| Autor: |
Yefsah, Lydia, Sdanghi, Giuseppe, Sassone, Giuseppe, Bassat, Jean-Marc, Hubert, Maxime, Djurado, Elisabeth, Laurencin, Jerome |
| Přispěvatelé: |
Djurado, Elisabeth, APPEL À PROJETS GÉNÉRIQUE 2018 - EleCtrOdes architecturées pour la Réalisation d'Electrolyseurs de la Vapeur d'Eau à haute température - - ECOREVE2018 - ANR-18-CE05-0036 - AAPG2018 - VALID, J. Mougin and J. Laurencin |
| Jazyk: |
angličtina |
| Rok vydání: |
2022 |
| Předmět: |
|
| Popis: |
La1-xSrxCoy-1FeyO3-δ (LSCF), a typical oxygen electrode in Solid Oxide Cells (SOCs), is an oxygen-deficient perovskite material. Although this mixed ionic and electronic conductor (MIEC) offers good electrochemical performances, it suffers from chemical decomposition in operation at high temperature. The oxygen over-stoichiometric electrode material La2NiO4+δ (LNO) is considered nowadays as an alternative solution to the classical perovskite-based electrodes. Indeed, LNO is chemically stable in a wide range of temperatures and oxygen partial pressures, providing high MIEC conductivity as well as fast oxygen reduction reaction kinetics. In our previous work [1], we showed that the deep understanding of the reaction mechanisms taking place in a SOC oxygen electrode is a prerequisite before microstructural optimization. In this work, we propose a coupled experimental and modeling approach aimed to investigate the reaction mechanisms for both under- and over-stoichiometric oxygen electrode materials. Two main reaction pathways have been considered, the oxygen incorporation/excorporation at the gas/electrode interface for the bulk path and the direct charge transfer at the TPBls for the surface path. Polarization curves and impedance diagrams under various operating conditions (650-750°C, 0.15-1 atm, and ± 100 mA cm-2) have been recorded by using a three-electrode setup. These data were used to calibrate the models based on elementary reactions. In addition, all the microstructural parameters required for the simulation have been computed on a 3D electrode reconstruction obtained by FIB-SEM tomography. A change from the bulk towards the surface path was observed for the LSCF electrode under low anodic polarization, which was explained by the progressive depletion of oxygen vacancies when increasing the anodic polarization. Conversely, a limitation of the bulk path was observed under cathodic polarization for the LNO electrode, which was due to the significant reduction of the oxygen over stoichiometry under these conditions. The impact of the temperature and the pO2 on the reaction pathways has been also investigated for both materials and will be deeply discussed in this presentation. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
