Bamboo-like Porous Carbon Nanotubes Encapsulating Bi2O3@Fe3O4 as Highly Efficient Sulfur Host Materials for Lithium–Sulfur Batteries

Abstract Lithium–sulfur batteries (LSBs) with high theoretical energy density and exceptional theoretical capacity are considered as a competitive next-generation energy storage. Nevertheless, the practical application of LSBs faces primary hindrances caused by the shuttle effect of polysulfides (LiPSs), volumetric expansion of sulfur, and poor conductivity of discharge products. Therefore, we synthesized conductive porous bamboo-like carbon nanotubes (CNTs) that uniformly encapsulate Bi2O3 nanorods and Fe3O4 nanoparticles (Bi2O3@Fe3O4) as highly efficient sulfur host materials (BFO@CNTs) for cathode composites and materials for separator modification (BFO@CNTs@CL). The three-dimensional network structure of bamboo-like CNTs provides rapid electronic transport channels to improve redox kinetics. Moreover, owing to the segmented encapsulation structure of bamboo-like CNTs, more exposed active sites of Bi2O3@Fe3O4 remain well dispersed without agglomeration, facilitating superior catalytic activity and adsorption capacity for LiPSs during long cycling. The LSBs assembled with BFO@CNTs composite as cathodes and BFO@CNTs@CL separator achieve a high initial capacity of 1265 mAh g–1 and retain 1060 mAh g–1 after 150 cycles at 0.5C. Therefore, this work proposes a stable structural design for anchoring LiPSs at active sites, offering an innovative pathway to explore stable host materials in the field of high-performance LSBs.