The article reports on the development of a highly concentrated electrolyte system using ether solvents and lithium bis(fluorosulfonyl)imide (LiFSI) salt, which enables high-rate and stable cycling of a lithium metal anode. The use of 4 M LiFSI in 1,2-dimethoxyethane (DME) as the electrolyte allows for dendrite-free plating of lithium at high rates, achieving Coulombic efficiencies up to 99.1% without dendrite growth. The electrolyte's superior performance is attributed to increased solvent coordination and higher lithium ion concentration, leading to reduced side reactions and improved stability. The study demonstrates that a CuLi cell can be cycled at 10 mA cm\(^{-2}\) for over 6,000 cycles, and a Li/Li cell can be cycled at 4 mA cm\(^{-2}\) for over 1,000 cycles with an average Coulombic efficiency of 98.4%. The formation of a compact and conductive solid-electrolyte interphase (SEI) layer further enhances the stability and efficiency of the lithium metal anode. The research provides a promising route for optimizing electrolytes to support the practical application of lithium metal anodes in rechargeable batteries.The article reports on the development of a highly concentrated electrolyte system using ether solvents and lithium bis(fluorosulfonyl)imide (LiFSI) salt, which enables high-rate and stable cycling of a lithium metal anode. The use of 4 M LiFSI in 1,2-dimethoxyethane (DME) as the electrolyte allows for dendrite-free plating of lithium at high rates, achieving Coulombic efficiencies up to 99.1% without dendrite growth. The electrolyte's superior performance is attributed to increased solvent coordination and higher lithium ion concentration, leading to reduced side reactions and improved stability. The study demonstrates that a CuLi cell can be cycled at 10 mA cm\(^{-2}\) for over 6,000 cycles, and a Li/Li cell can be cycled at 4 mA cm\(^{-2}\) for over 1,000 cycles with an average Coulombic efficiency of 98.4%. The formation of a compact and conductive solid-electrolyte interphase (SEI) layer further enhances the stability and efficiency of the lithium metal anode. The research provides a promising route for optimizing electrolytes to support the practical application of lithium metal anodes in rechargeable batteries.