Enhancing electrochemical conversion of lithium polysulfide by 1T-rich MoSe 2 nanosheets for high performance lithium-sulfur batteries

The sluggish conversion kinetics and shuttle effect of lithium polysulfides (LiPSs) severely hamper the commercialization of lithium-sulfur batteries. Numerous electrocatalysts have been used to address these issues, amongst which, transition metal dichalcogenides have shown excellent catalytic performance in the study of lithium-sulfur batteries. Note that dichalcogenides in different phases have different catalytic properties, and such catalytic materials in different phases have a prominent impact on the performance of lithium-sulfur batteries. Herein, 1T-phase rich MoSe 2 (T-MoSe 2 ) nanosheets are synthesized and used to catalyze the conversion of LiPSs. Compared with the 2H-phase rich MoSe 2 (H-MoSe 2 ) nanosheets, the T-MoSe 2 nanosheets significantly accelerate the liquid phase transformation of LiPSs and the nucleation process of Li 2 S. In-situ Raman and X-ray photoelectron spectroscopy (XPS) find that T-MoSe 2 effectively captures LiPSs through the formation of Mo-S and Li-Se bonds, and simultaneously achieves fast catalytic conversion of LiPSs. The lithium-sulfur batteries with T-MoSe 2 functionalized separators display a fantastic rate performance of 770.1 mAh/g at 3 C and wonderful cycling stability, with a capacity decay rate as low as 0.065% during 400 cycles at 1 C. This work offers a novel perspective for the rational design of selenide electrocatalysts in lithium-sulfur chemistry. & COPY; 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.