Steric‐Hindrance Effect Induced Fabrication of Lightweight, Bi‐Functional, and Easy‐to‐Infiltrate Hosts for 502 Wh kg ⁻¹ Lithium‐Sulfur Batteries

Abstract A promising strategy for constructing 500 Wh kg −1 cell‐level rechargeable lithium‐sulfur batteries (LSBs) is developing hosts with ultralight weight to reduce nonactive mass, bi‐functionality to ensure both efficient sulfur reactions and lithium plating under low N/P, and an easy‐to‐infiltrate architecture for full wetting with lean electrolyte. Edge‐doped carbons, combining light weight and unique bi‐functionality, are rare candidates as such hosts. However, their preparation, which generally involves increasing specific surface areas or forming micropores/mesopores, impairs host‐wetting under lean electrolyte. Herein, a steric‐hindrance‐induced approach is pioneered to create abundant edge‐doping‐sites on an easy‐to‐infiltrate host of carbon nanofibers (CNF). Boron‐containing carbon dots (BCDs) are elaborately utilized as heteroatom‐introducing agents. Their organic nature facilitates uniform integration of graft‐like BCD units, while their inorganic crystalline cores suppress graphitization of CNF precursors surrounding these graft‐like units via steric‐hindrance during carbonization, promoting bi‐functional edge‐B‐doping sites formation. Such a host enables 2 Ah pouch‐type LSBs to achieve an impressive energy density of 502 Wh kg −1 with enhanced cyclic stability.