Boosting Iodine Redox Kinetics by Nickel‐Cobalt Diatomic Electrocatalyst for Zinc‐Iodine Batteries

Abstract Single‐atom catalysts (SACs) offer an efficient solution of a well‐defined structure‐activity relationship for boosting iodine redox kinetics and suppressing the shuttle effect in zinc‐iodine (Zn‐I 2 ) batteries, but the further upgradation of their electrocatalytic activity is still constrained to date. Herein, atomically dispersed transition‐metal electrocatalysts comprised of heteronuclear nickel‐cobalt diatomic sites anchored on porous carbon nanosheets (Ni‐Co‐DA/PCNs) are proposed by a novel interlayer‐confinement pyrolysis strategy. Thereinto, the NiCoAl‐layered double hydroxides are employed as the 2D topological structure to induce the confined polycondensation of aromatic hydrocarbon precursors, and the transition‐metal ions are simultaneously trapped in hierarchical carbon frameworks by the oxygen‐containing species. The detailed experimental investigations combined with the in situ Raman spectroscopy reveal that the Ni‐Co‐DA/PCNs electrocatalyst with well‐defined M‐O 4 pair and high specific surface area is capable of facilitating the adsorption and fast conversion of polyiodides, thereby accelerating the redox kinetics of I 2 /I ‒ and protecting zinc anode. Consequently, the assembled Zn‐I 2 batteries with the Ni‐Co‐DA/PCNs/I 2 cathode exhibit a high discharge capacity of 216.7 mAh g ‒1 at 0.2 A g ‒1 with excellent rate capability and ultralong cycling lifespan over 9000 cycles with a capacity decay of only 0.0018% per cycle, which is far superior to those of Ni/Co SACs. This work provides a new insight into the design of dual‐atom catalysts for Zn‐halogens batteries.