A finite element method (FEM) based model was developed for performance simulation in SOFC, using a homogenized electrode microstructure at the cell level. The model was parametrized with electrode kinetics determined by electrochemical impedance spectroscopy (EIS) on planar anode supported cells and validated by current/voltage characteristics (C/V) over the technical relevant operating condition range of SOFC [1]. Model calculations on planar stack layer level have demonstrated that (i) cathode layer thickness and (ii) cathode layer porosity is key to avoid gas transport limitations and performance loss [2].

The model has been advanced by adopting mixed-ionic/electronic cathode (MIEC) kinetics, thus enabling the simulation of stack layer performance depending on the cathode’s chemical composition. Furthermore, it will be demonstrated how a functional gradient in pore and particle size distribution enhances stack performance compared to state-of-the-art cathodes. These simulations are not based on artificial, but on “real” microstructures, which were determined using a combined focused ion beam/scanning electron microscopy (FIB/SEM) and X-ray tomography reconstruction of a two-layer cathode.

[1] H. Geisler, A. Kromp, A. Weber and E. Ivers-Tiffée, JES 161 (6) F778-F788 (2014)
[2] H. Geisler, J. Joos, A. Weber and E. Ivers-Tiffée, ECS Transactions, 68 (1) 3043-3050 (2015)