Electrical conductivity, thermal expansion and electrochemical properties of Fe-doped La0.7Sr0.3CuO3−δ cathodes for solid oxide fuel cells

The electrical conductivity, thermal expansion and electrochemical properties of La0.7Sr0.3Cu1−xFexO3−δ (LSCuF) have been investigated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). The electrical conductivity decreases with Fe content and the system exhibits a metal to semiconductor transition at around x = 0.2. The composition with the best thermal expansion match to Sm0.2Ce0.8O2−δ (SDC) is La0.7Sr0.3Cu0.4Fe0.6O3−δ, with a TEC value of 13.3 × 10−6 K−1 over 20–600 °C. The electro-catalytic activity towards oxygen reduction of LSCUF cathode was evaluated by AC impedance measurements using SDC electrolyte. The area specific resistance (ASR) of LSCuF decreases with increasing x, reaches a minimum value of 0.16 Ω cm2 at 800 °C under open circuit condition around x = 0.6, exhibiting a potential cathode material for IT-SOFCs.