Net-Structured Filter of Co(OH)2‑Anchored Carbon Nanofibers with Ketjen Black for High Performance Li–S Batteries

Lithium sulfur batteries have been extensively explored in recent years owing to their high theoretical energy density (∼2600 Wh kg–1), environmental benignity, and low cost of raw materials. Besides the advanced sulfur cathode, various functional separators/interlayers are also being developed as the effective inhibitor of polysulfide diffusion. In this study, Co­(OH)2-anchored carbon nanofibers (CNFs) with Ketjen black (KB) dispersed in the void were designed as a dense net-like structure (denoted as Co­(OH)2@CNF/KB), which was coated at the surface of a typical commercial separator to help inhibit polysulfide migration. It was demonstrated that the Co­(OH)2@CNF/KB-modified separator could effectively increase the charge transfer of the cathode material, trap the dissolved polysulfides, and help to reuse the sequestered active material. As a result, the cell employing this functionalized separator and unmodified sulfur-based electrode exhibits an initial specific capacity of 1394 mA h g–1 at 0.1 C, which converts to 84% utilization of sulfur, and a capacity decay of 0.10% per cycle at 2 C for over 450 cycles. The unique design of Co­(OH)2@CNF/KB provides a promising modifying approach for future lithium batteries.