Separator Film Folding Device for Electrode Assembly
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The manufacturing of stacked/folded type electrode assemblies for secondary batteries faces issues such as peeling of electrode active material, low space utilization, and a high defect rate due to improper folding of the separator film during the winding process, leading to potential short circuits.
Innovation Solution
A method using a folding device with a mandrel and a pair of rollers to vertically and horizontally bend the surplus winding end portion of the separator film, ensuring it covers the upper surface of the first unit cell, thereby preventing secondary folding phenomena and reducing defect rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a blower method is used to fold the surplus winding end portion of the separator film inward, then the separator film can be folded toward the first unit cell, but the separator film may still not be properly folded and a folding phenomenon may occur causing short circuits
Solution Approach 1:
The patent replaces the blower method (pneumatic system) with a mechanical roller system to fold the surplus separator film. The first roller presses the surplus winding end portion from above while the second roller presses from below, providing controlled mechanical folding that reliably prevents the separator film from folding outward and causing short circuits between unit cells.
2Device complexity
If the surplus winding end portion of the separator film is not folded inward, then the folding process is simpler, but the separator film may fold outward during winding causing defects and short circuits
Solution Approach 1:
The patent performs the folding action before the winding process begins. The first and second rollers press the surplus winding end portion of the separator film inward toward the first unit cell in advance, ensuring that the separator film is properly positioned and folded before winding starts, thereby preventing any outward folding during the winding process.
Solution Approach 2:
The patent introduces rollers as an intermediary mechanical device between the separator film and the winding process. The rollers act as a mediating tool that applies controlled pressure to fold and secure the surplus separator film, ensuring precise folding without requiring complex device structures.
3Manufacturing precision
If additional pressure rollers are added to ensure proper folding of the separator film, then folding precision improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent designs the first and second rollers to serve dual functions: they press the surplus winding end portion of the separator film inward during the folding process, and simultaneously press the unit cells during the winding process. This multi-functionality achieves precise separator film folding without requiring additional dedicated pressure rollers, thereby reducing device complexity.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present disclosure provides a folding device for manufacturing an electrode assembly having a structure in which plate type unit cells are wound with a separator film, including: a mandrel configured to rotate and wind a web in which plate type unit cells are arranged on an upper surface of the separator film at predetermined intervals so that the unit cells are sequentially stacked with the separator film interposed therebetween; and a pair of rollers configured to horizontally bend a surplus winding end portion of the separator film, which is formed by arranging a first unit cell at a winding start portion of the web in a state of being spaced apart from a winding end portion of the separator film, in a direction covering an upper surface of the first unit cell, wherein the mandrel includes one or more grippers composed of one or more upper legs configured to fix an upper surface portion of the first unit cell and one or more lower legs configured to fix a lower surface portion of the separator film corresponding to the upper legs, and the pair of rollers operate to vertically bend the surplus winding end portion of the separator film upward and then horizontally bend the surplus winding end portion toward the upper surface of the unit cell.