Pouch Battery Case Structure to Eliminate Bat Ear Sealing
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Solution Overview
Problem
The existing pouch type secondary batteries suffer from size errors and reduced energy density due to the formation of bat ears during the sealing process, which complicates assembly and increases overall volume.
Innovation Solution
A battery case design featuring symmetrical cup parts with a bridge and complement parts that prevent bat ear formation, ensuring precise folding and sealing, thereby reducing unnecessary volume and facilitating easier assembly into modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the battery case is folded to seal the secondary battery, then the number of edges to be sealed is reduced to improve process rate, but a portion of the folded edge protrudes to form a bat ear that increases unnecessary volume and causes size errors
Solution Approach 1:
The invention extracts and removes the harmful protruding portion (bat ear) from the battery case structure. By designing the folding line to extend beyond the sealing line, the protrusion that would normally form the bat ear is eliminated, thereby removing the unnecessary volume while preserving the benefit of reduced sealing edges.
Solution Approach 2:
The invention introduces asymmetry in the positioning of the folding line relative to the sealing line. The folding line is deliberately positioned to extend beyond the sealing line by a specific distance, creating an asymmetric configuration that prevents the formation of the symmetric bat ear protrusion while maintaining the functional benefit of fewer sealing edges.
2Ease of operation
If the secondary battery is designed with a small size from the beginning to accommodate bat ears, then assembly becomes complicated, but the overall volume of the secondary battery increases
Solution Approach 1:
The invention removes the bat ear protrusion from the battery case structure by repositioning the folding line, thereby eliminating the need to design around this unnecessary volume. This extraction of the harmful element simplifies assembly operations while preventing the overall volume increase that would result from accommodating bat ears.
Solution Approach 2:
The invention performs a preliminary design action by positioning the folding line to extend beyond the sealing line before the sealing process. This preliminary configuration prevents the formation of bat ears during assembly, thereby simplifying the assembly process and preventing unnecessary volume increase before the problem can manifest.
3Productivity
If two cup parts are drawn and molded to be adjacent in one pouch film, then the number of edges to be sealed is reduced, but the electrode assembly requires greater thickness to accommodate both cup parts
Solution Approach 1:
The invention segments the pouch film structure into distinct functional zones: a first region containing the cup parts and a second region containing the folding line that extends beyond the sealing line. This segmentation allows the folding line to be positioned independently to prevent bat ear formation while maintaining the reduced number of sealing edges benefit from the adjacent cup part configuration.
Solution Approach 2:
The invention addresses the thickness issue by introducing a dimensional solution in the planar layout. By extending the folding line beyond the sealing line in the plane of the pouch film, the invention prevents bat ear formation without requiring changes to the electrode assembly thickness, thereby resolving the contradiction through a different dimensional approach.
Data Source
AI summary
To achieve the above objects, a battery case for a secondary battery, the battery case being a pouch type battery case that is configured to accommodate an electrode assembly therein, the electrode assembly including stacked electrodes and separators therein, the battery case according to an embodiment of the present invention including a first cup part and a second cup part, each formed as a respective recess extending downward from a top surface of a pouch film; a bridge formed between the first cup part and the second cup part and having a constant width and height; and two complement parts disposed outside of respective first and second longitudinal ends of the bridge, each of the complement parts protruding upward from the top surface of the pouch film.