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

ZnÀ I 2 batteries stand out in the family of aqueous Zn-metal batteries (AZMBs) due to their lowcost and immanent safety. However, Zn dendrite growth, polyiodide shuttle effect and sluggish I 2 redox kinetics result in dramatically capacity decay of ZnÀ I 2 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 À SO 3 À groups is beneficial to attract Zn 2 + ions and repel detrimental SO 4 2À / polyiodide, improving the stability of cathode/anode interfaces synergistically. Consequently, the Janus separator endows outstanding cycling stability of symmetrical cells and high-areal-capacity ZnÀ I 2 batteries with a lifespan over 2500 h and a high-areal capacity of 3.6 mAh cm À 2 .