MONTE-CARLO STUDY OF DIFFUSION IN POLYMER ELECTROLYTES

Polymer chain and ion dynamics properties are investigated in a lattic e model of polymer electrolytes, which emphasizes the difference in ca tion-polymer and anion-polymer interactions. The assumption of specifi c binding sites for cations on the chain molecules leads to a reductio n 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 commo n VTF-temperature, which increases with ion concentration. These findi ngs are discussed in connection with recent experiments revealing a sa lt-induced change of the glass transition temperature and a pronounced asymmetry in the cation and anion diffusion constants. (C) 1998 Elsev ier Science B.V. All rights reserved.