Electrode Assembly Side Film Bonding to Prevent Separator Wrinkling
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Solution Overview
Problem
The existing methods for manufacturing electrode assemblies, which involve using fixing tapes to bind the unit cells, often result in folding and wrinkling of the separators, leading to potential short circuits due to contact between the negative and positive electrodes.
Innovation Solution
The proposed solution involves a method where a thermally fused film is used to cover and fix the side surfaces of the electrode assembly instead of using fixing tapes. This film is made of a thermoplastic material, such as polyethylene terephthalate (PET), and is thermally fused to the bonding portion of the stacked unit cells, preventing the separator from being folded or deformed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fixing tapes are used to bind unit cells, then the electrode assembly is secured, but the separator may fold and wrinkle causing short circuits
Solution Approach 1:
The patent replaces the mechanical fixing tape system with a thermal bonding system. Instead of using external fixing tapes that apply localized pressure, the separator itself is thermally bonded to the electrode assembly at multiple points, distributing the binding force uniformly and eliminating the risk of localized folding and wrinkling that causes short circuits.
Solution Approach 2:
The patent introduces a bonding agent or thermal bonding process as an intermediary mechanism. This intermediary allows the separator to be securely attached to the electrode assembly without direct mechanical pressure from fixing tapes, thereby preventing separator deformation while achieving reliable binding.
2Ease of manufacture
If fixing tapes are attached to wrap the electrode assembly, then unit cells are bound, but the separator ends fold and wrinkle due to pressure
Solution Approach 1:
The patent replaces the mechanical tape attachment system with a thermal bonding system that does not require wrapping or applying pressure with external materials. The thermal bonding process secures the separator through localized heating that melts and bonds the separator material to the electrode assembly, maintaining separator flatness while achieving effective binding.
Solution Approach 2:
The patent changes the bonding mechanism from mechanical (fixing tape pressure) to thermal (heat-induced bonding). This parameter change allows the separator to be bonded without subjected to localized pressure that causes folding and wrinkling, thereby maintaining manufacturing precision while achieving ease of manufacture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively prevents the folding or wrinkling of the separators, thereby reducing the risk of short circuits and improving the stability of the electrode assembly during the manufacturing process.
Implementation Method 1
a film (30) disposed to cover one of side surfaces defined by stacking the negative electrode (3), the separator (1), and the positive electrode (2), wherein the film (30) is thermally fused to the side surface defined by stacking the negative electrode (3), the separator (1), and the positive electrode (2)
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A manufacturing method according to the present invention is a method for manufacturing an electrode assembly in which a negative electrode, a separator, and a positive electrode are repeatedly stacked, the method comprising: a unit cell manufacturing step (S10) of manufacturing a unit cell having a predetermined stack structure of the negative electrode, the separator, and the positive electrode, wherein ends of the separators are bonded to each other to form a bonding portion; a film inserting step (S20) of inserting a film into a die; a unit cell stacking step (S30) of stacking the unit cell into the die; and a thermal fusing step (S40) of applying heat and a pressure to thermally fuse the film to the bonding portion of the stacked unit cell within the die. An electrode assembly according to the present invention is an electrode assembly in which a negative electrode, a separator, and a positive electrode are repeatedly stacked, the electrode assembly comprising a film disposed to cover one of side surfaces defined by stacking the negative electrode, the separator, and the positive electrode, wherein the film is thermally fused to the side surface defined by stacking the negative electrode, the separator, and the positive electrode.