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Title: The Electrochemical Properties of Sr(Ti,Fe)O 3-δ for Anodes in Solid Oxide Fuel Cells

Reduction-stable mixed ionic and electronic conductors such as Sr(Ti,Fe)O 3-δ (STF) are promising materials for application in anodes of solid oxide fuel cells. The defect chemistry of STF and its properties as solid oxide fuel cell (SOFC) cathode have been studied thoroughly, while mechanistic investigations of its electrochemical properties as SOFC anode material are still scarce. In this study, thin film model electrodes of STF with 30% and 70% Fe content were investigated in H 2+H 2O atmosphere by electrochemical impedance spectroscopy. Lithographically patterned thin film Pt current collectors were applied on top or beneath the STF thin films to compensate for the low electronic conductivity under reducing conditions. Oxygen exchange resistances, electronic and ionic conductivities and chemical capacitances were quantified and discussed in a defect chemical model. Increasing Fe content increases the electro-catalytic activity of the STF surface as well as the electronic and ionic conductivity. Current collectors on top also increase the electrochemical activity due to a highly active Pt-atmosphere-STF triple phase boundary. Furthermore, the electrochemical activity depends decisively on the H 2:H 2O mixing ratio and the polarization. Lastly, Fe 0 nanoparticles may evolve on the surface in hydrogen rich atmospheres and increase the hydrogen adsorption rate.
Authors:
 [1] ;  [2] ;  [3] ; ORCiD logo [4] ;  [3] ;  [2]
  1. Federal Inst. of Technology, Zurich (Switzerland). Dept. of Materials
  2. Vienna Univ. of Technology (Austria). Inst. of Chemical Technologies and Analytics
  3. Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering
  4. Comision Nacional de Energia Atomica (CNEA), San Carlos de Bariloche (Argentina). Centro Atomico Bariloche (CAB), Dept. Caracterizacion de Materiales
Publication Date:
Grant/Contract Number:
NA0002135
Type:
Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 164; Journal Issue: 4; Journal ID: ISSN 0013-4651
Publisher:
The Electrochemical Society
Research Org:
Krell Inst., Ames, IA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; anode; defect chemistry; electrochemistry; impedance; mixed conductor; SOFC; solid oxide fuel cell; thin film; triple-phase boundary
OSTI Identifier:
1426161

Nenning, Andreas, Volgger, Lukas, Miller, Elizabeth, Mogni, Liliana V., Barnett, Scott, and Fleig, Jürgen. The Electrochemical Properties of Sr(Ti,Fe)O 3-δ for Anodes in Solid Oxide Fuel Cells. United States: N. p., Web. doi:10.1149/2.1271704jes.
Nenning, Andreas, Volgger, Lukas, Miller, Elizabeth, Mogni, Liliana V., Barnett, Scott, & Fleig, Jürgen. The Electrochemical Properties of Sr(Ti,Fe)O 3-δ for Anodes in Solid Oxide Fuel Cells. United States. doi:10.1149/2.1271704jes.
Nenning, Andreas, Volgger, Lukas, Miller, Elizabeth, Mogni, Liliana V., Barnett, Scott, and Fleig, Jürgen. 2017. "The Electrochemical Properties of Sr(Ti,Fe)O 3-δ for Anodes in Solid Oxide Fuel Cells". United States. doi:10.1149/2.1271704jes. https://www.osti.gov/servlets/purl/1426161.
@article{osti_1426161,
title = {The Electrochemical Properties of Sr(Ti,Fe)O 3-δ for Anodes in Solid Oxide Fuel Cells},
author = {Nenning, Andreas and Volgger, Lukas and Miller, Elizabeth and Mogni, Liliana V. and Barnett, Scott and Fleig, Jürgen},
abstractNote = {Reduction-stable mixed ionic and electronic conductors such as Sr(Ti,Fe)O3-δ (STF) are promising materials for application in anodes of solid oxide fuel cells. The defect chemistry of STF and its properties as solid oxide fuel cell (SOFC) cathode have been studied thoroughly, while mechanistic investigations of its electrochemical properties as SOFC anode material are still scarce. In this study, thin film model electrodes of STF with 30% and 70% Fe content were investigated in H2+H2O atmosphere by electrochemical impedance spectroscopy. Lithographically patterned thin film Pt current collectors were applied on top or beneath the STF thin films to compensate for the low electronic conductivity under reducing conditions. Oxygen exchange resistances, electronic and ionic conductivities and chemical capacitances were quantified and discussed in a defect chemical model. Increasing Fe content increases the electro-catalytic activity of the STF surface as well as the electronic and ionic conductivity. Current collectors on top also increase the electrochemical activity due to a highly active Pt-atmosphere-STF triple phase boundary. Furthermore, the electrochemical activity depends decisively on the H2:H2O mixing ratio and the polarization. Lastly, Fe0 nanoparticles may evolve on the surface in hydrogen rich atmospheres and increase the hydrogen adsorption rate.},
doi = {10.1149/2.1271704jes},
journal = {Journal of the Electrochemical Society},
number = 4,
volume = 164,
place = {United States},
year = {2017},
month = {2}
}