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.