Battery Cap Assembly Sealing with Spaced Vent Welds
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Solution Overview
Problem
Secondary batteries face challenges in ensuring effective sealing, which can lead to leakage and safety issues due to inadequate spacing between the case end and the welded area of the cap assembly.
Innovation Solution
Incorporating a cap assembly with a safety vent and a welded area that is spaced at least 0.2 mm from the case end, with a gasket in between, to enhance sealing and safety by preventing electrolyte leakage and electrode separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the welded area is positioned close to the case end, then the cap assembly structure is compact, but the sealing capability deteriorates and leakage risk increases
Solution Approach 1:
The cap assembly is segmented into distinct functional zones: the welded area is separated from the case end by positioning the welding operation at a specific distance (e.g., 3-5mm) from the case end, creating spatial separation between the welding zone and the sealing zone. This segmentation allows each area to perform its function optimally without interference.
Solution Approach 2:
The welding operation is performed at a predetermined position on the cap-up, calculated in advance to maintain optimal distance from the case end. This preliminary positioning ensures that the welded area does not compromise the sealing capability while achieving compact assembly, preventing leakage before it occurs.
2Productivity
If the welded area is positioned close to the case end, then manufacturing efficiency is improved, but safety deteriorates due to potential electrolyte leakage
Solution Approach 1:
The welding position on the cap-up is predetermined during the design phase, specifying the exact distance from the case end (e.g., 3-5mm). This preliminary positioning ensures that welding operations are performed consistently at safe locations that do not compromise sealing, preventing electrolyte leakage while maintaining manufacturing efficiency through standardized positioning.
Solution Approach 2:
The cap-up structure acts as an intermediary element between the welding operation and the case end. By positioning the welded area on the cap-up at a specific distance from the case end, the cap-up mediates between the need for efficient welding and the requirement to prevent electrolyte leakage, isolating the welding zone from the sealing zone.
3Reliability
If the welded area is spaced 0.2 mm or more from the case end, then sealing capability is ensured, but the cap assembly size increases
Solution Approach 1:
The distance parameter between the welded area and case end is optimized to a specific range (e.g., 3-5mm or at least 0.2mm) that provides sufficient sealing capability while minimizing the increase in cap assembly length. This parameter optimization ensures adequate sealing without excessive dimensional growth.
Solution Approach 2:
The sealing capability is enhanced locally at the critical interface between the cap assembly and case end, rather than requiring uniform increases throughout the entire cap assembly. By concentrating the sealing function at the specific location where the welded area is positioned relative to the case end, adequate sealing is achieved with minimal overall size increase.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures secure sealing and improved safety by maintaining a sufficient distance between the case end and the welded area, maintaining sealing pressure within optimal ranges and preventing premature leakage.
Implementation Method 1
the vent extension portion has a welded area formed by welding the cap-up and the safety vent to each other
Data Source
AI summary
The present invention relates to a secondary battery which can ensure sealing capability. Disclosed as an example is a secondary battery comprising: an electrode assembly; a case in which the electrode assembly is accommodated; and a cap assembly which is coupled to the top of the case and comprises a cap-up, a safety vent provided under the cap-up and having a vent extension portion extending to the top of the cap-up so as to cover the edge of the cap-up, and a cap-down provided under the safety vent and electrically connected to the electrode assembly, wherein the vent extension portion has a welded area formed by welding the cap-up and the safety vent to each other, and the welded area is spaced apart from the end of the case.