Supervisor: Prof. Enn Lust, TÜ Keemia Instituut
Opponent: Prof. Peter Holtappels, Technical University of Denmark, Denmark
Alternative energy conversion systems are novel solution for the energy and environmental crisis due to the limited resources of fossil fuels and the globally increasing pollution level. Many countries have invested into development of the environmental friendly renewable-and hydrogen energy technology. Solid oxide fuel cell is a promising alternative energy conversion system having very high electrical efficiency (75%) because the energy of the chemical reaction is directly converted into electrical energy. The overall efficiency can be increased even further if the generated heat is being used as well.
At the moment high temperature (900-1050°C) solid oxide fuel cell systems with moderate power densities are commercially available in Japan and soon in USA. The global use of solid oxide fuel cell is limited because of the high cost of the energy produced (materials used are expensive and time stability is poor). The cost of solid oxide fuel cell systems can be decreased and the time stability increased applying the medium working temperature (500-700°C), optimizing the structure of the materials used and/or developing new alternative materials.
In this work influence of the porous structures of the traditional Ni-cermet based anode and alternative ceramic anodes on the performance of the medium temperature solid oxide fuel cell single cells have been investigated. After the optimization of the Ni-Ce0.9Gd0.1O2-δ-cermet anode microstructure the single cell maximum power density increased approximately two times. Also, the maximum power density of the alternative La0.7Sr0.3VO3-δ-Ce0.85Sm0.15O2-δ-cermet anode consisting single cell increased almost three times after the anode microstructure optimization.