Effect of External Electric Field on the Proton Conductivity of Nafion Films

The current-voltage characteristics of Nafion films were studied depending on the ambient humidity, electrode voltage, and temperature. It was shown that the film can contain free (polarization current) and bound water; the latter can be completely removed under vacuum conditions. The current decreased with time at constant electrode voltage because of water removal from the film in the absence of electrochemical processes. A theoretical model in the form of the Nernst–Planck equation was considered; it describes the proton transport through the film in an electric field. The inverse problem of restoring the diffusion coefficient from the experimental proton conductivity was solved.