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On 3 April at 14:15 Martin Maide will defend his doctoral thesis „Influence of the microstructure and chemical composition of the fuel electrode on the electrochemical performance of reversible solid oxide fuel cell“
Senior Research Fellow Gunnar Nurk (PhD), UT Professor of Physical Chemistry
Prof. Enn Lust (PhD), UT Professor of Physical Chemistry
Assoc. prof. Bhaskar Reddy Sudireddy (PhD), Denmark
Due to increasing energy demand, the implementation of renewable energy resources is an urgent need. A most important step toward this goal is to develop efficient, environmentally friendly devices for sustainable energy conversion and storage. One of such technologies is reversible solid oxide cell (RSOC), which can work as high-temperature solid oxide fuel cell (SOFC) for fuel oxidation and as solid oxide electrolysis cell (SOEC) for fuel production from excess electricity and steam or carbon dioxide. The advantage of mentioned systems is high electrical and overall efficiency as well as fuel flexibility. However, research and development are still needed to improve reliability, lifetime, and lower the cost of the systems. The most commonly used anode materials for SOCs are metal-ceramic (cermet) composites, which are very sensitive to the redox cycles, catalyst recrystallization, carbon deposition, and sulfur impurities under standard working conditions. Alternatively, mixed ionic-electronic conductive (MIEC) materials have been in focus during the last years as a more stable alternative for cermet materials. So far, low catalytic activity and poor conductivity are still the most common throwbacks for MIEC electrodes, and therefore, additional activation of materials is necessary.
In this work, activation of several potential MIEC materials was investigated through the modifications in the chemical composition or through the infiltration of catalyst nanoparticles.
The influence of electrode microstructure on the electrochemical activity was also studied, and the most active material was characterized in H2O and CO2 co-electrolysis mode. The electrochemical activity of MIEC materials was found to be a complex combination of the electronic-, ionic - and surface catalytic properties of the used oxide. Finally, the importance of optimal electrode material loading in the case of different materials was demonstrated. Best electrochemical activity in fuel cell (1.08 A/cm2 at 0.5 V) and electrolysis (-1.37 A/cm2) modes was demonstrated by Pd and CeO2 infiltrated La0.8Sr0.2Cr0.5Mn0.5O3-δ.