Pouch Battery Case Geometry to Minimize Bat-Ears and Void Space
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Solution Overview
Problem
Pouch-type secondary batteries suffer from increased dead space due to bat-ears and void spaces, leading to reduced energy density and potential wrinkles in the battery case.
Innovation Solution
A pouch-type battery case design with inclined recess parts, specific edge and edge curvature radii, and a manufacturing apparatus using a die and punch to minimize void space and bat-ears, ensuring precise alignment and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional forming process is used to manufacture the pouch-type battery case, then the battery case can be manufactured with a recess part for accommodating the electrode assembly, but bat-ears protrude from the sealing part causing increased dead space and reduced energy density
Solution Approach 1:
The patent applies preliminary action by pre-forming inclined inner edges on the recess part before the sealing process. The inner edges are inclined at a specific angle (α) relative to the bottom surface, which allows the sealing part to be positioned at an optimal height that prevents bat-ear formation. This preliminary structural preparation ensures that when the sealing part is attached, it aligns properly with the recess part without protruding, thereby eliminating dead space caused by bat-ears while maintaining ease of manufacture through the standardized forming process.
2Reliability
If the sealing part is formed by attaching portions not pressed in the forming process, then sealing can be achieved, but a height difference is created between the sealing part and accommodation part causing sealing area deviation
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the recess part, specifically the inclination angle (α) of the inner edges relative to the bottom surface. By optimizing this angle within a specific range (30° to 60°), the patent achieves a balance where the sealing part can be properly attached (maintaining sealing reliability) while its height aligns with the accommodation part (improving manufacturing precision). This parameter optimization eliminates the height difference problem without compromising the sealing function.
3Adaptability or versatility
If void space is generated between the inner circumference of the recess part and the electrode assembly, then the electrode assembly can be accommodated, but wrinkles occur in the battery case after degassing process
Solution Approach 1:
The patent applies spheroidality by designing the inner edges of the recess part with a specific curvature radius (R1) that is greater than or equal to the curvature radius (R2) of the outer edges. This curved geometry allows the pouch sheet to smoothly transition from the flat sealing area to the recessed accommodation area, eliminating sharp corners and void spaces that would cause wrinkles during the degassing process. The curvature enables the electrode assembly to be accommodated while maintaining a smooth battery case surface.
Data Source
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AI summary
A pouch-type battery case according to an embodiment of the present invention may accommodate an electrode assembly, in which electrodes and separators are alternately stacked. The pouch-type battery case may include: a pair of recess parts, each of which has a recessed shape; a pair of terraces that are disposed around the pair of recess parts and are inclined downward in a direction closer to each other in a state, in which the battery case is unfolded; and a bridge disposed between the pair of recess parts, configured to connect the pair of recess parts to each other, having a pair of connection surfaces formed to be inclined upward from a bottom surface of each of the pair of recess parts in a direction closer to each other, In the state in which the battery case is unfolded, an angle formed by the pair of terraces may be an obtuse angle.