Spatial‐Confined and Bifunctional Nanoreactors Toward Dendrite‐Free Anode and Shuttle‐Suppressed Cathode in Zinc–Iodine Batteries

Abstract A 3D hollow carbon nanoreactor fiber (HCNF) host, capable of dual‐electrode regulation, is designed to simultaneously tackle the dendrite growth and hydrogen evolution reaction at the Zn anode, as well as the dissolution and shuttle effect of polyiodide species at the I 2 cathode in Zn‐I 2 batteries. The HCNFs are fabricated via a high‐temperature sintering process, composing nanoreactors whose inner walls are embedded with CdO‐CdS heterostructures. This architecture synergistically integrates spatial confinement and interfacial modulation, boosting electrical conductivity and catalytic activity. Specifically, the zincophilic CdO guides the uniform Zn deposition within the nanoreactor, effectively inhibiting dendrite formation and suppressing hydrogen generation. The CdO‐CdS heterointerface facilitates ion transport and redistributes the electric field, reducing the Zn nucleation overpotential and enhancing the rate performance of batteries. Furthermore, the interfacial effect of the CdO‐CdS heterostructure facilitates the adsorption–catalysis–conversion of polyiodides, thereby suppressing their dissolution and shuttle effect, and ultimately enhancing the cycling stability of the full battery. As a result, the Zn‐I 2 battery delivers a high capacity of 172.5 mAh g −1 with excellent stability over 1000 cycles at 5 C. It can even retain the capacity of 108 mAh g −1 after 20 000 cycles at 50 C with ≈100 % Coulombic efficiency.