Computer development of silicene anodes for lithium-ion batteries: A review

Lithium-ion batteries (LIB) have many advantages, the main ones being high energy density, long service life, small size, and low environmental pollution. This review is devoted to further development of LIBs based on quantum mechanical calculations in order to use them for energy storage in the future. Energetically favorite places occupied by lithium atoms on silicene are found. Lithium filling of free-standing two-layer silicene and single-layer silicene on graphene was studied. The geometric, energy, charging characteristics, as well as the open circuit voltage are determined. The effect of metallic (Al, Cu, Ni, Ag and Au) and non-metallic (C, SiC and BN) substrates on the geometric, energy and electronic properties of silicene has been studied. The effect of an intermediate nickel layer on the characteristics of the "silicene on a multilayer copper substrate" system has been studied. The effect of nuclear transmutation doping (NTD) of the silicene/graphite system with phosphorus on the density of electronic states of one- and two-layer silicene has been determined. Promising applications for silicene and the advantages of its use as an anode in a lithium-ion battery are discussed. keywords: lithium-ion batteries, silicene, binding energy, DFT calculation, substrate DOI: https://doi.org/10.15726/elmattech.2022.1.00

Modeling the UO2 reduction process

Methods of molecular dynamics and DFT calculations have been used to study the reduction mechanisms of UO2 as the most representative part of spent nuclear fuel to metallic uranium. It is shown that the critical softening of the combined modulus of elasticity C11-C12 to zero is the reason for the destruction of the UO2 crystal as a result of the removal of oxygen from it. This destruction is accompanied by an order-disorder phase transition in the oxygen subsystem of the crystal under consideration. DFT calculations indicate a continuous decrease in the band gap as oxygen is removed from the UO2 crystal. When the system reaches the composition U2O3, the band gap disappears and the system becomes electrically conductive. The appearance of the dielectric-conductor transition explains the realization of the FFC Cambridge process during the recovery of spent nuclear fuel. The passage of Li+ and Cl– ions of the LiCl melt through cylindrical channels in a UO2 crystal with cross-sectional radii from 0.25 up to 2 nm has been studied. The strength of the external electric field required for the passage of these channels decreases with an increase in the channel cross section, and the number of Cl– ions entering the channel increases. On the walls of the channels that pass ions with charges of both signs, colonies of adsorbed Cl– and Li+ atoms appear separated from each other, between which strong electric fields are formed. The existence of such fields can cause Li+ ions to move deep into the material being reduced.https://doi.org/10.15826/elmattech.2023.2.01

Simulation of silicon nanoparticles stabilized by hydrogen at high temperatures

Abstract The stability of different silicon nanoparticles are investigated at a high temperature. The temperature dependence of the physicochemical properties of 60-and 73-atom silicon nanoparticles are investigated using the molecular dynamics method. The 73-atom particles have a crystal structure, a random atomic packing, and a packing formed by inserting a 13-atom icosahedron into a 60-atom fullerene. They are surrounded by a ''coat'' from 60 atoms of hydrogen. The nanoassembled particle at the presence of a hydrogen ''coat'' has the most stable number (close to four) of Si-Si bonds per atom. The structure and kinetic properties of a hollow single-layer fullerene-structured Si 60 cluster are considered in the temperature range 10 K B T B 1760 K. Five series of calculations are conducted, with a simulation of several media inside and outside the Si 60 cluster, specifically, the vacuum and interior spaces filled with 30 and 60 hydrogen atoms with and without the exterior hydrogen environment of 60 atoms. Fullerene surrounded by a hydrogen ''coat'' and containing 60 hydrogen atoms in the interior space has a higher stability. Such cluster has smaller self-diffusion coefficients at high temperatures. The fullerene stabilized with hydrogen is stable to the formation of linear atomic chains up to the temperatures 270-280 K

Ab Initio Study of the Electronic Properties of a Silicene Anode Subjected to Transmutation Doping

In the present work, the electronic properties of doped silicene located on graphite and nickel substrates were investigated by first-principles calculations method. The results of this modeling indicate that the use of silicene as an anode material instead of bulk silicon significantly improves the characteristics of the electrode, increasing its resistance to cycling and significantly reducing the volume expansion during lithiation. Doping of silicene with phosphorus, in most cases, increases the electrical conductivity of the anode active material, creating conditions for increasing the rate of battery charging. In addition, moderate doping with phosphorus increases the strength of silicene. The behavior of the electronic properties of doped one- and two-layer silicene on a graphite substrate was studied depending on its number and arrangement of phosphorus atoms. The influence of the degree of doping with silicene/Ni heterostructure on its band gap was investigated. We considered the single adsorption of Li, Na, K, and Mg atoms and the polyatomic adsorption of lithium on free-standing silicene

Ab Initio Study of the Electronic Properties of a Silicene Anode Subjected to Transmutation Doping

In the present work, the electronic properties of doped silicene located on graphite and nickel substrates were investigated by first-principles calculations method. The results of this modeling indicate that the use of silicene as an anode material instead of bulk silicon significantly improves the characteristics of the electrode, increasing its resistance to cycling and significantly reducing the volume expansion during lithiation. Doping of silicene with phosphorus, in most cases, increases the electrical conductivity of the anode active material, creating conditions for increasing the rate of battery charging. In addition, moderate doping with phosphorus increases the strength of silicene. The behavior of the electronic properties of doped one- and two-layer silicene on a graphite substrate was studied depending on its number and arrangement of phosphorus atoms. The influence of the degree of doping with silicene/Ni heterostructure on its band gap was investigated. We considered the single adsorption of Li, Na, K, and Mg atoms and the polyatomic adsorption of lithium on free-standing silicene