Tungsten Carbide Embedded in a Porous Carbon Nanofiber Sandwich Structure Electrode: A Strategy to Improve the Performance of Lithium–Sulfur Batteries

Lithium-sulfur (Li-S) batteries hold significant promise due to high energy density, cost-effectiveness, and ecological sustainability, but their practical applications are constrained by suboptimal electrochemical performance and the detrimental shuttle effect. Herein, a porous, sandwich-structured composite was developed to function as a freestanding cathode designed for Li-S batteries without aluminum foil. Porous carbon nanofibers (PCNF) were employed as the conductive matrix for sulfur, with tungsten carbide (WC) being incorporated to furnish abundant active sites for polysulfide adsorption. The findings indicate that the WC-PCNF_<i>x</i> conductive network, formed by tungsten carbide embedded within the porous carbon nanofiber sandwich structure, markedly enhances the active material exploitation, improves polysulfide adsorption, and demonstrates superior sulfur loading capacity and cyclic stability. Consequently, the synthesized WC-PCNF₂ composite material exhibited an outstanding capacity of 872.5 mAh/g under a high sulfur loading of 4.0 mg/cm² after 200 cycles at 0.2 C, with a commendable capacity retention rate of 85%. The metal carbide-embedded porous carbon network cathode material presents a practical approach to enhancing sandwich-structured electrodes.