Durability study of an intermediate temperature fuel cell based on an oxide–carbonate composite electrolyte

It was reported that ceria–carbonate composites are promising electrolyte materials for intermediate temperature fuel cells. The conductivity stability of composite electrolyte with co-doped ceria and binary carbonate was measured by AC impedance spectroscopy. At 550 °C, the conductivity dropped from 0.26 to 0.21 S cm−1 in air during the measured 135 h. At a constant current density of 1 A cm−2, the cell performance keeps decreasing at 550 °C, with a maximum power density change from 520 to 300 mW cm−2. This is due to the increase of both series and electrode polarisation resistances. Obvious morphology change of the electrolyte nearby the cathode/electrolyte interface was observed by SEM. Both XRD and FT-IR investigations indicate that there are some interactions between the doped ceria and carbonates. Thermal analysis indicates that the oxide–carbonate composite is quite stable at 550 °C. The durability of this kind of fuel cell is not good during our experiments. A complete solid oxide-carbonate composite would be better choice for a stable fuel cell performance.