In-Cell Chromium Getters to Mitigate Cathode Poisoning in SOFC Stack

Abstract

Incorporation of a porous and electrically conducting chromium getter layer, comprising of a mixture of complex metal oxide getter and electrically conducting perovskite phase, has been examined as a cost-effective approach for the capture of gaseous chromium species originating from the metallic interconnect alloys conventionally used in SOFC stacks. Getter layer deposited on the cathode surface or placed away from the cathode, was electrically tested in a half cell configuration (3%H2O-Air/Pt//YSZ//LSM/Getter/3%H2O-Air-CrOx) at 850 ºC for 100 hours. Post tested cells were analyzed for composition of reaction products and changes in the morphology. Our observations indicate that getter placed away from the cathode and conductive getter paste deposited on cathode surface successfully capture all chromium incoming with air stream thus mitigating the poisoning of the cathode without performance degradation. The gaseous chromium predominantly concentrated at the impinging getter surface and the bulk electrode and electrode-electrolyte interface remained free of chromium.