Metal–Organic Framework-Derived Bimetallic FeNi/Carbon Nanotube Entanglement Structure Enabling High-Efficiency Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) have attracted significant attention as next-generation secondary batteries owing to their outstanding theoretical energy density. Nevertheless, the practical application of sulfur cathodes is hindered by intrinsic challenges, including low electronic conductivity, severe polysulfide shuttle effects, and sluggish redox kinetics, which collectively induce rapid capacity fading and poor rate capability, significantly hindering the progress of LSBs. Bimetallic catalysts have been regarded as promising electrocatalysts for lithium–sulfur batteries due to their ability to chemically interact with polysulfide and promote its kinetic conversion. Composites exhibiting synergistic effects from binary metal nanoparticles typically demonstrate superior catalytic performance compared to conventional single-metal particles. In this work, taking advantage of a bimetallic metal–organic framework (MOF), we synthesized spherical entanglement structures by intertwining iron–nickel alloy particles with carbon nanotubes (FeNi/CNT). This distinctive structural configuration offers a rich diversity of adsorption and catalytic active sites, while the porous carbon architecture further boosts its electrical conductivity. Electrochemical testing of the FeNi/CNT/S cathode showed a first discharge capacity of 963.43 mAh g–1 at a current density of 0.5C, with a remaining capacity of 464.58 mAh g–1 following 800 cycles. In brief, FeNi/CNT accelerates the polysulfide conversion and enables the high efficiency of LSBs.