Strong Lewis acidic AlF3 modified PVDF-based electrolytes for high-performance lithium metal batteries

● Strong Lewis acidic AlF 3 nanoparticles were synthesized and incorporated into PVDF-based electrolyte. ● AlF 3 anchors TFSI - and suppresses crystallinity to facilitate rapid Li + flux. ● AlF 3 modified electrolyte achieves high ionic conductivity of 3.10 × 10 −4 S cm −1 . ● Enables stable Li||Li cell cycling over 3300 h and robust NCM811 full cells. Solid-state lithium-metal batteries (LMBs) are promising for high-energy-density storage, yet their practical application is hindered by low ionic conductivity of electrolyte, poor interfacial compatibility and lithium dendrite growth. The poly(vinylidene fluoride) (PVDF) based solid state electrolytes enhanced by inorganic fillers have attracted much attention for the development and application of LMBs. In this work, a high-performance PVDF based composite electrolyte is developed by incorporating Lewis acidic AlF 3 nanoparticles. The AlF 3 fillers reduce polymer crystallinity and anchor TFSI - anions via Lewis acid-base interactions, facilitating rapid Li + transport. This enables a superior ionic conductivity of 3.10 × 10 −4 S cm −1 and an enhanced lithium-ion transference number of 0.302 at 25 °C. At the electrode interface, the Lewis acidity of the AlF 3 fillers inhibits uncontrolled electrolyte decomposition, promoting the formation of a dense and inorganic-rich solid electrolyte interphase. These improvements allow Li||Li symmetric cells to achieve a high critical current density of 1.4 mA cm −2 and an ultra-long cycling life exceeding 3300 h. Furthermore, the assembled NCM811||Li full cells demonstrate excellent electrochemical stability, maintaining a discharge capacity of 176.2 mAh g −1 at 0.5 C and 25 °C after 300 electrochemistry cycles. This study underscores the strategic role of Lewis acidic fillers in optimizing transport kinetics and interfacial chemistry for advanced solid-state batteries.