The purpose of the formation of lithium-ion batteries and the introduction of the steps of the SEI film formation process

Formation is an important process in the production process of lithium-ion batteries. During formation, a passivation layer is formed on the surface of the negative electrode, that is, the solid electrolyte interface film (SEI film). The quality of the SEI film affects the cycle life and stability of the battery. , Self-discharge, safety, and other electrochemical properties, to meet the requirements of secondary battery sealing and maintenance-free. However, the SEI film formed by different chemical conversion processes is different, and the impact on the battery performance is also very different. The purpose of formation is to activate the battery, charge the cell with a small current, activate its internal positive and negative materials, and form an SEI film on the surface of the negative electrode to make the battery performance more stable. The battery only passes through Hwaseong City In order to reflect the real performance, if the battery core cannot be charged and discharged normally if it is not transformed. Lithium ion battery formation to form SEI film process steps Lithium ion battery formation process SEI film formation process specifically includes the following four steps: Step ①: electrons are transferred from the inside of the current collector-conductive agent-graphite particles to the SEI film to be formed Step ②: The solvated lithium ions diffuse from the positive electrode to the point B on the surface of the SEI film being formed under the solvent package; Step ③: The electrons at point A diffuse to point B through the electron tunneling effect; Step ④ : The electrons that have jumped to point B react with lithium salts, solvated lithium ions, film-forming agents, etc., and continue to form SEI film on the surface of the original SEI film, thereby increasing the thickness of the SEI film on the surface of the graphite particles, and finally forming a complete SEI film . Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Lithium-ion battery safety detection indicators and safety solutions introduction