Theoretical Study Of Two-dimensional Phosphide-based Electrode Materials

In 2004,the successful preparation of graphene caused a wave of research on two-dimensional?2D?nanomaterials.After continuous research and efforts by scientific researchers,more and more2D nanomaterials are predicted and successfully prepared.Compared with bulk materials,the unique geometric configuration and excellent optical,electrical,mechanical,and magnetic properties of 2D nanomaterials have attracted people's attention.Among them,due to the large specific surface area,2D nanomaterials are very advantageous in terms of adsorbing more metal ions and rapid diffusion of metal ions.This paper is based on fully investigation of 2D nanomaterials.First,we introduce the nanoelectronics development and nanomaterials.Then,the theoretical basis and calculation method of this paper is introduced.Finally,the properties of three2D nanomaterials as electrode materials for ion batteries are studied.The main research contents of this article are as follows:The properties of BP₂ monolayer as electrode materials for lithium-ion and sodium-ion batteries are studied.The pristine BP₂ monolayer exhibits metallic characteristic,which facilitates the transportation of electrons.Furthermore,the BP₂ monolayer could maintain its metallic nature after the adsorption of the alkali metal atoms,which plays an important role in remarkable electrical conductivity.Moreover,the BP₂ monolayer can maintain its structural integrity after adsorbing oxygen atoms,which indicates that BP₂ is chemically stable in ambient air.The diffusion barriers of the BP₂ monolayer to lithium and sodium atoms are as low as 0.07 e V and 0.03 e V,respectively,indicating ultra-fast diffusion mobility and excellent charge/discharge rates.In addition,the BP₂monolayer has a very small volume change during the adsorption of the highest concentration of lithium or sodium,indicating the robustness of the substrate.The calculated average electrode potential of Li?Na?are 2.89 V and 2.49 V,respectively.These results reveal that the BP₂ monolayer is an appealing cathode material for alkali-metal batteries.Then,we predict the BP₃ monolayer as electrode material for magnesium-ion battery.The large adsorption energy between the magnesium atom and the substrate indicates that the magnesium atom can be firmly adsorbed on the surface of the BP₃ monolayer.The diffusion barrier of magnesium atoms on the substrate is as low as 0.11 e V,which indicates that it has a faster charge and discharge speed.It is found that a single Mg atom donates about 0.89 e to the substrate.As more and more magnesium atoms are adsorbed on the substrate surface,the conductivity of the system can be enhanced.In addition,the BP₃ monolayer has an extremely high specific capacity(1546.2 m A h g^-1).The calculated average electrode potential is 0.73 V,which suggests that BP₃ can be applied as an anode material for magnesium-ion battery.These properties ensure the potential application of BP₃ monolayer as a magnesium-ion battery anode material.Finally,the properties of 2D PC₆ monolayer as electrode materials for potassium ion batteries are studied.The pristine PC₆ monolayer is a semiconductor,so it is not conducive to electron transport.However,the PC₆ monolayer becomes metallic when adsorbing the K atom,which improves the conductivity during charging and discharging.The K atom donates about 0.58 e to the substrate,suggesting that K atom is chemically adsorbed on PC₆.The diffusion barriers of potassium atoms in the two diffusion paths of PC₆ monolayer are almost the same.In addition,the PC₆ monolayer exhibits high capacities of 780.6 m A h g^-1 for K-ions storage.The storage capacity of PC₆ from potassium-ion batteries is significantly larger than that of commercial graphite in lithium-ion batteries.The average electrode potential is 3.28 V,which indicates that PC₆ can be applied as a cathode material for potassium-ion battery.Clearly,PC₆ satisfies most of the important characteristics as a suitable electrode material,owing to its good electronic conductivity,ultrafast charging/discharging rate,and high capacity.