Multi‐functional TiO 2 nanosheets/carbon nanotubes modified separator enhanced cycling performance for lithium‐sulfur batteries

Summary TiO 2 nanosheets (TiO 2 NSs) have been investigated for lithium‐sulfur (Li‐S) batteries as strategically designed TiO 2 nanosheet/carbon nanotube (TiO 2 NS/CNT) composite modified polypropylene (PP) separator to inhibit the shuttling of the intermediate polysulfides. The modified separator was fabricated by the vacuum filtration method using the exfoliation TiO 2 NSs and untreated carbon nanotube (CNT) composites. The multi‐functional TiO 2 NS/CNT coating not only reduced the electrochemical resistance but also localized the migrating polysulfides by the cooperative effect of physical adsorption and chemical binding. Specifically, the composition ratio of TiO 2 NSs/CNTs and the interface character have been studied. It was found that the optimum ratio and perfect electrolyte wettability of the TiO 2 NS/CNT layers were all the critical reasons to achieve good battery performance. The high initial discharge capacity of 1247 mA h g −1 at 0.2 C rate, which was 75% of the theoretical capacity of sulfur, 98% average coulombic efficiency, and 627 mA h g −1 discharge capacity retention after 100 cycles were obtained with the TiO 2 NS/CNT coating separator.