Ionic Liquid Incorporated Metal Organic Framework for High Ionic Conductivity over Extended Temperature Range

The combination of ionic liquids (ILs) and metal organic frameworks (MOF) as a new type of hybrid ionic conductor has raised extensive concern. Novel solid electrolytes with high ionic conductivities and good cycle performance have been successfully synthesized by loading ILs into nanoarchitectures of MOF materials. In this work, two highly conductive ILs, 1-ethyl-3-methylimidazolium thiocyanate ([Emim][SCN]) and 1-ethyl-3-methylimidazolium dicyanamide ([Emim][DCA]), were embedded into the pores of MIL-101 via an effective soaking-volatilizing method. Using this method, a series of IL@MIL-101 composites with different IL contents were obtained. The effects of IL amount on pore volume, stability, morphology, and conductivity were investigated. The results showed that the conductivity of the composites improved with increasing the amount of ILs. When the pores of MIL-101 material are fully filled with [Emim][SCN], the ionic conductivity of the composites can reach up to 6.21 × 10–3 S·cm–1 at 150 °C under a N2 atmosphere, which is higher than traditional solid electrolytes. And the activation energy of this sample is estimated to be 0.18 eV, which is as low as other IL@MOF conductive composites. It is noteworthy that the IL@MOF hybrid composites can be regarded as promising ionic-conductors due to the value of high conductivity and low activation energy.