Results of the physicochemical characterization of poly(ethylene oxide)-sodium iodide polymer electrolytes by DSC, WAXS, microscopy, and ac conductivity, together with the values of transition temperatures reported in the literature, led to the determination of a phase diagram for this system. A study of the transport properties, based on ac impedance measurements of the total ionic conductivities and on measurement of the ionic diffusion coefficients by radiotracer, shows a predominant anionic mobility for amorphous single-phase PEO-NaI electrolytes. The mechanism proposed for the ionic transport process implies that associations are formed between ions. This associative process may determine the value of the apparent activation energy terms of the measured ionic diffusion coefficients. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.122.253.228 Downloaded on 2015-05-27 to IP