Silicified-montmorillonite assisted in-situ construction of LiF-rich phase for enhanced interfacial stability in...

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 (SiO₂-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 SiO₂-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 SiO₂-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 LiFePO₄||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 0.5C. 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.