Different from Li batteries, Mg batteries suffer from the lack of suitable cathode materials and electrolyte systems.It is necessary to discover a fight electrolyte with reversible Mg deposition and a wide electrochemical window for the development of magnesium batteries.Recently, Mohtadi et al.[1] confirmed reversible magnesium deposition/dissolution from a new class of electrolytes based on a relatively ionic and halide-free inorganic salt Mg(BH4)2 in both tetrahydrofuran (THF) and dimethoxyethane (DME) ether solvents.LiBH4 was employed as an additive to increase the electrochemical performance, and 94% coulombic efficiencies for Mg dissolution/dissolution were observed.Y.Y.Shao et al.[2] further developed Mg(BH4)2 based electrolyte with DGM (diglyme) as a solvent and LiBH4 also an additive, in which the coulombic efficiency of close to 100% was achieved in the electrolyte with 0.1 mol/L Mg(BH4)2 and 1.5 mol/L LiBH4 in DGM.Herein, quinquedentate ligand tetraglyme (TG) with higher safety was further developed as the solvent of Mg(BH4)2.More importantly, a high concentration electrolyte based on Mg(BH4)2 in TG with a higher anodic stability on non-inert metal electrode was pursued for practical application.As shown in Fig.la, the anodic stability of 0.5 mol/L heated Mg(BH4)2/LiBH4/TG ([LiBH4]=1.5 mol/L) electrolyte on SS electrode maintains at approximately 2.4 V.Moreover, the electrolyte exhibits good compatibility with M06S8 cathode, as shown in Fig.1b.