Abstract. An original 3D stochastic model, based on the truncated plurigaussian random fields, has been adapted to simulate the complex microstructure of SOC electrodes. The representativeness of the virtual microstructures has been checked on several synchrotron Xray and FIB-SEM tomographic reconstructions obtained on typical LSCF, LSC and Ni-YSZ electrodes. The validation step has been carried out by comparing numbers of electrode morphological properties as well as the phase effective diffusivities. This analysis has shown that the synthetic media mimic accurately the complex microstructure of typical SOC electrodes. The model capability to simulate different types of promising electrode architectures has also been investigated. It has been shown that the model is able to generate virtual electrode prepared by infiltration resulting in a uniform and continuous thin layer covering a scaffold.With a local thresholding depending on the position, continuous graded electrodes can be also produced. Finally, the model offers the possibility to introduce different correlation lengths for each phase in order to control the local topology of the interfaces. All these cases illustrate the model flexibility to generate various SOC microstructures. This validated and flexible model can be used for further numerical microstructural optimizations to improve the SOC performances.Keyword: Solid Oxide Cell, 3D microstructure model, truncated plurigaussian random fields, X-ray tomography, Electrode design.

The reaction mechanism and the impact of microstructure on performances for a porous LSCF‐CGO composite used as O2 electrode in SOCs have been investigated. For this purpose, an integrated approach coupling (i) electrochemical testing, (ii) advanced 3D characterizations, and (iii) modeling was proposed. In this frame, a symmetrical cell was tested in a three‐electrode setup and the microstructure of the LSCF‐CGO working electrode was reconstructed by FIB‐SEM tomography. The experimental polarization curves and the impedance diagrams along with the extracted microstructural parameters were used to validate an in‐house microscale electrochemical model. This model considers two parallel reaction pathways with (i) an oxidation/reduction at TPBls (surface path) and (ii) an oxygen transfer at the gas/LSCF interface (bulk path). It was shown that the LSCF‐CGO electrode reaction mechanism is mostly controlled by the charge transfer at TPBls whatever the polarization. Finally, the impact of electrode composition, porosity and particles size on the cell polarization resistance was investigated by using the electrochemical model in combination with a large dataset of synthetic microstructures generated by a geometrical stochastic model. The effect of each microstructural parameter on the electrode performance was analyzed in order to provide useful guidelines for the cell manufacturing.

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