Plant derived multifunctional binders for shuttle-free zinc-iodine batteries

Abstract

Zinc-iodine batteries (ZIBs) have emerged as promising candidates for next-generation batteries owing to their inherent cost-effectiveness, enhanced operational safety, and substantial theoretical capacity. Nevertheless, their further development is hindered by challenges such as active iodine dissolution and polyiodide shuttle effect. Designing functional binders is considered as a cost-effective strategy to break through this dilemma. Herein, guar gum (GG), locust bean gum (LBG) and konjac gum (KGM) derived from natural plant are investigated as binders for iodine loading cathode of ZIBs. The spectral characteristic analysis and theoretical calculation results reveal that the binders' functional groups possess significant chemisorption and high adsorption energy toward iodine species, effectively suppressing iodine dissolution and polyiodide shuttling. For instance, the GG binder exhibits a lower Gibbs free energy during the iodine conversion reactions, indicating accelerated iodine redox kinetics. As demonstrated, the GG-based ZIBs remain impressive reversible capacity of 136 mAh g⁻¹ after 10000 cycles at 1 A g⁻¹ with high-capacity retention ratio of 80 %. This work focuses on the rational design of aqueous binders for iodine-loading cathode of ZIBs, and promotes the practical application of iodine-based secondary batteries.