Chapter 6 – Cathode Degradation From Airborne Contaminants in Solid Oxide Fuel Cells: A Review

Fundamental understanding of the degradation processes pertinent to solid oxide fuel cell (SOFC) cathodes remains important in order to apply innovative approaches to achieve long-term electrical performance stability and establish long-term systems reliability for mass commercialization. Several processes leading to an increase in the cathode polarization including Nernst and ohmic losses have been identified. The processes include solid-solid and solid-gas interactions among electrochemically active and inactive components of the cell, stack and systems. The cathodic degradation in SOFCs remains most prominent, and the present review focuses on the effects of contaminants present in “real world” air such as H2O, CO2, and trace amounts of SOx on cathode performance. This review also studies the interactions of the cathode with chromium vapor evaporated from high-temperature alloys used in balance of plant components and the interconnect in direct contact with the air flow. Structural and electrochemical degradation mechanisms of the cathode have been discussed, along with novel approaches to mitigate the cathode poisoning.