Ionic liquid incorporated metal–organic framework as high conductivity solid conductor

Abstract

As a new type of composite ionic conductor, the combination of ionic liquids (ILs) and metal organic framework (MOF) shows a good application prospect. In this study, two ionic liquids, 1,3-dimethylimidazolium tetrafluoroborate ([Dmim][BF4]) and 1-Allyl-3-methylimidazolium dicyanamide ([Amim][N(CN)2]) were successfully combined with MIL-101(Cr). The influence of the amount of ionic liquid and temperature on the electrical conductivity of composite IL@MIL-101(Cr) was explored. The optimal electrical conductivity reached 3.73 × 10-3S·cm−1 ([Dmim][BF4]) and 2.69 × 10-3S·cm−1 ([Amim][N(CN)2]) respectively when exposed to air at 100 °C. It is worth noting that the ionic conductivity of all composites exhibits linear Arrhenius behavior. Since the activation energies of composites are closely related to the type of ionic liquid and MOF types, these two composites exhibit different activation energies. The reason for the difference in activation energies is analyzed with the aid of quantum chemical calculations.