skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: First principles study of Cr poisoning in solid oxide fuel cell cathodes: Application to (La,Sr) CoO 3

Authors:
; ; ;
Publication Date:
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1397662
Grant/Contract Number:
FE-0009682
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Computational Materials Science
Additional Journal Information:
Journal Volume: 137; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 21:41:10; Journal ID: ISSN 0927-0256
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English

Citation Formats

Krishnan, Sridevi, Mahapatra, Manoj K., Singh, Prabhakar, and Ramprasad, Rampi. First principles study of Cr poisoning in solid oxide fuel cell cathodes: Application to (La,Sr) CoO 3. Netherlands: N. p., 2017. Web. doi:10.1016/j.commatsci.2017.04.020.
Krishnan, Sridevi, Mahapatra, Manoj K., Singh, Prabhakar, & Ramprasad, Rampi. First principles study of Cr poisoning in solid oxide fuel cell cathodes: Application to (La,Sr) CoO 3. Netherlands. doi:10.1016/j.commatsci.2017.04.020.
Krishnan, Sridevi, Mahapatra, Manoj K., Singh, Prabhakar, and Ramprasad, Rampi. 2017. "First principles study of Cr poisoning in solid oxide fuel cell cathodes: Application to (La,Sr) CoO 3". Netherlands. doi:10.1016/j.commatsci.2017.04.020.
@article{osti_1397662,
title = {First principles study of Cr poisoning in solid oxide fuel cell cathodes: Application to (La,Sr) CoO 3},
author = {Krishnan, Sridevi and Mahapatra, Manoj K. and Singh, Prabhakar and Ramprasad, Rampi},
abstractNote = {},
doi = {10.1016/j.commatsci.2017.04.020},
journal = {Computational Materials Science},
number = C,
volume = 137,
place = {Netherlands},
year = 2017,
month = 9
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on May 21, 2018
Publisher's Accepted Manuscript

Save / Share:
  • The modification of the Mn charge-state, chemical composition and electronic structure of La0.8Sr0.2MnO3 (LSMO) cathodes for solid oxide fuel cell (SOFC) applications remains an area of interest, due to the poorly understood enhanced catalytic activity (often referred to as the "burn-in" phenomenon) observed after many hours of operation. Using a combination of core-level X-ray photoemission spectroscopy (XPS), X-ray emission/absorption spectroscopy (XES/XAS), resonant inelastic X-ray scattering (RIXS) and resonant photoemission spectroscopy (RPES), we have monitored the evolution of these properties in LSMO at various stages of fabrication and operation. By rapidly quenching and sealing in vacuum, we were able to directlymore » compare the pristine (as-fabricated) LSMO with both "heat-treated" (800°C in air, and no bias) and "burnt-in" (800°C in air, -1 V bias) LSMO cathodes i.e. before and after the activation observed in our electrochemical impendence spectroscopy measurements. Comparison between the O K-edge XAS/XES and Mn L3,2-edge XAS of pristine and “burnt-in” LSMO cathodes revealed a severe change in the oxygen environment along with a reduced Mn2+ presence near the surface following activation. The change in the oxygen environment is attributed to SrxMnyOz formation, along with possible passive SrO and Mn3O4 species. We present evidence from our “heat-treated” samples that SrxMnyOz regions form at elevated temperatures in air before the application of a cathodic bias. Our core-level XPS, Mn L3,2-edge RIXS and Mn L3 RPES studies of “heat-treated” and pristine LSMO determined that SOFC environments result in La-deficiency (severest near the surface) and stronger Mn4+ contribution, leading to the increased insulating character of the cathode prior to activation. The passive Mn2+ species near the surface and increased hole-doping (>0.6) of the LSMO upon exposure to the operating environment are considered responsible for the initially poor performance of the SOFC. Meanwhile, the improved oxygen reduction following the application of a cathodic bias is considered to be due to enhanced bulk oxygen-ion diffusion resulting from the migration of Mn2+ ions towards the LSMO/electrolyte interface and the SrxMnyOz regions facilitating enhanced bulk oxygen reduction reaction kinetics.« less
  • The evolution of the Mn charge state, chemical composition, and electronic structure of La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSMO) cathodes during the catalytic activation of solid oxide fuel cell (SOFC) has been studies using X-ray spectroscopy of as-processed, exposed, and activated dense thin LSMO films. Comparison of O K-edge and Mn L{sub 3,2}-edge X-ray absorption spectra from the different stages of LSMO cathodes revealed that the largest change after the activation occurred in the Mn charge state with little change in the oxygen environment. Core-level X-ray photoemission spectroscopy and Mn L{sub 3} resonant photoemission spectroscopy studies of exposed and as-processed LSMOmore » determined that the SOFC environment (800 C ambient pressure of O{sub 2}) alone results in La deficiency (severest near the surface with Sr doping >0.55) and a stronger Mn{sup 4+} contribution, leading to the increased insulating character of the cathode prior to activation. Meanwhile, O K-edge X-ray absorption measurements support Sr/La enrichment nearer the surface, along with the formation of mixed Sr{sub x}Mn{sub y}O{sub z} and/or passive MnO{sub x} and SrO species.« less