Electrode Plate Corner Geometry for Wrinkle-Free Pouch Battery Sealing
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Solution Overview
Problem
Conventional pouch-type lithium-ion batteries face challenges in achieving high energy density due to the inability to perform sealing and edge-folding operations at the top of the battery without compromising the hermetic sealing effect, often resulting in material damage and wrinkles.
Innovation Solution
The electrode plate design includes a blank foil region at one end corner and a notched region at another end corner, with specific angles between 30° to 60°, allowing for seamless sealing and edge-folding operations on both sides and the top, reducing gaps and preventing wrinkles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the top seal edge length is set to a relatively large value to ensure hermetic sealing, then the sealing effect is improved, but the energy density is reduced due to increased material usage and reduced active area
Solution Approach 1:
The patent extracts the sealing function from the traditional long top seal edge by introducing a folding structure at the top edge of the packaging film. This folding structure, combined with the notched region on the electrode plate, enables the top edge to be folded and sealed without requiring a long seal edge, thus reducing the sealed area and increasing the active area for energy storage while maintaining hermetic sealing through the folding mechanism
Solution Approach 2:
The patent transitions from a two-dimensional sealing approach (long seal edge) to a three-dimensional sealing approach by folding the top edge of the packaging film. This dimensional change allows the seal to be formed through folding and adhesive bonding in the vertical dimension rather than extending the seal edge in the horizontal dimension, thereby preserving energy density while achieving hermetic sealing
2Reliability
If a special-shaped electrode plate structure with complex notched region is adopted to enable top sealing and edge-folding, then the sealing capability is improved, but the manufacturing complexity increases and wrinkles are prone to form
Solution Approach 1:
The patent applies local quality by providing the notched region only at specific corners of the electrode plate where needed for the folding operation, rather than making the entire electrode plate structure complex. The notched region is strategically positioned to facilitate the folding of the packaging film at the top edge, enabling sealing capability while keeping the rest of the electrode plate structure simple and easy to manufacture
Solution Approach 2:
The notched region is pre-formed on the electrode plate before assembly, creating a preliminary structure that facilitates the subsequent folding and sealing operations. This preliminary action of creating the notched region in advance allows the packaging film to be folded smoothly without causing wrinkles or damage during the sealing process
3Shape
If the packaging film is stamped to form a pocket with small edge angles, then the electrode plate can be accommodated, but wrinkles are prone to form at the edge and the pocket may be damaged
Solution Approach 1:
The notched region on the electrode plate performs a preliminary anti-action by providing a pre-formed corner structure that prevents the packaging film from forming sharp folds or wrinkles during the stamping and folding operations. The notched region acts as a buffer that absorbs the stress concentration that would otherwise cause wrinkles, thereby protecting the pocket integrity
Data Source
AI summary
An electrode plate body includes a coated region and a blank foil region located at one end corner of the electrode plate body. A notched region is provided at another end corner of the electrode plate body. A first boundary line is between the blank foil region and the coated region. An angle between a right-angled edge of the blank foil region in the short-side direction of the electrode plate body and the first boundary line ranges from 30° to 60°. A second boundary line is between a notched region and the coated region. An angle between the right-angled edge of the notched region in the short-side direction of the electrode plate body and the second boundary line ranges from 30° to 60°.