Diffusive dynamics in polymer gel electrolytes investigated by quasi-elastic neutron scattering

Quasi-elastic neutron scattering has been performed on a polymer gel electrolyte consisting of lithium perchlorate dissolved in ethylene carbonate/propylene carbonate and stabilized with poly(methyl methacrylate). Two relaxational processes are observed, and their momentum transfer dependencies are studied. From this we attribute the faster process to a rotational motion and the slower process to diffusive motion of the solvent. The diffusive process was modelled with a jump diffusion model, giving a diffusion constant of 1.6 x 10(-10) m(2)/s, a mean residence time of 34 ps and mean jump length of 1.8 Angstrom. A jump rotation model analysis of the rotational motion yields a rotation radius of 1.5 Angstrom, which is compatible with the size of the solvent molecules. (C) 2001 Published by Elsevier Science B.V.