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Conductivity and n.m.r. measurements are reported for three poly(ethylene oxide)‐inorganic salt complexes: PEO‐LiCF3SO3‐NaI ([EO]/[Li]/[Na] = 8/1/1), PEO‐LiCF3SO3 ([EO]/[Li] = 4), and PEO‐NaI ([EO]/[Na] = 4). The mixed‐salt system was shown to have a larger amorphous phase content than either of the single‐salt systems and more potential charge carriers. A dramatic effect upon the lithium motion and the microviscosity of the amorphous phase was noted upon the mixing of salts. It is proposed that some lithium ions are in environments of low symmetry, possibly of the ion‐pair type, and do not contribute to the n.m.r. signal. The recrystallisation behaviour of the mixed‐salt material was studied by the n.m.r. technique and an initial fast recrystallisation appears to be due to the formation of the high‐melting temperature phase.

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The effect of the mixing of lithium triflate and sodium iodide at high and equal concentrations in a polymer-based (poly(ethylene oxide)) ionic conductor are investigated. A variety of characterisation techniques, namely conductivity, X-ray diffraction, DSC and NMR, are employed. The salient observations involve enhanced conductivities, reduced microviscosity, greatly enhanced mobility of those lithium ions observed by NMR and a recurring absence of NMR observability of a substantial fraction of the cations. The data are interpreted as indicating that the effects of mixing of the salts are to enhance greatly the volume of available amorphous phase. Another feature of the interpretation is the inhomogeneous distribution of the various cations and anions around the different phases present in the materials.

The dynamics of the crystallisation process in a mixed salt/polyethylene oxide (PEO) solid ionic conductor is investigated, using nuclear magnetic resonance techniques. The formation of the crystalline complex and the formation of the PEO crystals from 100% amorphous samples (obtained by a quenching technique) are observed, by 'H NMR, to occur with time constants sufficiently different to permit easy identification of the components of the inhomogeneoussamples at equilibriumat313 K. I9FNMR thenshowsin whichcomponent of the sample the anions reside. The evidence is that the anion/cation pairs of a particular salt do not in general reside in the same component of the samples.