TEM investigation on zirconate formation and chromium poisoning in LSM/YSZ cathode
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Cell durability is a crucial technological issue for SOFC commercialization, and considerable progress has been made in recent years. A number of degradation pathways have been established, amongst which microstructural changes, poisoning effects and formation of less conductive phases. In this study, transmission electron microscopy was used to observe submicron-scale effects on selected cathode zones of an anode supported cell tested in SOFC stack repeat element configuration. The test has been performed with a dedicated segmented test bench, at 800 °C for 1900 h, which allowed to spatially resolve degradation processes, and therefore to improve their correlation with localized post-test analysis. Evidence is presented of reaction products (mainly SrZrO3) at the LSM/YSZ interfaces as well as of contaminants, in particular Cr, but also Si. A polarized cell segment is compared to an unpolarized one, to assess any influence of cathode polarization.
KeywordsOxygen Reduction Reaction Solid Oxide Fuel Cell Yttria Stabilize Zirconia Triple Phase Boundary Zirconate Formation
The authors would like to thank the European Commission (FP6 contract SES6-019875.Flame-SOFC) and the Swiss Federal Office for Energy (OFEN, AccelenT project) for financial support, and Fabienne Bobard from CIME for the TEM lamella extraction by FIB.
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