Amorphous anion skeletons induced rapid and cation-selective ion flux towards stable aqueous zinc-iodine batteries

Abstract

The aqueous zinc-iodine battery is considered as a promising technology for large-scale energy storage due to its high safety, large energy density, and easy accessibility. However, its development suffers from two challenges: parasitic side reactions on the Zn anode and the polyiodide shuttling effects. To overcome them, we designed an artificial protective layer on the Zn anode based on the amorphous zeolite-like Na2Zn2(TeO3)3, whose crystalline counterpart possesses the periodic ion channels and anion skeleton. It not only preserves the original coordination environments and pore structures of the crystalline counterpart, but also exhibites the broaden ion channels and shorten the ion diffusion pathways. Combining the superior structural stability of the amorphous Na2Zn2(TeO3)3, the Zn anode can stable cycle for 2,790 h at 1 mA cm−2 with a low overpotential. Meanwhile, the Zn2(TeO3)32− anion skeleton can also repel I−-species and SO42− anions from the anode surface, thus enabling outstanding Zn plating/stripping reversibility and excellent cyclic ability of the full cells coupled with different cathodes. Significantly, the capacity retention of the high mass loading zinc-iodine pouch cell could arrive 92.7% after 600 cycles. This work provides a novel strategy to achieve high-performance zinc-iodine batteries and holds great promise for its practical applications.