Multifunctional integrated VN/V2O5 heterostructure sulfur hosts for advanced lithium–sulfur batteries

Abstract

Lithium–sulfur (Li–S) batteries show great potential in future electric transportation and large-scale grid storage applications because of their attractive theoretical energy density (2600 W h kg⁻¹) and relatively abundant sulfur reserves. However, the rapid capacity decay and unsatisfactory sulfur loading caused by the lithium polysulphide (LiPS) dissolution and low electrical conductivity of sulfur are the most urgent issues plaguing its practical applications. Herein, we report a multifunctional nanoporous (NP) VN/V₂O₅ binary host that can efficiently resolve the above conflicts by the synergy between the functions of two materials. The inner V₂O₅ facilitates rapid trapping of numerous LiPSs while the outer porous VN with abundant NP channels offers high conductivity and mild chemisorption, thereby improving the localization and catalytic conversion ability of LiPSs. Accordingly, the designed cathodes with 1.87 mg cm⁻² sulfur content achieve an acceptable areal specific capacity (2.72 mA h cm⁻²), excellent rate capability (963 mA h g⁻¹ at 5.0C), and cycling stability. Remarkably, the cathodes with ultrahigh sulfur loading of 9.02 mg cm⁻² deliver a satisfactory areal specific capacity (12.12 mA h cm⁻²) and still maintain excellent durability.