties of LPNO phases were investigated through the evolution of the oxygen over-stoichiometry, δ, measured as a function of temperature and pO 2 , the electrical conductivity, the diffusion and surface exchange coefficients versus x, showing that all compositions exhibit suitable characteristics as cathode materials for SOFCs. In particular, the electrochemical performances measured in symmetrical cells using LPNO materials sintered under low pO 2 , as requested in metal supported cell, (MSC-conditions) confirmed a decrease in polarization resistance values, R p , from 0.93 Ω cm 2 (LNO) down to 0.15 Ω cm 2 (PNO) at 600°C with increasing x.

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“…Degradation of LSCF cathodes is induced by impurities in air. One of the most recognized impurities is sulfur dioxide (SO 2 ) [1][2][3][4][5][6][7][8][9][10]. Our group has investigated the degradation behavior of LSCF cathodes induced by SO 2 containing air.…”

Section: Introductionmentioning

confidence: 99%

Degradation of LSCF Cathode Induced by SO₂ in Air

et al. 2015

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Sulfur dioxide (SO 2 ) is one of the major impurities in air and it induces performance degradation of SOFC cathodes. Our group has investigated the degradation behavior of (LaSr)(CoFe)O 3 (LSCF) cathodes by sulfur dioxide (SO 2 ) containing air. It is clearly observed that SO 2 -induced degradation is affected by cell operation conditions, such as impurity concentration and the operating temperature. We observed two degradation steps; one is a rapid degradation rate occurring at an early stage and the other is a constant degradation with relatively slow rate. During progress of degradation, both ohmic resistance, R ohm , and oxygen reduction reaction resistance (polarization resistance), R p , increased. There is a relationship between increasing rates of R p and R ohm in each degradation step.

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Effect of strontium concentration on sulfur poisoning of LSCF cathodes

Cited by 42 publications

References 13 publications

Sulfur Deposition and Poisoning of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δCathode Materials of Solid Oxide Fuel Cells

Sulfur Deposition and Poisoning of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δCathode Materials of Solid Oxide Fuel Cells

La2−Pr NiO4+ as suitable cathodes for metal supported SOFCs

Degradation of LSCF Cathode Induced by SO₂ in Air

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Effect of strontium concentration on sulfur poisoning of LSCF cathodes

Cited by 42 publications

References 13 publications

Sulfur Deposition and Poisoning of La0.6Sr0.4Co0.2Fe0.8O3-δCathode Materials of Solid Oxide Fuel Cells

Sulfur Deposition and Poisoning of La0.6Sr0.4Co0.2Fe0.8O3-δCathode Materials of Solid Oxide Fuel Cells

La2−Pr NiO4+ as suitable cathodes for metal supported SOFCs

Degradation of LSCF Cathode Induced by SO2 in Air

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Sulfur Deposition and Poisoning of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δCathode Materials of Solid Oxide Fuel Cells

Sulfur Deposition and Poisoning of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δCathode Materials of Solid Oxide Fuel Cells

Degradation of LSCF Cathode Induced by SO₂ in Air