Modelling and Characterization of Solid Oxide Cells: Impact of Microstructure and Reaction Mechanisms on Cell Performances and Degradation
Résumé
Solid Oxide Cells (SOCs) are electrochemical devices working at high temperature. In the recent years, they have gained interest due to their advantages such as high electrical efficiency, reversibility and fuel flexibility. However, the durability still needs to be improved for a large-scale deployment of this technology. Indeed, the high temperatures and the polarization activates degradation phenomena that lead to various material and mechanical instabilities in the electrodes limiting the SOCs durability. To date, the basic degradation mechanisms associated to the complex electrode multi-steps reaction pathways are still not precisely understood. To address this issue, a trifold approach has been developed coupling electrochemical tests with advanced post-mortem characterizations and multi-physic modelling. This methodology has been applied to the typical fuel electrode made of Nickel and Yttria Stabilized Zirconia (Ni-YSZ) and air electrode composed of a Lanthanum Strontium Cobalt Ferrite (LSCF) or Lanthanum Nickelate (LNO). For each case, a better understanding of the reaction mechanism has been proposed. Moreover, the microstructural evolutions, the material decompositions as well as mechanical damage in the electrodes have been studied.