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 S-8 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 S-8 ring opening near the first plateaus at approximate to 2.36 V versus Li/Li+ and the S-6(2-) configuration in CNT/S electrode is maintained below the potential of approximate to 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.

Automated summary

The study presents a facile and scalable spray-drying strategy to construct conductive Mo2C quantum dots-decorated carbon nanotube networks as an efficient absorbent and electrocatalyst for Li-S batteries. The MCN/S electrode exhibits high specific capacity and ultrastable cycling stability, providing deep insights into polar nanoarchitecture design and scalable fabrication for advanced Li-S batteries.