Size Engineering of Ni Nanoparticles via Dual Templates to Enhance Zinc–Iodine Batteries

Zinc–iodine (Zn–I₂) batteries have received widespread attention due to their higher safety, rich resources, and eco-friendly features and show a promising potential for large-scale energy storage. Nevertheless, challenges such as the shuttle effect of polyiodides and sluggish redox kinetics of iodine species during charge and discharge processes hinder their development. This work reports an effective strategy to improve the electrochemical performance of Zn–I₂ batteries through the size engineering of nickel nanoparticles on biomass carbon. In situ UV and in situ Raman spectroscopies reveal that the dual-template size engineering strategy enables the catalyst to provide more active sites for adsorption and catalysis of iodine species, thereby enhancing the adsorption capacity of iodine species and accelerating the kinetics of I^–/I₂ redox conversion reaction. The shuttle effect of polyiodides is also significantly inhibited. Consequently, Zn–I₂ batteries with the size-reduced catalyst as the iodine host cathode exhibit superior rate performance, low potential polarization, and long cycle life.