LSCF―Ag Cermet Cathode for Intermediate Temperature Solid Oxide Fuel Cells

Solid oxide fuel cells SOFCs can offer high energy-conversion efficiency greater than 50% by directly converting the chemical energy in fuels to electrical energy. SOFCs are operated at around 1000°C. To commercialize SOFCs, it is very important to reduce the operating temperature for cost reduction, long system lifetime, and short start-up time. However the performance of SOFCs sharply decreases due to an increase in the internal resistances, especially in the cathode, as the operating temperature decreases. To reduce the cathode resistance, Ag was investigated as a cathode material. 1-12 Ag has a high catalytic property for oxygen reduction at an intermediate temperature and the highest electronic conductivity. Furthermore oxygen atoms diffuse across the Ag bulk. Therefore oxygen ion transfer occurs across the two-dimensional interface between the Ag electrode and the electrolyte. This was confirmed by the studies of Kenjo and Takiyama 1 and Jimenez et al. 3 and also by our previous study. 11

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