Performance Modeling of Solid Oxide Fuel Cells with a Mixed Conducting Cathode

A one-dimensional performance model has been developed for a solid oxide fuel cell (SOFC) with a mixed electronic and ionic conductor as the cathode, such as the perovskite La 1−x Sr x FeO 3−δ . It is shown that for the specific fuel cell microstructure investigated, the cell ASR (area specific resistance) is dominated by the cathode for temperatures below ~700°C and anode-dominated for temperatures above ~800°C at an operating voltage of 0.7 V. Good agreement between the model and experiment was demonstrated with only one adjustable parameter (cathode exchange current density). The cell ASR computed from the model is in good agreement with experimental ASR, with an activation energy of ~0.8 eV for T<700°C and ~0.4 eV for T>800°C. The change in activation energy from low to high temperatures suggests a change in relative importance from cathode to anode respectively, with anode mass transport playing an important role at higher temperatures.