The Room Temperature Ionic Liquid 1‐Ethyl‐3‐methylimidazolium Tetrafluoroborate: Electrochemical Couples and Physical Properties

The room temperature ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate was demonstrated as a versatile electrolyte by examining three representative electrochemical couples: ferrocene and tetrathiafulvalene oxidations and lithium ion reduction. Square‐wave voltammetric data for ferrocene oxidation were fit to a reversible one‐electron process using the algorithm to give a half‐wave potential of 0.490 V vs. Al/Al(III) and a diffusion coefficient of . The two‐electron oxidation of tetrathiafulvalene was reversible and proceeded through two consecutive one‐electron steps; although data collected at lower square‐wave frequencies indicated a slow precipitation of the species. Lithium ion was reduced to lithium metal at a Pt electrode following the addition of water to the electrolyte, whereas lithium ion reduction at an Al wire produced the β‐LiAl alloy. Conductivities and kinematic viscosities of were measured from 20 to 100°C and had values of and , respectively, at 25°C.