Preparation of gadolinium-doped ceria barrier layer for intermediate temperature solid oxide fuel cells by spin coating and evaluation of performance degradation by impedance analysis

Thin gadolinium-doped ceria (GDC) films were deposited via the cost-effective aqueous spin coating technique and with rapid one-step sintering at 1200 °C, to be used as barrier layer between a lanthanum strontium cobalt ferrite (LSCF) cathode and a scandia-ceria-stabilised zirconia (ScCeSZ) electrolyte within a solid oxide fuel cell (SOFC) configuration. A 5.5 μm-thick GDC film was deposited using a 50 wt% GDC slurry in 3 cycles. The single cell comprising this GDC film produced a peak power density of over 1.00 W•cm−2 at 750 °C in hydrogen operation. Electrochemical impedance spectroscopy was carried out to investigate the SOFC performance evolution with potential changes in microstructure over time. An operational stability test was also conducted at a current density of 0.2 A•cm−2 for over 1200 h. The degradation behaviour of each electrochemical process as a function of cell operating time was evaluated by the distribution of relaxation times method based on the obtained electrochemical impedance spectra.