Adsorption and Mobility of Lithium on Pristine and Stone-Thrower-Wales Defective Silicenes

摘要

To explore and rationalize the enhancement of the capacity of lithium-ion batteries, ab initio density functional theory was employed to investigate the adsorption and diffusion properties of a lithium atom on and through pristine and Stone-Thrower-Wales (STW)-defective silicenes The theoretical calculations indicate that an enhancement of binding energy for a lithium atom on defective silicenes is found and the adsorption on pristine and defective silicenes is stronger than those on their graphene counterpart. The lithium mobility on pristine and defective silicenes is comparable to those on their graphene analogue, but the lithium atom migrates more easily and fast through the pores in silicene nanosheets than through the pores in corresponding graphene nanosheets In most cases, van der Waals (vdW) interactions contribute 0.78-0.99 eV to the binding energies They can cause either an increase or a decrease in diffusion barrier dependent on the competition of their contributions to the energies between the transition state and initial structures The vdW interactions are dominant for adsorption, but some time their effectson diffusion barrier are only marginal due to that their contributions may cancel each other out.