Sealing Cap Design for Rechargeable Battery Electrolyte Injection
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Solution Overview
Problem
The existing design of rechargeable batteries with a two-stage structure for the electrolyte injection opening and sealing cap, such as a cylindrical and circular shape, leads to a wide interference area, making it difficult to insert the sealing cap and resulting in poor productivity and welding quality due to thermal distortion and the need for a pre-welding process.
Innovation Solution
A rechargeable battery design featuring a cap plate with a first opening and a second opening of different diameters, connected by a guide portion, and a sealing cap with a fixing member that engages the inner wall of the second opening, allowing for easy insertion and one-time welding, reducing the interference area and preventing deformation during welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrolyte injection opening and sealing cap are formed in a two-stage structure (cylindrical and circular shapes), then the sealing cap can engage the opening, but a wide interference area is formed making insertion difficult and designing allowable tolerance difficult
Solution Approach 1:
The sealing cap is divided into multiple functional parts: a sealing ring for engagement, a guiding portion with tapered surface for alignment, and a protrusion for positioning. The electrolyte injection opening is also segmented into a first opening and second opening at different levels. This segmentation allows each part to perform its specific function while reducing overall interference during insertion.
Solution Approach 2:
The guiding portion with the tapered surface acts as an intermediary element between the sealing cap and the electrolyte injection opening. The tapered surface gradually guides the sealing cap into proper alignment and engagement with the opening, reducing sudden interference and facilitating smooth insertion.
2Reliability
If the electrolyte injection opening and sealing cap are formed in a two-stage structure, then sealing engagement is possible, but centers of the two stages may not be aligned making insertion difficult and productivity deteriorated
Solution Approach 1:
The sealing cap features an asymmetric design with a guiding portion having a tapered surface that is not radially symmetric. This asymmetric taper guides the sealing cap to self-align with the electrolyte injection opening during insertion, compensating for center misalignment and ensuring proper engagement without requiring precise centering.
Solution Approach 2:
Instead of requiring the centers of the two-stage structure to be perfectly aligned, the invention inverts the approach by using the tapered guiding surface to actively guide misaligned components into proper alignment during insertion. The alignment is achieved during the insertion process itself rather than requiring pre-alignment.
3Manufacturing precision
If a pre-welding process is required to weld the sealing cap to the electrolyte injection opening, then thermal distortion is prevented, but productivity is deteriorated
Solution Approach 1:
The guiding portion with the tapered surface performs the preliminary action of aligning and positioning the sealing cap relative to the electrolyte injection opening before welding. This pre-alignment ensures that the welding process can proceed directly without requiring a separate pre-welding step to prevent thermal distortion, as the components are already properly positioned.
Solution Approach 2:
The alignment and positioning functions are merged into the guiding portion structure, and the positioning is integrated with the welding process setup. By combining these functions into a single structural feature, the need for a separate pre-welding process is eliminated, improving productivity while maintaining welding quality.
4Device complexity
If the sealing cap is not smoothly fixed to the electrolyte injection opening, then welding process is simplified, but welding quality is deteriorated
Solution Approach 1:
The guiding portion with the tapered surface enables the sealing cap to self-align and self-position during insertion into the electrolyte injection opening. This self-service mechanism ensures smooth fixing without requiring complex pre-positioning fixtures or procedures, simplifying the welding process setup while ensuring high welding quality through consistent alignment.
Data Source
AI summary
A rechargeable battery includes an electrode assembly, a case housing the electrode assembly, an electrode terminal electrically connected to the electrode assembly and a cap plate sealing the case, the cap plate having an electrolyte injection opening. The electrolyte injection opening has a first opening having a first diameter and a second opening having a second diameter both defined by an inner wall of the cap plate, the second diameter being smaller than the first diameter, and a first guide portion between the first opening and the second opening. A sealing cap seals the electrolyte injection opening and includes a sealing member engaging the inner wall of the first opening and a fixing member coupled to the sealing member and engaging the inner wall of the second opening, wherein a portion of the fixing member is spaced from the inner wall of the second opening.