A Janus Separator based on Cation Exchange Resin and Fe Nanoparticles-decorated Single-wall Carbon Nanotubes with Triply Synergistic Effects for High-areal Capacity Zn-I2 Batteries

Abstract

Zn-I₂ batteries stand out in the family of aqueous Zn-metal batteries (AZMBs) due to their low-cost and immanent safety. However, Zn dendrite growth, polyiodide shuttle effect and sluggish I₂ redox kinetics result in dramatically capacity decay of Zn-I₂ batteries. Herein, a Janus separator composed of functional layers on anode/cathode sides is designed to resolve these issues simultaneously. The cathode layer of Fe nanoparticles-decorated single-wall carbon nanotubes can effectively anchor polyiodide and catalyze the redox kinetics of iodine species, while the anode layer of cation exchange resin rich in -SO₃ ^- groups is beneficial to attract Zn²⁺ ions and repel detrimental SO₄ ^2- /polyiodide, improving the stability of cathode/anode interfaces synergistically. Consequently, the Janus separator endows outstanding cycling stability of symmetrical cells and high-areal-capacity Zn-I₂ batteries with a lifespan over 2500 h and a high-areal capacity of 3.6 mAh cm^-2 .

Keywords: Cation Exchange Resin; Fe Nanoparticles-Decorated Single-Wall Carbon Nanotube; Janus Separator; Redox Kinetics; Zinc-Iodine Batteries.