Capture of Polysulfides\nEnabled by a Nitrogen-Doped\nCarbon-Coated Halloysite Nanotube-Modified Separator to Enhance Performance\nfor Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries stand out\nas highly\npromising energy storage systems because of their superior theoretical\ncapacity and the affordability of sulfur as an active material. However,\ntheir inherent drawbacks have hindered the commercialization of Li–S\nbatteries. Of these, the polysulfide shuttle effect is one of the\nmost critical issues, leading to the rapid decline in battery capacity.\nTo specifically address this issue, we successfully synthesized nitrogen-doped\ncarbon-coated halloysite nanotubes (HNT@NC) using a one-step sintering\nmethod and modified the Celgard 2325 separator on the side facing\nthe sulfur cathode (HNT@NC-Separator). The study found that HNT@NC-Separator\nexhibits excellent electrolyte wettability and superb mechanical strength.\nIts surface has abundant polar sites that effectively capture lithium\npolysulfides, thereby improving the cycling and rate performance of\nLi–S batteries. At a current density of 0.2 C, the Li–S\nbattery assembled with the HNT@NC-Separator achieved an initial discharge\ncapacity of 840.8 mAh g<sup>–1</sup>, maintaining a capacity\nof 486.1 mAh g<sup>–1</sup> after 100 cycles. At a current\ndensity of 1 C, the initial discharge capacity was 770.4 mAh g<sup>–1</sup>, maintaining a capacity of 412.9 mAh g<sup>–1</sup> after 100 cycles. In the rate performance test, the capacity retention\nrate exceeded 75%.