A Multifunctional Beryllium Silicide Monolayer with Negative Poisson's Ratio and High-Capacity Sodium-Ion Storage

Abstract

The development of high-performance anode materials for sodium-ion batteries (SIBs) has become a critical research focus. In this study, we employ a lightweight metal-based design strategy to propose a novel two-dimensional (2D) Be2Si monolayer utilizing global structure algorithm and first-principles calculations. The Be2Si monolayer with the lowest global energy exhibits an indirect bandgap of 1.15 eV, a negative Poisson's ratio of −0.25, and high optical absorption in the visible light range. More important, the sodium ion migration energy barrier is as low as 0.053 eV, and the theoretical specific sodium storage capacity is as high as 2330 mAh g−1. The results indicate that the Be2Si monolayer is a highly potential multi-functional material, which is applicable to multiple fields such as flexible electronic devices, stress sensors, auxetic materials, optoelectronic devices, and anode materials for sodium-ion batteries.