Dual‐Electrode Synergistic Electrolyte Enabling Highly Reversible Multi‐Electron Redox in Aqueous Zinc‐Iodine Batteries
Xuan Chen, Doudou Feng, Yucong Jiao, Peiyi Wu
Abstract
Abstract Multi‐electron redox strategies offer promising approaches to achieve high energy density in aqueous Zn‐iodine (Zn─I 2 ) batteries, yet the development is impeded by unstable intermediate species, slow redox kinetics, and poor reversibility, particularly at low current densities. Herein, 1‐pentyl‐3‐methylimidazolium bromide ([PeMIM] + Br − ) is employed to develop a dual‐electrode synergistic electrolyte (DESA‐E), which enables the multi‐electron conversion of Zn─I 2 batteries with high specific capacity and long‐term cycling stability. The Br − in DESA‐E induces dual‐halogen synergy, accelerating cascade I − /I 0 /I + four‐electron conversion kinetics and activating the Br − /Br 0 redox reactions for ultra‐high specific capacity. Meanwhile, hydrophobic [PeMIM] + alkyl chains stabilize interhalogen intermediates, suppress I + hydrolysis, and guide Zn deposition along the (002) plane via electrostatic effect. Consequently, the DESA‐E enables Zn─I 2 batteries with a specific capacity of 557 mA h g −1 after 500 cycles at 0.5 A g −1 with an average coulombic efficiency of 99.97%, and maintains a low degradation rate of 0.00055% per cycle over 60 000 cycles at 8 A g −1 . This work presents a facile and cost‐effective electrolyte design to enable durable multi‐electron Zn─I 2 batteries for high‐energy‐density systems.