What is the SEI, and what effect does it have on the battery? - Battery Monday | 05 Apr 2021

About this Video

• 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 details 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 is a thin film (100-120 nanometers) that forms on the anode's surface during the first charge/discharge cycle. It's formed by the electrochemical reduction of the electrolyte.
• SEI Composition: Primarily composed of inorganic components (lithium carbonate, lithium fluoride, lithium oxide, lithium hydroxide) and organic components (lithium alkyl carbonates).
• SEI 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 co-embedding of ions and damage to the electrode material, thus improving cycling performance and service life.
• Factors Affecting SEI Formation: Electrolyte composition, charge/discharge current intensity, and temperature significantly influence SEI formation and stability. The type of negative electrode material also affects SEI thickness.