A dynamically bare metal interface enables reversible magnesium electrodeposition at 50 mAh cm
2

The presence of a solid electrolyte interphase in halogen-free magnesium electrolytes plagues the facile nucleation/ growth of magnesium, causing its incomplete stripping with a Coulombic efficiency far below unity. Here, we report a phenomenon of dynamic, almost-bare magnesium/electrolyte interface formation that allows magnesium to spontaneously deposit into densely aligned, vertically stacked hexagonal platelets. This interface is kinetically stable due to the near-absent electrolyte decomposition during dynamic plating/ stripping, leading to low interfacial resistance, rapid charge transfer, and near-unity Coulombic efficiency under demanding conditions.