Validation of the Equivalent Circuit Diagram for SOFC Modeling

AC impedance spectroscopy, combined with equivalent circuit diagram (ECD) simulations, achieves to characterize a chemical reactor system in terms of electronics. Their application on solid oxide fuel cells (SOFCs) provides experimental data and physical models for cell designs, diagnostics, and performance improvements. However, different arrangements and combinations of circuit elements may yield the same dynamic response when three or more elements are involved in one EC diagram. To overcome the ambiguity in EC diagram interpretations, the impedances of the SOFCs were measured under different operating conditions. Temperature, current density and fuel composition were changed to validate the consistency of the derived EC diagram and to mechanistically distinguish the kinetics and processes limiting cell behaviors.