Covalently Grafted Polysulfur–Graphene Nanocomposites for Ultrahigh Sulfur-Loading Lithium–Polysulfur Batteries

Although lithium–polysulfur (Li–polyS) batteries employing organic polymeric sulfur as a cathode material outperform the lithium–sulfur (Li–S) battery system, the relatively low sulfur loading (<2 mg cm–2) in the current Li–polyS batteries compromises the areal capacity, constraining their practicality. We present here a new cathode active material (a covalently grafted polysulfur–graphene nanocomposite (polySGN)) for ultrahigh-loading Li–polyS batteries. The new cathode active material polySGN offers several advantages: (i) the well-dispersed graphene sheets offer highly electrically conductive pathways for electrons to travel within the polySGN matrix; (ii) the intermediate organosulfide moieties alleviate irreversible sulfide deposition on electrodes; and (iii) the in situ formed coating layer on the cathode-side surface of the polymeric separator further reduces polysulfide migration. The Li–polyS batteries employing polySGN as the cathode active material accomplish the highest sulfur loading (up to 10.5 mg cm–2) and the highest areal capacity (∼12 mA h cm–2) reported thus far in the literature.