Preparation of WN@CNT/S composite and application as the cathode material of lithium-sulfur batteries

Lithium-sulfur batteries were considered as one of the important candidate materials for high energy density devices due to their potential advantages of high energy density and low cost. However, problems such as lithium polysulfides' shuttle effects and sulfur cathode material volume expansion during the charge-discharge process limited its commercial development. In this paper, a tungsten-containing precursor material was first prepared by sol-gel method and the tungsten nitride (WN) nanoparticles were obtained by sintering at high temperature in a nitrogen atmosphere, which was used as the sulfur carrier for LSB after in situ compounding with carbon nanotubes (CNT). Depending on their synergistic effect, the electrochemical performance of the sulfur cathode had been improved. The composite morphology structure and composition were characterized by XRD, SEM, Raman, and nitrogen adsorption and desorption analysis. The results showed that the WN nanoparticles grew in situ on the cross-linked CNT network structure. The uniform distribution composite consisting of nano WN particles and CNT could significantly improve the LSB electrochemical performance. The LSB with the WN@CNT-3/S composite could provide a high initial discharge capacity of 1512.6 mAh & sdot;g-1 at 0.1 C. After 200 cycles at 1 C, the capacity decay rate per cycle was only 0.13 %, showing excellent electrochemical performance, indicating potential applications in high-performance LSB.