Battery Cap Recess and Projection for Laser Welding
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Solution Overview
Problem
Conventional caps for thin sealed batteries face challenges in achieving uniform welding strength and airtightness due to the presence of grooves along the entire periphery, which can lead to weak welding points and heat release during laser welding, making it difficult to position negative electrode terminals and maintain sealability.
Innovation Solution
A cap design featuring a recess surrounding the terminal hole with a projection inwardly overlapping the hole and a groove positioned away from the recess, ensuring uniform welding and preventing heat release, while allowing for easy positioning of electrode terminals and maintaining airtightness without a groove near the terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a groove is provided along the entire periphery of the cap, then heat release during welding is improved, but welding strength becomes non-uniform and airtightness deteriorates
Solution Approach 1:
The invention applies local quality by providing a groove only in a specific region of the cap (the first region) rather than along the entire periphery. This localized groove configuration allows heat release during welding in the groove region while maintaining uniform welding strength in the non-groove region, thereby resolving the contradiction between heat release and welding strength uniformity.
2Temperature
If a groove is provided along the entire periphery of the cap, then heat release during welding is improved, but airtightness of the terminal hole deteriorates
Solution Approach 1:
The invention applies local quality by confining the groove to a specific first region of the cap, away from the terminal hole area. This localized groove configuration enables heat release during welding without compromising the airtightness of the terminal hole, as the groove does not extend to regions that would affect terminal sealing.
3Reliability
If no groove is provided near the terminal hole, then airtightness is maintained, but heat release during welding is insufficient
Solution Approach 1:
The invention applies segmentation by dividing the cap periphery into different regions: a first region with a groove for heat release, and a second region without a groove for maintaining airtightness. This spatial segmentation allows the cap to simultaneously achieve both heat release capability and terminal hole airtightness by assigning different functional characteristics to different regions.
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
The cap design achieves uniform welding strength and improved airtightness by preventing heat release during welding and ensuring the electrode terminals are properly positioned, reducing the likelihood of cracks and maintaining seal integrity.
Implementation Method 1
The cap is welded to the battery case using a laser, for example
Data Source
AI summary
A cap for closing an opening of a battery case for containing an electrode assembly is formed by an elongated plate extending in a longitudinal direction. The cap includes: a terminal hole for allowing a negative electrode terminal of the electrode assembly to pass therethrough; a recess formed in an outer surface of the cap, the outer surface representing the exterior of the battery, the recess located in a region that surrounds the terminal hole and that is not in contact with the outer periphery of the outer surface. An edge of the recess includes a projection protruding inwardly. The projection is positioned to overlap the terminal hole as determined along the longitudinal direction.