Degradation mechanisms of porous La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-δ solid oxide fuel cell cathodes

Hongqian Wang, Scott A. Barnett

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-δ (LSCF) symmetric-electrode cells with Gd0.1Ce0.9O1.95 (GDC) electrolytes were aged in ambient air at temperatures ranging from 550 to 950°C for times up to 1400 h, without current/polarization. Electrochemical impedance spectroscopy measurements, taken periodically during the tests at a testing temperature of 700°C for cells aged at 700, 750 and 800°C, showed a continuous increase in polarization resistance. Focused ion beam-scanning electron microscopy (FIB-SEM) 3D tomography showed that the LSCF electrode did not coarsen measurably at ageing temperatures ≤ 800°C, ruling out LSCF microstructural changes as the mechanism behind the resistance increase. On the other hand, Sr surface segregation, determined by chemical etching with inductively coupled plasma-optical emission spectrometry (ICP-OES) detection, was found to increase with increasing ageing time and temperature > 650°C. The effect of Sr surface segregation on the oxygen surface exchange and diffusion processes is quantified by comparing the measured electrochemical and microstructural data.

Original languageEnglish (US)
Pages (from-to)F564-F570
JournalJournal of the Electrochemical Society
Volume165
Issue number7
DOIs
StatePublished - Jan 1 2018

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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