Influence of Cycling onto Electrolyte Distribution Inside a Silver-Based Gas Diffusion Electrode for Zn-Air Batteries

The understanding of the wetting behavior of gas diffusion electrodes (GDE) during operation is the key to developing gas diffusion electrodes with a stable triple-phase boundary and high electrochemical performance. In metal-air batteries, this is even more complex as the wide potential range during charge and discharge leads to several oxidation states with different molar volumes and wetting characteristics. In our work, we showed with a segmented cell the shift of current density to areas with less hydrostatic pressure for the oxygen reduction reaction and analyzed the hydrostatic pressure influence further with a cell enabling us to set the electrolyte pressure. We could also show the decrease of pore sizes and the influence of these smaller pores and higher wettability of the oxidized silver surface by using a pressure saturation setup. The knowledge of these findings offers the opportunity to design GDEs with lower tendency for flooding and therefore longer operation times.