What is Solid Electrolyte Interface (SEI) in a Li ion Battery | Decibels Lab

About this Video

• Video Title: What is Solid Electrolyte Interface (SEI) in a Li ion Battery | Decibels Lab
• Channel: Decibels Lab
• Speakers: Abino
• Duration: 00:06:16

Introduction

This video explains the Solid Electrolyte Interface (SEI) in lithium-ion batteries. It covers SEI formation, the reasons for its formation (including reduction), its effects on battery performance (including dendrite growth), its chemical composition, and the consequences of its growth.

Key Takeaways

• SEI (Solid Electrolyte Interface): A solid chemical layer formed on the anode (negative electrode) of a lithium-ion battery due to electrolyte decomposition. Its thickness increases with battery use.
• SEI Formation Causes: Electrolyte decomposition caused by high temperatures, high charge/discharge rates, over-voltage, extended storage, and cell age.
• Reduction: A chemical process where the electrolyte gains electrons, forming compounds that contribute to SEI layer formation.
• Dendrite Growth: Lithium metal ion deposits on the anode, forming branches that can cause short circuits and thermal runaway if the SEI layer doesn't restrict growth.
• SEI Composition: Decomposed electrolyte products, anode surface material, and lithium ions; including lithium fluoride (LiF), low-density carbon (LDC), and more complex carbonate compounds.