A detailed study of lithium storage on γ-BNyne; computational approach

Abstract

Lithium storage on γ-Graphyne-like boron nitride (γ-BNyne) was studied using density functional theory. Li atoms gradually were placed on the surface. At each step, in addition to the optimization of the structure with the size of the γ-BNyne unit cell, the effect of lithium concentration on the unit cell size was investigated. The results of the second method showed deviation from the planar form with increasing lithium concentration which was not observed in the first method. All of Li binding energies obtained by the second method are greater and demonstrate a stronger interaction with the surface. Also, the lowest adsorption energy was obtained for 2Li/BNyne structure. The band structure plots indicated that the adsorption of Li atoms on the surface causes converting the surface into an n-type semiconductor and improving its conductivity. Bader charges analysis and the charge density differences demonstrated the charge transfer from Li atom to the surface and a quasi-covalent bond between Li and sp-hybridized nitrogen atom. The energy barrier for the best Li diffusion pathway on the surface was found of 0.45 eV. Our calculations indicate that γ-BNyne can appropriate for application in the Li-ion batteries as an anode material.