A novel biomimetic dandelion structure-inspired carbon nanotube coating with sulfur as a lithium-sulfur battery cathode

摘要

Lithium-sulfur (Li-S) batteries have attracted considerable attention because of their high theoretical energy density. However, poor conductivity and a large volume change in S during cycling, together with a shuttle effect of polysulfides, severely restrict the battery performance, and remain a great challenge. Herein, inspired by a natural dandelion structure, we present a novel biomimetic S-coated carbon nanotube composite consisting of dandelion-like three-dimensional carbon nanotubes coated with S particles on the surface. Carbon nanotubes provide high-speed electron transfer pathways for S during cycling, while the special dandelion-like morphology provides a suitable environment for accommodating the volume change in S upon charge-discharge. The dandelion-like S-coated carbon nanotube-based Li-S batteries exhibit a stable capacity exceeding 760 mAh g(-1) after 500 cycles at 0.1 C, along with a Coulombic efficiency as high as 99.9%. Even under repeated rounds of rate-performance measurements, and cycling at different charge versus discharge rates, the batteries retain high capacities and good recovery capabilities. In addition, the proportion of capacitive contribution in the overall capacity is high, indicating a good reversible capacity provided by the composite.