Bifunctional TiS2/CNT as efficient polysulfide barrier to improve the performance of lithium–sulfur battery

Modifying the separator with functional materials is an effective strategy for building a polysulfide barrier to improve sulfur utilization in Lithium-sulfur (Li–S) batteries. Herein, flower-like TiS2 nanostructures consisting of ultrathin nanosheets are synthesized, and then coupled with highly conductive carbon nanotubes (CNTs) to construct TiS2/CNT modified separators, which provide sufficient active sites for anchoring polysulfides and offer a high-speed charge transport channel to accelerate the reaction kinetics. As a result, the TiS2/CNT cells display an initial specific capacity/reversible capacity of 1012/848 mAh g−1 after 100 cycles at 0.5 C and a specific capacity of 716 mAh g−1 at 3 C, which are significantly higher than those of the reference cells at corresponding current (729/471 mAh g−1 and 412 mAh g−1). Furthermore, the TiS2/CNT cells also provide a considerable capacity of 878 mAh g−1 under the sulfur areal-loading amount up to 10.5 mg cm−2, indicating the applicability of the TiS2/CNT modified separators in Li–S batteries. The results of cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) have confirmed that TiS2/CNT modified separators can improve the mobility of Li ions and accelerate the reaction kinetics, reducing the internal resistance as well as the polarization voltage furthermore. © 2020 Elsevier B.V.