Untersuchung von reversiblen Festoxidzellen für die elektrochemische Energieumwandlung und -speicherung

Recent scientific studies regarding energy engineering show that hydrogen will be an important factor as a future energy carrier. There already exist different approaches to make the chemical energy in hydrogen usable. One of these is the application of solid oxide cells, which may be operated in fuel cell mode (SOFC), converting the oxidation of hydrogen into electrical energy, or in electrolysis mode (SOEC), whereby hydrogen can be produced from water using electric energy. This reversible method to store and convert different energy sources is a crucial factor for e.g. integrated grid systems. Furthermore, this type of cell will be investigated throughout this thesis. In this thesis, different cell types of solid oxide cells operating in SOFC and SOEC mode are examined. These studies are conducted with a test stand at the Chair of Physical Chemistry at the Montanuniversitaet Leoben. This test stand was further optimized and improved, and its utilization described in a repeatable way. The purpose was to obtain comparable results of the cell tests. Within this thesis, nine tests were carried out. In these cases, the performance of the cells was tested by electrochemical measurements and their microstructure was examined by scanning electron microscopy. Results show that the area-specific resistance of all button cells is lower in electrolysis mode (SOEC) than in fuel cell mode (SOFC). This variation is especially significant for electrolyte-supported cells. Furthermore, it was found that the polarization resistance of the cells is highest at 90 vol% water vapor content in the feed gas in electrolysis mode. Moreover, the test results show that the anode-supported cell with Pr2Ni0.9Co0.1O4+δ (PNCO291) air electrode exhibits the best cell performance with the least degradation over the period of investigation.