Battery Pouch Case Molding for Vertical Cup Walls
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Solution Overview
Problem
In the manufacturing of pouch-type secondary batteries, the inclination of the outer wall of the cup part at the folding part connecting the first and second cases leads to increased space between the outer wall and the electrode assembly, resulting in reduced energy density and an 'edge high' phenomenon during the degassing process, which affects the battery's thickness and marketability.
Innovation Solution
An apparatus and method for molding a battery case where the outer wall of the cup part is formed close to vertical by using a die with inclined surfaces and a punch that descends with an inclination, reducing the angle of the outer wall and preventing deformation during degassing, thereby minimizing unnecessary volume and preventing the 'edge high' phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If draw-molding is performed by inserting a pouch film into a molding device with a clearance between the die inner wall and punch outer wall, then the pouch film can be molded into a cup part, but the outer wall of the cup part is formed with an inclination increasing the space between the outer wall and electrode assembly
Solution Approach 1:
The patent changes the geometric parameters of the molding device by providing inclined surfaces on the die and configuring the punch to descend along an inclined path. This parameter change transforms the molding process to produce a cup part with a vertical outer wall, eliminating the inclination problem caused by conventional clearances between die and punch.
Solution Approach 2:
The patent introduces asymmetry in the molding process by using inclined surfaces rather than symmetric vertical walls in the conventional molding approach. The die includes inclined surfaces that guide the pouch film to form a vertical outer wall, breaking the symmetric clearance-based molding method that produces inclined walls.
2Ease of manufacture
If the outer wall of the cup part has an inclination, then the cup part can be formed by conventional molding, but the outer wall may be deformed during degassing process causing edge high phenomenon
Solution Approach 1:
The patent applies preliminary action by pre-forming the cup part with a vertical outer wall through the inclined surface molding process before the degassing operation. This preliminary shaping ensures that the outer wall maintains its vertical geometry and resists deformation during subsequent degassing, preventing the edge high phenomenon.
Solution Approach 2:
The patent implements preliminary anti-action by creating a vertical outer wall geometry that inherently resists the deforming forces encountered during degassing. The vertical wall configuration counteracts the tendency toward inclination and deformation that would otherwise occur during the degassing process.
3Productivity
If the outer wall of the cup part is formed with inclination, then molding can be completed, but the unnecessary thickness of the secondary battery increases lowering energy density
Solution Approach 1:
The patent changes the geometric parameters of the cup part formation process by using inclined surfaces in the die and inclined descent of the punch. This produces a cup part with minimal wall thickness and vertical outer wall, reducing unnecessary volume and improving energy density while maintaining complete molding.
Data Source
AI summary
An apparatus for molding a battery case includes: a die having a top surface, on which a pouch film is seated, and having at least one molding space formed to be recessed inward from the top surface; and a punch disposed above the molding space and descending to insert the pouch film into the molding space so as to mold the pouch film, wherein the top surface of the die includes at least one die inclined surface.