Molecule‐Interhalogen Soft Colloidal Electrode for High‐Voltage Stable Aqueous Zinc‐Ion Batteries

Halogen anion-based interhalogen design offers an effective approach to enable multiple-electron halogen electrodes in aqueous zinc batteries. However, the high operating voltages of halogen redox couples often lead to parasitic side reactions outside the stable voltage window of aqueous electrolytes, resulting in reduced Coulombic efficiencies and hindering practical application. Herein, a molecule-based interhalogen is introduced (M-interhalogen), (I₂/Br_x)^x-, and a detailed investigation of its unique interactions as a cathode material for aqueous zinc batteries. By incorporating M-interhalogen within a soft colloidal host, a significant shift of the redox reactions to a voltage window of 1.2 to 1.6 V versus Zn/Zn²⁺, greatly suppressing the parasitic side reactions is achieved. Consequently, the battery exhibits Coulombic efficiencies approaching 100% and demonstrates stable cycling at a small current density of 0.05 mA cm^-2. This study provides critical insights into practical deployment of aqueous zinc-halogen batteries.