Karsten Agersted Nielsen

Initiation and Performance of a Coating for Countering Chromium Poisoning in a SOFC-stack

Minimising transport of chromium from the metallic interconnect (e.g. of Crofer 22APU) to the cathode in a planar solid oxide fuel cell is done by application of a coating between the two parts. The coating is applied by slurry coating, and taken through stack initialisation it transforms into a stable and densely grown barrier layer, which minimises both the evaporation of chromium from the interconnect surface and the electrical contact resistance between the interconnect and the cathode. Between comparable stack element tests with and without coatings at 750oC, the degradation rate in terms of power density decreased from 6.5% per 1000h to very low levels (<0.84% per1000 hour) during the first 1000 hours of stack element testing when using such type of coating, indicating that the cathode poisoning from chromium has reached levels interesting for commercial development.