Pouch Cell Sealing Structure for Electrode Lead Crack Prevention
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Solution Overview
Problem
Pouch-type secondary batteries often suffer from cracks around the electrode lead due to stress concentration at the folding part adjacent to the sealing part, particularly during assembly of battery modules or packs, where electrode leads are bent, leading to sharp folding and internal aluminum cracks.
Innovation Solution
A pouch-type secondary battery design with a sealing part formed along the periphery of the electrode assembly, where the first and second sealing parts are created within a predetermined distance from the upper and lower corner parts of the cup, respectively, and a third sealing part connects them, using a two-stage sealing process with different thicknesses for each section to prevent stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing part is formed to cover the electrode lead, then the electrode lead is protected and electrically connected, but stress concentrates at the folding part adjacent to the sealing part causing pouch cracks
Solution Approach 1:
The sealing part is designed with different thicknesses for different sections: a first thickness in the area adjacent to the folding part and a second thickness in other areas. This local quality variation allows the sealing part to have enhanced flexibility and stress absorption capability at the critical folding part region, preventing cracks while maintaining adequate protection of the electrode lead.
Solution Approach 2:
The patent changes the thickness parameter of the sealing part based on location. By forming the sealing part with a first thickness greater than a second thickness in specific regions, the structural parameters are optimized to distribute stress more evenly, preventing concentration at the folding part while ensuring sufficient coverage of the electrode lead.
2Strength
If the sealing part is formed away from the folding part, then stress concentration is reduced, but the electrode lead is not adequately covered and protected
Solution Approach 1:
The sealing part is designed with different thicknesses for different sections: a first thickness in the area adjacent to the folding part and a second thickness in other areas. This local quality variation allows the sealing part to have enhanced flexibility and stress absorption capability at the critical folding part region, preventing cracks while maintaining adequate protection of the electrode lead.
Solution Approach 2:
The patent introduces a thickness dimension variation to the sealing part structure. By making the sealing part thicker in certain regions and thinner in others, it creates a three-dimensional stress distribution pattern that protects the electrode lead while avoiding stress concentration at the folding part.
3Ease of manufacture
If the sealing part is formed with uniform thickness, then manufacturing is simplified, but stress cannot be effectively distributed causing cracks at the folding part
Solution Approach 1:
The sealing part is designed with different thicknesses for different sections: a first thickness in the area adjacent to the folding part and a second thickness in other areas. This local quality variation allows the sealing part to have enhanced flexibility and stress absorption capability at the critical folding part region, preventing cracks while maintaining adequate protection of the electrode lead.
Solution Approach 2:
The patent changes the thickness parameter of the sealing part based on location. By forming the sealing part with a first thickness greater than a second thickness in specific regions, the structural parameters are optimized to distribute stress more evenly, preventing concentration at the folding part while ensuring sufficient coverage of the electrode lead.
Data Source
AI summary
Disclosed are a pouch type secondary battery, a battery pack, and a method for manufacturing the pouch type secondary battery. In an exterior accommodating an electrode assembly, a sealing part is formed along a periphery of the electrode assembly, the sealing part includes a first sealing part formed to cover an electrode lead, and one end of the first sealing part is formed on an area within a predetermined distance from an upper corner part of a periphery of the cup formed in the pouch.