Polymer Electrolyte/Sulfur Double‐Shelled Anisotropic Reduced Graphene Oxide Lamellar Scaffold Enables Stable and High‐Loading Cathode for Quasi‐Solid‐State Lithium‐Sulfur Batteries

Lithium‐sulfur batteries (LSBs) can replace lithium‐ion batteries by delivering a higher specific capacity. However, the areal capacity of current LSBs is low because the intrinsic limitations of sulfur make achieving a high sulfur loading difficult. Herein, the authors report vertically aligned reduced graphene oxide (rGO) with sulfur and poly(ethylene oxide)‐based polymer electrolyte double‐shell layers (VRG@S@PPE) as a high‐loading sulfur cathode. The addition of vapor‐grown carbon fiber (VGCF) into rGO is the key to success, as it allows for gas evacuation from internal nano/micropores without structural collapse, enabling perfect double‐shell layer contact. Owing to the anisotropic rGO lamellar structure that enables straightforward ion/electron transport and provides numerous active sites, sulfur‐infiltrated rGO reinforced via VGCF (VRG@S) exhibits a high capacity of 998 mAh g(−1) after 100 cycles at 0.1 C under high sulfur loading (6 mg cm(−2)). Interestingly, an additional polymer electrolyte layer further increases the cycle retention (1005 and 718 mAh g(−1) after 100 cycles at 0.1 and 1 C, respectively), because intimate contact between the solid polymer electrolyte and sulfur could suppress the loss of sulfur due to lithium polysulfide (LPS) shuttling or volume change during lithiation/delithiation. Therefore, it is possible to realize safe and stable quasi‐solid‐state LSBs with high sulfur loading.