Interconnects for solid oxide fuel cells

Abstract

Interconnect materials serve an important role in solid oxide fuel cell (SOFC) technology, connecting the current collectors of each cell to either the next one or the electrical load. Up to date, two types of interconnects have been developed: (i) the ceramic and (ii) the metallic ones. The ceramic interconnects are oxides, which are very stable in oxidizing atmosphere, but their cost is high and they exhibit lower electrical conductivity in comparison with the metallic ones at the operating temperatures. The most studied ceramic interconnects are lanthanum and yttrium chromites, and perovskite p-type semiconductors. Currently, ceramic conductive materials are widely used as thin protective layers deposited on metallic interconnects. The metallic interconnects are cheaper than the ceramic ones, and they are used at lower operating temperatures. Compared with ceramics, they exhibit higher electronic conductivity, but they are not stable in oxidizing atmospheres. During the last decade, several solutions have been approached, predominating the surface modification of the metallic interconnects via protective oxide layers (ceramic one) deposition on them. This alternative approach increases the lifetime of metallic interconnects, especially under cathode conditions. Reactive element oxides, perovskites, spinels, and dual layers are the kind of coatings that have also been developed. © 2017, CISM International Centre for Mechanical Sciences.