Dry-processing of VN quantum dots/N, O, S-doped hierarchical porous carbon electrodes with high sulfur-loading for practical lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are poised to become the next-generation energy storage technology due to their ultra-high energy density of 2600 Wh kg −1 and the abundant reserves of sulfur on Earth. However, the practical use of Li-S batteries faces several challenges related to sulfur cathodes, including low sulfur loading, significant volumetric expansion, slow conversion kinetics, and the shuttle effect caused by polysulfides. To tackle these challenges, we have developed a hierarchical porous carbon co-doped with nitrogen, oxygen, and sulfur heteroatoms (NOSHPC) that is further loaded with monodispersed vanadium nitride quantum dots (VNQDs). This innovative combination serves as an efficient catalytic matrix to enhance charge transfer processes and facilitate the anchoring and conversion of lithium polysulfides. Moreover, we have fabricated dry-processed cathodes with ultrahigh sulfur loading by using fibrotic polytetrafluoroethylene (PTFE) as a binder, replacing the toxic solvent N-methyl-2-pyrrolidone and polyvinylidene fluoride. The dry-processed VNQDs/NOSHPC/S cathodes demonstrate a remarkable specific capacity of 1655mAh g −1 at 0.1C and achieve exceptional cycling stability, with a decay rate of only 0.0107 % per cycle over 1000 cycles at 1C with a sulfur loading of 5.2 mg cm −2 . Additionally, the pouch cells containing these dry-processed electrodes exhibit a practical areal capacity of 14.2mAh cm −2 (462 Wh kg −1 ) with a sulfur loading of up to 18.6 mg cm −2 and a low electrolyte-to-sulfur ratio of 5.3μL mg −1 . This work presents an innovative strategy for creating sulfur hosts and practical dry-processed Li-S electrodes, highlighting promising prospects for industrial application.