Scientific Achievement
A synergistic approach, combining methods known to enhance solid-state conductivity, is applied to a MOF resulting in a true solid-state lithium conducting MOF system with ionic conductivity similar to reported MOF/Li salt/solvent electrolytes.
Significance and Impact
Varying the degree of EO functionalization of the zirconium MOF UiO-68 affords two novel MOFs; UiO-68-EO and UiO-68-2EO exhibit solvent-free ionic conductivity upon melt-loading LiTFSI in their pores. Incorporating EO chains provides a lithium ion migration pathway lined with oxygen coordination sites resulting in an ionic conductivity of 3.8 × 10−7 S cm−1 and 3.9 × 10−4 S cm−1 at 90 °C for UiO-68-EO/LiTFSI and UiO-68-2EO/LiTFSI respectively.
Research Details
- The linkers for the two novel MOFs were synthesized via Suzuki coupling of 1,4-dibromobenzene derivatives, substituted with EO chains of different lengths, and 4-(methoxycarbonyl)phenyl boronic acid.
- The salt loading was monitored via PXRD and DSC.
- AC electrochemical impedance spectroscopy was used to determine the ionic conductivity of UiO-68-EO/LiTFSI and UiO-68-2EO/LiTFSI. UiO-68-2EO/LiTFSI, with larger EO chains, shows higher conductivity than UiO-68-EO/LiTFSI.
