Micro/nano-structure construct of carbon fibers reinforced graphene/CNT matrix composites for Li-S batteries

Abstract

Lithium‑sulfur (Li-S) batteries have been hindered by the difficulty of achieving satisfactory cycling stability of high sulfur loading owing to the structural instability and exaggerated shuttle problem. Here, we design and fabricate a “reinforced concrete” structure based on the carbon fibers (CFs) supporting graphene/carbon nanotubes (GC) matrix composites, followed by a slurry-casting process to produce the final CFs-S/GC cathode with 4.5– 5.5 mg cm−2 sulfur loading. The 3D architecture of the micro/nano-hybrid materials enhances the structural strength and builds an interconnected conductive network for efficient electrolyte infiltration and the rapid electric/ionic transport. Furthermore, carbon nanofibers (CNFs) are growth on the surface of CFs by chemical vapor deposition to formation of CFs@CNFs. The CFs@CNFs-S/GC cathode enables the effective confines of polysulfides on electrochemically active sites, leading to a much-improved cycling performance. The strategy reported in this paper provides a feasible way for the construction of CFs or modified CFs skeleton in nanostructured carbon materials for high energy density Li-S batteries.