Preparation and Interfacial Chemistry of Sulfide Electrolytes for High-Performance Solid-State Lithium-Metal Batteries

Sulfide electrolytes have received extensive attention for their surpassing ionic conductivity and mechanical plasticity. However, solid-state batteries with lithium metal anodes applied to sulfide electrolytes face problems such as short circuits caused by lithium dendrites and poor interfacial stability. Herein, a LiF-rich in-situ solidified Li⁺- conductive interlayer is used to stabilize the interface between Li metal anode and glassy Li₂S-P₂S₅ electrolyte. The LiF-rich elastic Li⁺- conductive interlayer (LCI) enables sufficient solid-solid contact, uniform Li-ion (Li⁺) flux, and flat Li deposition to inhibit interfacial reactions and Li dendrite growth. As a result, the Li-Li symmetric cell with LCI between Li metal anode and glassy Li₂S-P₂S₅ electrolyte demonstrates extra-stable Li plating/stripping over 1500 hours at 0.1 mA cm^-2 at room temperature. Furthermore, the LCI enhances the critical current density of SEs to a high value of > 5 mA cm^-2. An elastic LCI using in-situ polymerization of 1,3-dioxolane (DOL) monomers, with lithium hexafluorophosphate (LiPF₆) as an initiator is demonstrated to construct a stable Li anode-SEs interface. The LCI enables sufficient solid-solid contact and uniform Li-ion flux, inhibits interfacial reactions and Li dendrite growth. Moreover, the introduction of beneficial interface components could stabilize the interface between the Li anode and SEs. As a result, the Li-Li symmetric cell with GEI between Li metal anode and SEs demonstrates extra-stable Li plating/stripping over 1500 hours at 0.1 mA cm^-2at room temperature and realizes a high current density of > 5 mA cm^-2. The present in-situ gelation approach potentially provides a universal and efficient strategy that resolves the intrinsic interfacial issue toward Li metal anode and SEs and could pave the way for the next-generation high-energy solid-state Li metal batteries.