Performance stability of strontium-doped lanthanum cobaltite ceramic cathode synthesized by a wet chemical method

초록

Porous strontium-doped lanthanum cobaltite (La0.5Sr0.5CoO3-delta, LSC) thin film electrodes were deposited by a metal-organic chemical solution deposition method. These films were used as cathodic electrodes replacing precious metal electrodes for low-temperature solid oxide fuel cell (LT-SOFC) applications. They were characterized electrochemically and compared with devices that had platinum (Pt) cathodes. Pt was prepared by a DC magnetron sputtering method and LSC-YSZ-Pt and Pt-YSZ-Pt (cathode-electrolyte anode) SOFC unit cells were fabricated. The performance of each cell was continuously evaluated under operating conditions and the performance of fuel cells with a Pt cathode was superior to those using a LSC cathode at the initial stages of operation; however, the output power density started to decrease as a function of time due to the degradation that comes from the heat vulnerability of Pt. As a consequence, the performance of Pt-YSZ-Pt was significantly lower than LSC-YSZ-Pt, and the electrode resistance grew to be about four times larger compared to before operation. In contrast, neither the output power density nor the electrode resistance of LSC-YSZ-Pt changed during operation. These results imply that LSC has better long-term performance stability compared to Pt and feasibility of using ceramic electrode for low temperature solid oxide fuel cells.

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