Grafting polymeric sulfur onto carbon nanotubes as highly-active cathode for lithium-sulfur batteries

• 来源期刊: 能源化学
• 年，卷（期）: 2020,（3）
• 页码范围: 27-33
• 页数: 7页
• 语种: 英文

摘要

Lithium-sulfur (Li-S) batteries are being explored as promising advanced energy storage systems due to their ultra-high energy density.However,fast capacity fading and low coulombic efficiency,resulting from the dissolution of polysulfides,remain a serious challenge.Compared to weak physical adsorptions or barriers,chemical confinement based on strong chemical interaction is a more effective approach to address the shuttle issue.Herein,we devise a novel polymeric sulfur/carbon nanotube composite for Li-S battery,for which 2,5-dithiobiurea is chosen as the stabilizer of long-chain sulfur.This offers chemical bonds which bridge the polymeric sulfur and carbon nanotubes.The obtained composite can deliver an ultra-high reversible capacity of 1076.2 mAhg-1 (based on the entire composite) at the rate of 0.1 C with an exceptional initial Coulombic efficiency of 96.2％,as well as remarkable cycle performance.This performance is mainly attributed to the reaction reversibility of the obtained polymeric sulfur-based composite during the discharge/charge process.This was confirmed by density functional theory calculations for the first time.