Monolayer Honeycomb Borophene: A Promising Anode Material with a Record Capacity for Lithium-Ion and Sodium-Ion Batteries

Abstract

Two-dimensional (2D) materials are a promising candidate for the anode material of lithium-ion battery (LIB) and sodium-ion battery (NIB) for their unique physical and chemical properties. Recently, a honeycomb borophene ( h -borophene) has been fabricated by molecular beam epitaxy (MBE) growth in ultra high vacuum. Here, we adopt the first-principles density functional theory calculations to study the performance of monolayer (ML) h -borophene as an anode material for the LIB and NIB. The binding energies of the ML h -borophene-Li/Na systems are all negative, indicating a steady adsorption process. The diffusion barriers of the Li and Na ions in h -borophene are 0.53 and 0.17 eV, respectively, and the anode overall open-circuit voltages for the LIB and NIB are 0.747 and 0.355 V, respectively. The maximum theoretical storage capacity of h -borophene is 1860 mAh·g −1 for NIB and up to 5268 mAh·g −1 for LIB. The latter is more than 14 times higher than that of commercially used graphite (372 mAh·g −1 ) and is also the highest theoretical capacity among all the 2D materials for the LIB discovered to date. Our study suggests that h -borophene is a promising anode material for high capacity LIBs and NIBs.