Carbon Nanotube Modified Zn–Co Bimetallic Selenide Composites for Lithium–Sulfur Batteries

The cathode material of the lithium–sulfur (Li–S) battery poses several challenges, including inadequate conductivity, the "shuttle effect", and volume expansion, all contributing to its reduced cycle lifespan. To address these issues, high-performance Li–S batteries can be manufactured by using transition metal selenide nanomaterials. These nanomaterials exhibit polarity, porosity, electrochemical catalytic activity, and high conductivity, making them well-suited hosts for sulfur cathodes. In this study, a metal–organic framework material was employed as a precursor to produce hollow dodecahedral transition metal selenides. This involved combining the precursor with selenium powder and subjecting it to high-temperature calcination. By leveraging bimetallic synergism and incorporating carbon nanotubes, the material's conductivity was improved, providing a conductive pathway for electron transport. The hollow ZnSe/CoSe2 structure's surface is interconnected by carbon nanotubes, forming a conductive network. This arrangement facilitates efficient sulfur utilization and prevents structural collapse during battery cycling. Moreover, ZnSe/CoSe2 enhances the chemical anchoring of polysulfide, promotes polysulfide transformation, and induces homogeneous nucleation of Li2S. Experimental results demonstrate excellent electrochemical performance when 50 mg of carbon nanotubes. At a rate of 0.05 C, the initial discharge specific capacity reaches 1225.75 mA h·g–1, while at 1 C, it is 439.35 mA h·g–1. After 200 cycles, the battery exhibits a capacity retention of 71.25% with a reversible capacity of 313.08 mA h·g–1.