Theoretical Study On The Application Of New Two-Dimensional Material BP In Lithium Battery

In recent years,the numbers of all kinds of mobile electronic equipment,household appliances,electric vehicles are increasing,and the requirements for power supply and energy storage performance are becoming higher and higher.Therefore,the new lithium battery with high energy density has become a research hotspot.The application of superior materials plays an important role in developing high energy density batteries and alleviating the shuttle effect in lithium-sulfur batteries.Two-dimensional materials have many unique properties because of their unique structure and large specific surface area.Previous studies have also shown that two-dimensional materials have great application prospects in the field of lithium batteries.The new two-dimensional material novel borophosphene(N-BP)has excellent electrical conductivity,mechanical properties and thermal stability.Based on the first-principles calculation method of density functional theory,the applications of N-BP as anode material and anchoring material for lithium-ion battery were studied in this thesis.A brief description is as follows:(1)The results show that N-BP exhibits better electrical conductivity in the process of lithium ion adsorption.The theoretical specific capacity of the anode material is 1282.9m Ah/g,which is better than many other reported anode materials.At the same time,the low diffusion barrier(0.19 e V)and low open circuit voltage(0.17?0.99 V)further illustrate the favorable conditions of N-BP as a anode material.In addition,molecular dynamics simulations also show that lithium atoms can diffuse freely on the surface and N-BP still maintains good stability after saturated adsorption at the temperature of 350K.The reasons for the large specific capacity and small diffusion barrier of N-BP can be attributed to two aspects:one is that the substrate material is light,and the other is that N-BP has a hexagonal structure formed by B-B and P-P dimers.All these calculations show that N-BP is a suitable lithium ion anode material.(2)By calculating the adsorption between S₈,Li₂S_n(n=1-8)clusters and the N-BP substrate,the most stable adsorption configuration was obtained.It was found that the adsorption energies between N-BP and these clusters were higher(0.76-3.40e V).These adsorption energies are larger than those between the clusters and the electrolyte(DOL,DME),which is beneficial to inhibit the shuttle effect for the lithium sulfur battery.The analysis of the transferred charge also shows that there is a strong interaction between lithium polysulfide clusters and N-BP.Further,density of states analysis also show that the higher-order polysulfides adsorbed on N-BP strengthened the metallicity of N-BP and improved the conductivity of N-BP Therefore,N-BP is expected to be a suitable anchoring material for lithium-sulfur battery.