Understanding Temperature Stability of Surface Cation Dopants on LSCF Electrodes

Abstract

State-of-the-art solid oxide fuel cell (SOFC) oxygen electrode materials such as La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) continue to be plagued by degradation primarily through strontium (Sr) segregation to the electrode surface and subsequent passivating poisoning reactions with chromium- and sulfur-containing species. Surface infiltration of more oxidizable cations is of interest for LSCF electrodes in order to reduce the electrostatic driver of Sr segregation and due its reported success in reducing Sr segregation and electrochemical degradation on LSC electrodes. In this work, we investigate the thermal stability of Hf, Nd, and Pr infiltrated cations at porous LSCF electrode surfaces. These select cations are of interest as surface infiltrates due to their more oxidizable nature. We demonstrate that infiltrated Hf, Nd, and Pr cations are not thermally stable at the LSCF electrode surface at standard SOFC operating temperatures, diffusing substantially away from the surface above 800°C.