Departmental Papers (CBE)

Document Type

Journal Article

Date of this Version

January 2008


The influence of ionic conductivity on the performance of solid oxide fuel cell cathodes was studied for electrodes prepared by infiltration of 40 wt % La0.8Ca0.2FeO3 (LCF) La0.8Sr0.2FeO3 (LSF) and La0.8Ba0.2FeO3 (LBF) into 65% porous yttria-stabilized zirconia (LSZ). The ionic conductivities of LCF, LSF, and LBF, measured between 923 and 1073 K using permeation rates in a membrane reactor, showed that LSF exhibited the highest ionic conductivities, followed by LBF and LCF. When electrodes were calcined to 1123 K, the performance characteristics of each composite were essentially identical, exhibiting current-independent impedances of 0.2 Ω cm2 at 973 K. When the composites were calcined to 1373 K, the open-circuit impedances were much larger and showed a strong dependence on current density. The open-circuit impedances followed the ionic conductivities, with LSF– YSZ electrodes showing the lowest impedance and LCF–YSZ electrodes the highest. Scanning electron microscopy images and Brunauer–Emmett–Teller surface areas indicate that calcination at 1373 K causes the perovskites to form dense layers over the YSZ pores. A model is proposed in which diffusion of ions through the perovskite film limits the performance of the composite electrodes calcined at 1373 K.


Copyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. Reprinted in Journal of the Electrochemical Society, Volume 155, Issue 7, March 2008, pages B660-B665.
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Date Posted: 24 June 2008

This document has been peer reviewed.