Formation of an Artificial Mg²⁺-Permeable Interphase on Mg Anodes Compatible with Ether and Carbonate Electrolytes

Rechargeable Mg-ion batteries typically suffer from either rapid passivation of the Mg anode or severe corrosion current collectors by halogens within electrolyte, limiting their practical implementation. Here, we demonstrate broadly applicable strategy forming an artificial solid electrolyte interphase (a-SEI) layer on to address these challenges. The a-SEI is formed simply soaking foil in a tetraethylene glycol dimethyl ether solution containing LiTFSI and AlCl3, with Fourier transform infrared ultraviolet–visible spectroscopy measurements revealing spontaneous reaction foil. found mitigate Mg(TFSI)2/DME electrolytes symmetric cells exhibiting overpotentials that are 2 V lower compared when not present. This approach extended Mg(ClO4)2/DME Mg(TFSI)2/PC achieve reversible plating stripping, which achieved bare electrodes. interfacial resistance protected be two orders magnitude than all three electrolytes, indicating formation effective transporting structure. X-ray absorption photoemission show contains minimal MgCO3, MgO, Mg(OH)2, TFSI–, while being rich MgCl2, MgF2, MgS, Mg(TFSI)2/DME.