On 21 May at 14.15 Freddy Kukk will defend his doctoral thesis „Electrochemical Characterization of Structurally and Chemically Modified Solid Oxide Cells Operated in Electrolysis Mode“.
Supervisors:
Prof. Gunnar Nurk, PhD, University of Tartu
Prof. Enn Lust, PhD, University of Tartu
Sergii Pylypko, PhD, Elcogen AS
Martin Skov Skjøth-Rasmussen, PhD, Elcogen AS
Opponent:
Prof. Anke Hagen, PhD, Technical University of Denmark (Denmark)
Summary:
This dissertation describes the study of industrially produced solid oxide cells operating in electrolysis mode and the role of the hydrogen electrode active layer in the solid oxide cell performance. The electrochemical performance and durability of the solid oxide cell in fuel cell and electrolysis modes were evaluated through long-term testing. After electrochemical testing, the changes in the cells were investigated with microstructural and elemental analysis. Potential degradation mechanisms caused by long-term operation in electrolysis and fuel cell modes were identified. Microstructural changes and chemical modifications were introduced to the hydrogen electrode active layer, and the effect of these changes was investigated using electrochemical characterization. This work shows that the hydrogen electrode microstructure of the solid oxide electrolysis cell dictates the optimal operating conditions. In this study its is also demonstrated that chemical modification with iron oxide did not cause changes at lower operating temperatures (<750 °C) but increased electrolysis performance significantly at higher temperatures (>750 °C) through enhancing the reaction speed near the active sites. These results open new development paths for improving solid oxide cell technology and enhance our knowledge of electrolysis processes in the solid oxide electrolysis cell devices.
