Vanadium-Doped Molybdenum Diselenide Accelerates Sulfur Redox Kinetics in Lithium-Sulfur Batteries.

The persistent shuttle effect of polysulfides and slow liquid-solid redox kinetics remain major obstacles to the practical application of Lithium-Sulfur (Li─S) batteries. In this study, a vanadium-doped molybdenum diselenide catalyst designed to address these challenges are presented. Experimental analysis and theoretical calculations reveal that V doping slightly disrupts the 2D growth of MoSe₂, creating structural defects and abundant edge-active sites. These active sites enhance polysulfide adsorption, facilitate efficient catalytic conversion, and promote the utilization of S species. Additionally, electron redistribution induced by V dopants improves electronic conductivity and accelerates redox kinetics. As a result, Li─S batteries using V_0.1Mo_0.9Se₂ as a catalyst deliver a high discharge capacity of 1467.3 mA h g^-1 at 0.1 C and maintain a capacity of 651.9 mA h g^-1 after 1000 cycles at 1 C, with an ultralow decay rate of 0.036% per cycle. Under high sulfur loading (5.5 mg cm^-2), the batteries exhibit a specific capacity of 803.9 mA h g^-1 after 100 cycles and a decay rate of only 0.11% per cycle. This study demonstrates that V doping effectively activates inert MoSe₂, providing a promising strategy for designing high-performance sulfur cathode catalysts and advancing the development of next-generation Li─S batteries.