Increasing sulfur utilization in lithium-sulfur batteries by a Co-MOF-74@MWCNT interlayer

To improve lithium-sulfur battery performance, Co-MOF-74 has been applied for the first time as an interlayer with multiwalled carbon nanotubes (MWCNTs). Co-MOF-74@MWCNT was synthesized using a solvothermal method. The fabrication of Co-MOF-74@MWCNT was confirmed by scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and Brunauer-Emmett-Teller testing. The interlayer was fabricated using a filtration method. Assembled batteries were prepared using a CoMOF-74@MWCNT interlayer and an MWCNT interlayer and subsequently investigated via cyclic voltammetry tests. Co-MOF-74 promotes a redox reaction and shows a small peak at 1.85 V. A symmetric and full cell test revealed that the Co-MOF-74@MWCNT cell enables a faster redox reaction and higher capacity than that of the MWCNT cell. After 15 cycles, the Co-MOF-74@MWCNT cell achieved a value of 1112 mAh g(-1), which is 26% greater than that of the MWCNT cell (880 mAh g(-1)) at 0.2C. Voltage profile testing showed that the reason for the higher capacity of the Co-MOF-74@MWCNT cell is that it promotes the conversion of Li2S2 to Li2S. Various electrochemical analyses confirmed that the Co-MOF-74@MWCNT interlayer acts not only as a physical and chemical barrier but also promotes the transformation of Li2S2 to Li2S. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

In this study, Co-MOF-74 was used for the first time as an interlayer in lithium-sulfur batteries, combined with MWCNTs to enhance battery performance, promoting the redox reaction rate and capacity of the battery.