Tailored ZnO/Cellulose Separator Reconfigures Solvation Chemistry for Durable Magnesium Metal Batteries

Magnesium metal batteries represent highly promising candidates for sustainable energy storage owing to their extremely high volumetric capacity (3833 mAh cm-3), abundant raw materials, and intrinsic safety. However, their practical viability is severely impeded by uneven Mg deposition, catastrophic interfacial side reactions, and continuous gassing behavior driven by uncontrolled electrolyte decomposition. Herein, we first report an inorganic inter-reinforced organic composite separator, fabricated by pairing cellulose with a zinc oxide (ZnO)-enhanced layer and designed to regulate the electrolyte solvation architecture by effectively anchoring solvent molecules. Spectroscopic and theoretical analyses reveal that the electron-deficient Zn sites on ZnO enhance the solvent-capture ability of the polar hydroxyl groups on cellulose via bidirectional charge transfer. This interaction reconfigures the Mg2+ solvation sheath into a unique single-cluster structure, steering the formation of a dense, ultrathin, inorganic-rich solid electrolyte interphase (SEI) that facilitates rapid Mg2+ desolvation while suppressing parasitic side reactions. Consequently, the as-assembled Mg||Mg symmetric cells deliver an exceptional cycling lifespan exceeding 2000 h with minimal overpotential and exhibit robust compatibility across diverse electrolyte systems. This inorganic inter-reinforced organic strategy for modulating solvation chemistry offers a generalizable avenue toward long-life and high-safety magnesium metal batteries.