Anchoring polysulfides with ternary Fe3O4/graphitic carbon/porous carbon fiber hierarchical structures for high-rate lithium–sulfur batteries

Abstract

The poor electrical conductivity, sluggish reaction kinetics, and dissolution of polysulfides currently limit the application of lithium‑sulfur (Li–S) batteries. To address these issues, a unique hierarchical structure is designed as an interlayer, comprising Fe3O4 nanoparticle cores within a porous graphitic carbon (GC) shell, encapsulated within a carbon fiber (CF) framework. This synthesized composite is referred to as Fe3O4@GCF. Testing indicates effective anchoring and catalytic conversion of polysulfides by the generated Fe3O4 nanoparticle cores, resulting in significantly enhanced electrochemical performance, especially at high rates. The porous GC shell, characterized by its high conductivity, facilitate efficient electric charge flow, expediting the conversion between Fe3O4 and polysulfides. The utilized carbon fibers that are derived from commercial cotton tissues are found to construct a three-dimensional interlacing carbon network, enhancing electron and ion transfer and accelerating the reaction kinetics. The unique hierarchical architecture of Fe3O4@GCF endows it with superior electrical conductivity, abundant active catalytic sites, and excellent adsorptive properties for polysulfides, resulting in a high-capacity retention of 700 mAh g−1 at 1C after 100 cycles, with the excellent rate capability reaching 3C. The excellent cycling stability and rate performance of the hybrid interlayer demonstrates its effectiveness in enhancing the electrochemical performance of high-rate Li–S batteries. © 2024 Elsevier Ltd