Three-Pronged Approach Enhances Porous Carbon Spheres for High-Performance Aqueous Zinc–Iodine Batteries

Aqueous rechargeable zinc–iodine batteries (ZIBs) have demonstrated significant potential for large-scale grid energy storage systems. However, challenges such as weak thermostability, the “shuttle effect”, and the low electrical conductivity of iodine hinder their practical applications. Herein, the synthesis of oxygen-functionalized and nitrogen-doped porous carbon spheres (ONCs) derived from Prussian blue analogs is reported. ONCs are used as an efficient host material for I2 to realize high-performance ZIBs. These ONCs exhibit effective encapsulation and adsorption properties for iodine species due to the nitrogen doping and unique meso/micro-dominated porous structures. Specially, oxygen functionalities enhance electrode hydrophilicity, ion transport, and I2/I– redox kinetics while functioning as active sites for reversible H+/Zn2+ storage to boost capacity. The I2@ONC cathode achieves a high capacity of 245 mAh g–1 at 0.5 A g–1 and retains 74% of its initial capacity after 8000 cycles at 5 A g–1. This study offers a rational host design strategy for high-performance aqueous ZIBs.