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

Abstract

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 1...