Abstract: The research survey and formation principle of solid electrolyte interface（SEI） film applied on the surface of electrode material of lithium ion batteries were summarized.The effects of electrolyte，temperature，and current density on the establishment process of SEI film were analyzed.On the basis of that the modification（mainly including the modification of electrode material and adding electrolyte additive） of SEI were also discussed.It′s believed that the research of SEI film will have an important influence on the improvement research of electrode materials and electrolyte additive.

Key words: lithium ion batteries, electrode material, SEI film