In Situ Construction of Mo2C Quantum Dots‐Decorated CNT Networks as a Multifunctional Electrocatalyst for Advanced Lithium–Sulfur Batteries

The slow redox kinetics during cycling process and the serious shuttle effect caused by the solubility of lithium polysulfides (LiPSs) dramatically hinder the practical application of Li‐S batteries. Herein, a facile and scalable spray‐drying strategy is presented to construct conductive polar Mo2C quantum dots‐decorated carbon nanotube (CNT) networks (MCN) as an efficient absorbent and electrocatalyst for Li‐S batteries. The results reveal that the MCN/S electrode exhibits a high specific capacity of 1303.3 mAh g−1 at 0.2 C, and ultrastable cycling stability with decay of 0.019% per cycle even at 1 C. Theoretical simulation uncovers that Mo2C exhibits much stronger binding energies for S8 and Li2Sn. The energy barrier for the conversion between Li2S4 and Li2S2 decreases from 1.02 to 0.72 eV when hybriding with Mo2C. Furthermore, in situ discharge/charge‐dependent Raman spectroscopy shows that long‐chain Li2S8 configuration is generated via S8 ring opening near the first plateaus at ≈2.36 V versus Li/Li+ and the S62− configuration in CNT/S electrode is maintained below the potential of ≈2.30 V versus Li/Li+, indicating that the shuttle of soluble LiPSs happens during the whole discharge process. This work provides deep insights into the polar nanoarchitecture design and scalable fabrication for advanced Li‐S batteries. Mo2C quantum dots (QDs)‐decorated carbon nanotube networks are synthesized by a facile spray‐drying strategy. The excellent catalytic property of conductive Mo2C QDs can guarantee the fast redox kinetics and effective conversion of Li polysulfides thus dramatically suppress the shuttle effect in Li‐S batteries. This research provides a novel approach for the design of sulfur hosts.