Nonlinear Impedance Analysis of La0.4Sr0.6Co0.2Fe0.8O3-δ Thin Film Oxygen Electrodes
Abstract
Here, linear and nonlinear electrochemical impedance spectroscopy (EIS, NLEIS) were used to study 20 nm thin film La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF-6428) electrodes at 600°C in oxygen environments. LSCF films were epitaxially deposited on single crystal yttria-stabilized zirconia (YSZ) with a 5 nm gadolinium-doped ceria (GDC) protective interlayer. Impedance measurements reveal an oxygen storage capacity similar to independent thermogravimetry measurements on semi-porous pellets. However, the impedance data fail to obey a homogeneous semiconductor point-defect model. Two consistent scenarios were considered: a homogeneous film with non-ideal thermodynamics (constrained by thermogravimetry measurements), or an inhomogeneous film (constrained by a semiconductor point-defect model with a Sr maldistribution). The latter interpretation suggests that gradients in Sr composition would have to extend beyond the space-charge region of the gas-electrode interface. While there is growing evidence supporting an equilibrium Sr segregation at the LSCF surface monolayer, a long-range, non-equilibrium Sr stratification caused by electrode processing conditions offers a possible explanation for the large volume of highly reducible LSCF. Additionally, all thin films exhibited fluctuations in both linear and nonlinear impedance over the hundred-hour measurement period. This behavior is inconsistent with changes solely in the surface rate coefficient and possibly caused by variations in the surface thermodynamics over exposure time.
- Authors:
-
- Univ. of Washington, Seattle, WA (United States). Dept. of Chemical Engineering
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Mechanical Engineering
- Publication Date:
- Research Org.:
- Univ. of Washington, Seattle, WA (United States); National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division; USDOE Office of Fossil Energy (FE); Tohoku Univ., Sendai (Japan)
- OSTI Identifier:
- 1438528
- Grant/Contract Number:
- FE0009435; CNMS2013-292
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Journal of the Electrochemical Society
- Additional Journal Information:
- Journal Volume: 163; Journal Issue: 9; Journal ID: ISSN 0013-4651
- Publisher:
- The Electrochemical Society
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; impedance spectroscopy; perovskite; SOEC; SOFC; thin film
Citation Formats
Geary, Tim C., Lee, Dongkyu, Shao-Horn, Yang, and Adler, Stuart B.. Nonlinear Impedance Analysis of La0.4Sr0.6Co0.2Fe0.8O3-δ Thin Film Oxygen Electrodes. United States: N. p., 2016.
Web. doi:10.1149/2.0851609jes.
Geary, Tim C., Lee, Dongkyu, Shao-Horn, Yang, & Adler, Stuart B.. Nonlinear Impedance Analysis of La0.4Sr0.6Co0.2Fe0.8O3-δ Thin Film Oxygen Electrodes. United States. https://doi.org/10.1149/2.0851609jes
Geary, Tim C., Lee, Dongkyu, Shao-Horn, Yang, and Adler, Stuart B.. Sat .
"Nonlinear Impedance Analysis of La0.4Sr0.6Co0.2Fe0.8O3-δ Thin Film Oxygen Electrodes". United States. https://doi.org/10.1149/2.0851609jes. https://www.osti.gov/servlets/purl/1438528.
@article{osti_1438528,
title = {Nonlinear Impedance Analysis of La0.4Sr0.6Co0.2Fe0.8O3-δ Thin Film Oxygen Electrodes},
author = {Geary, Tim C. and Lee, Dongkyu and Shao-Horn, Yang and Adler, Stuart B.},
abstractNote = {Here, linear and nonlinear electrochemical impedance spectroscopy (EIS, NLEIS) were used to study 20 nm thin film La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF-6428) electrodes at 600°C in oxygen environments. LSCF films were epitaxially deposited on single crystal yttria-stabilized zirconia (YSZ) with a 5 nm gadolinium-doped ceria (GDC) protective interlayer. Impedance measurements reveal an oxygen storage capacity similar to independent thermogravimetry measurements on semi-porous pellets. However, the impedance data fail to obey a homogeneous semiconductor point-defect model. Two consistent scenarios were considered: a homogeneous film with non-ideal thermodynamics (constrained by thermogravimetry measurements), or an inhomogeneous film (constrained by a semiconductor point-defect model with a Sr maldistribution). The latter interpretation suggests that gradients in Sr composition would have to extend beyond the space-charge region of the gas-electrode interface. While there is growing evidence supporting an equilibrium Sr segregation at the LSCF surface monolayer, a long-range, non-equilibrium Sr stratification caused by electrode processing conditions offers a possible explanation for the large volume of highly reducible LSCF. Additionally, all thin films exhibited fluctuations in both linear and nonlinear impedance over the hundred-hour measurement period. This behavior is inconsistent with changes solely in the surface rate coefficient and possibly caused by variations in the surface thermodynamics over exposure time.},
doi = {10.1149/2.0851609jes},
journal = {Journal of the Electrochemical Society},
number = 9,
volume = 163,
place = {United States},
year = {Sat Jul 23 00:00:00 EDT 2016},
month = {Sat Jul 23 00:00:00 EDT 2016}
}
Web of Science
Works referenced in this record:
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Works referencing / citing this record:
Analyzing the dependence of oxygen incorporation current density on overpotential and oxygen partial pressure in mixed conducting oxide electrodes
journal, January 2017
- Guan, Zixuan; Chen, Di; Chueh, William C.
- Physical Chemistry Chemical Physics, Vol. 19, Issue 34
Controlling the Oxygen Electrocatalysis on Perovskite and Layered Oxide Thin Films for Solid Oxide Fuel Cell Cathodes
journal, March 2019
- Yang, Gene; Jung, Wonsang; Ahn, Sung-Jin
- Applied Sciences, Vol. 9, Issue 5
Controlling Oxygen Mobility in Ruddlesden–Popper Oxides
journal, March 2017
- Lee, Dongkyu; Lee, Ho
- Materials, Vol. 10, Issue 4