CoP/C Nanocubes-Modified Separator Suppressing Polysulfide Dissolution for High-Rate and Stable Lithium–Sulfur Batteries

A functioned PP was chosen as a separator to suppress the shuttling effect of soluble polysulfide in lithium–sulfur batteries (LSBs). Nanocubic cobalt phosphide/carbon (CoP/C) was modified on PP membrane through a simple vacuum filtration method. This CoP/C-modified PP separator not only efficiently captures polysulfides through strong chemical affinity but also facilitates the conversion of the soluble intermediates due to the fast transfer at the interface. In consequence, the cell with a CoP/C-modified separator exhibits a low-capacity decay of only 0.08% per cycle over 500 cycles at 1 C with an initial capacity of 938 mAh g–1 and a superior rate performance of 594 mAh g–1 at 4 C. Even with a high loading of 3.2 mg cm–2, the cell still exhibits an excellent reversible capacity of 601.3 mAh g–1 after 100 cycles at 0.5 C. This work provides a new strategy to effectively restrict the polysulfide shuttling.