Ion mobility and conductivity of hybrid ion-exchange membranes incorporating inorganic nanoparticles

Transport properties, hydration processes and ion transport mechanism in hybrid materials based on perfluorinated MF-4SC membrane (Nafion type) containing silica and phosphotungstic acid (PWA) nanoparticles in different salt forms have been investigated. Membrane modification results in water content increase both in hydrogen and in salt forms. Ion conductivity of all materials decreases with relative humidity (RH) decrease. The difference of conductivity at high and low RH values decreases among H+ > Li+ > Na+ > Cs+. The comparison between NMR and impedance spectroscopy data shows water molecule and incorporated nanoparticle participation in ion transport. The incorporation of dopants leads to the increase in ionic conductivity due to the increase of the number of oxygen atoms taking part in the transport process. It also results in membrane structure change including pore and channel expansion.