Lithiation and Sodiation of Hydrogenated Silicene: A Density Functional Theory Investigation

Abstract

The next-generation renewable energy machineries necessitate the electrodes with appropriate electrochemical performance. Here, the anodic properties of silicane for Li- and Na-ion batteries were scrutinized employing first-principle calculations. The projected single-layer hydrogen-functionalized Si (Si2H2) structure was energetically, mechanically, dynamically, and thermally stable based on theoretical simulations, confirming its experimental feasibility. The electronic properties revealed the semiconducting nature of silicane on the basis of PBE and HSE06 schemes with an indirect bandgap. As anode material for Li- and Na-ion batteries, hydrogenated silicene showed promising electrochemical performance because of the proper adsorption strength between Si2H2 and the adsorbed Li and Na. The average open circuit voltages for Li2xSi2H2 and Na2xSi2H2 were as low as 0.42 and 0. 64 V, while its specific capacity was as high as 921 and 1842 mAh g−1 for Li and Na, respectively. It also showed ultra-fast diffusion channels for Li and Na ions. The diffusion barriers for Li and Na migrations were as low as 0.18 and 0.14 eV, respectively, which revealed rapid charge/discharge processes using hydrogenated silicene as anode. These important features facilitate silicane as favorable anode material for Li/Na-ion batteries.