Prediction of SiS 2 and SiSe 2 as promising anode materials for sodium-ion batteries.

In this work, we suggest SiS 2 and SiSe 2 as anode materials for sodium-ion batteries based on a first-principles prediction. Both SiS 2 and SiSe 2 have suitable adsorption energies (-1.01/-1.24 eV) and large diffusion constants (1.24 × 10 -4 /6.72 × 10 -5 cm 2 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, SiS 2 and SiSe 2 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, SiS 2 and SiSe 2 are desired to be promising electrode materials for sodium-ion batteries.