N-doped porous carbon-graphene cables synthesized for self-standing cathode and anode hosts of Li–S batteries

Abstract

Lithium-sulfur batteries have high theoretical energy density, but still suffer from polysulfide shuttle effect and lithium dendritic growth. Here, we present a rollable and swellable 3D cable-like carbon material consisting of porous fibrous carbon coated with nitrogen-doped graphene foam as self-standing host for both sulfur cathode and lithium anode. A cathode exhibits high areal energy density (10.2 mWh cm−2) and power density (5.1 mW cm−2) with 92.2% retention for 200 cycles at 0.5 C, and a full cell delivers 525 mAh g−1 (1.8 mAh cm−2) after 100 cycles at 0.5 C with a fade rate of 0.14% per cycle. We found dense urea molecules can assist graphene foam formation, cellulose fibers activation and high-level nitrogen (7.58 atom% N) doping, and the resulting cable-like carbon can improve electrocatalytic polysulfide redox kinetics and lithium dendrite inhibition. This work provides a strategy and understanding of modifying commercial cloth with graphene for dual electrode of Li–S battery.