Charged lithium adsorption on pristine and defective silicene: a theoretical study

We investigated by first principle calculations the adsorption of Li(q= -1, 0 or +1) on a silicene single layer. Pristine and three different defective silicene configurations with and without Li doping were studied: single vacancy (SV), double vacancy (DV) and Stone-Wales (STW). Structural studies and the adsorption energies of various sites were obtained and compared in order to understand the stability of the Li on the surface. Moreover, electronic structure and charge density difference analysis were performed before and after adsorption at the most stables sites, which showed the presence of a magnetic moment in the undoped SV system, the displacement of the Fermi level produced by Li doping and a charge transfer from Li to the surface. Additionally, quantum capacity (QC) and charge density studies were performed on these systems. This analysis showed that the generation of defects and doping improves the QC of silicene in positive bias, because of the existence of 3p orbital in the zone of the defect. Consequently, the innovative calculations performed in this work of charged lithium doping on silicene can be used for future comparison with experimental studies of this Li-ion battery anode material candidate.