Battery End Cover Surface Roughness for Reliable Sealing Cap Welding
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Solution Overview
Problem
Poor welding of sealing caps on energy-storage apparatuses such as lithium batteries results in low product yield due to issues like laser reflection, impurity vaporization, and formation of defects during laser welding.
Innovation Solution
The end cover assembly features a top cover with a first sub-surface having greater roughness than the second sub-surface, designed with specific ratios and markings to reduce laser reflection, enhance adhesive force, and manage impurities, ensuring effective sealing and welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the top cover surface is made smooth for clean appearance, then the aesthetic quality is improved, but laser reflection increases causing poor welding quality
Solution Approach 1:
The patent applies different surface roughness to different regions of the top cover. The first sub-surface (around the liquid-injection hole) has greater roughness (Ra: 3.2-50) to reduce laser reflection and improve welding quality, while the second sub-surface has smaller roughness (Ra: 0.4-3.2) to maintain a clean appearance. This local differentiation resolves the contradiction between aesthetic smoothness and welding reliability.
2Temperature
If the first sub-surface roughness is increased to reduce laser reflection, then the welding temperature consistency is improved, but the adhesive force between top patch and top cover may be reduced
Solution Approach 1:
The patent carefully controls the roughness of the first sub-surface within a specific range (Ra: 3.2-50) to balance two opposing requirements: reducing laser reflection for consistent welding temperature and maintaining sufficient adhesive force for the top patch. This optimized local roughness range resolves the contradiction between welding temperature consistency and adhesive strength.
3Reliability
If the linewidth of the first sub-surface is increased to provide larger welding area, then the welding stability is improved, but the material consumption increases
Solution Approach 1:
The patent optimizes the linewidth of the first sub-surface within a specific range (1.5mm ≤ L1 ≤ 8.5mm) to balance welding stability and material consumption. This parameter optimization ensures sufficient welding area for stable sealing cap attachment while minimizing unnecessary material usage.
4Reliability
If the ratio of outer radius of first sub-surface to radius of liquid-injection hole is increased to provide better sealing, then the sealing performance is improved, but the welding portion area decreases
Solution Approach 1:
The patent optimizes the ratio of the outer radius of the first sub-surface to the radius of the liquid-injection hole within a specific range (1.2 ≤ R1/R2 ≤ 4.8) to balance sealing performance and welding portion area. This parameter optimization ensures adequate sealing effectiveness while maintaining sufficient welding area for reliable sealing cap attachment.
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 solution improves the sealing performance and yield by minimizing laser reflection, preventing defects, and ensuring consistent welding temperatures, thereby enhancing the durability and efficiency of the energy-storage apparatus.
Implementation Method 1
the reflection of laser by the top cover can be reduced, so as to reduce the laser absorptivity of the welding material of the top cover
Implementation Method 2
reduce the laser absorptivity of the welding material of the top cover, avoiding the problem that the temperature cannot reach a welding temperature caused by the reflection of laser
Implementation Method 3
when a top patch is attached to the first surface of the top cover, gas between the top patch and the first sub-surface of the top cover can be discharged through a rough micro-gap of the first sub-surface to avoid formation of local bubbles, which can increase the binding force (i.e., the adhesive force) between the top patch and the first sub-surface
Implementation Method 4
gas between the top patch and the first sub-surface of the top cover can be discharged through a rough micro-gap of the first sub-surface to avoid formation of local bubbles
Data Source
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AI summary
An end cover assembly, an energy-storage apparatus, and an electricity-consumption device are provided in the present disclosure. The end cover assembly is for an energy-storage apparatus and includes a top cover. The top cover has a first surface and further defines a liquid-injection hole extending through the first surface. The first surface includes a first sub-surface and a second sub-surface connected to the first sub-surface, the first sub-surface is around the liquid-injection hole, the second sub-surface is around a periphery of the first sub-surface, and roughness of the first sub-surface is greater than roughness of the second sub-surface. According to the end cover assembly in embodiments of the present disclosure, during welding of a sealing cap, the sealing cap can be welded to the top cover to achieve a better sealing effect, prolonging the service life of the energy-storage apparatus.