Experimental and Model‐Based Analysis of Electrolyte Intrusion Depth in Silver‐Based Gas Diffusion Electrodes

Abstract

AbstractThe electrolyte distribution is a central point of discussion for understanding the processes inside gas‐diffusion electrodes (GDE) for the oxygen reduction reaction in highly alkaline media. During first radiographic operando synchrotron experiments, the liquid electrolyte was located, however, the through‐plane distribution remains unclear. Therefore, model electrodes consisting of nickel and silver layers are developed to determine the electrolyte intrusion depth. Nickel‐based GDEs are modified to achieve a pore system morphology suitable for the oxygen reduction reaction and subsequently coated with silver‐PTFE catalyst layers. These graded electrodes form gas‐diffusion (nickel) and reaction (silver) layers. The electrodes performance is determined under industrial conditions (80 °C, 30 wt % NaOH electrolyte) as a function of the silver layer thickness and thus of the effective intrusion depth of the electrolyte. The model‐based analysis confirms the experimental determined intrusion depths. Nevertheless, additional operando tomography measurements would help to further improve the understanding of the processes inside GDE.