Rational Design of Two-Dimensional Buckled-Hexagonal Nb2S2 Monolayer as an Efficient Anode Material for Ca-ion Batteries: A First-Principles Study

Presently, great attention is being paid to the search for promising anode materials for metal-ion batteries due to the rapid evolution of numerous modern electronic gadgets. In this investigation, we have predicted for the first time that the buckled-hexagonal Nb2S2 monolayer that may be an efficient anode material for calcium-ion batteries (CIBs). To that objective, we have explored the pristine monolayer system's energetical, dynamical, and thermal stability. The inherent metallicity of the pristine monolayer facilitates its electrical conductivity as an electrode material. Our study also reveals the structural and electrical properties of the Ca-adsorbed Nb2S2 monolayer. It is observed that Ca-atoms prefer to get intercalated on top of the buckled hexagon of the pristine monolayer, and the metallicity of the 2D nanosheet remains preserved. In the adsorption process, bader charge analysis is used to determine the amount of charge transfer from the Ca atom to the Nb2S2 monolayer. Furthermore, this system exhibits a high storage capacity of 1288.86 mAh/g and a moderately low diffusion energy barrier of 0.76 eV. The calculated open-circuit voltage of 0.49 V and the other results suggest that the Nb2S2 monolayer may be a potential candidate for anode material for rechargeable Ca-ion batteries.