Computational Investigation of Two-Dimensional Vanadium Boride Compounds for Na-Ion Batteries.

Abstract

Sodium (Na)-ion batteries have received widespread attention due to their low cost and good safety. The possibility of two-dimensional vanadium boride (V2B2, MBene) as the anode material for Na-ion batteries is explored by first principles. It is found that V2B2 has good dynamic stability, thermodynamic stability, and conductivity. V2B2 has a good performance as anode material: it can adsorb nearly 3 layers of Na ions, and the maximum capacity reaches 814 mAhg–1. It is found that V2B2 has a very low Na ion diffusion barrier, about 0.011 eV, which represents the ultrahigh ion diffusion rate of Na ions on the surface of V2B2. The average open circuit voltage of V2B2 is 0.65 V, and good metallicity is maintained during the entire Na ion adsorption process. The results indicate that two-dimensional V2B2 has a low diffusion barrier, low open circuit voltage, and high theoretical capacity and is a potential anode material for Na-ion batteries.