Rational Design of Two-dimensional Anode Materials: B 2 S as a Strained Graphene.

Alkali metal atom adsorption energy is an important descriptor for anode material design. In this study, an energy decomposition model is developed to provide valuable insights in understanding how the adsorption behavior can be tuned. As an example, Li adsorption on graphene enhanced by a tensile strain is analyzed based on this model. Such an analysis then motivates us to find a system with similar electronic structure but larger lattice parameter compared to graphene as an anode material. Our first-principles calculations indicate that B2 S, as an isoelectronic system of graphene, is a good candidate. Its capacity is as high as 1498 mA h g-1 for both Li and Na ion batteries. Li and Na diffusion barriers on B2 S are 0.45 and 0.23 eV, respectively. This study opens a new avenue for adsorption-behavior-guided two-dimensional material design.