Self-Assembled Janus Layers on Zinc Interface to Repel Water Molecules and Polyiodides toward Long-Life Aqueous Zinc Iodine Batteries

Abstract

Aqueous zinc iodine (Zn//I₂) batteries have garnered widespread attention due to their high theoretical specific capacity and high safety. However, the corrosion of Zn metal anodes, induced by H₂O molecules and polyiodides, leads to a short cycling life. Herein, 4-tert-Butylcalix[6]arene (TBCX)-based Janus molecular layers, self-assembled on Zn interface, are utilized to inhibit hydrogen evolution reaction (HER) and confine polyiodides, thereby stabilizing the Zn anode and achieving a long-life Zn//I₂ battery. The hydrophobic tertiary butyl (C(CH₃)₃) functional groups in the TBCX layers repel H₂O molecules, depressing the HER. Significantly, the H₂ evolution rate at the Zn@TBCX anode is reduced to 0.7 μmol h⁻¹ cm⁻². Additionally, the hydroxyl (OH) functional groups in TBCX, with their lone pair electrons, demonstrate a polar affinity for polyiodides, preventing them from reaching the Zn interface and thus suppressing Zn corrosion induced by polyiodides. Furthermore, the zincophilic TBCX layer also acts as an ionic redistributor, enabling rapid and homogeneous Zn²⁺ flux. Owing to these attributes, the symmetric Zn@TBCX cell can cycle stably for 2200 h at 5 mA cm⁻², and Zn@TBCX//I₂ full cells deliver an extended lifespan of 6000 cycles at 5 A g⁻¹ with a high capacity retention ratio of 98.8%.