Overcoming phase instability of RBaCo2O5+δ (R = y and Ho) by Sr substitution for application as cathodes in solid oxide fuel cells

Jung Hyun Kim, Young Nam Kim, Zhonghe Bi, Arumugam Manthiram, M. Parans Paranthaman, Ashfia Huq

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26 Scopus citations

Abstract

Phase instabilities of the RBaCo2O5+δ (R = Y and Ho) layered-perovskites and their decompositions into RCoO3 and BaCoO3-z at 800 C in air were investigated. The phase instability will restrict their high temperature applications such as cathodes in solid oxide fuel cells (SOFC). However, appropriate amount of Sr substitution (≥ 60% for R = Y and ≥ 70% for R = Ho) for Ba successfully stabilized the R(Ba1-xSrx)Co2O5+δ phase at elevated temperatures. This can be explained to be due to the decrease in oxygen vacancies in the R-O layer, decrease in RO bond length, and consequent improvement in structural integrity. In addition, the Sr substitution (x = 0.6-1.0) for Ba provided added benefit with respect to the chemical stability against Ce0.8Gd0.2O1.9 (GDC) electrolyte, which is a critical requirement for the cathodes in SOFC. Among the various compositions investigated, the Y(Ba0.3Sr0.7)Co 2O5+δ + GDC composite cathode delivered the optimum electrochemical performances with a stable phase, demonstrating the potential as a cathode in SOFC.

Original languageEnglish
Pages (from-to)81-87
Number of pages7
JournalSolid State Ionics
Volume253
DOIs
StatePublished - 2013

Funding

This work was sponsored by the Laboratory Directed Research and Development (LDRD) Program of Oak Ridge National Laboratory (ORNL) . Jung-Hyun Kim and Zhonghe Bi acknowledge the support of the ORISE postdoctoral fellowship . Support (MPP) for electrochemical measurements was provided by Office of Basic Energy Sciences, Materials Sciences and Engineering Division, US Department of Energy . The authors would also like to thank Andrew E. Payzant of Neutron Scattering Science Division in ORNL for supporting XRD measurements. Financial and technical supports by Spallation Neutron Source, ORNL SHaRE user facility, and Center for Nanophase Materials Sciences which are sponsored by the Division of Scientific User Facilities, Office of Basic Energy Sciences, US Department of Energy , under contract DE-AC05-00OR22725 with UT-Battelle, LLC, are gratefully acknowledged. Financial support by the Welch Foundation grant F-1254 for the work carried out at the University of Texas at Austin is gratefully acknowledged by Young Nam Kim and Arumugam Manthiram.

FundersFunder number
Center for Nanophase Materials Sciences
Division of Scientific User Facilities
Office of Basic Energy Sciences
US Department of EnergyDE-AC05-00OR22725
Young Nam Kim and Arumugam Manthiram
Welch FoundationF-1254
Oak Ridge National Laboratory
Laboratory Directed Research and Development

    Keywords

    • HoBaCoO
    • Layered perovskite cathode
    • Phase decomposition
    • Solid oxide fuel cells
    • YBaCoO

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