Development of the Air Side Current Collector for Solid Oxide Fuel Cells.

Abstract

An air side current collector (ASCC) for a solid oxide fuel cells (SOFC) was fabricated and evaluated. Thirty mass% YSZ-LSM, was selected as a candidate material for ASCC. Its electrical conductivity at 1000°C and its average thermal expansion coefficient between room temperature and 1000°C were 65S·cm-1 and 10.9×10-6K-1, respectively. The gas channel width of ASCC is very important factor, because the current collecting resistance depends on it strongly. A 1cm2 cell was operated with different current collecting length, which corresponded to the width of the gas channel. We made it clear that the current collecting resistance was very small when the channel width was ≤3mm. The SOFC short-stack was built with a 140cm2 cell and two ceramic gas separators. The separator was composed of MgO-MgAl2O4 separate plates, La(Sr)CrO3 current passages and current collectors. The electric power generation test was carried out at 1000°C for 700h. The cell attained the output power 36W at the current 48A. The voltage loss at the gas separator with a current 45A was 68mV, accordingly the electric resistance of the separator was 1.5mΩ. The electric resistance did not change after a thermal cycle conducted between 1000°C and room temperature.