Study of La0.6Sr0.4Co1-xFexO3-δ (x = 0.2 & 0.8) Electrochemical Response as SOFC Cathodes and Its Relation with Microstructure

J. Ascolani-Yael; A. Montenegro-Hernández; Q. Liu; S. A. Barnett; L. Mogni

doi:10.1149/2.0281916jes

Study of La_0.6Sr_0.4Co_1-xFe_xO_3-δ (x = 0.2 & 0.8) Electrochemical Response as SOFC Cathodes and Its Relation with Microstructure

J. Ascolani-Yael, A. Montenegro-Hernández, Q. Liu, S. A. Barnett, L. Mogni

Materials Science and Engineering

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

8 Scopus citations

Abstract

This work presents the study of the O₂-Reduction Reaction (ORR) by electrochemical impedance spectroscopy of La_0.6Sr_0.4Co_0.8Fe_0.2O_3-δ and La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ cathodes as a function of temperature and pO₂. The combination of the impedance data, modeled with a Transmission Line Model, with the microstructural data obtained by FIB-SEM tomography, allowed to obtain and compare the chemical diffusion coefficients (D_chem), O₂ equilibrium molar exchange rates (R₀) and the oxygen surface exchange rates (k_chem) for both compounds. The obtained values were, at 700°C in air, D_chem = 5.4.10^-7 cm² .s^-1 and k_chem = 1.4.10^-6 cm. s^-1 for La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ, while D_chem = 2.6.10^-6 cm² .s^-1 and k_chem = 3.1.10^-6 cm. s^-1 were obtained for La_0.6Sr_0.4Co_0.8Fe_0.2O_3-δ. The detailed analysis of these parameters as a function of pO₂ (10^-4 < pO₂ ≤ 1) and temperature (500°C ≤ T ≤ 700°C) by means of the Adler-Lane-Steele model, adapted to a finite length porous electrode, allowed identifying the O-ion diffusion and surface exchange as processes co-limiting the ORR. From this analysis, a predominantly surface limited ORR was found for La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ, changing to a more bulk limited ORR for La_0.6Sr_0.4Co_0.8Fe_0.2O_3-δ, which has higher oxygen-vacancy concentration.

Original language	English (US)
Pages (from-to)	F1301-F1307
Journal	Journal of the Electrochemical Society
Volume	166
Issue number	16
DOIs	https://doi.org/10.1149/2.0281916jes
State	Published - 2019

Funding

The authors at Centro Atómico Bariloche aknowledge Alberto Baruj for the SEM images, the financial support of Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Agencia Nacional de Promoción de Ciencia y Tecnología (AGNPCyT ANPCyT PICT 2016-2965) and Instituto Balseiro-Universidad Nacional de Cuyo. J. Ascolani-Yael is especially grateful to the Fulbright Program. The authors at North-western University gratefully acknowledge financial support from the National Science Foundation Ceramics program DMR-1912530. The authors at Centro Atómico Bariloche aknowledge Alberto Baruj for the SEMimages, the financial support of Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Agencia Nacional de Promoción de Ciencia y Tecnología (AGNPCyT ANPCyT PICT 2016-2965) and Instituto Balseiro-Universidad Nacional de Cuyo. J. Ascolani-Yael is especially grateful to the Fulbright Program. The authors at Northwestern University gratefully acknowledge financial support from the National Science Foundation Ceramics program DMR-1912530.

ASJC Scopus subject areas

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

UN SDGs

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

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10.1149/2.0281916jes

Cite this

@article{6b8dc59d160d43d4b6f52ef6e222b003,

title = "Study of La0.6Sr0.4Co1-xFexO3-δ (x = 0.2 & 0.8) Electrochemical Response as SOFC Cathodes and Its Relation with Microstructure",

abstract = "This work presents the study of the O2-Reduction Reaction (ORR) by electrochemical impedance spectroscopy of La0.6Sr0.4Co0.8Fe0.2O3-δ and La0.6Sr0.4Co0.2Fe0.8O3-δ cathodes as a function of temperature and pO2. The combination of the impedance data, modeled with a Transmission Line Model, with the microstructural data obtained by FIB-SEM tomography, allowed to obtain and compare the chemical diffusion coefficients (Dchem), O2 equilibrium molar exchange rates (R0) and the oxygen surface exchange rates (kchem) for both compounds. The obtained values were, at 700°C in air, Dchem = 5.4.10-7 cm2 .s-1 and kchem = 1.4.10-6 cm. s-1 for La0.6Sr0.4Co0.2Fe0.8O3-δ, while Dchem = 2.6.10-6 cm2 .s-1 and kchem = 3.1.10-6 cm. s-1 were obtained for La0.6Sr0.4Co0.8Fe0.2O3-δ. The detailed analysis of these parameters as a function of pO2 (10-4 < pO2 ≤ 1) and temperature (500°C ≤ T ≤ 700°C) by means of the Adler-Lane-Steele model, adapted to a finite length porous electrode, allowed identifying the O-ion diffusion and surface exchange as processes co-limiting the ORR. From this analysis, a predominantly surface limited ORR was found for La0.6Sr0.4Co0.2Fe0.8O3-δ, changing to a more bulk limited ORR for La0.6Sr0.4Co0.8Fe0.2O3-δ, which has higher oxygen-vacancy concentration.",

