Central subproject: Preparation and characterization of technical silver electrodes

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Gas-diffusion electrodes (GDE) are key components for several relevant electrochemical processes such as fuel cells and metal-air batteries with fundamental importance for the energy turnaround. In the proposed research unit, the oxygen reduction over silver-based GDE in alkaline electrolyte shall be studied as an example. The preparation methods for these GDE must ensure high electro-catalytic activity, low electronic resistance as well as high chemical and mechanical stability. The morphology of the GDE pore system plays a decisive role for these requirements, since only a proper combination of hydrophilic and hydrophobic properties gives rise to intimate contact between liquid electrolyte, gaseous oxygen and the electro-catalyst. A detailed description of GDEs has been until now only partially possible. This is caused by the complex interplay of processes, missing methods for spatially resolved in situ and in operando observations using working GDEs, and the limited availability of models with sound physico-chemical basis. The proposed research unit shall combine competencies in the fields of electrode preparation, tomography, modeling of phase distribution and transport, micro-electrochemistry as well as analysis and modeling of micro- and macro-kinetics on all relevant scales. Thus, the complex interaction of transport and reaction processes can be understood and quantitatively described. In the proposed central project, the preparation and characterization of electrodes as well as the manufacture of half cells will be conducted for all partners.