Theoretical Study of the Structures and Properties of WLin (n=2-12) Bimetallic Clusters

Doping W into Li can greatly enhance the activity of Li-ion battery. However, the structures and properties of W-doped Li clusters remain elusive. In this study, we combined the global-minimum optimization and the density-functional theory calculations to systematically explore the lowest-energy structures of WLin (n = 2-12) bimetallic clusters and found it evolves from a triangle structure to a polyhedron pyramid structure, and finally to an endohedral cluster with W atom inside. In particular, W@Li-12 is identified as a superatom. The cluster exhibits an icosahedral structure with 18 valence electrons, which has a notable HOMO-LUMO gap of 1.56 eV. The ab initio molecular dynamics simulations confirm the thermal stability of this cluster. Furthermore, the infrared spectrum has two vibration peaks, corresponding to the bending vibration and stretching vibration of the tungsten-lithium bond, respectively. The UV-Vis spectrum has two absorption peaks at the excitation energy of 2-4 eV, revealing the characteristics of the orbital electron transition. This study paves the way for the study of Li-W alloy to understand its mechanism in Li-ion battery.