Improvement of thermal cycle characteristics of a planar-type solid oxide fuel cell by using ceramic fiber as sealing material

The objective of this paper is to improve the endurance of solid oxide fuel cell (SOFC) against thermal cycles by reducing the stress caused by the difference in thermal expansion coefficients of alloy separator and electrolyte. The thermal cycle characteristics were improved by using a ceramic fiber for the sealing material. The ceramic fiber seemed to play the role of suppressing electrolyte-cracking by relaxing the stress set up during thermal cycles. The appropriate structure for the sealing material was investigated with 200 mm×150 mm×4 combined-cell single-layer modules. The glass was arranged around the internal manifold to suppress gas leakage, and the ceramic fiber was arranged around the electrolyte to prevent the glass from contacting the electrolyte. It was confirmed that the thermal cycle characteristics can be improved and that good cell performance can be maintained by adopting this gas seal structure.