Vanadium-based compounds and heterostructures as functional sulfur catalysts for lithium-sulfur battery cathodes

Lithium-sulfur (Li-S) batteries have attracted wide attention for their high theoretical energy density, low cost, and environmental friendliness. However, the shuttle effect of polysulfides and the insulation of active materials severely restrict the development of Li-S batteries. Constructing conductive sulfur scaffolds with catalytic conversion capability for cathodes is an efficient approach to solving above issues. Vanadium-based compounds and their heterostructures have recently emerged as functional sulfur catalysts supported on conductive scaffolds. These compounds interact with polysulfides via different mechanisms to alleviate the shuttle effect and accelerate the redox kinetics, leading to higher Coulombic efficiency and enhanced sulfur utilization. Reports on vanadium-based nanomaterials in Li-S batteries have been steadily increasing over the past several years. In this review, first, we provide an overview of the synthesis of vanadium-based compounds and heterostructures. Then, we discuss the interactions and constitutive relationships between vanadium-based catalysts and polysulfides formed at sulfur cathodes. We summarize the mechanisms that contribute to the enhancement of electrochemical performance for various types of vanadium-based catalysts, thus providing insights for the rational design of sulfur catalysts. Finally, we offer a perspective on the future directions for the research and development of vanadium-based sulfur catalysts.