This work demonstrates a quasi-solid electrolyte (QSE) confined within a 6.5 Å metal-organic framework (MOF), exhibiting enhanced properties compared to typical liquid electrolytes: higher boiling points, aggregated configurations, good ionic conductivity, wide electrochemical stability window (≈5.4 V vs. Li/Li+), and nonflammability. Lithium-metal batteries (LMBs) using this QSE show a CEI-free cathode and dendrite-free Li-metal surface. High-voltage LiNi0.8Co0.1Mn0.1O2//Li (NCM-811//Li) pouch cells with high NCM-811 mass loading (20 mg cm-2) maintain stable performance even at 90 °C (171 mAh g-1 after 300 cycles, 89% retention; 164 mAh g-1 after 100 cycles even after damage). This QSE fabrication strategy shows promise for safe, high-energy-density LIBs/LMBs.
