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Hydrogel electrolytes (HEs) hold great promise in tackling severe issues emerging in aqueous zinc‐ion batteries, but the prevalent salting‐out effect of kosmotropic salt causes low ionic conductivity and electrochemical instability. Herein, a subtle molecular bridging strategy is proposed to enhance the compatibility between PVA and ZnSO4 from the perspective of hydrogen‐bonding microenvironment re‐construction. By introducing urea containing both an H‐bond acceptor and donor, the broken H‐bonds between PVA and H2O, initiated by the SO42−‐driven H2O polarization, could be re‐united via intense intermolecular hydrogen bonds, thus leading to greatly increased carrying capacity of ZnSO4. The urea‐modified PVA‐ZnSO4 HEs featuring a high ionic conductivity up to 31.2 mS cm−1 successfully solves the sluggish ionic transport dilemma at the solid‐solid interface. Moreover, an organic solid‐electrolyte‐interphase can be derived from the in situ electro‐polymerization of urea to prohibit H2O‐involved side reactions, thereby prominently improving the reversibility of Zn chemistry. Consequently, Zn anodes witness an impressive lifespan extension from 50 h to 2200 h at 0.1 mA cm−2 while the Zn‐I2 full battery maintains a remarkable Coulombic efficiency (>99.7 %) even after 8000 cycles. The anti‐salting‐out strategy proposed in this work provides an insightful concept for addressing the phase separation issue of functional HEs. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc iodine (Zn‐I2) batteries offer benefits such as low cost and high safety. Nevertheless, their commercial application is hindered by hydrogen evolution reaction (HER) and polyiodide shuttle, which result in a short lifespan. In this study, 1‐(2‐hydroxyethyl)imidazole (HEI) organic molecules featuring pyrrole‐N groups are introduced as dually‐functional electrolyte additives to simultaneously stabilize Zn anode and confine polyiodide through ion‐dipole interactions. The pyrrole‐N groups in HEI can preserve the interfacial pH equilibrium at Zn anode by reversibly capturing H+ ions and dynamically neutralizing OH− ions, thereby suppressing the HER. Notably, the H2 evolution rate at the Zn anode is reduced to a mere 2.20 μmol h−1 cm−2. Furthermore, the pyrrole‐N moieties in HEI effectively curtail the polyiodide shuttle at I2 cathode, which show adsorption energies of −0.174 eV for I2, −0.521 eV for I3−, and −0.768 eV for I−, as indicated by density functional theory calculations. Electrochemical testing demonstrates that the Zn//Zn symmetric cell maintains stable cycling for up to 4,200 hours at 1 mA cm−2. Most strikingly, at a high I2 mass loading of 9.7 mg cm−2, the Zn‐I2 battery achieves an extraordinary cycle life of 50,000 cycles. [ABSTRACT FROM AUTHOR]

Hydrogel electrolytes (HEs) hold great promise in tackling severe issues emerging in aqueous zinc-ion batteries, but the prevalent salting-out effect of kosmotropic salt causes low ionic conductivity and electrochemical instability. Herein, a subtle molecular bridging strategy is proposed to enhance the compatibility between PVA and ZnSO 4 from the perspective of hydrogen-bonding microenvironment re-construction. By introducing urea containing both an H-bond acceptor and donor, the broken H-bonds between PVA and H 2 O, initiated by the SO 4 2- -driven H 2 O polarization, could be re-united via intense intermolecular hydrogen bonds, thus leading to greatly increased carrying capacity of ZnSO 4 . The urea-modified PVA-ZnSO 4 HEs featuring a high ionic conductivity up to 31.2 mS cm -1 successfully solves the sluggish ionic transport dilemma at the solid-solid interface. Moreover, an organic solid-electrolyte-interphase can be derived from the in situ electro-polymerization of urea to prohibit H 2 O-involved side reactions, thereby prominently improving the reversibility of Zn chemistry. Consequently, Zn anodes witness an impressive lifespan extension from 50 h to 2200 h at 0.1 mA cm -2 while the Zn-I 2 full battery maintains a remarkable Coulombic efficiency (>99.7 %) even after 8000 cycles. The anti-salting-out strategy proposed in this work provides an insightful concept for addressing the phase separation issue of functional HEs., (© 2024 Wiley-VCH GmbH.)