Nitrogen-doped tubular/porous carbon channels implanted on graphene frameworks for multiple confinement of sulfur and polysulfides

Abstract

Graphene has excellent potential as a sulfur host in a lithium–sulfur (Li–S) battery owing to its outstanding electrical conductivity and robust mechanical properties. However, graphene itself cannot effectively confine sulfur and suppress polysulfide diffusion, leading to severely fast capacity decay. Herein, nitrogen-doped tubular/porous carbon channels were implanted on graphene sheets (NTPC–G) via a double-template method, with graphene sheets as the shape-directed agents and NiCo–carbonate hydroxide nanowires as the guides of tubular channels. The resultant one-dimensional hollow tubular carbon and two-dimensional graphene nanosheets were wrapped by nitrogen-doped porous carbon layers to construct the unique three-dimensional sandwich-type architectures. The adopted graphene sheets functioned as conductive networks and robust frameworks; moreover, the nitrogen-doped tubular/porous carbon channels comprising hollow tubular carbon and porous carbon coating layers implanted on graphene frameworks served as the sulfur-confined space and polysulfide reservoirs. On integrating these fascinating benefits into one electrode material, sulfur and NTPC–G composites (S@NTPC–G) delivered high rate capability (563 mA h g⁻¹ at 6 C) and good cycle stability up to 600 cycles. This rational construction of tubular/porous carbon channels on nanosheet materials with comprehensive advantages could be promising and applicable in rechargeable Li–S batteries and other advanced energy storage devices.