Revealing dynamic sulfidation of WC-WO3 heterogeneous nanoparticles: In situ formation of WS2 facilitates sulfur redox in Li–S battery

Abstract

The sluggish redox kinetics of S species and the notorious shuttling effect of lithium polysulfides (LiPSs) severely impeded the practical application of lithium-sulfur (Li–S) batteries. Herein, we successfully synthesized WC-WO₃ heterogeneous nanoparticles dispersed on porous carbon substrate (WC-WO₃/C) as the promoter for high-efficiency LiPSs conversion. These nanoparticles combine the robust adsorption capacity of WO₃ with the excellent electrical conductivity of WC. Additionally, we studied the dynamic sulfidation behavior of WC-WO₃ heterogeneous nanoparticles during the electrochemical process through in situ characterization. A new active phase of WS₂ was generated, effectively enhancing the bidirectional redox of Li₂S. The Li–S battery armed with the WC-WO₃-WS₂/C@S cathode demonstrated outstanding cycling stability, with a capacity retention of 95.3 % at 2C after 800 cycles. The pouch cell exhibited an impressive energy density of 423.3 Wh kg⁻¹. This work not only contributes to a thorough understanding of the mechanism behind sulfidation behavior in regulating redox kinetics of LiPSs but also offers guidance for the design of electrocatalysts for high-performance Li–S batteries based on sulfidation.