Study On Strain Control Of 2D Ⅳ-Ⅴ Main Group Elements And Its Application In Lithium Battery Electrode Materials

Graphene was successfully synthesized in 2004.Its excellent performance is expected to become the next generation of emerging materials to replace silicon.However,the intrinsic zero-band gap characteristic of graphene has limited its practical application in the field of optoelectronic devices.Therefore,it is urgent to find a semiconductor two-dimensional material with a suitable band gap.While modifying the graphene defect to obtain a suitable band gap,researchers have begun to focus on other two-dimensional materials.However,due to various defects,they also face many application difficulties.In the case of the above-mentioned two-dimensional materials constantly hitting the wall,a new type of carbon-based two-dimensional semiconductor C₃N was synthesized by the Shanghai Laboratory of the Chinese Academy of Sciences.This material has an indirect band gap of0.39 e V,and the band gap can be adjusted by the size effect of the nanostructure.To make up for the defect of zero band gap of graphene,everyone’s attention has returned to the field of carbon-based two-dimensional materials.Based on the basic theory of mechanics,the stiffness matrix and the conditions for judging the mechanical stability of two-dimensional materials in different crystal systems are derived.Then use the CASTEP module to optimize the geometric structure of the two-dimensional material unit cell,and then give the calculation formulas of in-plane stiffness,Poisson’s ratio,layer modulus,and shear modulus along the axial direction and different directions in space by the energy method.Two methods are given by curve fitting to obtain the elastic constant under ideal conditions.The in-plane stiffness,layer modulus,shear modulus and Poisson’s ratio are calculated.Finally,based on the classical Euler-Bernoulli beam theory,a comparison of the mechanical parameter formulas of the hexagonal structure with the first-principles results is given.The structural,electronic,and optical properties of these compounds were studied using theoretical methods.In order to select a suitable plane wave cut-off energy and k-point sampling scheme for our calculations,different cut-off energies,k-point sampling and vacant layer thickness were used to test the calculated rate of total energy convergence.In the electrical part,first of all,new structures are predicted and nine new structures that can exist stably are proposed.The band structure and the density of states of the structure were studied.Influence of different layers on its photoelectric properties and electronic local functions were studied to explain its related mechanism.The calculation formula of the effective mass of electrons（holes）is given and the relevant parameters are obtained by fitting the band structure.The calculation formula of the electron mobility is also derived,the carrier mobility of the structure is given based on the deformation potential theory.Finally,the previous researches on IV-V main group elements are summarized,compared with the results of this paper in order to highlight the article.Based on the analysis of the polymerization energy and the theoretical storage capacity of the nine structures,C₃N materials were selected for adsorption application research.The optimal adsorption site was determined by studying the possible adsorption sites of a single lithium.The adsorption energy and layout analysis are researched to determine the corresponding electron relationship and electron transfer amount.The energy barrier is obtained by studying the diffusion path of lithium atoms between adjacent lowest adsorption sites.The maximum lithium storage capacity and average open-circuit voltage were studied by different amounts of lithium concentration adsorption.The effects of considering the historical correlation of stress on the Young’s modulus and Poisson’s ratio of a single-layer structure were studied.The stress-strain curve is given by the method of applying strain.First-principles-based methods are used to study the deformation process,crack fracture form,ultimate fracture strength and critical crack propagation location of single-layer structures.By applying uniaxial and biaxial strains,the energy band structure and the density distribution of states and optical properties of two-dimensional materials can be adjusted.The effect of stacking between different layers depend on its related electrical properties.Finally,the change of strain to the adsorption energy of different adsorption sites was also studied.