Cap Assembly CID Fixing via Segmented Gasket
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Solution Overview
Problem
In secondary batteries, the current interrupting device (CID) is not adequately fixed, leading to floating during gas discharge, which affects short-circuit pressure and complicates the assembly process due to insufficient support and positioning control.
Innovation Solution
A cap assembly design featuring a safety vent with a downwardly protruding CID fixing portion and a CID gasket that supports the CID, ensuring it is fixed both upwardly and downwardly, with a ring-shaped CID gasket and integrated height differences to prevent floating and improve assembly control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CID is supported downwardly by the sealing gasket, then the CID is prevented from floating under normal conditions, but the CID may still float when gas is produced and pressure increases
Solution Approach 1:
The sealing gasket is divided into multiple functional regions: a first sealing surface for supporting the CID downwardly under normal conditions, and a second sealing surface positioned at a different location to support the CID upwardly when gas pressure increases. This segmentation allows the single gasket to provide bidirectional support, preventing CID floating in both normal and high-pressure conditions while maintaining the integrity of the gas discharge path.
2Ease of manufacture
If the CID filter is welded to the safety vent without sufficient fixing, then assembly is simpler, but the position of the CID filter cannot be controlled and assembly processability deteriorates
Solution Approach 1:
The sealing gasket serves as an intermediary component between the CID filter and the battery case. It provides dedicated positioning structures including a first positioning portion that fits into a positioning groove and a second positioning portion that fits into another positioning groove. This intermediary mechanism enables precise positioning of the CID filter during assembly without requiring complex welding or fixing procedures, achieving both ease of manufacture and manufacturing precision.
3Device complexity
If the CID is not sufficiently fixed, then the assembly process is easier, but floating occurs during impact or gas discharge affecting safety
Solution Approach 1:
Multiple fixing functions are merged into a single sealing gasket component. The gasket simultaneously provides: (1) downward support through the first sealing surface, (2) upward support through the second sealing surface, (3) positioning through the first and second positioning portions, and (4) sealing through the first and second sealing surfaces. This merging eliminates the need for separate fixing structures, reducing device complexity while ensuring reliable CID positioning under impact and gas discharge conditions.
Data Source
AI summary
The present disclosure relates to a cap assembly for a secondary battery and a secondary battery including the same. Specifically, a CID filter is fixed in the cap assembly such that, even when a gas is discharged due to the rupture of a safety vent, the CID short-circuit pressure is not affected.