Pouch Battery Outer Shell Forming Without Stretch Cracks
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Solution Overview
Problem
Existing methods for manufacturing pouch-type lithium secondary battery shells often result in physical damage such as cracks due to stretching, compromising the stability and reliability of the battery.
Innovation Solution
A method involving an electrode assembly mold and a pulling unit to deform the outer shell without pushing, ensuring the shell's shape conforms to the electrode assembly, thereby minimizing stretching and maintaining uniform thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a forming punch pushes through the pouch-type shell to form the battery shape, then the shell can be shaped to accommodate the electrode assembly, but the shell may be stretched and develop cracks causing physical damage
Solution Approach 1:
Instead of pushing the pouch shell from one direction with a forming punch, the invention inverts the approach by pulling the pouch shell from both ends simultaneously using forming punches. This bidirectional pulling method distributes the deformation force evenly, preventing localized stretching and crack formation while still achieving the desired battery shape.
Solution Approach 2:
The invention changes the deformation parameters by controlling the pulling force distribution and displacement amount. By adjusting the forming punches to pull from both ends with controlled force and displacement, the pouch shell undergoes uniform deformation without exceeding its elastic limit, thereby maintaining shell integrity while achieving proper shaping.
2Productivity
If the pouch shell is stretched in one direction during forming, then the battery can be shaped, but cracks develop in the stretched region compromising stability and reliability
Solution Approach 1:
The invention inverts the conventional one-directional pushing method by implementing bidirectional pulling from both ends of the pouch shell. This approach maintains manufacturing efficiency while eliminating the crack formation problem that compromises reliability, thus resolving the contradiction between productivity and battery stability.
Solution Approach 2:
The invention applies different local deformation characteristics by using multiple forming punches positioned at both ends of the pouch shell. Each forming punch applies localized pulling force tailored to the specific requirements of that region, ensuring uniform overall deformation without creating weak points that would reduce battery reliability.
3Ease of manufacture
If a conventional forming method is used, then the manufacturing process is simple, but the physical structure of the pouch-type outer shell becomes unstable
Solution Approach 1:
The invention maintains ease of manufacture by using a forming process that is conceptually similar to conventional methods but inverts the force application direction. Instead of one-directional pushing, both ends are pulled simultaneously, which keeps the process simple while dramatically improving the physical structure stability of the outer shell.
Solution Approach 2:
The invention segments the forming action into two independent pulling operations at opposite ends of the pouch shell. This segmentation allows each forming punch to work independently with controlled force and displacement, simplifying the control mechanism while ensuring uniform deformation and stable physical structure throughout the battery housing.
Data Source
AI summary
A method for manufacturing an outer shell for a lithium secondary battery according to an embodiment of present disclosure comprising: (a) a step of preparing an electrode assembly mold and the outer shell; (b) a step of wrapping the electrode assembly mold with the outer shell and grapping a portion of the outer shell; and (c) a step of pulling a part of the outer shell grabbed in the step (b) and adjoining the electrode assembly mold and the outer shell.