Dumbbell-Shaped Octasilsesquioxanes Functionalized with Ionic Liquids as Hybrid Electrolytes for Lithium Metal Batteries

Exploring solid-state electrolytes as alternatives for flammable liquid carbonate electrolyte is considered as one of the key routes toward next-generation lithium polymer batteries assembled with a high-capacity electrode. In this work, we synthesized an organic-inorganic hybrid solid electrolyte with ionic liquid moieties tethered onto dumbbell-shaped octasilsesquioxanes through oligo(ethylene glycol) spacers. The hybrid electrolyte is featured by its high room-temperature ionic conductivity (1.2 × 10^-4 S/cm at 20 °C with LiTFSI salt), excellent electrochemical stability (4.6 V vs Li⁺/Li), and great thermal stability. Excellent capability of the hybrid electrolyte to mediate electrochemical deposition and dissolution of lithium has been demonstrated in the symmetrical lithium cells. No short circuit has been observed after more than 500 h in the polarization tests. Decent charge/discharge performance has been obtained in the prepared electrolyte based all-solid-state lithium battery cells at ambient temperature.