Spatial Confinement Strategy of Electrolyte System Enabling High Performance Aqueous Zinc–Iodine Batteries with Wide Temperature Range

ABSTRACT Aqueous zinc‐iodine (Zn/I ₂ ) batteries are considered a promising candidate for energy storage; however, their commercial deployment is hindered by significant challenges such as detrimental polyiodide shuttling and instability at the Zn/electrolyte interface. Here, we report a spatial confinement chemistry strategy to engineer a synergistic electrolyte‐separator system, integrating the non‐protonic polar solvent diethylene glycol dimethyl ether (DGDE) additive and a sulfonated‐polyethersulfone (E‐SPES) separator enriched with sulfonate groups. This system operates through dual functional mechanisms: For the I ₂ cathode, sulfonate groups of the E‐SPES separator enforce dynamic spatial confinement of polyiodides via sustained electrostatic repulsion, effectively mitigating shuttle effects. In addition, DGDE disrupts the inherent hydrogen‐bonding network of the aqueous electrolyte, thereby suppressing water decomposition and boosting electrode reversibility with wide temperature range. Consequently, the Zn/I ₂ battery with the DGDE40/E‐SPES system exhibits a high CE of 93.5% at a record current density of 0.1 C (0.021 A g ⁻¹ ). Notably, the Zn/I ₂ cells with DGDE40/E‐SPES exhibit stable cycling over 30 000 cycles at a current density of 10 C. In addition, the Zn/I ₂ battery exhibits an ultralong cycling life of 2000 cycles with 98.5% capacity retention under 2 C at both −30°C and 40°C.