DFT-based investigation of silicon diboride (SiB2) monolayer as a promising anode material for alkali metal-ion batteries

Abstract

Silicon diboride (SiB₂) is a newly formed 2D monolayer material with metallic characteristics and a unique graphene-like structure; these features make it an attractive candidate for electrochemical applications. To investigate SiB₂'s feasibility as an anode of alkali-metal-ion batteries, we adopted density functional theory (DFT) based first-principles calculations in this research. The stability of the material is confirmed through formation energy calculations, phonon dispersion analysis, and ab initio molecular dynamics simulations. Our findings reveal that the adsorption of lithium, sodium, and potassium on the SiB₂ generates remarkably superior conductive efficiency, accompanied by significant adsorbate interaction energies of −1.72 eV (lithium), −2.84 eV (sodium), and −1.54 eV (potassium). The findings suggest that SiB₂ exhibits remarkable stability when lithiation, sodiation, and potassiation occur. The SiB₂ maintained the structural integrity during the ions' adhesion while exhibiting remarkable storage capabilities of 1012.2, 708.56, and 337.41 mAh/g for LIBs, SIBs, and KIBs, respectively. The mean open circuit voltage (OCV) values noted for SiB₂ are 0.62, 0.57, and 0.71 V for Li, Na, and K, respectively, while preserving its metallic properties during the adhesion mechanism. In addition, the estimated migrating barrier energies of lithium, sodium, and potassium are 0.59 eV, 0.63 eV, and 0.43 eV, respectively. Alkali metal adsorption on both sides of SiB₂ enhances its stability and conductivity, making it a potential candidate for battery applications. A convex hull plot has been generated for a more detailed analysis of the OCV. These distinctive attributes render SiB₂ an outstanding anode material for Li/Na/K-ion batteries.