Unlocking Mg²⁺ Transport in Magnesium Batteries: Aromatic Architectures and Systemic Co-Design

Magnesium batteries have attracted interest as post-lithium energy-storage systems because Mg metal offers high volumetric capacity, dendrite-free deposition under many conditions, and favorable elemental abundance. However, their practical development remains limited by sluggish Mg²⁺ transport across length scales, including interfacial ion desolvation and solid-state diffusion. Against this backdrop, aromatic compounds have emerged as a platform for magnesium-battery design, not simply because they provide redox-active motifs, but because their low-electronegativity frameworks, delocalized π-electron systems, and molecular programmability can mitigate localized electrostatic trapping and regulate Mg²⁺ migration pathways. This review discusses how aromatic chemistry can address the key bottlenecks of magnesium batteries from three interconnected perspectives: cathode design, anode interphase engineering, and electrolyte compatibility. Particular emphasis is placed on perylene diimide (PDI)-based systems, which provide a rare model platform in which molecular structure, conjugation mode, steric distortion, ion-accessible geometry, and storage mechanism can all be deliberately tuned. We further discuss aromatic artificial interphases for Mg-metal protection, including fullerene-derived networks as mechanistically illustrative examples, and analyze how electrolyte chemistry governs storage species, interfacial compatibility, and active-material stability. Rather than treating cathodes, anodes, and electrolytes as isolated components, this review emphasizes mechanism-oriented co-design and critically assesses the limitations of aromatic materials for magnesium batteries.