Electrolytes are of great importance to various electrochemical energy storage systems, particularly high-energy-density lithium (Li) metal batteries (LMBs). Among different electrolytes for LMBs (including solid-state or polymer electrolytes, ionic liquids , and so on), conventional organic electrolytes are still the most widely used electrolytes for LMBs. A promising electrolyte that is stable against reactive Li metal anode and high-voltage cathodes at the same time is highly desirable. However, metallic Li is difficult to be compatible with commonly used organic carbonate solvents due to their low redox potential (-3.04 V versus the standard hydrogen electrode), since solid-electrolyte interphase forms on the Li anode as a result of uncontrollable electrochemical reduction of carbonate electrolytes, which is chemically unstable and mechanically fragile. To have better reductive stability with Li metal, ether solvents are undoubtedly more attractive for LMBs compared to carbonates. However, conventional dilute ether electrolytes, which have salt concentrations of around 1 M (M, moles per liter of solution), have long been excluded from being used with high-voltage cathodes, such as LiCoO2 and LiNixMnyCo1-x-yO2 (NMC), due to their low oxidation stability (less than 4 V vs.