A comprehensive review on electrode materials and full-cell architectures for aqueous magnesium batteries

Aqueous magnesium-ion batteries (AMIBs) have attracted considerable attention as promising next-generation energy-storage systems because of their low cost, high safety, environmental compatibility, and high ionic conductivity. As conventional lithium-ion batteries face growing concerns regarding resource availability, material cost, and safety, Mg has emerged as an attractive alternative owing to its high theoretical capacity, natural abundance, and economic potential. However, the reversible use of Mg metal is hindered by severe interfacial passivation, which led early rechargeable Mg battery research to focus largely on non-aqueous electrolytes. Their high viscosity, low ionic conductivity, complex handling, high cost, and flammability have subsequently motivated the development of aqueous systems. Nevertheless, AMIBs remain limited by the narrow electrochemical stability window of water, sluggish Mg 2+ desolvation and solid-state diffusion, structural instability of electrode materials, Mg metal passivation, and parasitic hydrogen evolution. This review summarizes recent progress in electrolyte design, insertion-type cathode and anode materials, Mg metal interfacial stabilization, and full-cell configurations, while highlighting the key challenges and future directions for high-performance AMIBs. These developments are connected here to a single underlying variable, namely the strong electrostatic interaction between the divalent Mg 2+ ion and its surrounding anionic environment, which most successful electrode and electrolyte designs act to screen.