M.Sc Thesis


M.Sc StudentZohar Drach
SubjectElectrical Characterization of Physical Processes in Solid
Oxide Fuel Cell/Electrolysis Cell
DepartmentDepartment of Chemical Engineering
Supervisor Professor Tsur Yoed
Full Thesis textFull thesis text - English Version


Abstract

In this work the analysis of electrochemical impedance spectroscopy (EIS) data of solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) using impedance spectroscopy genetic programming (ISGP) is presented. A complete cell was fabricated in the lab. Ni/gadolinium doped ceria (GDC) was chosen as the fuel electrode, GDC as the electrolyte and barium strontium cobalt ferrite (BSCF) or lanthanum strontium cobalt ferrite (LSCF) as the air electrode. The chosen materials have shown good performance for intermediate temperature (500-800 °C) operation when each component of the cell was examined separately, yet the suggested configuration in this work is not common. During the cell fabrication we have been struggling with three major problems: (1) the obtained fuel electrode was not porous enough; (2) the electrolyte was not dense; and (3) it was not easy to bind all three cell components. Finally, we overcame the first two problems while the third one has been reduced to only the binding of the air electrode and the electrolyte.

EIS measurements were conducted using NorECs' ProboStat?. This system was designed for the measurements of electrical properties of electroceramic specimens and it can also be used for the measurement of SOFC/SOEC. The implementation of EIS measurements using ProboStat? was performed on a cell bought from Elcogen?, Estonia, and were longer than anticipated. The measurements were inconsistent thus we did not succeed in retrieving sufficient data for ISGP analysis. A collaboration with Prof. Massimo Santarelli group from the department of energy at the Politechnico di Torino (POLITO), Italy, provided us with EIS data of different solid oxide cells operated in various conditions in both SOFC and SOEC modes. The EIS data received from POLITO was analyzed using ISGP and the results are presented in this work.