Nouvelles architectures de surfaces d’échanges de piles à combustible de type SOFC pour l’amélioration de l’efficacité électrochimique

Abstract : The present work aims to explore, theoretically and experimentally, how the increase of exchange surfaces via the mesoscopic scale corrugation of electrode / electrolyte interfaces in an anode-supported SOFC could improve its performance. First, an optimization of the microstructural characteristics of the anode was performed by adjusting the initial composition of the slurry, favoring the percolation of the network of Ni by a "hierarchical" microstructure and gas permeability measurements identifying the choice of the anode. Next, an electrochemical model showed an increase in the exchange currents with respect to the planar surface in the case of a periodic pattern for an electrolyte thickness substantially smaller than the dimensions of the pattern. The latter must have concave and convex singularities so as to confine the electrode material in the vicinity of the interface, as well as geometrical characteristics reducing the concentration overvoltage. Such architectures have been carried out by ceramic shaping techniques on self-supported anodes (YSZ + Ni) on which a thin layer of electrolyte (YSZ) has been deposited, and then the co-sintered along with the anode. To finalize the cell, a diffusion barrier (CGO) and a bi-layered cathode (LSCF48 + CGO / LSCF48) were then deposited and then sintered. The first electrical and electrochemical results show an increase in the current density from 130 to 300 at an operating voltage of 0.7V, which is still higher than what was anticipated by modeling, reaching more than the double of the value for flat interfaces. The results are discussed here in terms of geometry of the pattern and its evolution during sintering, as well as activation and concentration overvoltages.
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Submitted on : Monday, October 22, 2018 - 5:59:07 PM
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  • HAL Id : tel-01901236, version 1


Maya Geagea. Nouvelles architectures de surfaces d’échanges de piles à combustible de type SOFC pour l’amélioration de l’efficacité électrochimique. Matériaux. PSL Research University, 2017. Français. ⟨NNT : 2017PSLEM046⟩. ⟨tel-01901236⟩



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