Conductivity of Nafion-117 membranes intercalated by polar aprotonic solvents

Abstract

The Nafion-117 membranes in the Li+ form with pore-intercalated aprotonic organic solvents were prepared. The prepared materials were characterized by IR, impedance, and 7Li NMR spectroscopy. The solvent uptake of the membranes is shown to be controlled by the composition of organic solvents and their mixtures as well as by the conditions of the preliminary treatment of the initial membranes. For the Nafion-117 membrane, the degree of solvation can be improved by the preliminary treatment with alcohols, especially by the thermal treatment in methanol. Conductivity of the membranes is shown to increase with increasing content of the sorbed solvents. The best conductivity at 25 °C (2.5 × 10−3 and 1.6 × 10−3 S cm−1) was attained for the electrolytes based on the Nafion-117 membrane in lithium form with sorbed ethylene carbonate-propylene carbonate and ethylene carbonate-dimethoxyethane mixtures, respectively.