Dependence of the Transport Properties of Perfluorinated Sulfonated Cation-Exchange Membranes on Ion-Exchange Capacity

Membranes and Membrane Technologies (Russia). 2020. Vol. 2. No. 4. P. 265–271.

Prikhno I. A., Safronova E. Y., Stenina I., Yurova P., Yaroslavtsev A. B.

The transport properties of ion-exchange membranes depend on many factors, primarily, on ion-exchange capacity and chemical composition. Therefore, the correlation of transport properties with a single particular parameter is generally not quite strict. In this study, the dependence of transport properties of several perfluorinated sulfonated cation-exchange membranes that differ in side chain length and fraction of fragments containing ether groups on ion-exchange capacity is analyzed. It is shown that, with a decrease in the ion-exchange capacity from 1.35 to 0.66 mg-equiv/g, the proton conductivity of membranes contacting water and their diffusion permeability with respect to a 0.1 M HCl solution decrease by two orders of magnitude. A decrease in relative humidity leads to the most significant decrease in the conductivity of membranes with a low ion-exchange capacity. Thus, at a relative humidity of 32%, the conductivity of the studied membranes decreases more than 600-fold with a decrease in ion-exchange capacity. In general, the oxygen permeability of membranes is characterized by a similar dependence. However, in this set of membranes, it varies as little as threefold.

Keywords: Permselectivity, zirconia, silica, Fuel-cells, Electrodialysis