Role of the gadolinia-doped ceria interlayer in high-performance intermediate-temperature solid oxide fuel cells

In this study, Ba_0.5Sr_0.5Co_0.8Fe_0.1Zn_0.1O_3-δ (BSCFZ) is used as a cathode with anode-supported scandia-stabilized zirconia (ScSZ) as the electrolyte to achieve intermediate-temperature solid oxide fuel cells (SOFCs). A gadolinia-doped ceria (GDC) interlayer is used between the BSCFZ cathode and the ScSZ electrolyte to protect ScSZ against interfacial reaction with the Co-containing cathode. However, an unfavorable reaction occurs at the GDC/ScSZ interface when the sintering temperature of the GDC interlayer is higher than 1200 °C. Thus, the performance of anode-supported SOFCs with GDC interlayers prepared at different sintering temperatures has been evaluated using I-V measurements and AC impedance spectroscopy. The results demonstrate that the sintering temperature of the GDC interlayer should be optimized for both the reaction between the BSCFZ cathode and ScSZ electrolyte and the reaction at the GDC/ScSZ interface. A maximum power density of 0.78 W cm^-2 has been achieved at 700 °C with a GDC interlayer sintered at 1200 °C. Furthermore, the cell with the optimized GDC interlayer has been shown to maintain excellent reliability with respect to load cycling and thermal cycling.