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.