Physical properties of silicene electrodes for Li-, Na-, Mg-, and K-ion batteries

The transition from lithium-ion batteries to sodium- and potassium-ion batteries will increase the power of electrochemical current sources and the rate of their charging. On the basis of the first principles of density functional theory and ab initio molecular dynamics simulations, the interaction of Li, Na, Mg, and K atoms with an autonomous silicene has been studied. The adsorption energies and the Si-Me (Me=Li, Na, Mg, K) bond lengths for different locations of the adsorbed metal atoms are calculated. The favorable adsorption site of Me on silicene nanosheet is identified and reported. In the approximation of the generalized gradient, the band structure of the silicene/Me systems is calculated. The metallic state of an autonomous metallized silicene can arise for various cases of adsorption of an alkali metal and when the ratio between the Mg and Si atoms in the system is 1:1. Metallization of the semiconductor does not occur when the number of adsorbed Mg atoms is less than the number of Si atoms.