Electrode Assembly Separator Layout to Block Lithium Precipitation
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Solution Overview
Problem
Existing lithium secondary batteries face issues with lithium precipitation on the negative electrode when disconnections occur, leading to potential short circuits and heat generation.
Innovation Solution
An electrode assembly design with a separator having a pore closure portion with a porosity of 1% or less is introduced, positioned between the negative and positive electrodes, to minimize lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the negative electrode active material layer width is greater than the positive electrode active material layer width, then the charge capacity is improved, but lithium precipitation occurs on the negative electrode extension portion when disconnection occurs
Solution Approach 1:
The separator is divided into two functional regions: a separator main body portion with normal porosity for lithium ion transport, and a separator extension portion with reduced porosity (pore closure portion) that acts as a barrier. This segmentation allows the battery to maintain high charge capacity while preventing lithium precipitation on the negative electrode extension portion.
Solution Approach 2:
Different regions of the separator are given different porosity characteristics. The separator main body portion maintains high porosity for efficient lithium ion conduction, while the separator extension portion has reduced porosity (pore closure portion) to locally prevent lithium ion migration to the negative electrode extension portion, thus preventing lithium precipitation only where needed.
2Object-affected harmful factors
If a pore closure portion with low porosity is introduced to prevent lithium precipitation, then lithium precipitation is minimized, but the device structure becomes more complex
Solution Approach 1:
The separator is segmented into functional zones with different porosity characteristics. The pore closure portion is strategically positioned only on the separator extension portion, creating a simple yet effective structure that prevents lithium precipitation without requiring complete redesign of the entire separator system.
Solution Approach 2:
The pore closure portion acts as an intermediary barrier between the electrolyte and the negative electrode extension portion. This intermediate structure with reduced porosity selectively blocks lithium ion migration while allowing the rest of the separator to function normally, providing a simple solution to prevent lithium precipitation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents lithium precipitation on the negative electrode, thereby avoiding short circuits and heat generation, even in cases of disconnection.
Implementation Method 1
the pore closure portion is disposed on one surface or both surfaces of the separator extension portion and has a porosity of 1% or less
Data Source
AI summary
The present disclosure relates to an electrode assembly and a lithium secondary battery including the same, wherein the electrode assembly includes a negative electrode including a negative electrode active material layer; a positive electrode including a positive electrode active material layer; a separator; and a pore closure portion, wherein the separator is disposed between the negative electrode and the positive electrode, wherein a width of the negative electrode active material layer is greater than a width of the positive electrode active material layer, wherein the separator includes a separator main body portion that overlaps the positive electrode active material layer in a vertical direction and a separator extension portion that does not overlap the positive electrode active material layer in the vertical direction and extends from the separator main body portion, and wherein the pore closure portion is disposed on one surface or both surfaces of the separator extension portion and has a porosity of 1% or less.