Abstract:

The rational design of high-performance anode materials is crucial for advancing sodium-ion battery technology. Among potential candidates, two-dimensional transition metal carbides, particularly those incorporating C₂ dimer structures, exhibit superior electrode material properties owing tothe high carbon atomic mass on their surfaces. Consequently, we selected the VC₂ monolayer, featuring a highly stable a C₂ dimer structure, for investigation.Utilizing first-principles calculations, we evaluated its structural and electronic properties, as well as its sodium-ion storage performance on the surface, includingadsorption sites, multilayer adsorption dynamics, diffusion pathways, and open-circuit voltage. Our findings reveal that the VC₂ monolayer exhibits exceptional structural stability and electrical conductivity, strongly suggesting its suitability for sodium-ion storage applications. Theoretical calculations predict a substantial sodium-ion adsorption capacity for multi-layer VC₂, reaching 715 mAh/g. Furthermore, the calculated low-diffusion energy barrier of 0.23 eV ensures swift charging and discharging rates. Notably, as the sodium-ion concentration escalates, the average total adsorption energy remains consistently negative. Furthermore, open-circuit voltage calculations underscore the stability of sodium intercalation voltage. Collectively, these results underscore the potential of VC₂ monolayers as an ideal anode material for sodium-ion batteries. This study not only introduces a novel perspective for the pursuit of high-performance anode materials but also lays a theoretical foundation for the subsequent optimization and design of such materials.

Key words: sodium ion battery, first principles calculations, two-dimensional materials