Sandwich-structural ionogel electrolyte with core–shell ionic-conducting nanocomposites for stable Li metal battery

Ionogel electrolytes (IGEs) containing ionic liquids as the unique liquid component can guarantee high ionic conductivity, wide electrochemical window, and high thermal stability simultaneously for developing stable and safe Li metal batteries, yet suffer from relatively low Li + transference. In this work, ceramic ionic conductor-metal organic framework (MOF) core–shell nanocomposites are introduced as active matrix to fabricate a reinforcement layer with a high mechanical modulus. The ceramic core provides Li + conduction pathway and the MOF shell possesses open pores and metal sites for ionic selectivity. Beyond this, the reinforcement layer is sandwiched by two buffer layers with a flexible polymer matrix to improve the interface compatibility and wettability with electrodes. Here, the nanocomposites powder can be synthesized through solid sintering followed by facile in-situ solution growth, promising the scalable production and practical application of the IGEs. As a result, the sandwich-structural IGE shows a high ionic conductivity of 3.87 × 10 −4  S cm −1 at 25 ℃, wide electrochemical window (up to 5.2 V vs Li/Li + ), and high thermal stability. The full cell (LiCoO 2 cathode) maintains 97.9 % capacity after 500 cycles at 0.2 C.