Degradation of cathode current-collecting materials for anode-supported flat-tube solid oxide fuel cell

Different types of cathode current-collecting material for anode-supported flat-tube solid oxide fuel cells are fabricated and their electrochemical properties are characterized. Current collection for the cathode is achieved by winding Ag wire and by painting different conductive pastes of Ag–Pd, Pt, La0.6Sr0.4CoO3 (LSCo), and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) on the wire. Cell performance at the initial operation time is in the order of Pt > LSCo > LSCF > Ag–Pd. On the other hand, the performance degradation rate is in the order of LSCo < LSCF < Pt < Ag–Pd. LSCo paste as a cathode current-collector shows the most stable long-term performance of 0.8 V, 300 mA cm−2 at 750 °C, even under a thermal cycle condition with heating and cooling rates of 150 °C h−1. The performance degradation of the Ag–Pd and Pt pastes is caused by increased polarization resistance due to metal particle sintering. From these results, it is concluded that a cathode current-collector composed of wound silver wire with LSCo paste is useful for anode-supported flat-tube cells as it does not experience any significant degradation during a long operation time.