Electronic properties and geometric structure of Li-Si/Gr system under strain

Abstract

Graphene-silicon composite (Si/Gr), an excellent anode material for a lithium battery, undergoes internal stress during charging and discharging. In this paper, The effect of strain on Si/Gr system and Li-Si/Gr system are systematically investigated based on the first-principles method. It is found that both tensile strain and compressive strain can affect the electronic properties and geometric structure. Moreover, the effect of compressive strain is more obvious, and it is easy to cause structural distortion. Strain can open the band gap. The band gap widens with the increase of strain. When tensile strain reaches 6% and 8%, the Si/Gr system exists a band gap of 0.164 eV and 0.374 eV, respectively. The effect of strain on energy levels in the range of −2 eV to 2 eV is weakened due to the lithium atom being adsorbed in Si/Gr system. This study provides a theoretical basis for the subsequent research.