Separator Edge Adhesion for Power Storage Cell Shrinkage
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Solution Overview
Problem
The separator in power storage elements may shrink due to reduced adhesive force, leading to potential short circuits and performance degradation.
Innovation Solution
A power storage cell design featuring a separator with a central and edge portion adhesion layer configuration, where the edge portion is adhered to the current collector and spacer, and optionally the active material layers, to maintain adhesive force and prevent shrinkage, using thermosetting adhesives for enhanced reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the separator is not adhered to the current collector and spacer, then the device complexity is reduced, but the separator shrinks causing short circuits and performance degradation
Solution Approach 1:
The separator is divided into a central portion and an edge portion, with adhesion layers selectively applied only to the edge portion. This segmentation approach prevents separator shrinkage while minimizing the added structural complexity by limiting the adhesion layers to specific regions rather than covering the entire separator surface.
Solution Approach 2:
Adhesion layers are applied locally to the edge portion of the separator rather than uniformly across the entire separator. This local quality approach provides the necessary adhesive functionality at the edges to prevent shrinkage while maintaining simplicity in the central region, thus resolving the contradiction between reliability and device complexity.
2Manufacturing precision
If adhesion layers are provided only at the edge portion of the separator, then the manufacturing precision is improved by preventing shrinkage, but the ease of manufacture is reduced due to additional coating steps
Solution Approach 1:
The adhesion layer application is segmented to cover only the edge portion of the separator, which is the critical region for preventing shrinkage. This selective coating approach improves manufacturing precision by ensuring proper separator positioning while reducing the overall manufacturing complexity compared to coating the entire separator surface.
Solution Approach 2:
The adhesion layers are applied with local quality focus on the edge portion where they are most needed for preventing separator shrinkage. This localized application method achieves the required manufacturing precision for separator position control while minimizing the additional manufacturing steps compared to full-surface coating.
3Reliability
If thermosetting adhesives are used in the adhesion layers, then the reliability is improved by preventing adhesive melting, but the ease of repair is reduced due to permanent bonding
Solution Approach 1:
The adhesive material undergoes a parameter change through thermosetting, where it transitions from a soft, adhesive state during application to a hardened, heat-resistant state after curing. This parameter change enables the adhesive to maintain reliability at high operating temperatures while the initial soft state allows for easier positioning and assembly before final bonding occurs.
Solution Approach 2:
The adhesion layers are applied in a preliminary soft state that allows for easy positioning and assembly of the separator. After assembly, the adhesive undergoes curing to achieve its final heat-resistant properties. This preliminary action approach enables easier initial assembly while ensuring high reliability during operation, effectively managing the trade-off between ease of repair and reliability.
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 design effectively suppresses separator shrinkage, maintains contact area, and prevents short circuits, thereby improving the stability and performance of power storage devices.
Implementation Method 1
the separator has, at least in the edge portion of the separator, a first adhesion layer provided on a first surface of the base material layer, and a second adhesion layer provided on a second surface of the base material layer. One of the first current collector and the second current collector is adhered to the first adhesion layer in the edge portion of the separator. The spacer is adhered to the second adhesion layer in the edge portion of the separator.
Implementation Method 2
At least one of the first adhesion layer and the second adhesion layer may contain a thermosetting adhesive. In this case, even when the power storage cell is heated after curing of the thermosetting adhesive, the thermosetting adhesive does not melt.
Data Source
AI summary
A power storage cell is provided with a positive electrode, a negative electrode, a separator, and a spacer. The positive electrode has: a first current collector; and a positive electrode active material layer provided on a one surface of the first current collector. The negative electrode has: a second current collector; and a negative electrode active material layer provided on a one surface of the second current collector. The separator has a base material layer, a first adhesive layer, and a second adhesive layer. The one surface of the first current collector is adhered to the first adhesive layer in an edge portion of the separator. The spacer is adhered to the second adhesive layer in the edge portion of the separator.