Adsorption and Diffusion of Lithium on Monolayer Transition Metal Dichalcogenides (MoS2(1–x)Se2x) Alloys

On the basis of first-principles plane-wave calculations, we examine the adsorption and diffusion of lithium on the hexagonal MoS 2(1– x ) Se 2 x monolayers with variation of x for 0.00, 0.33, 0.50, 0.66, and 1.00. We find that the lowest energy adsorption positions of Li adatom is at the top site of Mo atom in both MoS 2 and MoSe 2 monolayers, while Li moves through the Mo—S bond for MoS 2(1– x ) Se 2 x . While bare MoS 2(1– x ) Se 2 x compounds are nonmagnetic semiconductor and its energy band gap varies with x, they can be metallized by Li adsorption. NEB calculation results show that their energy barriers make them suitable for using in electrode materials. The lithium adsorption energy is sensitive to the external strain, when we elongate the lattice constants, the adsorption energy decreases quickly. We also examine the penetration energy barrier for single lithium atom to pass through the MoS 2(1– x ) Se 2 x monolayers, this barrier is decreasing from ∼2.5 eV to ∼1.3 eV with increasing selenium concentration.