Optimization of BaZr_(0.1)Ce_(0.7)Y_(0.2)O_(3-δ)-based proton-conducting solid oxide fuel cells with a cobalt-free proton-blocking La_(0.7)Sr_(0.3)FeO_(3-δ)-Ce_(0.8)Sm_(0.2)O_(2-δ) composite cathode

摘要

BaZr_(0.1)Ce_(0.7)Y_(0.2)O_(3-δ) (BZCY)-based proton-conducting solid oxide fuel cells (H-SOFC) with a cobalt-free proton-blocking La_(0.7)Sr_(0.3)FeO_(3-δ)-Ce_(0.8)Sm_(0.2)O_(2-δ) (LSF-SDC) composite cathode were fabricated and evaluated. The effect of firing temperature of the cathode layer on the chemical compatibility, microstructure of the cathode and cathode-electrolyte interface, as well as electrochemical performance of single cells was investigated in detail. The results indicated that the cell exhibited the most desirable performance when the cathode was fired at 1000 ℃; moreover, at the same firing temperature,the power performance had the least temperature dependence. With humidified hydrogen (～2% H_2O) as the fuel and ambient air as the oxidant, the polarization resistance of the cell with LSF-SDC cathode fired at 1000 ℃ for 3 h was as low as 0.074 Q cm~2 at 650 ℃ after optimizing microstructures of the anode and anode-electrolyte interface, and correspondingly the maximum power density achieved as high as 542 mW cm~(-2), which was the highest power output ever reported for BZCY-based H-SOFC with a cobalt-free cathode at 650 ℃.