Metal-organic ionogel nanocomposite electrolytes for efficient and stable solid-state lithium batteries

High-quality solid-state electrolytes with excellent ionic conductivity and interface compatibility are essential for high-performance solid-state batteries. However, at present, all-solid-state electrolytes severely suffer from low intrinsic ionic conductivity and high interface impedance, while quasi-solid-state electrolytes face great challenges of structural metastability due to the heterogeneity. Here, we propose a new metal-organic ionogel concept for extending solid-state electrolytes and investigate their electrochemical properties in Li metal batteries. A simple sol-gel method is used for metal-organic ionogel self-assembly, in which ferric nitrate trimer reacts with trimeric acid to form ordered mesoporous metal-organic frameworks, while ionic liquid electrolyte is in-situ confined within mesoporous channels. The resulting metal-organic ionogel exhibits a glassy homogeneous structure with fast room-temperature Li-ion conduction (1.02 × 10⁻³ S cm⁻¹), high electrochemical oxidation potential (4.8 V vs Li/Li⁺), and excellent thermal stability (300 °C), accordingly demonstrating great potential for Li batteries, where both LiFePO₄//Li and LiNi_0.8Co_0.1Mn_0.1O₂//Li cells display high initial capacities (160 and 202 mAh g⁻¹) and excellent capacity retention (98.6% and 85.4%) after 200 cycles.