Atomic mechanism of lithium intercalation induced phase transition in layered MoS2

The phase transition in layered MoS2 has attracted wide attention but the detailed phase transition process is still unclear. Here, the H -> T ' phase transition mechanism of single- and bilayer MoS2 induced by lithium intercalation has been systematically studied using first principles. The results indicated that the lithium intercalation can effectively reduce the sliding barrier of the S atom layer. Moreover, we demonstrated that the phase transition process in bilayer MoS2 is induced by S atom transition one by one instead of the collective behavior of the S atoms. Importantly, we found that the phase transition process in bilayer MoS2 consists of the formation, diffusion and recombination of S vacancies, and the phase transition originates from interlayer lithium defects. In addition, the lithium defects cannot induce phase transition in monolayer MoS2 due to the larger sliding barrier of the S atom.