Effect of current cycles on performance of anode-supported SOFC

Abstract

Performance of an anode-supported solid oxide fuel cell was investigated under several conditions of current cycles. The current cycles between 0 A/cm2 and the maximum current density were repeated. The cell was composed of 8 mol % Y2O3-ZrO2 (YSZ) electrolyte, Ni-YSZ fuel electrode and La0.8Sr0.2MnO3 air electrode, and did not have other active functional layers which contact with the electrolyte. By repeating a current cycle at the operating temperature of 1273 K, the terminal voltage gradually decreased. It was found that the deterioration of performance was due to the increase of the resistance in the higher frequency region, not the ohm resistance by electrochemical impedance spectroscopy. This deterioration of performance was not influenced by hydrogen gas flow rate over the range of 30 to 100 ml/min. As the time of non-current constituted between the cycles was extended, the deterioration of performance decreased, and the deterioration did not occur at all under the condition of the time of non-current exceeding 5 hours. As the operating temperature decreased to 1123 K, also, the increase of the resistance in the higher frequency region by the current cycles was reduced.

Keywords

• solid oxide fuel cell
• anode-supported cell
• current cycle
• deterioration
• electrochemical impedance spectroscopy