Enhanced Electrochemical Performance of MWCNT-Intercalated Silica/Sulfur Composite Cathode for Rechargeable Lithium-Sulfur Batteries

Abstract

Sulfur (S)/silicon dioxide (SiO2)/multiwalled carbon nanotube (MWCNT) ternary composites with potential application in high-performance lithium-sulfur (Li-S) batteries have been prepared by a heat treatment method. The S/SiO2/MWCNT composite with MWCNT content of 20 wt.% exhibited efficient electrochemical performance for use as a cathode in Li-S batteries, with initial discharge capacity of 926 mAh g−1 and coulombic efficiency of 99% at 0.2 C rate. A discharge capacity of 501 mAh g−1 was observed after 300 cycles with a decay rate of 0.15% per cycle. The average capacity retention was found to be 81.7% and 54.1% after 100 cycles and 300 cycles, respectively. These results demonstrate that a high content of MWCNT improved the electronic conductivity while the SiO2/MWCNT matrix represents a strong physical and chemical host for the polysulfides and active material. This study determines the combined effect of silica and MWCNT to improve the performance of the sulfur cathode.