Eutectic Network Driven Interfacial Synergy Toward Long‐Life and Wide‐Temperature Zn‐I ₂ Batteries

Despite their intrinsic safety, low cost, and high output voltage, Zn‐I 2 batteries (ZIBs) still suffer from severe shuttle effects of polyiodides and uncontrollable side reactions triggered by active H 2 O. In this work, a hydrated eutectic electrolyte (HEE) is proposed to achieve concurrent stabilization of the I 2 cathode and Zn anode through hydrogen‐bond reconstruction and interfacial engineering. The introduced imidazolidinyl urea (IU) reconstructs the hydrogen‐bond networks to restrain H 2 O activity and inhibit water‐induced side reactions. Combined theoretical and experimental results further reveal that the imidazole moieties in IU effectively mitigate polyiodide shuttling via ion‐dipole interactions, minimizing active material loss and Zn corrosion. As a result, the HEE enables stable Zn plating/stripping over 5000 h with dendrite‐free morphology. The fabricated ZIB using HEE demonstrates a high capacity of 170.1 mAh g −1 at 10 A g −1 and outstanding long‐term cycling stability (81.2% retention over 20 000 cycles). Furthermore, this cell exhibits stable operation over a wide temperature range from −40°C to 65°C. This work provides a HEE‐enabled dual‐stabilization approach for long‐lifespan and temperature‐resilient ZIBs.