Solid oxide fuel cell (SOFC) is considered a highly promising technology for clean power and heat generation.¹ One critical component in SOFC stack is metallic interconnect, which works as an oxidant/fuel gases separator as well as an electricity conductor.^{2, 3} However, Fe-Cr based ferritic stainless steels, the most common interconnect alloys, have been reported to cause rapid performance degradation of SOFC cathodes.⁴ Cr species evaporating from chromia-forming alloys deposit on the cathode, which deteriorates the ORR activity of the cathode. In this study, Cr-poisoning effect on pure layered perovskite PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ cathode and La₂NiO_4+δ-coated PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ cathode are investigated. After 20 h aged at 750°C in the presence of SUS430 interconnect and under cathodic current, the performance of pure PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ cathode shows severe degradation, and BaCrO₄ product is identified on the cathode surface. However, La₂NiO_4+δ-coated PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ cathode shows remarkable tolerance and resistance towards chromium, and the performance of cathode maintains stable during the test. The results indicate that the presence of La₂NiO_4+δ coating not only improves the electrochemical performance, but also prevents the cathode from being poisoned by chromium.

References

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2. J. W. Fergus, Materials Science and Engineering: A, 397, 271 (2005).

3. J. C. W. Mah, A. Muchtar, M. R. Somalu and M. J. Ghazali, Int. J. Hydrogen Energy (2016).

4. S. P. Jiang and X. Chen, Int. J. Hydrogen Energy, 39, 505 (2014).