[PhD defense] MISSP - Julien Riviere
Soutenance de thèse
Amphi Chevreul Michel Delhaye
Dear All,
It is my pleasure to invite you to the defense of my PhD thesis entitled :
« New innovative lanthanum-free air electrode materials for high-temperature electrolysis »
The defense will take place the 10th of July, at 2.30 pm in the amphitheater of Michel Delhaye (Institut Chevreul, ground floor) - Av. Paul Langevin, 59650 Villeneuve-d'Ascq.
The jury of my defense is composed of:
| Reporter | M. Fabrice MAUVY | Professeur, ICMCB, Bordeaux |
| Reporter | M. Pierre-Marie GEFFROY | CNRS, IRCER, Limoges |
| Examiner | M. Lionel MONTAGNE | Université de Lille, UCCS, Lille |
| Examiner | Mme. Armelle RINGUEDE | CNRS, IRCP, Paris |
| Examiner | Mme. Annie LE GAL LA SALLE | CNRS, IMN, Nantes |
| Examiner | Mme. Vesna MIDDELKOOP | VITO, Belgique |
| Thesis co-supervisor | M. Victor DUFFORT | UCCS, Lille |
| Thesis director | Mme. Rose-Noëlle VANNIER | UCCS, Lille |
Key words
| SOEC, SOFC, air electrode, di-calcium di-iron oxyde, impedance spectroscopy, distribution of relaxation times (DRT), oxygen evolution reaction (OER) |
Summary
| Most of Solid Oxide Fuel/Electrolyser Cells (SOFC/SOEC) air electrode materials, display the perovskite structure or related structures. They are made of Rare Earth Elements (REE) on the A site whose partial substitution allows to tune their transport properties. However, REE have been listed as critical resource by the European Union, mostly due to the concentration of the mining industries in China. As part of the European Horizon Resilience programme, the aim of the NOUVEAU project, funded by the EU, is the development of novel electrode coatings and interconnect for sustainable and reusable SOEC with the objective to reduce by at least 30 % the amount of REE used in a SOEC stack. This implies to find new REE free materials, mainly for the air electrode. Interestingly, recent papers showed good mixed ionic-electronic conductivity, promising oxygen permeability, thermal expansion coefficients (TECs) compatible with typical solid electrolytes and low area specific resistance (ASR) values for Ca2Fe2O5 derivatives. Ca2Fe2x(Co,Mn)xO5+δ materials were synthesized via a citrate-nitrate route. Initial measurements of ASR and electrical conductivity by impedance spectroscopy for the substituted compounds revealed two promising compositions Ca2Fe0.5Mn1.5O6-δ et Ca2Fe0.5Co1.5O5-δ. Optimisation of the mass ratios with GDC enabled to develop a composition gradient electrode with promising performance and a reduced amount of rare earths compared with conventional composite electrodes. The oxygen evolution reaction on symmetrical cells was studied using impedance spectroscopy and relaxation time distribution function analysis on pure, composite and composition gradient electrodes in order to determine the limiting processes operating within each electrode. The promising performance obtained for symmetrical and full cell studies suggests that there is scope for further improvements in these new electrode materials. |
After the defense, a get-together party will follow.
I hope to see you there!
Kind regards,
Julien Riviere