The curious case of two dimensional Si2BN: A high-capacity battery anode material

The ubiquity of silicon in the semiconductor industry and its unique charge transport features has consistently fueled interest in this element and recent realization 2D silicene is a new feather in its cap. In what could be considered as opening up the Pandora's box with many possible virtues, buckled silicene, planar graphene and a host of other newly discovered 2D materials have redefined a whole new paradigm of research. To this end, the quest for new 2D materials and finding potential applications, particularly to the realm of energy storage, is a curiosity driven task. From first principle density functional theory studies, a newly reported graphene like 2D material Si2BN is investigated as a probable anode material for Li and Na ion batteries. In contrast to pristine silicene, which is inherently buckled, the material Si2BN is planar. However, an interesting transition from planar to buckled structure takes place upon subsequent adsorption of Li and Na ions. Concomitantly, this transition is associated with superior specific capacity (1158.5 and 993.0 mA h/g respectively for Li and Na) which is significantly higher than several other 2D analogues. Furthermore, the substrate Si2BN regains the planar structure on subsequent desorption of ions and stability of the material remains intact, as evidenced from ab initio molecular dynamics simulations. As we delve deep into the electronic structure and compute the diffusion pathways and barriers, it is observed that the ionic diffusion is very fast with significantly lesser barrier heights, particularly for Na-ion. These findings suggest that for the 2D Si2BN, there is no diminution in order to be a potential anode material for Li and Na ion batteries.