The Theoretical Study Of Antimonene And Its Heterostructure As Lithium/Sodium Ion Battery Anode Materials

Secondary ion batteries are the main electrochemical energy storage technology.The development of secondary ion batteries with low-cost and large-capacity can not only address the large-scale power storage needs for clean energy generation,but also is very important for environmental protection.Lithium-ion batteries and sodium-ion batteries are the hot research directions of energy storage batteries technology.People urgently hope to increase the battery's energy storage capacity and extend the working life.Electrode material is an important part of energy storage batteries,and it is extremely critical to improve battery performance.The graphite material used in the negative electrode of the traditional lithium-ion battery is close to the theoretical limit due to the limited energy storage density,and because of the large Na ion size,it is not suitable to use graphite as the electrode.Therefore,finding new suitable anode materials for Li/Na ion batteries with higher energy storage density and longer cycle life has received great attention.Antimonene is a new two-dimensional material,which has been successfully prepared in recent two years.Due to its large specific surface area,it is beneficial to improve the storage capacity of Li and Na.The existence of weak van der Waals interaction can reduce the material volume expansion and contraction caused by ion insertion/extraction,and improve the battery's cycle life.Preliminary experimental results indicate that antimonene is an excellent cathode material for lithium ion batteries,but the theoretical research is still lacking.In this paper,based on the density functional theory(DFT)of the first principles,Li/Na simulation calculation and analysis of monolayer and bilayer antimonene were performed by VASP software.including adsorption energy,density of states,adsorption density,differential charge density and diffusion barrier,and the potential of antimonene as negative electrode material for Li/Na ion batteries was studied.In addition,antimonene/graphene heterostructure(Sb/G)was constructed to study the properties of the composite material.The study found that the optimal adsorption site for Li/Na on single-layer antimonene is the valley site,and the adsorption energy is 1.63/1.21 eV.No matter Li atoms adsorb on one side or both sides of single-layer antimonene,with the increase of Li adsorption density,the antimonene crystal structure undergoes a large deformation,and the energy band shows metallic characteristics.When Na atoms adsorb at the valley sites on both sides,the forces on both sides are balanced and the system maintained good stability.According to the density of states,the s and p orbitals of Li/Na atoms overlap with the s and p orbitals of Sb atoms,reflecting the ionic characteristics.In the study of double-layer antimonene,Li tends to adsorb in the interlayer with a maximum adsorption energy of 2.71 eV,while Na tends to adsorb outside the layer with a maximum adsorption energy of 1.72 e V.When one layer of Li atoms adsorb in a double-layer antimonene sandwich,the periodic configuration of antimonene remains unchanged.When three layers of Na atoms adsorb in the interlayer and on two surfaces,the configuration of the system remains stable.Thus,the double-layer antimonene has a higher storage density and better stability than a single-layer antimonene.In the study of Sb/G,Li/Na tends to adsorb in the interlayer,with an adsorption energy of 2.94/2.09 eV.At the same time,the storage density of Sb/G is higher than that of single-layer antimonene and single-layer graphene,especially greatly improving the performance of Na storage.In addition,it was found that the diffusion barriers of Li/Na on monolayer and bilayer antimonene and Sb/G heterostructure are small,which was very conducive to the rapid charging and discharging of the battery.These results indicate that antimonene is a potential anode material for Li/Na ion batteries.