A Self‐Assembled Zincophobic/Zincophilic Bilayer Interphase from a Hydrated Eutectic Electrolyte for Dendrite‐Free Zn Metal Anodes

Aqueous Zn batteries are promising for safe and low‐cost large‐scale energy storage, yet their practical deployment is hindered by severe Zn anode instability arising from coupled hydrogen evolution, corrosion, and dendritic electrodeposition, particularly under temperature extremes. Here we report a solvation–interphase coupled strategy enabled by a hydrated eutectic electrolyte formulated from zinc trifluoromethanesulfonate (Zn(OTf) 2 ), ethylene glycol (EG), and an SnF 2 additive (optimized as ZOTF‐16/SF30), which delivers stable Zn electrochemistry over an exceptionally wide temperature window from −40°C to 60°C. Spectroscopic and physicochemical analyses reveal that EG confines H 2 O within a reinforced hydrogen‐bond network and reconstructs the Zn 2+ coordination environment, thereby suppressing active‐water reactivity and mitigating hydrogen evolution and corrosion. Concurrently, SnF 2 programs interfacial chemistry to generate an in situ zincophobic/zincophilic bilayer interphase, wherein the zincophobic component blocks water penetration and parasitic reactions while the zincophilic component homogenizes Zn 2+ flux and nucleation, enforcing uniform Zn deposition and dendrite‐free growth. Consequently, Zn||Zn symmetric cells exhibit ultrastable cycling for over 2400 h at 1 mA cm −2 . Moreover, Zn||I 2 full cells deliver remarkable long‐term durability over 120 000 cycles, sustaining extended lifetimes at 60°C and −40°C. This work establishes a practical electrolyte‐interphase co‐design blueprint for climate‐resilient aqueous Zn batteries, highlighting hydrated eutectic chemistry as a versatile platform for stabilizing reactive metal anodes.