Fast Iodine Conversion Kinetics Enabled by Highly Electrocatalytic Molybdenum Carbide Nanocrystal-Embedded Ordered Carbon Nanocages

Aqueous zinc-iodine (Zn-I₂) batteries are promising for large-scale energy storage but suffer from sluggish redox kinetics and polyiodide shuttling. Herein, molybdenum carbide nanocrystals embedded within ordered carbon nanocages (MoC-OCNCs) are developed as a highly efficient electrocatalyst. The MoC nanocrystals exhibit strong polyiodide adsorption and significantly reduced energy barriers for iodine redox reactions, as validated by theoretical simulations and <i>in situ</i> Raman spectroscopy. Simultaneously, the interconnected hollow OCNC framework ensures rapid electrolyte penetration and efficient mass transport, while acting as a physical barrier to polyiodide diffusion. Consequently, Zn-I₂ batteries with the MoC-OCNCs electrocatalyst deliver an impressive rate capability (142 mAh g^-1 at 50 C) and good long-term stability. This performance extends to batteries with high iodine loadings and pouch-cell configurations. This work demonstrates that the synergistic integration of highly active nanocrystals within a conductive, porous matrix is critical for accelerating polyiodide conversions in high-performance Zn-I₂ systems.