Ionic Liquid (IL) Laden Metal–Organic Framework (IL-MOF) Electrolyte for Quasi-Solid-State Sodium Batteries

An ionic liquid (IL) laden metal–organic framework (MOF) sodium-ion electrolyte has been developed for ambient-temperature quasi-solid-state sodium batteries. The MOF skeleton is designed according to a UIO-66 (Universitetet i Oslo) structure. A sodium sulfonic (−SO3Na) group grafted to the UIO-based MOF ligand improves the Na+-ion conductivity. Upon lading with a sodium-based ionic liquid (Na-IL), sodium bis(trifluoromethylsulfonyl)imide (NaTFSI) in 1-n-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Bmpyr-TFSI), the Na-IL laden sulfonated UIO-66 (UIOSNa) quasi-solid electrolyte exhibits a Na+-ion conductivity of 3.6 × 10–4 S cm–1 at ambient temperature. Quasi-solid-state sodium batteries with the Na-IL/UIOSNa electrolyte are demonstrated with a layered Na3Ni1.5TeO6 cathode and sodium-metal anode. The quasi-solid-state Na∥Na-IL/UIOSNa∥Na3Ni1.5TeO6 cells show remarkable cycling performance.