Mg2+/S Co-Decorated V, O Sites to Construct Multi-Defect V2O5 as a Sulfur-Wrapped Matrix for High-Performance Lithium–Sulfur Batteries

Abstract

Vanadium pentoxide (V₂O₅) is regarded as a promising sulfur-wrapped matrix for high-performance lithium–sulfur batteries, owing to its desirable structural and functional characteristics. In this paper, a large number of defective sites arise in the vanadium pentoxide structure via a codecoration strategy of the V, O sites, which is more beneficial to improving the electroconductivity and allows for the uniform loading of sulfur on the surface, thereby reducing the polarization resistance and elevating the kinetic rates during the electrochemical reaction. Electrochemical test results indicate that Mg²⁺/S-codecorated V₂O₅/S composite cathodes have 1131.15, 942.39, and 804.71 mAh·g^–1 of discharge-specific capacities at 0.1, 0.2, and 0.5 C rates, respectively, with the lowest charge/discharge plateau voltage difference, and the capacity retention rate after 140 cycles can be 57.95%. Besides that, the multidefect V₂O₅ can effectively promote the adsorption strength of lithium polysulfide and catalytically accelerate the rate of liquid-phase conversion between lithium polysulfide so as to achieve the stable electrochemical properties for sulfur composite cathodes.