Built-in electrocatalytic nanoreactors anchoring ultrahigh iodine utilization for long-lasting zinc-iodine batteries

Zinc-iodine (Zn-I2) batteries have attracted considerable interest thanks to their high energy density, low cost, and inherent safety. However, challenges such as dissolution/shuttle of polyiodides and sluggish iodine redox kinetics limit their practical applications. In this paper, a nano-microreactor with highly catalytic center was employed as an iodine host material. Benefiting from the synergistic advantages of the electronic and geometric microenvironments of the nanoreactor, the nanoreactor with integrated adsorption-catalytic-conversion functionality enables the iodine conversion reaction to be carried out in a highly utilizable and stable manner without the undesired intermediate I3−, realizing a highly efficient Zn-I2 conversion reaction. An impressive near-theoretical capacity (213.9 mAh g−1) and ultra-long cycling stability (60,000 cycles at 10 A g−1 accompanied by an initial capacity of up to 164.9 mAh g−1 and capacity retention of 85.4%) were achieved. The nano-microreactor principle with accurate active site location and regulated reaction space will precisely modulate the catalytic program in the nanometer range, which suggests an effective strategy and new inspiration for realizing high-performance Zn-I2 batteries.