▎ 摘　　要

Lithium-dendrite growth is one of the most challenging problems affecting the safety performance of Li-ion batteries. Understanding the evolution process of Li-dendrite growth at the atomic scale is critical for solving this problem. In this paper, the adsorption processes, geometrical configurations, and electronic structures of Li clusters on double-layered graphene with two types of defects were investigated by first-principles calculations. It was found that single vacancy (SV) defects tend to promote the nucleation of Li dendrites, and the adsorption energy of Li clusters near the SV defect decreases with increasing number of Li atoms. Meanwhile, the Li atoms accumulated on the surface of SV-defect graphene with distances between the Li atoms similar to those in bulk metallic Li. However, in the case of double vacancy (DV) defects, the Li atoms could diffuse freely in the direction perpendicular to the graphene sheets through DV defects at the top-layer graphene, thus hindering nucleation and dendrite growth. Density of states analyses suggested that the Li atoms on SV-defect graphene transform from the fully ionized state to the metallic state with continuously increasing number, while the ionic properties of the Li atoms remain and even increase on DV-defect graphene. Our conclusions can help to understand the Li-graphite interaction from an atomistic point of view and provide theoretical hints for the development of graphite anodes with high charge-rate properties.