Monte Carlo study of diffusion in polymer electrolytes

Polymer chain and ion dynamics properties are investigated in a lattice model of polymer electrolytes, which emphasizes the difference in cation-polymer and anion-polymer interactions. The assumption of specific binding sites for cations on the chain molecules leads to a reduction of chain mobilities, which in turn suppresses diffusion of ions. We find a correlation between cation and chain diffusion constants, both of which closely follow a Vogel-Tammann-Fulcher (VTF) law with a common VTF-temperature, which increases with ion concentration. These findings are discussed in connection with recent experiments revealing a salt-induced change of the glass transition temperature and a pronounced asymmetry in the cation and anion diffusion constants. (C) 1998 Elsevier Science B.V. All rights reserved.