Computer Study of Atomic Mechanisms of Intercalation/ Deintercalation of Li Ions in a Silicene Anode on an Ag (111) Substrate

Abstract

The ability of silicon to hold a large amount of lithium puts silicene in a series of the most promising materials for the anode of lithium-ion batteries. An increase in the rate of movement of lithium ions through silicene can be achieved with silicene having vacancy-type defects. The effect of vacancy-type defects on the fill ability with lithium of the channel formed by silicene sheets on the Ag (111) substrate, as well as on the structural and kinetic properties of lithium, has been studied by the molecular dynamics method. The limit number of intercalated lithium atoms and their self-diffusion coefficient increase with the transition from the perfect silicene channel to the channel containing mono-and bivacancies. The lithium structure in the channel was studied using the method of statistical geometry. The packing of the lithium atoms in the channel turns out to be partially ordered due to the regular placement of some of the atoms at their fixation opposite the centers of hexagonal Si-cells. The σ zz stress in the sheets of silicene decreases during intercalation of lithium and increases at the final stage of deintercalation.

Computational Study of Lithium Intercalation in Silicene Channels on a Carbon Substrate after Nuclear Transmutation Doping

“…The remaining hg values were separated from each other by a distance of 0.1 nm. The lithium atoms in the channel with the gap hg = 0.75 nm could move quite freely along the channels located on the metal (Ag, Al, and Cu) substrates [5][6][7]35]. In the present work, the initial distance between the lower silicene sheet and the graphite substrate was 0.222 nm and corresponded to a similar value determined using the DFT calculations in Reference [36].…”

“…In References [5][6][7], it was shown that using the same procedure for lithium filling in an identical silicene channel that has no defects and is located on metal substrates (Ag, Al, Cu, and Ni) can achieve the presence of 39 to 74 Li atoms. The best channel occupancy with lithium (91 Li atoms) was achieved in the presence of monovacancies in the channel walls if the channel was placed on the Ni(111) substrate and in the presence of bivacancies (85 Li atoms) in silicene when the channel was on the Cu(111) substrate.…”

“…The value h g = 0.24 nm was determined in the DFT calculations as a gap in two-layer free-standing silicene [34]. The gap h g = 0.75 nm was used to study the intercalation/deintercalation of lithium in a silicene channel on metal substrates [5][6][7]. The remaining h g values were separated from each other by a distance of 0.1 nm.…”

“…Thin films of silicon and (in particular) silicene are the most promising anode materials for lithium-ion batteries [5][6][7]. The advantage of their use in electrochemical devices is that they allow for the maintenance of a high theoretical electrode capacity (4200 mAh/g), which characterizes the intercalation of lithium in bulk silicon.…”

A New Model to Predict Optimum Conditions for Growth of 2D Materials on a Substrate

“…For a piece of silicene sheet of 336 Si atoms on the (111) surface of an Ag substrate with 2640 Ag atoms located in perfect fcc lattices (Figure 5a), the Tersoff potential was employed to describe the interactions between Si atoms with the parameters taken from [36], and the interaction between the Si atoms and the Ag atoms as described by a Morse pairwise function [52]. The system was cooled down to 0.01 K by a damping method [43,44] to determine the lowest energy U0 and the most stable structure.…”