Silver–bismuth oxide cathodes for IT-SOFCs: Part II — Improving stability through microstructural control

Abstract

Porous composite electrodes consisting of pure silver and Er 0.4Bi 1.6O 3 (ESB20) were synthesized and characterized using impedance spectroscopy. In Part I of this study the electrode area specific resistance (ASR) of this system was found to increase by nearly 70% in 100 h at 650 °C due to migration and ultimate growth and agglomeration of the silver phase. In the present study, two approaches were used to combat silver migration. First, nano-sized 8-mol% YSZ powders were added to the electrode slurries. Stability improvement was achieved at 5, 10, and 15 vol.% YSZ. Second, ESB20 starting particle size was reduced using vibratory milling. This approach yielded a 25% reduction in initial ASR, a 95% reduction in ASR degradation rate under no applied bias at 650 °C, and a 50% reduction in degradation rate under a 250 mV applied bias at 650 °C.