Abstract

Producing efficient solid oxide fuel cells (SOFC) without the use of harmful elements is one of the current challenges. Increasing the safety of people and reducing production costs is possible, among others, thanks to the use of iron doped strontium titanates as porous oxygen electrodes. In this thesis, the results of research on iron doped strontium titanates as potential oxygen electrodes for SOFC are presented. The research focused on: 1. Solid state reaction synthesis of iron doped strontium titanates with different amounts of substituted iron (SrTi1-xFexO3-δ, STFx) and materials with different nonstoichiometry in the strontium sublattice (SrxTi0.3Fe0.7O3-δ, STF-x). Electrical and microstructural studies have proven that these materials can be an alternative to those currently used not only at 800 °C but also at 700 °C. 2. Determining the electrochemical processes occurring in the STFx and STF-x materials during the oxygen reduction reaction and distinguishing which process limits the yield depending on the material used. Thanks to electrochemical impedance spectroscopy, a distribution of relaxation times analysis and microstructural studies, it was possible to identify the electrochemical processes occurring in these porous cathodes and indicate which ones limit the efficiency of the electrodes depending on the stoichiometry.

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