Electrochemical Characterization of Silver Gas Diffusion Electrodes during Oxygen Reduction in Alkaline Solution

Kurzfassung

In order to analyze in detail the kinetics of the oxygen reduction reaction (ORR) and the influence of the porous electrode structure on the electrode performance in alkaline solution (10 M NaOH) at 80°C electrochemical impedance measurements (EIS) and cyclic voltammograms (CV) have been performed. The investigated electrodes were technical silver gas diffusion electrodes (GDE) and porous silver membranes with different pore radii ranging from 0.2 µm to 5 µm. Silver gas diffusion electrodes were used as cathodes for the oxygen reduction reaction in alkaline solution, as oxygen depolarized cathodes (ODC) in NaCl electrolysis and as cathodes in Li-air batteries. Electrochemical impedance spectra (EIS) were recorded at different experimental conditions like current density, temperature, gas composition and electrolyte concentration in the frequency range from 50 mHz to 100 kHz. The measured impedance spectra can be simulated using an equivalent circuit taking into account the kinetic of the ORR and the porous structure of the electrode.