NA-23 NMR AND COMPLEX IMPEDANCE STUDIES OF GEL ELECTROLYTES BASED ON POLY (ACRYLONITRILE)

Highly conducting gel electrolytes prepared from mixtures of poly(acrylonitrile) (PAN), ethylene carbonate (EC), propylene carbonate (PC) and NaClO4 have been studied by complex impedance, differential scanning calorimetry (DSC) and Na-23 nuclear magnetic resonance (NMR) spectroscopy. Ionic motional correlation times spanning nearly five orders of magnitude, probed by temperature-dependent dynamical features of the Na-23 quadrupole-broadened NMR lineshape, are strongly influenced by the single glass transition temperature observed in the gel electrolyte. Dielectric measurements of mixtures of PAN, EC and PC suggest that the polar nitrile group in PAN may interact with Na+ ions in the gel. All results are consistent with the conclusion that PAN provides stability to the gel network down to the immediate vicinity of the Na+ ions, rather than acting as a rigid framework for regions of liquid electrolyte.