First-principles Study on Structural and Thermodynamics Properties of Li₃Si₂ Alloy

Using the First-principles method based on density functional theory, we have studied the electronic structure and the phonon dispersion of Li-Si alloy (Li₃Si₂). The results show that Li₃Si₂ presents the metallic electronic structure. The thermodynamic properties were studies by using the quasi-harmonic Debye model. We found that the thermal expansion coefficient increases almost exponentially for the temperature from 0 K up to 300 K. However, above 300 K, this trend begins to slow down. This indicates that the thermal expansion coefficient of the crystal is less affected at high temperature. Therefore, Li₃Si₂ has a good structural stability at high temperature. Our results provide a theoretical reference for the design of stable Si-based anode materials.