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.