Cap Assembly Vent Recess Design for Battery Sealing
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Solution Overview
Problem
Existing cap assemblies for cylindrical secondary batteries face challenges in maintaining a stable connection between the safety vent and the cap-up without increasing the thickness of the cap assembly, which can lead to compromised sealing characteristics and mechanical strength.
Innovation Solution
A cap assembly design where the end of the safety vent is bent to cover the cap-up, with a thinner first region in contact with the safety vent and a thicker second region, incorporating a current interrupt device and a positive temperature coefficient thermistor, and featuring semi-circular or chamfered cross-sections to enhance electrical and mechanical connections without increasing the overall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the safety vent is connected to the cap-up using conventional methods, then the electrical connection is established, but the mechanical strength and sealing characteristics are compromised and the thickness increases
Solution Approach 1:
The safety vent is inserted into a recess formed in the cap-up, creating a nested structure where one component fits within another. This nesting approach establishes stable electrical and mechanical connections while minimizing the increase in overall cap assembly thickness, as the safety vent is housed within the cap-up's recess rather than adding external thickness.
Solution Approach 2:
Instead of connecting the safety vent to the cap-up in a straightforward linear manner that increases thickness, the invention utilizes a recess dimension to create a three-dimensional integration. The safety vent extends into the recess, establishing connections through vertical and lateral positioning rather than simple end-to-end attachment, thereby maintaining a compact overall thickness.
2Strength
If the cap-up thickness is increased to accommodate the safety vent connection, then the mechanical strength improves, but the sealing characteristics deteriorate
Solution Approach 1:
By nesting the safety vent within the cap-up recess, the design achieves strong mechanical connections through precise fit and contact surfaces without requiring excessive cap-up thickness. The recess provides structural support and positioning that enhances mechanical strength while maintaining the cap-up's overall dimensions and sealing integrity.
Solution Approach 2:
The cap-up is designed with a recess that provides localized structural reinforcement at the connection point with the safety vent. This localized feature enhances mechanical strength and sealing characteristics at the critical connection area without requiring uniform thickness increase throughout the entire cap-up structure, thereby preserving overall sealing characteristics.
3Reliability
If the safety vent end is bent to cover the cap-up, then the electrical connection is improved, but the manufacturing complexity increases
Solution Approach 1:
The safety vent is pre-formed with a bent end configuration before assembly. This preliminary shaping ensures proper electrical connection and positioning when the safety vent is inserted into the cap-up recess, eliminating the need for complex post-assembly bending operations and reducing overall manufacturing complexity.
Solution Approach 2:
The bending of the safety vent end changes its geometric parameters to achieve optimal electrical connection with the cap-up. By pre-forming this specific geometry, the design achieves reliable electrical connection while the bending process itself remains a simple, low-complexity manufacturing step that can be integrated into standard production workflows.
Data Source
AI summary
A cap assembly includes a cap-up and a safety vent wherein an end of the safety vent is bent to cover an end of the cap-up, a first thickness of a first region of the cap-up in contact with the end of the safety vent is smaller than a second thickness of a second region of the cap-up not in contact with the end of the safety vent.