Optimization of Support Materials for Intermediate Temperature Molten Carbonate Fuel Cells (IT-MCFC)

Molten carbonate fuel cells (MCFCs) normally operate at between 600 and 700 °C, but intermediate temperature (ca. 500 °C) MCFCs could be achieved by a combination of improved materials design, properties, and processing. A lower operating temperature would reduce heat loss, thermal stress and corrosion problems, and would also improve mechanical robustness. Thus the implementation of alternative materials and structures could yield significant cost savings.

Two types of MCFC design were considered in this study: cathode-supported and metal-supported. The support substrates were selected on the basis that they should exhibit sufficient mechanical strength to withstand a ΔT of 80 °C for a 100 cm² cell at the operating temperature without imparting significant performance loss through electrical resistance increase or electrode deactivation.

In this study, lithiated nickel oxide (LiNiO) has been selected as the main candidate for cathode support; this material is closely related to state-of-the-art cathode compositions used in high temperature MCFCs. The candidate metal support materials are mostly austenitic ferritic stainless steels such as SS 310S, SS316L, SS446 etc [1], which are used as the state of art bipolar plate materials to withstand the molten salt corrosion during fuel cell operation [2]. A critical evaluation has been performed of these candidate cell support materials, and potential substrate coating materials and techniques have also been considered [3]. The mechanical strength, electronic conductivity and material compatibility have been evaluated to optimize the support materials. 

References:

[1] Frangini, S. et al. J. Power Sources, 2008,182, 462-468.

[2] Frangini, S. et al. Recent Patents on Corrosion Science, 2011, 1, 93-107

[3] Dicks, A. et al. Current Opinion in Solid State and Materials Science, 2004, 8, 379–383