First-Principles Search Prediction Of Novel MXene Anode Materials For Lithium-Ion Batteries

In the context of global fossil energy scarcity,new energy electric vehicles to take advantage of the trend to flourish,in 2021 China’s new energy electric vehicle sales have reached 2.989 million.New energy electric vehicles can optimize resource allocation,reduce the burden of traditional energy,which is the dawn of China’s automobile industry to achieve curve overtaking.Lithium-ion batteries are currently used energy storage tools for commercial new energy electric vehicles,the cruising range of the car depends on the capacity of the lithium-ion battery,and the safe use of the car is inseparable from the stability of the lithium-ion battery during the use of the process.At present,the capacity of lithium-ion batteries is not enough to meet the requirements of the rapid development of electric vehicles,and the safety accidents that occur from time to time are often caused by the instability of lithium-ion batteries.The search for lithium-ion battery electrode materials with outstanding performance is a key factor in breaking through battery technology.MXene is currently a hot research topic for new lithium-ion battery anode materials,and this thesis uses first principles to search and predict 16 MXene structures based on density functional theory.Taking carbon-based MXene as a comparison,the anode materials of Lithium-ion batteries with outstanding performance,Ti₂N and V₂N,were screened by calculating adsorption energy,migration energy barrier,electron property analysis,theoretical capacity calculation and stability analysis.They have an extremely low migration barrier that determines their high cycle rate,and also has an ultra-high theoretical capacity of 975m Ah/g and924m Ah/g,while the extremely low deformation rate and excellent thermal stability determine their strong stability.Therefore,they have strong potential as an anode material for new lithium-ion batteries.In the process of calculation,the linear function relationship between d-band center,adsorption energy and adsorption concentration was also found,which lays a foundation for searching more pure MXene with better performance and better performance in the future.In this thesis,on the basis of Ti₂N and V₂N,in order to solve the problem of pure MXene interlayer stacking and the large theoretical capacity of functional group attached MXene,the graphene heterostructure of M₂NT₂/was further constructed.Compared with M₂NT₂ monolayer and bilayer,through adsorption energy calculation,migration barrier calculation,electronic property analysis,theoretical capacity calculation and stability analysis,it is found that M₂NT₂/graphene heterojunction has a new characteristic of high adsorption energy and low migration barrier.At the same time,it is determined that the Ti₂NO₂/graphene heterojunction has the theoretical capacity of 604m Ah/g and with a good stability,so it is a strong candidate to become the anode material of lithium ion battery.