Theory of a thin film model of porous gas-diffusion electrodes

✍ Scribed by S. Srinivasan; H.D. Hurwitz

• Publisher: Elsevier Science
• Year: 1967
• Tongue: English
• Weight: 955 KB
• Volume: 12
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(67)80019-7

✦ Synopsis

All forms of polarization losses are considered.

It is not possible to obtain analytical solutions for the apparent current-density/overpotential and current-distribution relations under these conditions. Analytical solutions are, however, possible for some special cases, viz activation-ohmic and concentration-ohmic.

Numerical calculations are carried out in the case where all forms of polarization are present, varying the kinetic and physical parameters.

This model yields higher current densities than the simple pore model under identical conditions. The general shapes of the curves are similar for the two models, A region of normal Tafel slope is followed by a region of double this slope at higher overpotentials which then passes over into the limiting current region. The current-distribution relations show a special type of behaviour. At low overpotentials, there is uniform current distribution, followed by increasing uneven distribution, but close to the limiting current, there is again a region of uniform current distribution.

Numerical calculations for the current and potential distribution in the case of only activation and ohmic polarization are presented in a simplified manner in terms of a parameter which contains all the kinetic and physical quantities. For this case, the apparent current density is slightly lower than that for the simple pore model at high overpotentials.