Dual-Metal MOF-Derived Carbon Fibers Achieve Efficient Polysulfide Anchoring and Conversion Simultaneously in Li-S...

Lithium-sulfur (Li-S) batteries are regarded as strong contenders for next-generation high-energy-density energy storage systems. However, the practical application of Li-S batteries is severely hampered by the notorious polysulfide shuttle effect and sluggish redox kinetics. Herein, we designed and synthesized CoS₂-ZnS-modified carbon nanofiber networks (CoS₂-ZnS@CNF) using bimetallic metal-organic frameworks (MOFs) as precursors for Li-S batteries. This integrates the synergistic catalytic activity of bimetallic sulfides with the structural benefits of a conductive carbon nanofiber network to improve the electrochemical performance of the battery. Experimental results demonstrate that the CoS₂-ZnS nanoparticles are uniformly anchored on the carbon nanofibers. These strong chemisorptions of polysulfides and accelerated conversion kinetics through synergistic bimetallic catalysis. This inhibits polysulfide dissolution and diffusion in the electrolyte, alleviating the shuttle effect. Furthermore, the three-dimensional porous CNF framework provides sufficient space for the physical adsorption of polysulfides. Simultaneously, its continuous conductive framework constructs efficient electron transport pathways, significantly enhancing the conductivity of the electrode material. Electrochemical tests show that the battery with the CoS₂-ZnS@CNF maintains a high discharge specific capacity of 788.5 mAh g^-1 after 500 cycles at 0.5 A g^-1. Even under a high sulfur loading of 5.8 mg cm^-2, the battery exhibits an initial discharge capacity of 1042.6 mAh g^-1.