Influence of the start-up rate on the electrochemical impedance of a low-temperature solid oxide fuel cell fabricated by reactive sputtering

Sungmin Kang1, Ikwhang Chang, Rojana Pornprasertsuk, Joongmyeon Bae#, Suk Won Cha#

Low-temperature solid oxide fuel cells were heated from room temperature to an operating temperature of 450 °C. The start-up heating rate was controlled at three levels (10 K min−1, 30 K min−1, and 50 K min−1). For as-fabricated single cells, greater grain growth of the yttria-stabilized zirconia (YSZ) electrolyte and cathode platinum cluster growth were observed with an increasing start-up heating rate. As a result, the faradaic area-specific resistance (ASR) significantly increased, and the performance of the cell decreased due to the sluggish oxygen reduction reaction originating from the loss of the reaction sites. However, after preannealing the single cells at 400 °C for 2 h prior to start-up, the change in grain size and faradaic ASR varied with the start-up heating rate was well suppressed by the enhanced interfacial stability between the electrolyte and cathode. The single cell samples for the experiments are composed of Pt-YSZ-Pt thin films supported on nanoporous anodic aluminum oxides.