Solutions for Material Corrosion Problems in MCFC

Abstract

It is widely recognized that metallic corrosion of the cathode current collector is a key technological problem that must be fully resolved before Molten Carbonate Fuel Cells can be commercialized on a more competitive basis. This paper presents a short overview on the corrosion mitigation strategies that appear more appropriate for MCFC current collectors. As alternative to the current use of the 300-series austenitic stainless steels, specialty high-Mn stainless steels, corrosion-resistant Ni-based alloys and sol-gel coatings of thin conductive spinel or perovskite ceramic layers are seen as the most promising corrosion solutions for the cathode-side environment. The use of basic additives into electrolyte for inhibiting molten carbonate corrosion is a further mitigation option yet with less practical perspectives due to the high constraints on the electrolyte properties. Recent and current studies conducted at ENEA on MCFC corrosion solutions are also mentioned.

Perovskite Conversion Coatings as Novel and Simple Approach for Improving Functional Performance of Ferritic Stainless Steel SOFC Interconnects

“…Molten salts are in general not much investigated for chemical surface treatments, although their corrosive nature appears suitable to activate the surface of typically passive or low‐reactive ferrous materials such as stainless steels and high temperature alloys. In this context, stainless steels exhibit an advantageous pseudo‐passive corrosion behavior in molten carbonates caused by a moderate protective oxide scale that retards but not stops entirely the steel surface reactivity . Moreover, it is well documented in literature that perovskite oxides easily grow in carbonate‐containing media including molten alkali carbonates , .…”

Development of Protective Coating for Molten Carbonate Fuel Cell Current Collector

“…% Cr) and 304 L (16-18 wt. % Cr) have emerged as materials of choice for MCFC hardware [1]. However, the hot corrosion in the presence of the carbonate melt is a critical issue with these materials for long-term operation.…”