First-Principles Study On Modified MoO₂ As The Anode Material For Lithium-Ion Batteries

The study on materials that can replace the traditional graphite anode has attracted researchers'considerable attention owing to the urgent demand of human society for high-performance lithium-ion batteries.Among various candidates,MoO₂ has been regarded as a promising anode material due to its unique structure,good electronic conductivity,high theoretical capacity and natural abundance.Herein,as an anode material of lithium-ion batteries,the electronic characteristics,lithium adsorption and diffusion properties of modified MoO₂ have been studied by the first-principles calculations.Firstly,the influence of B,C,N doping and O vacancy on the electronic characteristics,lithium adsorption and diffusion properties of modified MoO₂ are studied.The influence of B doping on the lithium adsorption depends on the distance between the adsorption site and the defect.MoO₂ with O vacancy has the highest lithium diffusion barrier,indicating that lithium diffusion is most difficult.C and N doped MoO₂ have high adsorption energies,low lithium diffusion barriers and high lithium diffusion coefficients near the defects,which indicates that C and N doping can improve the lithium adsorption and diffusion properties of MoO₂ that is used as an anode material.Secondly,two new two-dimensional porous MoO₂?P2-MoO₂ and O-P2-MoO₂?are designed.Their structural stability,electronic characteristics,lithium adsorption and diffusion properties are studied.O-P2-MoO₂ is more stable.The lithium adsorption of O-P2-MoO2 is stronger,and the lithium diffusion barrier of O-P2-MoO2is lower.These findings indicate that O-P2-MoO₂ can also be used as a new anode material for lithium-ion batteries.Finally,the influence of B,C and N doping on the electronic characteristics,lithium adsorption and diffusion properties of O-P2-MoO₂are studied.B,C and N doping can adjust the electronic characteristics of O-P2-MoO₂.While the adjustment effects of B and N doping on the band structures disappear after lithium adsorption.On the contrary,the C doped O-P2-MoO₂ remains metallic after lithium adsorption.In addition,B,C and N doping can enhance lithium adsorption.The B doped structure has the lowest lithium diffusion barrier.And N doped structure has the highest lithium diffusion barrier.In summary,it is found that C doping has the best effect on adjusting and improving the electronic characteristics,lithium adsorption and diffusion properties of O-P2-MoO₂.The study in this paper shows that doping and dimension reduction can effectively adjust the electronic characteristics,lithium adsorption and diffusion properties of MoO₂.These findings provide theoretical reference for the design and research of anode materials for lithium-ion batteries.