Long-Term Stability Studies of Anode-Supported Microtubular Solid Oxide Fuel Cells

A long-term stability study of an anode-supported NiO/YSZ-YSZ-LSM/YSZ microtubular cell was performed, under low fuel utilization conditions, using pure humidified hydrogen as fuel at the anode side and air at the cathode side. A first galvanometric test was performed at 766 degrees C and 200mAcm(-2), measuring a power output at 0.5V of approximate to 250mWcm(-2). During the test, some electrical contact breakdowns at the anode current collector caused sudden current shutdowns and start-up events. In spite of this, the cell performance remains unchanged. After a period of 325h, the cell temperature and the current density was raised to 873 degrees C and 500mAcm(-2), and the cell power output at 0.5V was approximate to 600mWcm(-2). Several partial reoxidation events due to disturbance in fuel supply occurred, but no apparent degradation was observed. On the contrary, a small increase in the cell output power of about 4%/1,000h after 654h under current load was obtained. The excellent cell aging behavior is discussed in connection to cell configuration. Finally, the experiment concluded when the cell suffered irreversible damage due to an accidental interruption of fuel supply, causing a full reoxidation of the anode support and cracking of the thin YSZ electrolyte.