Battery Cell Separator Adhesive Layer Design
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Solution Overview
Problem
Secondary batteries face safety risks due to separator shrinkage, which can cause short circuits during the falling process, restricting their further development and usage.
Innovation Solution
A battery cell design featuring a separator with an extension portion and an adhesive layer that adheres to the separator's extension portion, preventing it from shrinking into the gap between electrodes, thereby avoiding short circuits. The adhesive layer includes materials like ethylene-vinyl acetate copolymer and has a thickness of 10 to 300 um, with a porous structure to enhance adhesion and integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the separator is extended beyond the electrodes at the end portion, then the separator can be adhered to prevent shrinkage, but the device complexity increases due to the additional adhesive layer structure
Solution Approach 1:
The adhesive layer is divided into a body portion and a connection portion that extends to the housing. This segmentation allows the adhesive layer to perform multiple functions: the body adheres to the separator extension portion while the connection portion anchors to the housing, effectively preventing separator shrinkage without requiring a completely different structural approach.
Solution Approach 2:
The adhesive layer acts as an intermediary element between the separator extension portion and the housing. It mediates the mechanical constraint force needed to prevent separator shrinkage during battery assembly and operation, transforming the complex direct constraint problem into a simpler adhesive bonding solution.
2Strength
If the adhesive layer thickness is increased to improve adhesion strength, then the bonding reliability improves, but the manufacturing precision requirements increase due to thicker layer control
Solution Approach 1:
The adhesive layer thickness is optimized within a specific range (10-300 μm) to balance adhesion strength and manufacturing feasibility. This parameter optimization ensures sufficient bonding strength to prevent separator shrinkage while maintaining thickness control within standard manufacturing capabilities, avoiding excessive precision requirements.
3Reliability
If the separator extension portion is adhered firmly to prevent movement, then the short circuit risk decreases, but the ease of manufacture decreases due to additional adhesion steps
Solution Approach 1:
The adhesive layer integration merges the separator fixation function with the existing battery assembly structure. By incorporating the adhesive layer into the natural extension portion configuration and using materials compatible with standard battery manufacturing processes, the solution combines multiple functions (adhesion, constraint, and structural integration) into a single manufacturing step rather than requiring separate fixation operations.
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
The adhesive layer effectively restricts separator movement, preventing short circuits and enhancing the battery cell's integrity, significantly improving the pass rate in drop tests by reducing the likelihood of separator shrinkage and electrode exposure.
Implementation Method 1
an adhesive layer (6) having a body (63) and a connecting portion (61) extending from the body (63), the body (63) being adhered to the extension portion (41), and the connecting portion (61) being adhered to the extension portion (41)
Data Source
AI summary
The present application provides a battery cell including a first electrode, a second electrode, and a separator disposed therebetween, wherein the separator comprises an extension portion beyond the first electrode and the second electrode at an end portion of the battery cell. The battery cell further includes an adhesive layer including a body and a connecting portion extending from the body. The body is adhered to the extension portion, and the connecting portion is adhered to the extension portion. It is an object of the present application to provide a battery cell that effectively eliminates invalidation resulted from short circuit caused by the separator shrinkage. The present application further provides an electrochemical device and a method of manufacturing thereof.