Numerical computation of electrical potential on a gas evolving electrode.

Electrochemical systems using a gas evolving electrode, such as metal-air batteries or electrolyzers, are confronted with recurrent problems related to gas production. Indeed, the production of gas at the surface of the electrodes causes a masking of the active surface which induces overvoltages and unstable electrical signals in time. We propose here numerical computations that take into account the spatial heterogeneity of the electrode and allow to account for the size distribution of the produced bubbles. We compare these computations to experiments on a Platinum-Carbon plate cell in the presence or absence of electrolyte flow. They reproduce the observed behavior and allow us to predict the stability of the signals. They are also a guide for the synthesis of efficient electrodes.