Efficient Trapping and Catalytic Conversion of Polysulfides by VS₄ Nanosites for Li–S Batteries

Massive efforts have been devoted to enhancing performances of Li–S batteries to meet the requirements of practical applications. However, problems remain in enhancing the energy density and improving the cycle life. We present a free-standing structure of walnut-shaped VS₄ nanosites combine with carbon nanotubes (NTs) as cathodes. In this framework, NT arrays provide high surface area and conductivity for high sulfur loadings, and VS₄ nanosites facilitate trapping and catalytic conversions of lithium polysulfides. The synergistic effects of free-standing NT arrays and VS₄ nanosites have enabled high rate capability up to 6 C and long-term cycling with a low decay rate of 0.037% up to 1200 cycles at 2 C. Moreover, the designed cathode can achieve high areal capacities up to ∼13 mAh·cm^–2 and estimated gravimetric energy density of 243.4 Wh·kg^–1 at a system level, demonstrating great potential in practical applications of Li–S batteries.