Uniaxial Tensile Strain Impact on 1T-NbS2 Monolayers as Cathode Material for Lithium-Sulfur Batteries

In this work, we report our study on asymmetrical Janus TiSSe monolayers as cathode materials for lithium-sulfur batteries by first-principles calculations, encompassing adsorption, catalytic, and conductive properties. The results indicate that all Lithium Polysulfides (LiPSs) are adsorbed onto the S/Se surface of the TiSSe monolayer with a moderate adsorption energy, effectively suppressing the shuttle effect. The bond formation process were investigated by charge transfer, physical/chemical adsorption and projected crystal orbital Hamiltonian population (pCOHP), which confirmed its occurrence in the early lithiation stage. The Gibbs free energies for the reduction reaction of sulfur on the S/Se surface demonstrate a significant enhancement in the transformation kinetics. Additionally, the low decomposition and diffusion energy barriers for lithium atoms on the S/Se surface of TiSSe monolayer indicate its catalytic potential in facilitating sulfur redox transformation. Furthermore, the TiSSe monolayer exhibits metallic properties prior to and after polysulfide absorption, thereby enhancing electron transport capacity in Li-S batteries. The adsorption, diffusion, and reaction kinetics of TiSSe demonstrate superior performance compared to TiS2 and TiSe2. Therefore, the Janus TiSSe monolayer presents a novel perspective for the selection of battery adsorption materials as a high-performance positive cathode material in Lithium-sulfur batteries.