Cylindrical Secondary Battery Tab Layout to Prevent Welding Shorts
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Solution Overview
Problem
Existing ultra-small secondary batteries face issues with welding defects and short-circuit defects due to the positive electrode tab extending from the outer circumference, which increases the risk of interference during the welding process, especially when the battery size is reduced.
Innovation Solution
The positive electrode tab is positioned to be spaced apart from the outer circumferential surface of the electrode assembly, with a bend configuration that minimizes interference during welding, using a cover tape to secure the tab and prevent contact with the cap plate, and a cap assembly design that includes insulating layers to enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the positive electrode tab extends from the outer circumference of the electrode assembly, then the battery structure is simpler and easier to manufacture, but welding defects and short-circuit defects occur more frequently
Solution Approach 1:
The positive electrode tab is extracted from the outer circumference position and relocated to the inner circumferential surface of the electrode assembly. This extraction removes the tab from the harmful welding zone, eliminating the source of welding defects and short-circuit defects while maintaining manufacturing simplicity through the straightforward relocation process
Solution Approach 2:
A cover tape is introduced as an intermediary component to cover the positive electrode tab on the inner circumferential surface. This mediator prevents direct contact between the tab and welding operations, eliminating welding defects and short-circuit defects while allowing the tab to remain in its relocated position
2Volume of moving object
If the battery size is reduced to create ultra-small secondary batteries, then the battery meets the demand for wearable devices, but the risk of welding defects and short-circuit defects increases
Solution Approach 1:
The positive electrode tab is extracted from the outer circumference and repositioned to the inner circumferential surface, removing it from the welding interference zone. This extraction prevents welding defects and short-circuit defects in ultra-small batteries where space constraints amplify the risks of traditional configurations
Solution Approach 2:
The tab position is changed from a radial outer dimension to a radial inner dimension, and the cover tape adds a layer dimension to protect the tab. This dimensional reconfiguration allows the battery to be miniized while maintaining reliability by eliminating welding interference through spatial redistribution
3Reliability
If the positive electrode tab is repositioned to the inner circumferential surface, then welding defects and short-circuit defects are prevented, but the device complexity increases
Solution Approach 1:
The tab is extracted and repositioned to the inner circumferential surface, preventing welding defects and short-circuit defects. This simple positional change achieves reliability improvement without requiring complex structural modifications or additional functional components
Solution Approach 2:
The cover tape is applied locally only to the positive electrode tab area on the inner circumferential surface, providing targeted protection against welding defects and short-circuit defects. This localized approach improves reliability while minimizing the addition of complex components throughout the entire battery structure
Data Source
AI summary
A secondary battery, including, in some examples: an electrode assembly comprising a positive electrode plate and a negative electrode plate separated by a separator and wound in a cylindrical shape, a positive electrode tab spaced apart from an outer circumferential surface of the cylindrical shape toward an inside of the cylindrical shape and connected to the positive electrode plate, and a negative electrode tab connected to the negative electrode plate; a housing can configured to receive the electrode assembly, electrically connected to the negative electrode tab, and having an open area at one side; and a cap assembly electrically connected to the positive electrode tab and configured to close the open area to seal the electrode assembly from an outside region.