Battery Cap Assembly Insulator Protrusions to Prevent Vent Rotation
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Solution Overview
Problem
Existing cap assemblies in secondary batteries face challenges in maintaining strong binding strength between the vent and the cap down, leading to potential rotation and cracking at welded portions, which can compromise the reliability and safety of the battery.
Innovation Solution
The cap assembly incorporates an insulator with protrusions that protrude towards the vent, forming a ring shape around its outer circumference, enhancing the binding strength by filling voids and minimizing rotation, thereby stabilizing the connection between the vent and the cap down.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the vent is directly coupled to the cap down without an insulator, then the device complexity is reduced, but the binding strength between vent and cap down deteriorates, leading to rotation and cracking
Solution Approach 1:
An insulator is introduced as an intermediary component between the vent and the cap down. The insulator includes protrusions that extend into the void between the vent and cap down, providing mechanical interlocking that enhances binding strength while preventing rotation and cracking at welded portions.
Solution Approach 2:
The insulator adds a dimensional element by introducing protrusions that extend radially into the void space. This three-dimensional feature creates mechanical engagement surfaces that prevent relative rotation between the vent and cap down, addressing the strength issue without significantly increasing overall structural complexity.
2Strength
If the protrusions are made thicker to increase binding strength, then the strength improves, but the ease of manufacture deteriorates due to tighter tolerances
Solution Approach 1:
The thickness of the protrusions is optimized to a specific range (10% to 30% of the insulator height) that balances mechanical strength with manufacturability. This parameter optimization ensures sufficient binding strength while maintaining reasonable tolerance requirements for production.
Solution Approach 2:
The protrusions are designed with sufficient thickness to provide adequate mechanical interlocking, but not excessively thick to the point of creating manufacturing difficulties. The design achieves the minimum necessary thickness to prevent rotation and cracking while remaining practical for manufacturing.
Data Source
AI summary
A cap assembly includes a cap down, a vent above the cap down, and an insulator between the cap down and the vent, the insulator including one or more protrusions protruding toward the vent. A secondary battery includes a case accommodating an electrode assembly, and a cap assembly coupled to an opening of the case, wherein the cap assembly includes a cap down, a vent above the cap down, and an insulator between the cap down and the vent, the insulator including one or more protrusions protruding toward the vent.