Enhanced lithium adsorption and diffusion on silicene nanoribbons

For developing lithium (Li)-ion batteries with large energy densities and high rate capabilities, it is crucial that electrode materials show good reactivity with charge carrying Li ions, and simultaneously allow for their fast transport. Using first principles density functional theory calculations, here we investigate the interaction of Li with the edges of monolayer as well as multilayer silicene and identify the low energy Li binding sites and the pathways for Li diffusion. Both Li binding and diffusion are found to be significantly controlled by the morphology of the silicene edges. We show that among known structural forms of silicon, monolayer silicene edges provide the strongest binding with Li. The energy barriers for Li diffusion on monolayer silicene nanoribbons are generally very low (0.14-0.26 eV), and in particular, zigzag edges can allow for up to 80 times faster diffusion than on a silicene monolayer. Our results indicate that monolayer silicene nanoribbons terminated with zigzag edges can provide promising candidate materials for the negative electrodes of Li-ion batteries.