Nano LiF-Enabled In Situ Synergistic Catalytic Polymeric Electrolytes for Stable Lithium Metal Batteries

Solid polymer electrolytes (SPEs) with excellent ionic conductivity and a wide electrochemical stability window are critical for high-energy lithium metal batteries (LMBs). However, the widespread application of polymer electrolytes is severely limited by inadequate room-temperature ionic conductivity, sluggish interfacial charge transport, and uncontrolled reactions at the electrode/electrolyte interface. Herein, we present a uniform polymerized 1,3-dioxolane (PDOL) composite solid polymer electrolyte (PDOL-S/F-nano LiF CSE) that satisfies these requirements through the in situ catalytic polymerization effect of nano LiF on the polymerization of 1,3-dioxolane-based electrolytes. The synergistic catalytic effect of well-dispersed nano LiF and lithium tetrafluoroborate (LiBF₄) enhances the polymerization of DOL monomers, achieving a conversion rate of up to 83.19% and extending its electrochemical window. Furthermore, the well-dispersed nano LiF forms a stable LiF-rich CEI and SEI, providing exceptional interfacial stability. Based on the PDOL-S/F-nano LiF CSE, the symmetric lithium cell exhibits an ultra-low overpotential of 10 mV at 0.1 mA cm^-2 and 0.1 mAh cm^-2 and maintains steady cycling for over 1500 h at 0.2 mA cm^-2 and 0.2 mAh cm^-2. The Li∥LiCoO₂ LMB using the PDOL-S/F-nano LiF CSE also delivers a brilliant rate capability and long cycling stability over 200 cycles at 4.4 V (capacity retention of 82.6%). This study provides solutions to the ongoing pain point issues of SPEs and facilitates practical applications of solid-state LMBs.