In the present study, a novel computational scheme for the assessment of the activation polarization of LSM/YSZ composite cathodes is proposed. The scheme consists of modeling techniques of three-dimensional microstructures and an evaluation method of electrochemical characteristics. Two modeling techniques of microstructures are employed, i.e. the stochastic reconstruction (SR) method and the random packing model (RPM). In the SR method, the 3-D structure is reconstructed statistically from the two-point correlation function of the cross-sectional image of SEM-EDX. In RPM, on the other hand, spherical LSM and YSZ particles are randomly packed in the computational domain. This model is mainly used for the parametric survey, because control parameters used in the model have good correspondence to the parameters used in the actual cell manufacturing process. The lattice Boltzmann method coupled with the Butler-Volmer equation is employed for the detailed assessment of the electrochemical characteristics inside the constructed 3-D cathode microstructures. The oxygen diffusion and the electronic and ionic conductions are calculated simultaneously, and coupled with the charge transfer at the three-phase boundary (TPB) using the Butler-Volmer equation. As a result, potential, polarization and current density distributions are fully investigated. The results from the SR method reveal that the cathode sintered at 1150 °C shows the smaller overpotential than the cathodes sintered at 1200 and 1250 °C. The RPM results show that particle diameter and its standard deviation as well as volume fraction of species have large effects on the cathode performance.

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