Long-Lasting Zinc-Iodine Batteries with Ultrahigh Areal Capacity and Boosted Rate Capability Enabled by Nickel Single-Atom Electrocatalysts.

Zinc-iodine (Zn-I 2 ) batteries have garnered significant attention for their high energy density, low cost, and inherent safety. However, several challenges, including polyiodide dissolution and shuttling, sluggish iodine redox kinetics, and low electrical conductivity, limit their practical applications. Herein, we designed a highly efficient electrocatalyst for Zn-I 2 batteries by uniformly dispersing Ni single atoms (NiSAs) on hierarchical porous carbon skeletons (NiSAs-HPC). In situ Raman analysis revealed that the conversion of soluble polyiodides (I 3 - and I 5 - ) was significantly accelerated using NiSAs-HPC because of the remarkable electrocatalytic activity of NiSAs. The resulting Zn-I 2 batteries with NiSAs-HPC/I 2 cathodes delivered exceptional rate capability (121 mAh g -1 at 50 C), and ultralong cyclic stability (over 40 000 cycles at 50 C). Even under 11.6 mg cm -2 iodine, Zn-I 2 batteries still exhibited an impressive cyclic stability with a capacity retention of 93.4% and 141 mAh g -1 after 10 000 cycles at 10 C.