Video Title: What is the SEI, and what effect does it have on the battery? - Battery Monday | 05 Apr 2021
Channel: Grepow Battery
Speakers: Zach
Duration: 00:03:49
Introduction
This video explains the Solid Electrolyte Interphase (SEI) layer in lithium-ion batteries. It describes the SEI's formation, composition, impact on battery performance (both positive and negative), and the factors influencing its formation.
Key Takeaways
SEI Formation: The SEI (Solid Electrolyte Interphase) forms on the anode's surface during the first charge/discharge cycle of a lithium-ion battery through the electrochemical reduction of the electrolyte. It's a thin film (100-120 nanometers thick) composed of inorganic (lithium carbonate, lithium fluoride, lithium oxide, lithium hydroxide) and organic (lithium alkyl carbonates) components.
SEI's Impact on Battery Performance: The SEI consumes some lithium ions, leading to irreversible capacity loss and reduced charge/discharge efficiency. However, it also acts as a protective layer, preventing further electrolyte decomposition, improving cycling performance, and extending battery life. It's insoluble in organic solvents and prevents co-embedding of ions, protecting the electrode material.
Factors Affecting SEI Formation: The electrolyte's composition (lithium salts, solvents, admixtures), the intensity of the initial charge/discharge current, and temperature influence SEI formation and stability. The type of negative electrode material also impacts SEI thickness.
