Pouch Battery Case Die-Edge Curvature for Tab Clearance
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Solution Overview
Problem
Pouch-type battery cases face issues with interference between die edges and electrode tabs, wrinkling in corner portions, and insulation breakdown due to whitening phenomena during the manufacturing process of secondary batteries.
Innovation Solution
The design incorporates die edges with distinct curvature radii, where the region for the electrode tab has a larger first curvature radius and the adjacent region has smaller second curvature radii, preventing interference and reducing the risk of wrinkling and insulation breakdown by optimizing the shape of the die edges and the pouch film formation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the curvature radius of the die edge is reduced to improve formability and create vertical outer walls, then the cup portion shape is improved, but the die edge presses and interferes with the electrode tabs
Solution Approach 1:
The die edge is designed with different curvature radii for different regions: a first curvature radius for the first region and a second curvature radius (smaller than the first) for the second region. This local differentiation allows the die edge to have appropriate curvature in the electrode tab region to prevent interference, while having smaller curvature in other regions to achieve vertical outer walls and improved formability.
Solution Approach 2:
The die edge is divided into multiple regions (first region and second region) with different curvature characteristics. The first region has a larger curvature radius to protect electrode tabs, while the second region has a smaller curvature radius for optimal shaping, thereby segmenting the functional requirements of the die edge.
2Ease of manufacture
If the curvature radius of the die edge is determined uniformly irrespective of the bridge portion, then the manufacturing process is simplified, but wrinkling occurs in the corner portions of the pouch-type battery case
Solution Approach 1:
Different curvature radii are assigned to different regions of the die edge based on their specific functional requirements. The first region (associated with bridge portion) has one curvature radius while the second region (corner portion) has a different curvature radius, optimizing the shape stability in each region without significantly complicating the manufacturing process.
3Shape
If the curvature radius of the die edge is reduced to improve formability, then the outer wall becomes vertical, but a whitening phenomenon occurs and insulation breakdown risk increases in the side folding portion
Solution Approach 1:
The die edge curvature is optimized locally: the second region has a smaller curvature radius to achieve vertical outer walls for improved formability, while the first region maintains a larger curvature radius to prevent excessive stress concentration that causes whitening and insulation breakdown in critical areas like the side folding portion.
Data Source
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AI summary
A pouch-type battery case includes a cup portion, which accommodates therein an electrode assembly formed by stacking an electrode and a separator, and a plurality of die edges connecting an outer wall of the cup portion to a side extending from the outer wall. The die edges include a first region, which is rounded at a first radius (r1) of curvature and at which an electrode tab extending from the electrode is positioned, and a second region which is other than the first region and rounded at one or more second radii (r2, r3, r4) of curvature less than or equal to the first radius (r1) of curvature. The second region is divided into an inner region and an outer region with respect to the first region, and the radius (r2) of curvature in the inner region differs from the radii (r3, r4) of curvature in the outer region.