Jelly-Roll Electrode Tab Structure for Battery Symmetry and Heat Dissipation
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Solution Overview
Problem
Conventional jelly-roll type electrode assemblies in secondary batteries suffer from asymmetry and distortion due to the positioning of electrode tabs, leading to inconsistent performance in impact tests and shape deformation during charging and discharging.
Innovation Solution
A jelly-roll type electrode assembly design where the first electrode tab is joined to an uncoated portion and positioned at the central portion, with a wider joining portion that is wound 3/4 times or less to maintain symmetry, featuring a joining portion with specific structural modifications such as stepped or recessed grooves to facilitate one-time winding and prevent overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrode tabs are positioned at the edge of the electrode assembly, then the assembly structure is simpler to manufacture, but the battery exhibits asymmetry and distortion during charging and discharging
Solution Approach 1:
The patent applies asymmetry principle by deliberately positioning the electrode tab at the edge of the electrode assembly rather than at the center. This edge positioning creates a specific asymmetric structure that, when wound into a jelly-roll configuration, results in the tab being located at the outer peripheral surface of the wound assembly. This design resolves the contradiction by maintaining manufacturing simplicity while achieving symmetric external shape through the winding process that distributes the tab position uniformly around the cylindrical axis.
Solution Approach 2:
The patent utilizes dimensionality change by transitioning from a flat, two-dimensional electrode assembly layout to a three-dimensional cylindrical wound structure. The electrode tab positioned at the edge in 2D space becomes distributed around the outer peripheral surface in 3D cylindrical space, eliminating asymmetry and distortion issues while maintaining manufacturing ease.
2Ease of manufacture
If electrode tabs are positioned asymmetrically, then manufacturing is easier, but impact test performance becomes inconsistent
Solution Approach 1:
The patent applies asymmetry principle by deliberately positioning the electrode tab at the edge of the electrode assembly rather than at the center. This edge positioning creates a specific asymmetric structure that, when wound into a jelly-roll configuration, results in the tab being located at the outer peripheral surface of the wound assembly. This design resolves the contradiction by maintaining manufacturing simplicity while achieving symmetric external shape through the winding process that distributes the tab position uniformly around the cylindrical axis.
3Shape
If electrode tabs are positioned at the center, then symmetry is maintained, but the joining portion requires complex winding structures
Solution Approach 1:
The patent applies inversion principle by reversing the conventional approach: instead of positioning the tab at the center and managing the complexity of keeping it centered during winding, the tab is positioned at the edge where it naturally remains at the outer peripheral surface during the winding process. This inverts the problem from 'how to keep the tab centered' to 'how to allow the tab to naturally position itself at the edge,' significantly simplifying the joining portion structure.
4Temperature
If the joining portion width is increased, then heat dissipation is improved, but the winding process becomes more complex
Solution Approach 1:
The patent applies inversion principle by reversing the conventional approach: instead of positioning the tab at the center and managing the complexity of keeping it centered during winding, the tab is positioned at the edge where it naturally remains at the outer peripheral surface during the winding process. This inverts the problem from 'how to keep the tab centered' to 'how to allow the tab to naturally position itself at the edge,' significantly simplifying the joining portion structure.
Data Source
AI summary
A secondary battery including a jelly-roll type electrode assembly in which a first electrode sheet, a second electrode sheet are wound with a separator interposed between the first electrode sheet and the second electrode sheet and a first electrode tab which is joined to an uncoated portion of the first electrode sheet and is positioned at a central portion of the jelly-roll type electrode is provided. The first electrode tab includes a joining portion joined to the uncoated portion and an extension portion extended outward from the joining apportion. A width of the joining portion is wider than a width of the extension portion. The joining portion is wound ¾ times or more and once or less in the central portion of the jelly-roll electrode assembly.