Secondary Battery Cap Vent Welding for Leak and Oxidation Control
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Solution Overview
Problem
The coupling force between the safety vent and the cap-up in secondary batteries is inadequate, leading to potential leakage and oxidation issues.
Innovation Solution
A secondary battery design that includes a cap assembly with a cap-up and a safety vent, where the safety vent and cap-up are laser-welded in a line shape, and the welding region is spaced apart from the end of the vent extension to be covered by a gasket, enhancing the coupling force and preventing oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the safety vent and cap-up are coupled using conventional methods, then the device complexity is reduced, but the coupling force between the safety vent and cap-up is inadequate
Solution Approach 1:
The patent replaces conventional mechanical coupling methods (such as crimping or riveting) with laser welding to join the safety vent to the cap-up. This substitution provides superior coupling force and sealing capability while maintaining manufacturing efficiency through automated laser welding processes.
Solution Approach 2:
The patent employs a composite structure where the safety vent and cap-up are joined through laser welding to create a unified component with enhanced mechanical strength and sealing performance. The welded joint creates a composite structure that leverages the properties of both components while adding the strength of metallurgical bonding.
2Reliability
If the welding region is positioned at the end of the vent extension part, then the manufacturing process is simplified, but the cap-up is exposed to oxidation
Solution Approach 1:
The gasket serves as an intermediary element that performs multiple functions: it provides sealing between the safety vent assembly and the case, and simultaneously covers the welding region to protect the cap-up from oxidation. This intermediary component resolves the conflict between manufacturing simplicity and oxidation prevention.
Solution Approach 2:
The patent positions the welding region away from the end of the vent extension part in advance, specifically designing it to be covered by the gasket. This preliminary positioning ensures that the cap-up is protected from oxidation before the battery is put into service, preventing degradation that would occur during operation.
3Strength
If a point-shaped welding region is used, then the welding process is faster, but the coupling force between the safety vent and cap-up is insufficient
Solution Approach 1:
The patent transitions from a point-shaped welding region (zero-dimensional contact) to a line-shaped welding region (one-dimensional contact). This dimensional change increases the welding area and improves coupling force while still maintaining a relatively efficient welding process compared to area welding methods.
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 improved coupling force between the safety vent and the cap-up enhances the sealing capacity and prevents oxidation of the cap-up, thereby improving the overall quality and reliability of the secondary battery.
Implementation Method 1
a welding region, in which the safety vent and the cap-up are welded and coupled by laser welding, is formed in the vent extension part
Implementation Method 2
the welding region is spaced apart from an end of the vent extension part... thereby improving quality by preventing the cap-up from being oxidized
Data Source
AI summary
The present invention relates to a secondary battery capable of improving the coupling force between a safety vent and a cap-up. For example, disclosed is a secondary battery comprising: an electrode assembly; a case for accommodating the electrode assembly; a cap assembly coupled to the upper part of the case; and a gasket interposed between the cap assembly and the case, wherein the cap assembly includes a cap-up and a safety vent, which is provided at the lower part of the cap-up and has a vent extension part extending to the upper part of the cap-up so as to encompass the edge of the cap-up, a welding region, in which the safety vent and the cap-up are welded and coupled by laser welding, is formed in the vent extension part, and the welding region is formed in a line shape.