| The energy crisis,as well as environmental issues,have put higher demands on the field of electrochemical energy storage.Meanwhile,2D materials have been considered as ideal materials for improving battery performance in recent years due to their superior physicochemical properties.2D BSi is a new 2Dmaterial with the structure similar to graphene.The research on 2DBSi has been increasing in recent years.In this paper,the mechanical and energy storage properties of 2D BSi and several elemental doping structures have been investigated by first-principles calculations based on density function theory.The following conclusions were obtained in the study of mechanical properties:(1)2D BSi has good structural stability,while it is easy to oxidize,but can remain stable in a moisture environment;(2)Among the eight doping structures,the doping of nitrogen substituted silicon atoms is the easiest to form,and the doping of carbon substituted boron atoms is the most difficult to form;(3)2D BSi has a large Young’s modulus,high tensile strength,and good ductility.There are significant differences in stress-strain curves along the armchair and zigzag directions.The study also shows that elemental doping will reduce Young’s modulus and ultimate tensile strength;(4)Elemental doping can modulate the anisotropic distribution of Young’s modulus of 2D BSi.The following conclusions were obtained in the study of 2D BSi energy storage applications:(1)The stable adsorption sites of lithium and magnesium atoms on 2D BSi are located at the central hole sites of the two types of six-membered rings;(2)The adsorption energies of both lithium and magnesium atoms with 2D BSi at different adsorption sites are relatively low than the cohesion energies of lithium and magnesium atoms,respectively;(3)The differential charge density as well as charge population analysis indicate that lithium and magnesium transfer lots of negative charges to 2D BSi,and magnesium atoms transferred more negative charges than lithium atoms.The differences between different stable adsorption positions are small and consistent with the adsorption energy results;(4)The theoretical capacities of 2D BSi reached 1374 m Ah/g and 2749 m Ah/g when used as anode materials for Li-ion and Mg-ion batteries,respectively;(5)The average electrical potentials of 2D BSi as anode for both Li-ion and Mg-ion batteries are low,which will make the ion battery have a large voltage window;(6)The diffusion energy barrier of the optimal diffusion path of lithium and magnesium atoms on 2D BSi is low,and lithium and magnesium atoms show better diffusivity;(7)The energy band structure and the density of states distribution before and after the storage of lithium and magnesium indicate that 2D BSi can always maintain metallic conductivity when used as anode material.In conclusion,it is found that 2D BSi has good structural and environmental stability.Its mechanical properties show orthogonal anisotropy and have high Young’s modulus and ultimate tensile strength with good ductility.Elemental doping decreases the mechanical properties of 2D BSi,and modulates the distribution of the isotropic Young’s modulus.Theoretically,2D BSi has good anti-dendritic properties,large voltage window and good multiplicative properties when used as anode for Li-ion or Mg-ion batteries. |
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