Connectivity, ionic interactions, and migration in a fast-ion-conducting polymer-in-salt electrolyte based on poly(acrylonitrile) and LiCF3SO3

The ionic conductivity of a polymeric fast-ion-conductor based on LiCF3SO3 salt and poly(acrylonitrile), [CH2CH(CN)](n)), is enhanced by similar to 5 orders of magnitude when the composition approaches the "polymer-in-salt" r egime; i.e., when the salt content increases from N:Li=12:1 to 1.2:1 (or si milar to 70 wt % of salt). This is in contrast to common salt-in-polymer el ectrolytes where a conductivity maximum typically is encountered at interme diate compositions. We suggest that connectivity effects in a microscopical ly phase segregated material may influence the long-range migration of char ge carriers. Conductivity data are augmented with Raman spectroscopic inves tigations, thus probing microscopic details regarding the state of the diss olved salt. (C) 1999 American Institute of Physics. [S0021-8979(99)00116-4] .