Sulfur-containing polymer/carbon nanotube composite cathode materials for high-energy lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries have attracted the attention of researchers because of their excellent theoretical capacity and the advantages of cost-saving and environmental friendliness of their cathode materials. However, due to the shuttling of soluble intermediate polysulfides and other issues, the performance of current Li-S batteries is far from satisfactory. Herein, a sulfur-containing polymer (S-TVTCSi4) synthesized by the copolymerization of sulfur with 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane (TVTCSi), was combined with carbon nanotubes (CNTs) to obtain a sulfur-containing polymer/carbon nanotube composite cathode material for Li-S batteries. S-TVTCSi4 can effectively anchor lithium polysulfide through covalent bonding, and CNTs can improve the electrochemical reaction kinetics inside the battery. As a result, the S-TVTCSi4-CNT-based battery exhibited prominent rate capacity and stable cycling performance at different current densities, the reversible capacity of 980 mA h g−1 can be achieved after 100 cycles at 0.3C, with the capacity retention of 88.3%, and even at a high current density of 1C, 64.6% of the initial capacity can be retained after 1000 cycles, with a capacity decay of only 0.035% per cycle. The impressive cycling performance demonstrated the enormous potential of the S-TVTCSi4-CNT composite cathode in high-energy Li-S batteries.