Silicified-montmorillonite assisted in-situ construction of LiF-rich phase for enhanced interfacial stability in solid-state lithium batteries

The interfacial failure of solid polymer electrolytes (SPEs) with Li anode, particularly those containing succinonitrile (SN) types, has significantly hindered the practical development of solid-state lithium-metal batteries. Herein, we introduce silicified montmorillonite (SiO 2 -MMT) into polyethylene oxide (PEO)/SN-based SPEs to facilitate the in-situ formation of a LiF-rich phase, thereby significantly enhancing the electrolyte/Li anode interface stability. Specifically, the SiO 2 -MMT strongly anchors the SN molecules, preventing their migration to the Li anode side. Meanwhile, the TFSI − reacts competitively with Li to generate a dense LiF phase, further blocking the SN chemical corrosion of Li metal. Furthermore, the SiO 2 -MMT greatly accelerates the Li + transportability and enhances the thermal stability and mechanical strength of the composite electrolyte. Consequently, the composite electrolyte has a high ionic conductivity of 1.2 × 10 −4 S cm −1 at 30 °C, which almost twice as higher as the counterpart. As for the solid-state battery, the LiFePO 4 ||Li cell demonstrates remarkable cycling stability, achieving a high discharge capacity of 141.7 mA h g −1 with a remarkable capacity retention of 90.2 % after 350 cycles at 0.5   C. Additionally, the high electrochemical window (4.6 V) ensures compatibility with high-voltage cathode materials. The NCM83||Li cell demonstrates a satisfactory initial discharge capacity and excellent capacity retention of 179.2 mA h g −1 and 81.8 % at 0.2 C after 100 cycles. This work offers a new insight for achieving a highly stable electrolyte/Li anode interface in SN-containing SPEs, facilitating the practical application of solid-state lithium metal batteries with enhanced safety and lifespan.