Stress mitigation during thermal cycling of planar solid oxide fuel cells : final report

The purpose of the reported project was to evaluate an internally manifolded, counter-flow separator plate geometry and a soft sealing technology suitable for use in planar solid oxide fuel cell (SOFC) stacks. This technology does not induce stress into the active components during a thermal cycle but still maintains good electrical contact with the electrodes at operating temperatures. The work has shown the feasibility of the soft-seal approach using soft metal foil for planar SOFC. A small-scale (35 square centimeters active area per cell), three-cell, internally manifolded stack was assembled and operated. It had soft metallic seals and soft metallic electrical contacts. The work focused on evaluating the performance of selected gas sealant materials, and on the thermal cycling behaviors of the stack with different cell components at temperatures up to 800 degrees C. The sealing efficiency and electrical contact resistance were assessed in cells having nickel cermet anodes, yttria stabilized zirconia electrolytes, and strontium doped lanthanum manganite cathodes and using gas manifold/current collector structures fabricated from stainless steel.