YS2 monolayer as a high-efficient anode material for rechargeable Li-ion and Na-ion batteries

Here, we propose a new two-dimensional (2D) monolayer YS2 and investigate its properties as electrode material for Li-ion and Na-ion batteries (LIBs and NIBs), by combining the density functional theory (DFT) and the crystal structure prediction techniques. The results of phonon dispersion and ab-initio molecular dynamics (AIMD) simulations confirm that it is dynamically and thermally stable. The adsorption energies of Li and Na on YS2 are - 2.038 and -1.939 eV, respectively. Besides, the superior electrical conductivity is maintained during the whole lithiation/sodiumation process. The calculated diffusion energy barriers for Li and Na on this YS2 monolayer are 0.33 and 0.24 eV, respectively, demonstrating a fast ion transfer rate. The theoretical specific capacities for Li and Na adatoms on YS2 are both 350 mA h(-1), comparable to the graphite electrode. These features indicate that 2D YS2 monolayer could be considered as a promising electrode material for both LIBs and NIBs.