Using density functional theory calculations, we determine the band structure and DOS of graphene and silicene supercell models. We also study the adsorption mechanism of Li metal atoms and Li-ions onto free-standing silicene (buckled, θ = 101.7°) and compare the results with those of graphene. In contrast to graphene, interactions between Li metal atoms and Li-ions with the silicene surface are quite strong due to its highly reactive buckled hexagonal structure. As a consequence of structural properties the adsorption height, the most stable adsorption site and energy barrier against Li diffusion are also discussed here to outline the prospects of using silicene in electronic devices such as Li ion batteries (LiBs), hydrogen storage and molecular machines. However, in most LiBs, graphene layers are used as anode electrodes. Here, it is shown that graphene has very limited Li storage capacity and low surface area than silicene. As our models are in good agreement with previous predictions, this finding presents a possible avenue for creating better anode materials that can replace graphene for higher capacity and better cycling performance of LiBs.