Pouch Battery Side Folding Structure for Stable Fold Retention
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Solution Overview
Problem
Pouch-type secondary batteries face challenges in maintaining the folded state due to adhesion between the side and cup parts, leading to reduced retention force and increased manufacturing complexity, which affects energy density and yield.
Innovation Solution
A pouch-type secondary battery design featuring a side that does not adhere to the cup part, with a specific folding mechanism and layer structure in the pouch film, including a moisture barrier layer and sealant layer made of aluminum alloy, to maintain the folded state while reducing unnecessary volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the side is folded to reduce volume, then the energy density relative to volume increases, but the side unfolds again due to adhesion between the side and cup part
Solution Approach 1:
The side is divided into a sealing part and a non-sealing part. The non-sealing part is folded to reduce volume while the sealing part remains attached to the cup part, preventing the entire side from unfolding due to adhesion. This segmentation allows the folded portion to maintain its shape without being pulled back by adhesive forces.
Solution Approach 2:
Different parts of the side have different properties: the sealing part is adhesive and remains attached to the cup part, while the non-sealing part is non-adhesive and can be folded. This local differentiation in adhesive properties allows the folded section to maintain its reduced volume without being constrained by adhesion to the cup part.
2Stability of the object's composition
If a tape is attached to the side to prevent unfolding, then the folded state is maintained, but the overall thickness of the battery increases
Solution Approach 1:
The adhesive function is extracted from the entire side and concentrated only in the sealing part. The non-sealing part is made non-adhesive, eliminating the need for additional tapes or fasteners to maintain the folded state. This extraction of the adhesive function to a specific location avoids adding extra thickness components.
3Stability of the object's composition
If a tape is separately attached to the side, then the folded state is maintained, but the number of manufacturing processes increases
Solution Approach 1:
The adhesive property is merged into the sealing part of the side during the pouch film manufacturing process. This integration means the side structure itself provides the necessary adhesive function without requiring separate tape attachment processes, thereby reducing manufacturing complexity and process count.
4Length of stationary object
If the moisture barrier layer has a thin thickness, then the battery is more compact, but the side is not fixed at a predetermined angle when folded
Solution Approach 1:
The sealing part is given adhesive properties while the non-sealing part remains non-adhesive. This local differentiation allows the thin pouch film to maintain its folded angle without requiring increased thickness throughout, as only the sealing portion needs adhesive characteristics to maintain the folded configuration.
Data Source
AI summary
A pouch-type secondary battery according to an embodiment of the present invention for achieving the above object includes: an electrode assembly in which electrodes and separators are stacked; a pouch-type battery case comprising a cup part configured to accommodate the electrode assembly therein, wherein the pouch-type battery case comprises a side extending from the cup part, and the side includes: a sealing part disposed along an outer portion of the side; and a non-sealing part disposed between the cup part and the sealing part, wherein the side is configured to contact the cup part without adhering to the cup part and is folded at the non-sealing part.