author = "J. Ascolani-Yael and A. Montenegro-Hern{\'a}ndez and Q. Liu and Barnett, {S. A.} and L. Mogni",

note = "Publisher Copyright: {\textcopyright} 2019 The Electrochemical Society.",

year = "2019",

doi = "10.1149/2.0281916jes",

language = "English (US)",

volume = "166",

pages = "F1301--F1307",

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T1 - Study of La0.6Sr0.4Co1-xFexO3-δ (x = 0.2 & 0.8) Electrochemical Response as SOFC Cathodes and Its Relation with Microstructure

AU - Ascolani-Yael, J.

AU - Montenegro-Hernández, A.

AU - Liu, Q.

AU - Barnett, S. A.

AU - Mogni, L.

PY - 2019

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N2 - This work presents the study of the O2-Reduction Reaction (ORR) by electrochemical impedance spectroscopy of La0.6Sr0.4Co0.8Fe0.2O3-δ and La0.6Sr0.4Co0.2Fe0.8O3-δ cathodes as a function of temperature and pO2. The combination of the impedance data, modeled with a Transmission Line Model, with the microstructural data obtained by FIB-SEM tomography, allowed to obtain and compare the chemical diffusion coefficients (Dchem), O2 equilibrium molar exchange rates (R0) and the oxygen surface exchange rates (kchem) for both compounds. The obtained values were, at 700°C in air, Dchem = 5.4.10-7 cm2 .s-1 and kchem = 1.4.10-6 cm. s-1 for La0.6Sr0.4Co0.2Fe0.8O3-δ, while Dchem = 2.6.10-6 cm2 .s-1 and kchem = 3.1.10-6 cm. s-1 were obtained for La0.6Sr0.4Co0.8Fe0.2O3-δ. The detailed analysis of these parameters as a function of pO2 (10-4 < pO2 ≤ 1) and temperature (500°C ≤ T ≤ 700°C) by means of the Adler-Lane-Steele model, adapted to a finite length porous electrode, allowed identifying the O-ion diffusion and surface exchange as processes co-limiting the ORR. From this analysis, a predominantly surface limited ORR was found for La0.6Sr0.4Co0.2Fe0.8O3-δ, changing to a more bulk limited ORR for La0.6Sr0.4Co0.8Fe0.2O3-δ, which has higher oxygen-vacancy concentration.

AB - This work presents the study of the O2-Reduction Reaction (ORR) by electrochemical impedance spectroscopy of La0.6Sr0.4Co0.8Fe0.2O3-δ and La0.6Sr0.4Co0.2Fe0.8O3-δ cathodes as a function of temperature and pO2. The combination of the impedance data, modeled with a Transmission Line Model, with the microstructural data obtained by FIB-SEM tomography, allowed to obtain and compare the chemical diffusion coefficients (Dchem), O2 equilibrium molar exchange rates (R0) and the oxygen surface exchange rates (kchem) for both compounds. The obtained values were, at 700°C in air, Dchem = 5.4.10-7 cm2 .s-1 and kchem = 1.4.10-6 cm. s-1 for La0.6Sr0.4Co0.2Fe0.8O3-δ, while Dchem = 2.6.10-6 cm2 .s-1 and kchem = 3.1.10-6 cm. s-1 were obtained for La0.6Sr0.4Co0.8Fe0.2O3-δ. The detailed analysis of these parameters as a function of pO2 (10-4 < pO2 ≤ 1) and temperature (500°C ≤ T ≤ 700°C) by means of the Adler-Lane-Steele model, adapted to a finite length porous electrode, allowed identifying the O-ion diffusion and surface exchange as processes co-limiting the ORR. From this analysis, a predominantly surface limited ORR was found for La0.6Sr0.4Co0.2Fe0.8O3-δ, changing to a more bulk limited ORR for La0.6Sr0.4Co0.8Fe0.2O3-δ, which has higher oxygen-vacancy concentration.

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