Materials for Symmetrical Solid Oxide Fuel Cells

Abstract

A new concept of Solid Oxide Fuel Cell (SOFC), Symmetrical SOFC (SFC), has been investigated. In this new configuration, the same electrode material is used simultaneously as anode and cathode. Interconnector materials, such as chromites, could be potential symmetrical electrodes, at least, under pure hydrogen at relatively high temperatures. However, their lack of catalytic activity towards hydrocarbon oxidation led to the use of substituted-chromites to enhance the aforementioned catalytic activity. Thus, La0.75Sr0.25Cr0.5Mn0.5O3-δ (LSCM) is a good option for such symmetrical configuration, rendering fuel cell performances in excess of 500 and 300mW/cm2 using pure H2 and CH4 as fuel, at 950oC. Other potential materials could be typical n-type anode materials, such as strontium titanates, that could be activated for oxidising conditions by substituting some of Ti content for Fe to introduce p-type conductivity. Preliminary electrochemical experiments on La4Sr8Ti12-xFexO38-δ-based SFCs show that they perform reasonably well under humidified H2.