Rechargeable magnesium batteries have received extensive attention as the Mg anodes possess twice the volumetric capacity of their lithium counterparts and are dendrite-free.However,Mg anodes suffer from surface passivation film in most glyme-based conventional electrolytes,leading to irreversible plating/ stripping behavior of Mg.Here we report a facile and safe method to obtain a modified Mg metal anode with a Sn-based artificial layer via ion-exchange and alloying reactions.In the artificial coating layer,Mg2Sn alloy composites offer a channel for fast ion transport and insulating MgCl2/SnCl2 bestows the necessary potential gradient to prevent deposition on the surface.Significant improved ion conductivity of the solid electrolyte interfaces and decreased overpotential of Mg symmetric cells in Mg(TFSI)2/DME electrolyte are obtained.The coated Mg anodes can sustain a stable plating/stripping process over 4000 cycles at a high current density of 6 mA cm-2.Tb.is finding provides an avenue to facilitate fast ion diffusion kinetics of Mg metal anodes in conventional electrolytes.