Investigation of the Reaction Mechanisms in La1-XSrxCo1-YFeyO3 Electrode by DFT Calculations

Abstract

La1-xSrxCoy-1FeyO3-δ (LSCF) is a widely used oxygen electrode in Solid Oxide Cells (SOCs). Despite its high electrochemical activity combined with a good mixed ionic and electronic conductivity, it is prone to a phase decomposition upon operation decreasing the global cell performance. However, the underlying mechanisms for the reaction mechanism and the degradation are still not precisely understood and require investigations at atomic scale. Therefore, Density Functional Theory (DFT) calculations are used to better unravel the mechanisms occurring in the electrode. In particular, the interaction of the dioxygen gas with the AO-terminated (100) surface is studied. In this context, the oxygen reduction reaction is decomposed in a series of elementary steps including oxygen vacancy formation, adsorption of the dioxygen molecule on the bare surface and into a surface vacancy accompanied with the formation of intermediate oxygen species, followed by the dissociation and incorporation into the bulk. The calculations have been carried out at two different Cobalt contents (y=0.125 and y=0.25).