Preparation and properties of small diameter tubular solid oxide fuel cells for rapid start-up

The feasibility of producing solid oxide fuel cells (SOFCs) which could be rapidly heated to operating temperature was investigated. Small diameter (2.4 mm) 3 and 8 mol% yttria-stabilised zirconia (YSZ) tubes were used both as the electrolyte and the cell support tube. Cells were prepared by winding with pure silver, Ni80/Cr20 and Nimonic 90 wires over lanthanumstrontiummanganite (LSM) cathodes. Specific power outputs of up to 250 mA/cm2 at 900 °C, 0.7 V were achieved in silver wound cells with 5 mm long cathodes. Longer cathodes produced progressively lower specific outputs. This was attributed to increasing cathode and winding resistance with length. The base metal windings achieved up to 80% of the performance of a similar length cell wound with pure silver wire. Silver wound cells were successfully cycled between 200 and 900 °C at an average 25 °C/min (peak 100 °C/min) over 50 cycles with no degradation due to the thermal cycling. Degradation in cells wound with base metals was attributable to the increase in contact resistance found between the cathode and the wire with time.