Electrode Tab Forming Jig to Prevent Buckling in Wound Cells
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Solution Overview
Problem
Conventional methods for forming electrode tabs in secondary batteries face issues such as high resistance, limited current paths, and the risk of internal short circuits due to buckling phenomena during the multi-step processing of uncoated portions, which complicates equipment and prolongs processing cycles.
Innovation Solution
A forming device with a forming jig that includes an opposing surface with controlled indentation depth and curvature to manage the overlapping thickness of electrode tabs, preventing buckling by aligning with the profile of different stack sections and ensuring uniform contact without excessive pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple processing steps are used to radially bend the uncoated portion (first processing to gather ends, second processing to gather and press while rotating, third processing to press flat), then the uncoated portion can be properly formed, but the equipment structure becomes complex and the processing cycle is prolonged
Solution Approach 1:
The patent combines multiple processing steps (gathering ends, gathering, pressing, and flattening) into a single integrated forming jig. The jig includes a first forming portion to gather ends of the uncoated portion radially, a second forming portion to gather and press the uncoated portion while rotating, and a third forming portion to press the uncoated portion flat, all within one device structure.
Solution Approach 2:
The forming jig performs multiple functions simultaneously: it gathers the ends of the uncoated portion, presses them radially, and flattens them in a single operation. The rotation mechanism enables the jig to perform both gathering and pressing operations universally without requiring separate dedicated devices for each step.
2Ease of operation
If the uncoated portion is pressed without rotating the jig during the second processing, then the equipment operation is simplified, but the buckling phenomenon occurs due to frictional force between the jig and the ends of the uncoated portion
Solution Approach 1:
The forming jig incorporates a rotation mechanism that allows the jig to rotate about a rotation axis corresponding to the axis of the electrode assembly during the second processing step. This dynamic rotation enables the pressing operation to proceed without causing buckling, as the rotating motion reduces frictional force between the jig and the uncoated portion ends.
3Productivity
If the uncoated portion is pressed without first gathering the ends radially, then the processing steps are reduced, but the buckling phenomenon in which the uncoated portion slumps cannot be avoided
Solution Approach 1:
The forming jig includes a first forming portion that performs preliminary gathering of the ends of the uncoated portion in the radial direction before the main pressing operation. This preliminary action prepares the uncoated portion for subsequent pressing, preventing buckling and ensuring proper flatness formation.
4Strength
If conventional welding is used to connect tabs to the foil of the jelly-roll, then the connection is secure, but the current path is limited and the resistance of the jelly-roll becomes very high
Solution Approach 1:
The patent transitions from connecting tabs at single-point locations to a distributed network of current collector plates positioned at multiple locations around the jelly-roll. This dimensional expansion from point-to-point connections to multi-point distributed connections creates multiple current paths, reducing electrical resistance while maintaining secure mechanical connections through welding.
Data Source
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AI summary
A forming device according to an embodiment of the present disclosure is a forming device for radially bending an electrode tab in which a first electrode of an electrode assembly where a first electrode, a separator, and a second electrode are stacked and wound around a central axis is extending to an axial end further than a separator and exposed, wherein the forming device includes a forming jig for bending the electrode tab, the forming jig includes an opposing surface facing the electrode assembly, and the opposing surface has an indentation depth of the opposing surface that is indented in a direction opposite to the pressing direction.