Density Functional Theory Study of Bilayer Borophene-Based Anode Material for Rechargeable Lithium Ion Batteries

The bilayer borophene has been successfully fabricatedin experimentsrecently and possesses superior antioxidation and robust metallicproperties, which holds great promise for the future anode materialsof Li-ion batteries. Herein, using first-principles calculations,two bilayer borophenes including P6/mmm or P6 m2 symmetry groupswith or without vacancy defects are comprehensively explored and actedas electrode materials with high performance in Li-ion batteries.The charge density difference, adsorption energies, and Bader chargeanalysis are calculated and discussed for single lithium adsorbedon bilayer borophene. The results shown that with the increase oflithium concentration, the adsorption energies are rapidly decreaseddue to the repulsion of boron atoms except for the P6 m2 systems with double side adsorption andcorresponding energies remain the narrow range. Meanwhile, the partialdensity of states shows metallic character after lithium adsorptionand indicates good conductivity for the charge-discharge process.Furthermore, small diffusion barriers, low average open-circuit voltage,can be achieved, and large storage capacity is up to 930.2 mA h/gat the lower lithium content of 0.375. These results propose thatbilayer borophene might be a good choice for anode material applicationsin future Li-ion batteries with fast ion diffusion and high powerdensity.