Pouch Battery Side-Seal Structure to Prevent Aluminum Layer Cracking
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Solution Overview
Problem
Pouch-type secondary batteries experience frequent cracking in the aluminum layer of the pouch case due to stress concentration at the edge during stretching processing, leading to potential electrolyte leakage.
Innovation Solution
A pouch-type secondary battery design with a structured pouch case that includes a side bonding portion spaced apart from a side folding line by a predetermined gap, featuring a multilayered construction with insulating and metal layers, and an adhesive layer to prevent cracking, ensuring the aluminum layer is not directly stressed during folding and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pouch case is sealed by bonding the side portions of the main body and cover together, then sealing reliability is improved, but stress concentration occurs at the edge during stretching processing causing cracking in the aluminum layer
Solution Approach 1:
The sealing portion is divided into a side bonding portion and a side folding line portion, separating the bonding function from the folding function. This segmentation prevents stress concentration at the edge during stretching processing by ensuring the aluminum layer is not directly stressed at the bonding edge, thereby maintaining aluminum layer integrity while achieving reliable sealing.
Solution Approach 2:
The side folding line acts as an intermediary element between the side bonding portion and the cell portion. By introducing this intermediate folding structure, the patent distributes stress away from the aluminum layer at the bonding edge, preventing cracking while maintaining the sealing function.
2Device complexity
If the side bonding portion is positioned close to the side folding line, then device complexity is reduced, but stress concentration causes cracking in the aluminum layer leading to electrolyte leakage
Solution Approach 1:
The patent applies different structural qualities to different regions of the sealing portion. The side bonding portion is designed for bonding functionality, while the side folding line portion is designed for stress distribution and folding functionality. This local differentiation ensures that the aluminum layer is protected from stress concentration at critical locations while maintaining overall structural integrity and electrolyte containment.
3Ease of manufacture
If the pouch case uses a simple single-layer structure, then manufacturing cost is reduced, but cracking occurs in the aluminum layer during stretching processing
Solution Approach 1:
The pouch case employs a composite multilayer structure consisting of an aluminum layer and an insulating layer. This composite structure provides both the necessary mechanical strength to resist cracking during stretching processing and the insulating properties required for battery safety. The layered construction allows each material to perform its specific function optimally.
Solution Approach 2:
The sealing portion is segmented into distinct functional regions: a side bonding portion for achieving bonding between main body and cover, and a side folding line portion for stress distribution. This segmentation, combined with the multilayer structure, prevents cracking in the aluminum layer while maintaining manufacturability through a systematic construction approach.
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 cracking of the aluminum layer, thereby preventing electrolyte leakage and enhancing the structural integrity of the battery.
Implementation Method 1
an adhesive layer interposed between the insulating layer of the main body and the insulating layer of the cover
Implementation Method 2
Each of the main body and the cover may be formed in a multilayered or laminated structure including the metal layer and the insulating layer
Data Source
AI summary
Disclosed is a pouch-type secondary battery having a structure for preventing occurrence of cracking in an aluminum layer of a pouch case. The secondary battery includes an electrode assembly, a pouch case including a main body and a cover, and an electrode tab portion. The pouch case includes a side sealing portion, and the side sealing portion includes a side bonding portion configured to achieve bonding between a side portion of the main body and a side portion of the cover and a side folding line configured to allow a side portion of the pouch case to be folded to an inner side of the side bonding portion. Methods of manufacturing the pouch-type secondary battery are further disclosed herein.