Bi0.5Sr0.5MnO3 as cathode material for intermediate-temperature solid oxide fuel cells

Bi0.5Sr0.5MnO3 (BSM), a manganite-based perovskite, has been investigated as a new cathode material for intermediate-temperature solid oxide fuel cells (SOFCs). The average thermal-expansion coefficient of BSM is 14 x 10(-6) K-1, close to that of the typical electrolyte material. Its electrical conductivity is 82-200 S cm(-1) over the temperature range of 600-800 degrees C, and the oxygen ionic conductivity is about 2.0 x 10(-4) S cm(-1) at 800 degrees C. Although the cathodic polarization behavior of BSM is similar to that of lanthanum strontium manganite (LSM), the interfacial polarization resistance of BSM is substantially lower than that of LSM. The cathode polarization resistance of BSM is only 0.4 Omega cm(2) at 700 degrees C and it decreases to 0.17 Omega cm(2) when SDC is added to form a BSM-SDC composite cathode. Peak power densities of single cells using a pure BSM cathode and a BSM-SDC composite electrode are 277 and 349 mW cm(2) at 600 degrees C, respectively, which are much higher than those obtained with LSM-based cathode. The high electrochemical performance indicates that BSM can be a promising cathode material for intermediate-temperature SOFCs. (C) 2010 Elsevier B.V. All rights reserved.