The efficiency of solid oxide fuel cells depends strongly on the oxygen reduction reaction (ORR) rate on the cathode. Recent studies have suggested that large enhancements in defect thermokinetics and catalytic rates may be possible through use of epitaxially strained materials. Using ab-initio methods to simulate defect energetics under epitaxial strain, we quantify the effects of strain on oxygen stoichiometry in La_(1-x)Sr_xCoO_(3-δ) (x=0.125) thin-films. We find at most a 2-3 fold increase in the vacancy concentration (at near 1000K) compared to bulk LSC over the range of strains from -2% (compressive) to about 4% (tensile). The results of this study suggest that epitaxial strain alone has a relatively weak effect of LSC oxygen vacancy concentration under SOFC conditions.
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