Solid oxide fuel cells (SOFCs) have potential for efficiently and cleanly generating electrical power.  The goal of reducing SOFC operating temperatures has led many authors to propose mixed ion-electron conductors (MIECs) for improving the oxygen reduction reaction (ORR) kinetics at the cathode.  The baseline MIEC is La1-xSrxCo1-yFeyO3 (LSCF) which has been shown to be a reasonable cathode for intermediate temperature SOFCs.We present an ab initio DFT+U study of oxygen diffusion in La1-xSrxFeO3 and La1-xSrxCoO3 which are end members of the LSCF family.  We calculate the oxygen vacancy formation energy and the oxygen migration pathway from which the oxygen diffusion coefficient may be determined.  We use the results of our DFT+U calculations to analyze how A-site (La/Sr) and B-site (Fe/Co) composition affects the oxygen diffusion coefficient.  From this analysis, we provide insights into how to design and optimize MIECs based on La1-xSrxFeO3 and La1-xSrxCoO3 for use in SOFC devices.

Ab initio DFT+U investigation of oxygen diffusion in solid oxide fuel cell materials La1-xSrxFeO3 and La1-xSrxCoO3

243rd National Meeting (2012)

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