Ultrathin dense double-walled carbon nanotube membrane for enhanced lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are considered as next-generation technology for energy storage due to their high energy density. However, the rapid capacity fading resulted from the shuttle effect obstructs their practical application. Herein, ultrathin dense double-walled carbon nanotube (DWCNT) membrane has been designed to impede the shuttle effect. The outer wall of DWCNT helps to keep the integrity and conductivity for its inner wall. The defects on DWCNT are less than those on multi-walled CNT (MWCNT), which helps DWNCT to stack and form dense membrane. The tiny areal density of 0.00477 mg cm⁻² of DWCNT membrane would not weaken the Li-S battery’s energy density too much. The electrochemical tests suggested that the DWCNT membrane improved the cycling performance effectively. A possible reason was discussed. The cathode electrolyte interphase (CEI) grown on the DWCNTs made the membrane further dense, which promoted the blocking effect on polysulfides.