Degradation mechanisms of porous La                         0.6                         Sr                         0.4                         Co                         0.2                         Fe                         0.8                         O3-δ solid oxide fuel cell cathodes

Hongqian Wang; Scott A. Barnett

doi:10.1149/2.1211807jes

Degradation mechanisms of porous La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O3-δ solid oxide fuel cell cathodes

Hongqian Wang, Scott A. Barnett

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

35 Scopus citations

Abstract

La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O3-δ (LSCF) symmetric-electrode cells with Gd0.1Ce0.9O1.95 (GDC) electrolytes were aged in ambient air at temperatures ranging from 550 to 950°C for times up to 1400 h, without current/polarization. Electrochemical impedance spectroscopy measurements, taken periodically during the tests at a testing temperature of 700°C for cells aged at 700, 750 and 800°C, showed a continuous increase in polarization resistance. Focused ion beam-scanning electron microscopy (FIB-SEM) 3D tomography showed that the LSCF electrode did not coarsen measurably at ageing temperatures ≤ 800°C, ruling out LSCF microstructural changes as the mechanism behind the resistance increase. On the other hand, Sr surface segregation, determined by chemical etching with inductively coupled plasma-optical emission spectrometry (ICP-OES) detection, was found to increase with increasing ageing time and temperature > 650°C. The effect of Sr surface segregation on the oxygen surface exchange and diffusion processes is quantified by comparing the measured electrochemical and microstructural data.

Original language	English (US)
Pages (from-to)	F564-F570
Journal	Journal of the Electrochemical Society
Volume	165
Issue number	7
DOIs	https://doi.org/10.1149/2.1211807jes
State	Published - 2018

Funding

The authors gratefully acknowledge financial support by the US National Science Foundation grant # DMR-1506925. The authors also acknowledge the assistance of the Electron Probe Instrumentation Center (EPIC) at the NUANCE Center-Northwestern University, which has received support from the soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. The metal analysis was performed at the Northwestern University Quantitative Bio-element Imaging Center.

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Renewable Energy, Sustainability and the Environment
Condensed Matter Physics
Surfaces, Coatings and Films
Electrochemistry
Materials Chemistry

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1149/2.1211807jes

Cite this

Wang, H., & Barnett, S. A. (2018). Degradation mechanisms of porous La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O3-δ solid oxide fuel cell cathodes Journal of the Electrochemical Society, 165(7), F564-F570. https://doi.org/10.1149/2.1211807jes

Wang, Hongqian ; Barnett, Scott A. / Degradation mechanisms of porous La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O3-δ solid oxide fuel cell cathodes In: Journal of the Electrochemical Society. 2018 ; Vol. 165, No. 7. pp. F564-F570.

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title = " Degradation mechanisms of porous La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-δ solid oxide fuel cell cathodes ",

abstract = " La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-δ (LSCF) symmetric-electrode cells with Gd0.1Ce0.9O1.95 (GDC) electrolytes were aged in ambient air at temperatures ranging from 550 to 950°C for times up to 1400 h, without current/polarization. Electrochemical impedance spectroscopy measurements, taken periodically during the tests at a testing temperature of 700°C for cells aged at 700, 750 and 800°C, showed a continuous increase in polarization resistance. Focused ion beam-scanning electron microscopy (FIB-SEM) 3D tomography showed that the LSCF electrode did not coarsen measurably at ageing temperatures ≤ 800°C, ruling out LSCF microstructural changes as the mechanism behind the resistance increase. On the other hand, Sr surface segregation, determined by chemical etching with inductively coupled plasma-optical emission spectrometry (ICP-OES) detection, was found to increase with increasing ageing time and temperature > 650°C. The effect of Sr surface segregation on the oxygen surface exchange and diffusion processes is quantified by comparing the measured electrochemical and microstructural data.",

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Wang, H & Barnett, SA 2018, ' Degradation mechanisms of porous La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O3-δ solid oxide fuel cell cathodes ', Journal of the Electrochemical Society, vol. 165, no. 7, pp. F564-F570. https://doi.org/10.1149/2.1211807jes

Degradation mechanisms of porous La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O3-δ solid oxide fuel cell cathodes . / Wang, Hongqian; Barnett, Scott A.
In: Journal of the Electrochemical Society, Vol. 165, No. 7, 2018, p. F564-F570.

Research output: Contribution to journal › Article › peer-review

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AB - La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-δ (LSCF) symmetric-electrode cells with Gd0.1Ce0.9O1.95 (GDC) electrolytes were aged in ambient air at temperatures ranging from 550 to 950°C for times up to 1400 h, without current/polarization. Electrochemical impedance spectroscopy measurements, taken periodically during the tests at a testing temperature of 700°C for cells aged at 700, 750 and 800°C, showed a continuous increase in polarization resistance. Focused ion beam-scanning electron microscopy (FIB-SEM) 3D tomography showed that the LSCF electrode did not coarsen measurably at ageing temperatures ≤ 800°C, ruling out LSCF microstructural changes as the mechanism behind the resistance increase. On the other hand, Sr surface segregation, determined by chemical etching with inductively coupled plasma-optical emission spectrometry (ICP-OES) detection, was found to increase with increasing ageing time and temperature > 650°C. The effect of Sr surface segregation on the oxygen surface exchange and diffusion processes is quantified by comparing the measured electrochemical and microstructural data.

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Wang H, Barnett SA. Degradation mechanisms of porous La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O3-δ solid oxide fuel cell cathodes Journal of the Electrochemical Society. 2018;165(7):F564-F570. doi: 10.1149/2.1211807jes