Bi-Based Oxide Anodes for Direct Hydrocarbon SOFCs at Intermediate Temperatures

Abstract

Doped Bi-based oxides were investigated as potential anode materials for direct hydrocarbon solid oxide fuel cells (SOFCs) at intermediate temperatures. (Bi2O3)0.85(Ta2O5)0.15 met this criterion most successfully. A fraction of Bi2O3 in this material was reduced to BiO and Bi metal under fuel conditions, which yielded high conductivities (<1 S cm^-1) based on oxide ions and electrons above 500°C. Carbon deposition was successfully prevented when butane was used as the fuel below 800°C. The catalytic activities for hydrocarbon oxidation were high enough to promote the complete oxidation of butane during cell operation. These abilities provided an enhanced anode performance with increasing temperature from 600 to 750°C, and the resulting polarization resistance reached 1.4Ωcm^2 at 750°C.