Microstructural optimization of Solid Oxide Cells : a coupled stochastic geometrical and electrochemical modeling approach applied to LSCF-CGO electrode

Abstract : This work aims at better understanding the impact of Solid Oxide Cells (SOC) microstructure on their performance, with an illustration on an LSCF-CGO electrode. A coupled 3D stochastic geometrical and electrochemical modeling approach has been adopted. In this frame, a plurigaussian random field model and an in-house sphere packing algorithm have been adapted to simulate the microstructure of SOCs. The geometrical models have been validated on different electrodes reconstructed by synchrotron X-ray nano-holotomography or focused ion-beam tomography. Afterwards, semi-analytical microstructural correlations have been proposed and validated on a large dataset of representative synthetic microstructures. These relationships allow establishing the link between the electrode ‘basic’ parameters (composition, porosity and grain size), to the ‘key’ electrochemical parameters (Triple Phase Boundary length density and Specific surface areas), and are particularly useful for cell manufacturers who can easily control the first set of parameters. Concerning the electrochemical part, a reference symmetrical cell made of LSCF-CGO has been tested in a three-electrode setup. This enabled the validation of an oxygen electrode model that links the electrode morphological parameters to its polarization resistance, taking into account the thermodynamic data. Finally, the coupling of the validated models has enabled the investigation of the impact of electrode composition, porosity and grain size on the cell electrochemical performance, and thus providing useful insights to cell manufacturers.
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Hamza Moussaoui. Microstructural optimization of Solid Oxide Cells : a coupled stochastic geometrical and electrochemical modeling approach applied to LSCF-CGO electrode. Physics [physics]. Université Grenoble Alpes, 2019. English. ⟨NNT : 2019GREAI028⟩. ⟨tel-02186032⟩

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