(Invited) Role of Mixed Conduction in Chromium Poisoning of Oxygen Electrodes of SOFCs and SOECs

Abstract

Oxygen electrodes in solid oxide fuel cells (SOFCs) and solid oxide electrochemical cells (SOECs) can either be predominantly electronic conductors like Sr-doped lanthanum manganite (LSM) or a mixed ionic and electronic conductor (MIEC) such as Sr-doped lanthanum ferrite (LSF) or lanthanum nickelate (LNO). Ferritic stainless steels are currently the preferred interconnection material in both SOFCs and SOECs. During cell operation, it is well known that chromium from the ferritic stainless steel volatilizes and transports into the oxygen electrode. However, it has been observed that the response to chromium exposure of electronic conductors like LSM is very different from mixed conductors like LSF and LNO. In this work we present recent experimental results of in operando response of predominantly electronic and mixed conducting electrodes to chromium exposure, and discuss thermodynamic and transport models that explain the differences in the observed responses.