A novel ionic-conduction mechanism based on polyurethane electrolyte

A series of poly(ethylene glycol)-polyurethane (PEG-PU)/sodium perchlorate (NaClO4) solid electrolytes were prepared, and their properties were charac terized with Fourier transform infrared spectroscopy, differential scanning calorimetry, complex impedance analysis, and atomic force microscopy. Resu lts showed that the oxygen atoms of carbonyl and ether oxygen groups had di fferent activities on cations. Both carbonyl and ether oxygen groups partic ipated in the ionic-transport process in PU-based electrolytes. There exist ed a coordination competition between sodium cations and different oxygen a toms in soft and hard segments of PU. For the PEG-PU/NaClO4 system investig ated, amorphous regions and interfacial regions between the amorphous and m icrocrystalline phases were responsible for ionic conduction. A new ionic-t ransport mechanism, based on the existence of conduction pathways not only in amorphous regions but also in interfacial regions of microphase-separate d PU-based electrolytes, is sketched. Moreover, at a particular concentrati on of doped salt (EO/NaClO4 12), the PEG-PU/NaClO4 complex revealed a phase -transition point in the morphology and exhibited minimum apparent activati on energy and maximum ionic conductivity. (C) 2001 John Wiley & Sons, Inc.