Prediction of SiS2 and SiSe2 as promising anode materials for sodium-ion batteries

In this work, we suggest SiS2 and SiSe2 as anode materials for sodium-ion batteries based on a first-principles prediction. Both SiS2 and SiSe2 have suitable adsorption energies (-1.01/-1.24 eV) and large diffusion constants (1.24 × 10-4/6.72 × 10-5 cm2 s-1) for Na ions at 300 K, resulting in low diffusion barriers (less than 0.1 eV) at high Na adsorption concentrations. As anode materials, SiS2 and SiSe2 exhibit excellent electrochemical stability with high theoretical capacities (517/864 mA h g-1) and desirable average voltages (0.19/0.25 V). Given these exceptional properties, SiS2 and SiSe2 are desired to be promising electrode materials for sodium-ion batteries.