Artificial Interphases for Magnesium Metal Anodes: Mechanisms, Design Strategies, and Perspectives

Rechargeable magnesium batteries (RMBs) have attracted extensive attention as promising postlithium energy storage systems owing to their high volumetric capacity, intrinsic dendrite-less plating behavior, low cost, and natural abundance. Nevertheless, their practical implementation is severely hindered by persistent interfacial challenges, including the formation of surface passivation layers, sluggish Mg²⁺ transport kinetics, and continuous parasitic electrolyte decomposition. To address these issues, extensive efforts have been devoted to artificial interface engineering for stabilizing Mg metal anodes. Recent advances demonstrate that halide-rich artificial interphases, alloy-based artificial interphases, polymeric artificial interphases, and organic/inorganic hybrid interphases can fundamentally reconstruct Mg interfacial electrochemistry. These artificial interphases effectively regulate Mg²⁺ solvation structures, homogenize interfacial electric fields and ion flux distributions, suppress electrolyte decomposition, and promote highly reversible Mg plating/stripping behavior. In this review, we systematically summarize the recent progress in artificial interface engineering for Mg metal anodes, with emphasis on halide, alloy, polymeric, and hybrid interfacial systems. The underlying design principles, interfacial regulation mechanisms, and electrochemical functionalities are comprehensively discussed from the perspectives of Mg²⁺ transport, charge redistribution, solvation regulation, and mechanical stabilization. Finally, the remaining challenges and future opportunities toward scalable and high energy density RMBs are critically outlined.