Freestanding flexible multilayered Sulfur–Carbon nanotubes for Lithium–Sulfur battery cathodes

Abstract

A freestanding, flexible, multilayered sulfur–carbon nanotube film (MLSC) cathode was prepared for use in lithium–sulfur (Li–S) batteries without a metal current collector and binder using an economical and simple vacuum filtration method. The sulfur content in the MLSC electrode was maintained at 60 wt%. The MLSC electrode delivered a high initial reversible discharge capacity of 913 mAh g−1 and maintained a capacity of 736 mAh g−1, indicating excellent capacity retention. In addition, the coulombic efficiency of the MLSC electrode was over 92% throughout the total cycling, demonstrating superior cycling stability. It exhibited the initial discharge capacities at 0.2 and 2C of 951 and 642 mAh g−1, respectively, with 68% rate capability (2C/0.2C). These results indicate that the carbon nanotube film–wrapped structure of the MLSC electrode enables rapid electron transport in the electrode owing to its good electrical conductivity, and that it successfully suppresses the dissolution of lithium polysulfide in the electrolyte. Further, the MLSC electrode was stable during folding and bending in pouch cells. © 2020 Elsevier Ltd