Application of GDC-YDB bilayer and LSM-YDB cathode for intermediate temperature solid oxide fuel cells

Yttria-doped bismuth (YDB) and gadolinia-doped ceria (GDC) are investigated as a bilayer electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). LSM-YDB is used as a cathode material in order to improve the poor ionic conduction of LSM and the compatibility with the YDB electrolyte. The performance of the bilayer cell was measured under humidified H₂ (3 % H₂O) atmosphere and an operating temperature between 500 C and 650 C. The polarization resistance and ohmic resistance of the GDC-YDB bilayer cell were 0.189 cm² and 0.227 cm² at 650 C, respectively. The bilayer cell showed 0.527 Wcm^-2 in the maximum power density at 650 C, which is about two times higher than the single-layer cell of 0.21 Wcm ^-2. The OCV of the bilayer cell was 0.89 V at 650 C, suggesting that the electronic conduction caused by the reduction of ceria was successfully suppressed by the YDB layer. The introduction of an YDB-GDC bilayer cell with LSM-YDB cathode thus appears to be a promising method for improving the performance of GDC-based SOFCs and reducing operating temperature.