Asymmetric Structure Design of Polymer Gel Electrolyte with a Functional Metal-Organic Framework Layer for Stable...

Ionogel electrolytes (IGEs) containing ionic liquids (ILs) as the unique liquid component can guarantee high ionic conductivity, a wide electrochemical window, and high thermal stability simultaneously for developing stable and safe Li metal batteries. Li⁺ transport in IGEs depends on the content of IL; however, increasing the IL content improves ionic conductivity but sharply decreases mechanical properties and leads to low Li⁺ transference, limiting the ability to resist Li dendrites. Thus, IGEs must strike a balance between ionic conductivity and mechanical properties. Herein, we adopt a new strategy to suppress Li dendrites by introducing a functional metal-organic framework (MOF) layer onto IGE. The IGE provides an asymmetric SSE (ASSE) with good interfacial contact, whereas the MOF layer regulates uniform dissolution/deposition of lithium and inhibits Li dendrite growth. Thereby, the ASSE not only demonstrates excellent ion-transport properties at 30 °C with an ionic conductivity of 1.1 × 10^-4 S cm^-1, but also enables the Li symmetric battery to cycle for 900 h stably. Besides, the full cell (LiFePO₄ cathode) maintains 94.1% capacity after 200 cycles at 0.5C.