The low symmetry 1T′-MoS2 enabling the lithium directional diffusion through ferroelastic domain switching

The 1T phase of transition metal dichalcogenides (TMDs) is predicted to be an excellent anode material of lithium batteries (LIBs) by many previous theoretical investigations, especially in Mo- and W-TMDs, mainly because of its metallic character. However, the Peierls instability will induce a spontaneous transition from 1T to 1T′ phase, which was ignored by previous studies but should play an important role during the cycling process of LIBs. In this paper, the density functional theory calculations were adopted to systematically studied Li diffusion behavior on the different variants of low symmetry 1T′-MoS2. It was revealed that the diffusion barrier parallel to the Mo-Mo dimerization zigzag chain is almost two times to the perpendicular direction. Besides, the diffusion direction will be turned to ∼120° after Li crosses the domain boundary in a 1T′ multi-domain nanosheet. Similar results could also be observed in Na and K diffusion. Our finding not only revealed the Li (Na or K) diffusion behavior of 1T′-MoS2 but also propose to control the atom diffusion direction through strain engineering, which may inspire the further development of electronic devices.