First principles study of Li adsorption properties of a Borophene based hybrid 2D material B5Se

Abstract

In this work we investigate the Li adsorption properties of a hybrid 2D material, namely monolayer B5Se with first principles calculations. The density functional theory (DFT) calculations are performed with the generalized gradient approximation (GGA) and Perdew-Burke-Ernzerhoff (PBE) exchange correlation functional, inclusive of van der Waals corrections with Grimme's DFT-D3 scheme. Structural optimization calculations show 2 dimensional B5Se to have a distorted hexagonal structure with five B atoms and one Se atom at the vertices of each hexagon, with a favourable cohesive energy of formation of 0.648 eV/atom. A metallic nature was observed for the hybrid material from the band structure and density of states calculations. Electrode performance metrics, as the most preferred adsorption sites and adsorption energies, open circuit anode potentials, charge density differences and specific capacities for varying adatom coverage were evaluated with the DFT calculations. The adatom diffusion barriers were evaluated with a nudged elastic band (NEB) method. The ab-initio calculations predict a maximum theoretical specific capacity of 1486.87 mAhg−1 for Li adsorption on 2D B5Se, which is over four times that of conventional Li ion battery anode materials. This coupled with an open circuit anode potential of 0.291–0.179 V for different degrees of Li coverage, and a small Li diffusion barrier of 0.15 eV, metallic nature of the sheet under pure and lithiated conditions and good charge density variations, make monolayer B5Se a potent anode material for Li-ion battery applications.