Fast Li+ transport pathways of quasi-solid-state electrolyte constructed by 3D MOF composite nanofibrous network for dendrite-free lithium metal battery

Lithium metal batteries with quasi-solid-state electrolytes are promising in the advanced energy storage system due to the high theoretical capacity and safety. Herein, a unique quasi-solid-state electrolyte (PUIE) containing 3D ion transport pathways based on UIO-66 has been constructed by a flexible process: electrospinning combined electrostatic spraying, followed by impregnation and roll press. In particular, UIO-66 with abundant Lewis acidic sites and channels enhances the ion transport and the restriction to anion in the electrolyte. The rationally designed PUIE-3 exhibits a high ionic conductivity of 1.08 mS/cm at 25 °C, a wide electrochemical window of 5.5 V, and a high Li+ transference number of 0.52. On the basis of the regulating effect of UIO-66, the growth of Li dendrites is significantly restrained and the electrolyte exhibits long-life electrochemical stability with Li anode during the Li plating/stripping. In consequence, lithium metal batteries loaded with PUIE-3 exhibit remarkable cycling and rate performance. Our results indicate that rational design polymer nanofiber/metal-organic framework membranes offer a new avenue for developing high performance quasi-solid-state electrolytes.