Zinc‐Doping‐Induced Electronic States Modulation of Molybdenum Carbide: Expediting Rate‐Determining Steps of Sulfur Conversion in Lithium‐Sulfur Batteries

Abstract Enhancing Li 2 S deposition and oxidation kinetics in lithium‐sulfur batteries, especially the potential‐limiting step under lean electrolyte, can be effectively achieved by developing conductive catalysts. In this study, by using ZnMoO 4 as precursors, Zn‐doped molybdenum carbide microflowers (Zn‐Mo 2 C) composed of speared porous sheets are fabricated with a hierarchically ordered structure. Density functional theory calculations indicate that Zn doping shifts the d‐band center on Mo atoms in Mo 2 C upward, promotes the elevation of certain antibonding orbitals in Mo─S bonds above the Fermi level, enhances d‐p interaction between lithium polysulfides (LiPSs) and catalysts, weakens both S─S and Li─S bonds of LiPSs. Incorporating Zn significantly reduces the Gibbs free energy barrier for the rate‐limiting step of the Li 2 S 2 → Li 2 S conversion, from 0.52 eV for Mo 2 C to just 0.05 eV for Zn‐doped Mo 2 C. Thus, the synthesized Zn‐Mo 2 C demonstrates impressive bifunctional electrocatalytic performance, significantly advancing sulfur reduction and Li 2 S decomposition. Moreover, this modification enhances charge transfer within the Zn‐Mo 2 C/LiPSs system, synergistically accelerating the kinetics of Li 2 S 4 to Li 2 S reduction and Li 2 S oxidation. The Zn‐Mo 2 C/S cathode demonstrates impressive electrochemical performance, achieves remarkable cycling stability with a minimal capacity decay of 0.021% per cycle over 1000 cycles at 5 C, underscoring its potential for high‐energy applications.