Effect of high-temperature ageing on (La,Sr)(Co,Fe)O3-δ cathodes in microtubular solid oxide fuel cells

Hongqian Wang, Hirofumi Sumi, Scott A. Barnett*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Microtubular solid oxide fuel cells with La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathodes were aged in ambient air at temperatures ranging from 700 to 1000 °C for up to 700 h. Distribution of relaxation time analysis of electrochemical impedance spectroscopy (EIS) measurements indicated an increase in the cathode resistance with increasing ageing temperature up to 900 °C. The cells aged at 1000 °C were not measurable. The degradation did not result from microstructural changes, as shown by focused ion beam-scanning electron microscopy (FIB-SEM) 3D tomography that showed no significant changes at ageing temperatures ≤900 °C. On the other hand, the amount of segregated Sr, present both on LSCF surfaces and in Sr-rich particles, increased with increasing ageing temperature and correlated well with the increase in cathode resistance. Analysis of the EIS and microstructural data using the Alder-Lane-Steele model indicates that the Sr surface segregation increases cathode resistance via a decreased oxygen surface exchange rate.

Original languageEnglish (US)
Pages (from-to)85-91
Number of pages7
JournalSolid State Ionics
Volume323
DOIs
StatePublished - Oct 1 2018

Keywords

  • AC impedance
  • Distribution of relaxation time (DRT)
  • Focused ion beam-scanning electron microscopy (FIB-SEM)
  • Perovskite cathode
  • Solid oxide fuel cell (SOFC)

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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