The role of carbon bond types on the formation of solid electrolyte interphase on graphite surfaces
Solid electrolyte interphase (SEI) has been extensively investigated in advanced lithium ion batteries, especially on graphite anode surface. However, the role of the carbon bond types on the formation of solid electrolyte interphase (SEI) on graphite surface has never been compared. In this work, single, double and triple carbon bonds on a graphite anode acting as SEI templates are comparatively investigated. Sodium propionate, sodium acrylate and sodium propynate are uniformly applied onto a natural graphite surface. It is found that different carbon types exhibit remarkable difference in the electrochemical behavior of the graphite anode. The acrylate SEI template demonstrates the best film-forming properties via in-situ polymerization between the carbon double bonds producing robust SEI film and the decorated graphite anode shows much enhanced rate capability and cycling stability. Moreover, life-span of the full cell with LiFePO4 cathode is significantly prolonged. By contrast, single and triple carbon bonds shows some limitations in the SEI formation. Therefore, constructing SEI film by in-situ polymerization of carbon double bonds is an effective strategy enhancing the durability and reliability of graphite anode.