Polymer-ion interactions in PVDF@ionic liquid polymer electrolytes: A combined experimental and computational study

Polymer electrolytes based on poly (vinylidene fluoride) (PVDF) with different concentrations (40, 55, 65, and 75 wt.%) of 1-methyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide [EMIM][FSI] were investigated by experimental and molecular dynamics (MD) simulation techniques. The addition of ionic liquid (IL) slightly decreases the electrochemical stability window, as estimated by linear scanning voltammetry. For the neat PVDF, the simulated glass transition temperature (Tg) was obtained at 233.1 K, which is in good agreement with experimental data. Higher contents of IL promoted an increase of the glass transition temperature of the system, indicating a reduction of the polymer segmental mobility, possibly due to the increase of the interactions with the ions. Ionic conductivities were obtained through experimental measurements and MD simulations, which were calculated by Nernst-Einstein and Einstein-Helfand methods. The MD simulation results reproduced the general trend of the experimental ionic conductivities for the GPEs. The studied GPEs systems present an ionic conductivity that obeys a linear Arrhenius behavior, confirming that the ionic mobility is not dependent on the polymer motion.