Eutectic Network Synergy Interface Modification Strategy to Realize High‐Performance Zn‐I2 Batteries

Zn‐I2 batteries suffer from uncontrollable shuttle effects of polyiodine ions (I3− and I5−) at the cathode/electrolyte interface and side reactions induced by reactive H2O at the anode/electrolyte interface. In this study, a hydrated eutectic electrolyte is designed that synergizes the eutectic network and functional interfacial adsorbed layer to develop high‐performance Zn‐I2 batteries. The eutectic network can restrain active H2O molecules in the electrolyte to inhibit the side reaction at the anode/electrolyte interface and shuttle effect at the cathode/electrolyte interface. Additionally, the functional interfacial adsorbed layer guides the nucleation behavior of Zn2+ to inhibit the growth of dendrites and also separates the zinc anode from direct contact with active H2O molecules and polyiodine ions to inhibit corrosion. Theoretical calculation, in situ Ultraviolet–visible spectroscopy (UV‐vis) and Raman characterizations, and visualization experiments demonstrate that the hydrated eutectic electrolyte effectively inhibits the shuttling effect and improves the reversibility of zinc deposition/stripping behavior. Consequently, the Zn‐I2 battery can maintain a capacity of 133 mAh g−1 after 5000 cycles at 5 C. This highly efficient synergistic strategy offers a practical approach to the development of advanced Zn‐I2 batteries.