Sulfur-rich polymer/Ketjen Black composites as lithium-sulfur battery cathode with high cycling stability

Abstract

Lithium-sulfur (Li-S) battery is considered as one of the most promising energy storage devices due to its exceptional energy density. However, its development is largely hampered by the shuttle effect of lithium polysulfide and the sluggish electrochemical kinetics of sulfur cathode. In this study, a novel sulfur-rich polymer is synthesized through the inverse vulcanization of sulfur with 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane (TVTCSi) and used as cathode material for Li-S batteries, which can effectively immobilize the lithium polysulfides through covalent bonds to impede its shuttling, leading to marked improvement in the cycling performance of the batteries. Furtherly, with the addition of Ketjen Black, the resulting composite cathode exhibited faster electrochemical reaction kinetics and higher cycling stability, which could deliver a reversible discharge capacity of 652 mAh g−1 after 500 cycles at a high current density of 0.5 C,0.5C with quite a low capacity decay rate of only 0.037% per cycle, which indicates broad perspectives of sulfur-rich polymer/Ketjen Black composite as cathode material in lithium-sulfur battery.