Nanocrystalline cathode functional layer for SOFC

Abstract

Recently, it was shown that thin functional layers introduced between an electrolyte and cathode might improve cathode performance. However, the mechanism of this improvement still needs analysis. In this paper, a thin (∼140 nm), spin-coated perovskite layer (La0.6Sr0.4Co0.2Fe0.8O3-δ) was placed between a cathode (La0.6Sr0.4Co0.2Fe0.8O3-δ) and an electrolyte (Ce0.8Gd0.2O2-δ) and the effects of this investigated. The microstructure of this layer was varied in order to determine its impact on the electrical and electrochemical properties. It has been shown that a mesoporous, nanocrystalline layer increases the active area for oxygen reduction and charge transfer through the cathode/electrolyte interface, which improves performance. Moreover, the stability of the cathode from thermal stresses is increased. In contrast, the coarsening of the grain and the layer densification has a reduced impact on the cathode performance.