Study of self-diffusion of alkali metal cations inside a Nafion membrane

Abstract

A novel radiotracer method, based on the rotating electrode technique used in electrochemistry, was used for the study of the self-diffusion properties of ions in ion-exchange membranes; the self-diffusion coefficients of Na⁺ and Cs⁺ ions were determined in a Nafion 117 membrane. The influence of electrolyte concentration and temperature was investigated and an important influence of the former was observed. The results indicate that the diffusion process inside the membrane for Na⁺ ion depends linearly on the water volume fraction. The results for Cs⁺ may be a sign of stronger interactions than for Na⁺ ions with the membrane.