Anchoring polyiodide with flexible interlayer for high-performance aqueous zinc-iodine batteries

Zinc-iodide (Zn-I₂) batteries have attracted widespread attention owing to the advantages of low cost, high specific capacity, and integrated safety. However, challenges involving the dissolution and shuttle of polyiodides and sluggish iodine redox kinetics constrain their practical applications. Herein, we designed a freestanding carbon nanofibers (CNFs) membrane embedded with ultrafine Sn nanoparticles (uSn-CNFs) as an efficient interlayer for Zn-I₂ batteries. Experimental and theoretical results indicate that ultrafine Sn nanoparticles (about 10 nm) provide abundant catalytically active sites for strong chemisorption of polyiodides and excellent electrocatalytic conversion, which synergize with the physical inhibition of CNFs to capture and realize the rapid conversion of iodine species. Consequently, batteries with uSn-CNFs interlayers exhibit excellent cycling stability (capacity degradation of only 0.0005 % per cycle after 30,000 cycles at 10 C) as well as outstanding rate performance (176 mAh g^-1 at 5 C). This study provides a reference to realize high-performance Zn-I₂ cells.