Thin, flexible sulfide-based electrolyte film and its interface engineering for high performance solid-state lithium metal batteries

Abstract

Sulfide electrolytes have attracted increasing attention due to their ultrahigh ionic conductivity and intrinsically soft properties. However, current solid-state lithium metal batteries (SSLMBs) based on sulfide electrolyte generally suffer from poor electrochemical performance due to the thick electrolyte layer and its terrible compatibility with Li metal anode. Herein, an ultrathin (∼60 μm) sulfide-based electrolyte film is prepared by a scalable slurry-casting method using Li10GeP2S12, polyethylene oxide, (3-chloropropyl)trimethoxysilane and nylon mesh (as a scaffold). Such film exhibits high ambient-temperature ionic conductivity (2.4 × 10−4 S cm−1), wide electrochemical window (4.7 V versus Li/Li+), outstanding heat-resistance and high mechanical strength (13.8 MPa). Furthermore, the compatibility of anode interface has been tremendously enhanced by the interface engineering of fluorine-rich gel protective layer on Li anode (Gel-Li) via in-situ polymerization, which can effectively prevent the lithium dendrite growth and endow outstanding long-term cyclic stability of the Li symmetric battery. As a result, the assembled MWCNT@S/Gel-Li and LiNbO3@LiNi0.6Mn0.2Co0.2O2/Gel-Li batteries based on such electrolyte film display desirable discharge specific capacities and outstanding cycling stability at ambient-temperature. In addition, the integrated pouch cell can operate well even under harsh environments of bending, cutting, punching situations, demonstrating that such thin electrolyte and its interface engineering applied in SSLMBs with high safety and durability.