Zn ²⁺ ‐Rich Microgel‐Liquid Biphase Electrolyte to Alleviate Interface Concentration Polarization for Advanced Aqueous Zinc Batteries

ABSTRACT The deployment of aqueous zinc‐based batteries is hindered by Zn 2+ concentration polarization at the zinc anode interface, which triggers dendrites and side reactions. Existing electrolyte strategies seldom address this kinetic bottleneck. Herein, we report a biphasic electrolyte in which trace amounts of guar gum (GG) undergo in situ self‐assembly with Zn 2+ to form a “guar gum‐Zn 2+ ‐SO 4 2− ” (ZSO‐GG microgel). This microgel functions as a heterogeneous dynamic Zn 2+ reservoir, continuously releasing Zn 2+ to the interface via a complexation‐dissociation equilibrium, thereby mitigating concentration polarization. Concurrently, the system reconfigures the hydrogen‐bond network to reduce H 2 O activity, releasing GG adsorbed on the Zn anode to regulate the electric double layer structure. When paired with iodine cathodes, the positively charged microgel network immobilizes polyiodides and suppresses the shuttle effect. Consequently, the Zn||Zn symmetric cell achieves a cycle life exceeding 5360 h at 1 mA cm −2 /1 mAh cm −2 . The Zn||I 2 full cell operates stably over 16 500 cycles at 10 C with coulombic efficiency consistently above 99.5%. Furthermore, the full cell paired with an oxygen‐deficient NH 4 V 4 O 10 cathode also delivers outstanding performance. This work presents a novel electrolyte structural design to address interfacial failure in aqueous batteries.