Breath-like interlayer bonding facilitates efficient metal-ion storage in bilayer borophene with decreased adherence capabilities on Ag substrate

Abstract

The fabrication of bilayer borophene presents an alternative approach to tackle the challenges related to thermodynamic stability and the detachment of monolayer borophene from the metal substrate, which currently restrict its practical application. However, recent theoretical investigations have revealed that the structural arrangement of the most energetic free-standing bilayer borophene, denoted as BL-α+ borophene, is different from the configuration observed experimentally (Nat. Mater. 2022, 21, 35–40). Herein, the effects of introducing an additional stratum of borophene on the electronic properties, mechanical performance, adherence capabilities towards Ag (111), and electrochemical performance as an anode material for alkali-ions batteries has been thoroughly examined. The results demonstrate that free-standing BL-α+ borophene manifests a reduced energy adhesion (Eadh) of −0.059 eV Å−2 when contrasted with its monolayer counterpart. Furthermore, the interlayer B-B bonding exhibits a breath-like dilatation and contraction behavior during metal-ion adsorption/desorption, leading to remarkable theoretical capacities of 1351.6 mAh/g for Li-ion anodes, 1351.6 mAh/g for Na-ion anodes, and 450.53 mAh/g for K-ion anodes, accompanied by moderate diffusion barriers of 0.58 eV, 0.34 eV, and 0.23 eV for Li, Na, and K ions, respectively. These results provide valuable insights into the application of borophene-based electrode materials that exhibit improved stability through a “self-stacking” mechanism.