Research On Electronic And Mechanical Properties,and Energy Storage Behavior Of Two-dimensional Antimonene/Graphene Heterostructure

Two-dimensional materials refer to crystals or amorphous materials with single or several layers of atoms,whose electrons only move freely in a two-dimensional space of non-nanometer scale(1-100nm).Since two-dimensional graphene(Graphene)was successfully separated by Andre·Geim and Konstantin·Novoselov in 2004,two-dimensional materials represented by graphene have attracted much attention because of their excellent electrical,optical,mechanical,magnetic and thermal properties.Compared with bulk materials,two-dimensional materials such as nano-graphene,phosphene and antimonene have larger specific surface area,more active sites and open lithium/sodium ion diffusion channels,which make up for the defects of traditional electrode materials such as low rate performance and volume expansion during charging and discharging.This makes two-dimensional materials a great application prospects in secondary battery energy storage electrode materials.In this paper,the crystal structure,electronic properties and mechanical properties of graphene,antimonene and G/Sb heterostructures in two-dimensional monoatomic layers are systematically simulated by the first-principles calculation method based on density functional theory(DFT)and ab initio molecular dynamics(AIMD)simulation.On this basis,we studied and compared the absorption and diffusion properties of lithium/sodium on two-dimensional materials with single layer and heterostructure were compared and the micro-mechanism of the macro-electrochemical properties such as stability,rate performance and cycle life of these materials as negative electrode energy storage materials for secondary batteries was analyzed,which provided theoretical reference for the optimization and design of high performance secondary electrode energy storage materials.The main contents of this paper are as follows:Through the first-principles calculation method based on DFT,we optimized the structure and obtained the lattice constants of two-dimensional graphene,antimonene and G/Sb heterostructures.One for more,we compared and analyzed the electronic structures of the heterostructure.The calculated results were compared with the theoretical and experimental literature values to ensure the accuracy and reliability of the calculation method.By comparing the calculated results with the literature values of theory and experiment,the accuracy and reliability of the calculation method are guaranteed.On this basis,we calculated the elastic constants of these materials.The results show that the heterostructure system has higher stiffness and excellent shear resistance than the two-dimensional single-layer material.Meanwhile,the molecular dynamics characteristics of G/Sb heterostructures at 300,500 and 1000 K are calculated by AIMD simulation.The results show that there is no obvious structural deformation and chemical bond breakage of G/Sb heterostructure at 1000 K after 10 ps,which indicates that the heterostructure has good thermodynamic stability.The adsorption,electronic and diffusion properties of lithium/sodium ions in graphene,antimony monolayer and graphene/antimonene heterostructure were studied by first-principles calculation method.The results show that Li/Na can be adsorbed stably on graphene,antimony and G/Sb heterostructure,but the adsorption of Li/Na on graphene/antimony heterostructure is more stable and tends to be interlayer adsorption.Secondly,Li/Na system shows good conductivity after it is embedded in graphene,antimony and heterostructure.Moreover,by studied the diffusion properties of Li/Na on these materials with CI-NEB method we found that Li/Na ions have lower diffusion barriers on single antimonene than on single graphene,which means better rate performance;In G/Sb heterostructures,the diffusion path and barrier of Li/Na ions on the surfaces of G/Sb heterostructures are almost the same as those in monolayer graphene and antimonene;Compared with lithium ion,the diffusion barrier of sodium ion in the same system is obviously lower,which indicates that sodium ion will diffuse faster in two-dimensional single layer and heterostructure than lithium ion.In addition,through systematic comparative analysis of Li/Na energy storage behavior in this kind of two-dimensional materials,it found that when G/Sb heterostructure is used as negative electrode material for secondary batteries,Lithium ion battery has better adsorption stability,while sodium-ion battery has better rate performance.