Titanium-based nanorods/ketjen black modified separator as polysulfides barrier for lithium sulfur cell

The practical application of lithium sulfur (Li/S) cells is mainly hindered by the shuttle effect. Herein, the titanium-based nanorods/ketjen black (KB) composite prepared by a facile hydrothermal reaction is deposited on polypropylene to fabricate a bi-functional separator (KTO-2/PP) for Li/S cell. Using bare sublimed sulfur cathode, the cell based on KTO-2/PP separator exhibits excellent rate capability, delivering 1122, 856, and 566 mAh g−1 at 0.2, 1 and 2C, respectively. Moreover, the reversible capacity of the KTO-2/PP based cell can reach 754 mAh g−1 (1C) in the 200th cycle. Such performance boost is primarily ascribed to the KTO-2/PP separator, that Li+ is allowed to pass through but lithium polysulfides (LiPS) is shielded against shuttle. The conductive KB facilitates electron transport and adsorbs LiPS physically. The titanium-based nanorods adsorbs LiPS chemically by forming Ti–S bond which is confirmed by XPS analysis. Regarding the aged Li/S cell using KTO-2/PP, the smooth surface of PP (facing lithium anode) and the less sediment and negligible corrosion on anode indicate that the KTO-2/PP separator acts as an efficient barrier to inhibit the LiPS migration and enhances the electrochemical performance. [Display omitted] •KTO-2/PP prepared via a hydrothermal method is employed as bi-functional separator.•The strong chemical adsorption of KTO-2 to LiPS is proved by XPS analysis.•KTO-2/PP based cell presents 1122 and 856 mAh g−1 at 0.2 and 1C, respectively.•KTO-2/PP based cell remains 754 mAh g−1 after 200 cycles at 1C.•Little sediments are found on the lithium anode for aged KTO-2/PP based cell.