On 25 May at 14:15 Ove Korjus will defend his doctoral thesis chemistry “The development of ceramic fuel electrode for solid oxide cells” for obtaining the degree of Doctor of Philosophy (in Chemistry).
Assoc. Prof. Gunnar Nurk, University of Tartu
Prof. Enn Lust, University of Tartu
Prof. Anke Hagen, Technical University of Denmark (Denmark)
Tackling climate change is one of the challenging yet vital problems of modern society. Solid oxide cells (SOC) as highly efficient energy conversion devices can be useful in several ways in this field. Firstly, in solid oxide electrolysis mode, the cell can convert surplus electric energy from intermittent energy sources like wind and solar to fuels. Secondly, when electricity demand is high, the conversion system is switched to a solid oxide fuel cell (SOFC) mode. It can convert chemical energy back to electrical energy. However, some issues need to be addressed to increase the stability and economic viability of SOC based devices.
This work aimed to demonstrate a powerful novel approach for analysing the SOC hydrogen electrodes and to develop a robust, stable and catalytically active fully ceramic fuel electrode for SOCs. The high temperature operando X-ray diffraction (XRD) method has been developed and applied for studies of two different SOC hydrogen electrodes to understand the processes taking place in the SOC fuel electrode during its operation. This knowledge has proven useful for designing new cells with fewer degradation problems.
The second part of the theses focused on developing novel redox stable electrode materials. One of these stable and catalytically active materials developed in this work is La0,25Sr0,25Ca0,4Ti0,95Ni0,05O3-d. It has a polarization resistance value of 0.084 Ω cm2 at 850 °C and OCV conditions, and no degradation was observed during 120 h. The power density of 325 mW cm-2 was achieved in fuel cell mode using this material.