Structural Design Of New Two-Dimensional Transition Metal Carbide Y₄C₃ And Its Application In Metal Sodium-Ion Battery

Due to the burning of fossil fuels,excessive carbon dioxide is produced,which leads to the greenhouse effect,aggravating environmental pollution and energy crisis,making the situation increasingly serious.In the past decades,efforts have been made to develop renewable energy,and rechargeable metal ion batteries have been widely used in various reported sustainable energy storage systems.At present,although lithium ion batteries（LIBs）are the most mature electrochemical energy storage equipment,they are faced with problems such as low content and uneven distribution of lithium natural resources,resulting in the price of LIBs is too expensive to meet the needs of modern large-scale energy storage.Compared with LIBs,sodium-ion battery（SIBs）is a new type of"post-lithium ion battery".SIBs is considered as a new type of secondary battery to replace LIBs due to its advantages of abundant sodium in nature,wide distribution and similar energy density to LIBs.It shows a broad application prospect in the field of large-scale cheap energy storage and has been paid great attention to by domestic and foreign researches in recent years.With the development of research,it is found that the lack of suitable anode materials for SIBs is the main obstacle to its development.In this paper,we systematically explore the two-dimensional structure space of Y-C system by using particle swarm intelligence search algorithm combined with first-principles calculation,and propose a new stable chemical composition of Y₄C₃.It has P-3m1 symmetry,good thermodynamic and kinetic stability,and intrinsic gold properties.Further evaluation of the application of P-3m1 Y₄C₃as SIBs electrode shows that P-3m1 Y₄C₃has excellent anode potential for metal sodium ion battery,showing high sodium ion adsorption capacity,low migration barrier（～0.10 e V）,high specific capacity（～752 m A h g-1）,and low open circuit voltage（0.15 e V）.This work provides a new chemical composition and candidate structure model for SIBs anode materials,and provides reference for subsequent experimental research.