In Situ Construction of Mo2 C Quantum Dots-Decorated CNT Networks as a Multifunctional Electrocatalyst for Advanced
Bo Yu1, Aijian Huang1, Dongjiang Chen2
1School of Electronic Science and Engineering, and State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, P. R. China.
Abstract:
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 Mo2 C 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 Mo2 C exhibits much stronger binding energies for S8 and Li2 Sn . The energy barrier for the conversion between Li2 S4 and Li2 S2 decreases from 1.02 to 0.72 eV when hybriding with Mo2 C. Furthermore, in situ discharge/charge-dependent Raman spectroscopy shows that long-chain Li2 S8 configuration is generated via S8 ring opening near the first plateaus at ≈2.36 V versus Li/Li+ and the S6 2- 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.
