Iodine-functionalized Ti3C2Tx MXene interfacial layers drive ultrastable iron–iodine batteries to achieve high iodine loading and cycling durability

Abstract

The development of iron–iodine (Fe–I₂) batteries has been hindered by the dissolution and shuttle effect of iodine cathodes, leading to insufficient cycling stability. This study addresses these challenges by fabricating Ti₃C₂T_x MXene through hydrofluoric acid (HF) etching of the Ti₃AlC₂ precursor, which serves as an efficient iodine host with high conductivity and abundant surface functional groups. Experimental results demonstrate that the 3D porous architecture of Ti₃C₂T_x enables exceptional iodine loading exceeding 40.8 wt%, while its surface-abundant –F/–OH functional groups establish strong chemisorption with iodine species, effectively suppressing polyiodide dissolution and shuttle phenomena. The highly conductive MXene network significantly accelerates I₂/I⁻ redox kinetics. The optimized Fe–I₂ battery based on this configuration retains 96.1% of its initial capacity after 200 cycles at 0.5C, with coulombic efficiency exceeding 99%. This work proposes a novel strategy for resolving iodine cathode stability issues through MXene interface engineering, advancing the practical development of high-energy-density Fe–I₂ battery systems.