A review of Solid Oxide Fuel Cell cathode materials with respect to their resistance to the effects of chromium poisoning

Solid Oxide Fuel Cell (SOFC) cathode materials have been shown to be susceptible to a 'chromium poisoning' phenomenon that can significantly deteriorate cell output during operation. Chromium-containing species, released from stack and system materials, migrate to the SOFC cathode where they are able to form new phases through reaction with the cathode material. Such phases have been shown to diminish the catalytic and conductive performance of the electrodes and even block the pathways through which oxygen must diffuse. To date, there has been a significant body of research afforded to this subject area. Efforts have been made towards understanding the chromium poisoning effect, whilst also considering how it may be mitigated. In this review, we discuss the effects of chromium-containing phases on both conventional and non-conventional cathode materials. This is in order to understand the most successful approaches towards developing chromium-tolerant cathode materials. The influences of environmental parameters such as temperature and humidity are also discussed. This is to explore how degradation rates may be affected by the operating conditions themselves and the extent to which the phenomenon can be mitigated by suitable control of such factors. In the most part, these environmental effects are studied in relation to the most common cathode materials, La1-xSrxCo1-yFeyO3 and La1-xSrxMnO3, where there has been the largest body of work conducted.