Chromium Poisoning of LSM/YSZ and LSCF/CGO Composite Cathodes

Bentzen, Janet Jonna; Høgh, Jens Valdemar Thorvald; Barfod, Rasmus

doi:10.1002/fuce.200800143

Cited by 72 publications

(46 citation statements)

References 11 publications

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“…in the case of the LSM [5] or (La, Sr)(Co,Fe)O 3 -(Ce,Sm)O 2 (LSCF-CSO) composites (1.2 eV-2 eV) [26]. The results of polarization resistances for STF mixed conductor cathode are between pure electronic conductors like LSM and mixed conductors based on composites, e. g. LSCF-(Ce,Gd)O 2 system [27] or state-of-the-art (Ba,Sr) (Co,Fe)O 3 (BSCF) [28]. For pure LSM on YSZ an ASR of 3.5 Ωcm 2 at 750ºC was obtained [29], while for LSCF on YSZ an ASR of~0.1 Ωcm 2 was obtained at the same temperature [30].…”

Section: Resultsmentioning

confidence: 96%

Structural and electrical properties of Sr(Ti, Fe)O3-δ materials for SOFC cathodes

et al. 2012

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Doped strontium titanates are very versatile materials. Iron doped SrTiO 3 can be used, for example, as a material for resistive gas sensors and fuel cell electrodes. In this paper, two compositions based on Fe doped SrTiO 3 were studied as possible candidates for cathode application in SOFCs. Namely, SrTi 0.65 Fe 0.35 O 3 and SrTi 0.50 Fe 0.50 O 3 were examined. A chemical reactivity between electrode and YSZ electrolyte material was investigated, since Sr containing cathode materials in contact with YSZ electrolyte are prone to form insulating phases. Electrical conductivity of bulk samples showed relatively low total conductivities of 0.4 S cm −1 and~2 S cm −1 for STF35 and STF50 respectively. Suitability for cathode application was studied by Electrochemical Impedance Spectroscopy in a symmetrical electrode configuration. Area specific resistance (ASR) was determined in the temperature range from 600°C to 800°C. At 790°C samples show polarization ASR of approximately 0.1Ω cm 2 . It can be expected that further reduction of electrode ASR can be obtained by introduction of ceria barrier layer and tailoring of the electrode microstructure.

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Section: Resultsmentioning

confidence: 96%

Structural and electrical properties of Sr(Ti, Fe)O3-δ materials for SOFC cathodes

et al. 2012

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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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“…Taniguchi et al reported that Cr moves to cathode/electrolyte interface by cathodic current, and cathode polarization increases in correlation with the intensity of chromium at the interface. 8 Konysheva et al 9 and Bentzen et al 10 observed that Cr-containing deposits can fill up the pores close to the cathode/electrolyte interface and extend into the bulk cathode. Krumpelt et al found that both the amount of Cr deposition and the rate of performance degradation increase with increasing current density.…”

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confidence: 99%

Chromium Poisoning Effects on Performance of (La,Sr)MnO₃-Based Cathode in Anode-Supported Solid Oxide Fuel Cells

Wang

Pal

Gopalan

et al. 2017

J. Electrochem. Soc.

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Chromium (Cr) vapor species from chromia-forming alloy interconnects are known to cause cathode performance degradation in solid oxide fuel cells (SOFCs). To understand the impact of Cr-poisoning on cathode performance, it is important to determine its effects on different cathode polarization losses. In this study, anode-supported SOFCs, with a (La,Sr)MnO 3 (LSM) + yttria-stabilized zirconia (YSZ) cathode active layer and a LSM cathode current collector layer were fabricated. At 800 • C, cells were electrochemically tested in direct contact with Crofer22H meshes, under different cathode atmospheres (dry air or humidified air) and current conditions (open-circuit or galvanostatic). Significant performance degradation was observed when cell was tested under galvanostatic condition (0.5 A/cm 2 ), which was not the case under open-circuit condition. Humidity was found to accelerate the performance degradation. By curve-fitting the experimentally measured current-voltage traces to a polarization model, the effects of Cr-poisoning on different cathodic polarization losses were estimated. It is found that, under normal operating conditions, increase of activation polarization dominates the cathode performance degradation. Microstructures of the cathodes were characterized and Cr-containing deposits were identified. Higher concentrations of Cr-containing deposits were found at the cathode/electrolyte interface and the amounts directly correlated with the cell performance degradations. Performance degradation during long-term operation is one of the major challenges that needs to be overcome for successful commercialization of solid oxide fuel cells (SOFCs).1-3 At SOFC operating temperature, chromium (Cr) vapor species that evaporate over chromia-forming alloy interconnect, can transport and deposit within the cathode and thereupon cause degradation of the cathode performance. [4][5][6][7] Cr-poisoning has been studied extensively on (La,Sr)MnO 3 (LSM)-based cathode. Taniguchi et al. reported that Cr moves to cathode/electrolyte interface by cathodic current, and cathode polarization increases in correlation with the intensity of chromium at the interface.8 Konysheva et al. 9 and Bentzen et al. 10observed that Cr-containing deposits can fill up the pores close to the cathode/electrolyte interface and extend into the bulk cathode. Krumpelt et al. found that both the amount of Cr deposition and the rate of performance degradation increase with increasing current density. 11For understanding the effects of Cr-poisoning on the cathode performance, it is important to identify what is the most affected cathode process, namely, the nature of the polarization loss in the cathode. To separate the contributions of various polarization losses, deconvolution of the impedance spectra data into equivalent circuit model is usually performed.12,13 Matsuzaki and Yasuda analyzed the impedance spectra using a Randles-type equivalent circuit and found that both charge transfer and surface diffusion resistance increased due to Cr-poisoning....

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Chromium Poisoning of LSM/YSZ and LSCF/CGO Composite Cathodes

Cited by 72 publications

References 11 publications

Structural and electrical properties of Sr(Ti, Fe)O3-δ materials for SOFC cathodes

Structural and electrical properties of Sr(Ti, Fe)O3-δ materials for SOFC cathodes

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

Chromium Poisoning Effects on Performance of (La,Sr)MnO₃-Based Cathode in Anode-Supported Solid Oxide Fuel Cells

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Chromium Poisoning of LSM/YSZ and LSCF/CGO Composite Cathodes

Cited by 72 publications

References 11 publications

Structural and electrical properties of Sr(Ti, Fe)O3-δ materials for SOFC cathodes

Structural and electrical properties of Sr(Ti, Fe)O3-δ materials for SOFC cathodes

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

Chromium Poisoning Effects on Performance of (La,Sr)MnO3-Based Cathode in Anode-Supported Solid Oxide Fuel Cells

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Chromium Poisoning Effects on Performance of (La,Sr)MnO₃-Based Cathode in Anode-Supported Solid Oxide Fuel Cells