Li adsorption was also performed on similarly defected single vacancy and Stone-Wales defective graphene substrates and it was found that in the case of both pristine graphene and SW graphene, the Li binding energies were much lower than the cohesive energy of lithium, thus showing the superiority of silicene over graphene as a viable substrate. These results can be seen in the supplementary information in Fig S3.
In order to understand the electronic interaction between the lithium atom and the silicene substrate, the projected density of states (pDOS) of the Li(s) and Li(p) orbitals along with the Si(p) orbitals for the different Si atoms in the SV silicene and SW silicene systems were plotted. The pDOS plots can be observed in Fig. 5 and confirm the electronic interaction that takes place between the Li atom and the Si atoms respectively. An overlap between the Li orbitals with the Si(s) orbital can be seen from -10 to -8 eV along with overlap just before and after the Fermi level which indicates strong chemical adsorption of the Li adatom onto the surface. The extent of the overlap can be seen to be greater, especially in the region from -8 to -4 eV in the SV silicene system which indicates stronger electronic interactions and hence stronger binding energies compared to the SW silicene system. The symmetric nature of the Li bonding can also be observed via the pDOS plots of the Si (25) and Si (27) atoms for the SV silicene system shown in Fig. 5c which completely overlap with one another. This coupled with the same Si-Li bond length in these atoms indicate that the Li atoms bonds similarly to both the atoms in the SV silicene system. Similar behaviour can be observed in the interactions of Li with atom 23 and 33 in the SW silicene system which are also alike in nature.