Highly stable Ah-level Zn-iodine batteries enabled by physical shielding and interface electronic reconstruction

Constructing a stable solid electrolyte interphase (SEI) for isolating the anode from electrolyte is extensively employed to inhibit side reactions and achieve uniform Zn deposition. However, since the SEI inherently allows Zn²⁺ transfer, it also inevitably permits H⁺ migration across the interface, thereby triggering hydrogen evolution reactions (HER) and corrosion. Therefore, this work in-situ constructs a hierarchical multifunctional SbZn and ZnF₂ interface layer (SZZF) on the Zn anode surface to address these challenges. Specifically, the outer ZnF₂-rich layer with hydrophobic properties acts as a physical barrier, facilitating Zn²⁺ desolvation and homogenizing Zn²⁺ flux. The inner SbZn alloy-rich layer provides abundant nucleation sites and weakens Zn-H⁺ bonding through d-p hybridization, effectively suppressing HER activity and enabling uniform Zn²⁺ deposition. Furthermore, the SZZF interface effectively suppresses corrosion-related side reactions induced by the iodine shuttle. Consequently, the SZZF@Zn symmetric cells exhibit exceptional cycling durability of 7000 h. Even under 85% depth of discharge (DOD) at 10 mA cm^-2 and 30 mAh cm^-2, the symmetric cell achieves a long cycling life for over 550 h. Remarkably, the SZZF@Zn||I₂ full cell maintains a capacity of 97% after 50,000 cycles, and the SZZF@Zn||I₂ pouch battery with 1.65 Ah stably cycles over 115 cycles. The results present a feasible and efficient interface optimization strategy for realizing highly reversible aqueous zinc iodine batteries.