Cell Pouch Film Sealant Composition for High-Temperature Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secondary battery pouch films face challenges in maintaining high-temperature sealing strength, which can lead to electrolyte leakage and safety issues, especially in medium-sized and large-sized batteries used in automotive and ESS applications.
Innovation Solution
A cell pouch film with a sealant layer formed by non-lamination extrusion, having a glass transition temperature of -10°C to -7°C and crystallinity of 28% to 32%, which enhances high-temperature sealing strength by maintaining or increasing it relative to ambient temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealant layers are used in cell pouch films, then the film can be manufactured with standard properties, but the sealing strength decreases at high temperatures leading to electrolyte leakage and safety issues
Solution Approach 1:
The patent applies parameter changes by precisely controlling the glass transition temperature (Tg) of the sealant layer within -50°C to 0°C and crystallinity within 20% to 40%. These parameter adjustments enable the sealant to maintain optimal sealing performance across a wide temperature range, particularly preventing high-temperature sealing failure that causes electrolyte leakage.
Solution Approach 2:
The patent uses composite materials by formulating the sealant layer as a blend of polypropylene (60-80 wt%) and ethylene-propylene rubber (20-40 wt%). This composite structure combines the heat resistance of polypropylene with the flexibility and adhesion of EPR, creating a sealant that maintains both high-temperature stability and sealing strength.
2Reliability
If the sealant layer is made more adhesive to prevent leakage, then reliability improves, but the manufacturing complexity and control difficulty increase
Solution Approach 1:
The patent simplifies manufacturing control by establishing clear parameter ranges: Tg of -50°C to 0°C and crystallinity of 20% to 40%. These well-defined parameters provide manufacturers with straightforward quality control targets, making it easier to produce consistent high-performance sealants without excessive process complexity.
Solution Approach 2:
The patent applies local quality by optimizing only the sealant layer's specific properties (Tg and crystallinity) while maintaining standard structures for other pouch film layers. This focused approach improves sealing performance without requiring complex changes to the entire film structure or manufacturing process.
3Reliability
If the glass transition temperature and crystallinity are optimized for high-temperature sealing, then sealing strength is maintained, but the manufacturing precision requirements increase
Solution Approach 1:
The patent manages manufacturing precision by setting practical parameter ranges rather than extreme values: Tg of -50°C to 0°C and crystallinity of 20% to 40%. These ranges are wide enough to accommodate normal manufacturing variations while still achieving the desired high-temperature sealing performance, thereby reducing the burden on manufacturing precision.
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 solution provides excellent high-temperature stability, preventing electrolyte leakage and ensuring battery safety, particularly for medium-sized to large-sized batteries used in electric vehicles and energy storage devices.
Implementation Method 1
the sealant layer has a glass transition temperature (Tg) of -10°C to -7°C
Implementation Method 2
a crystallinity of the sealant layer, as measured by a method below, is 28% to 32%
Data Source
Figure 1~2
AI summary
Disclosed is a cell pouch film, comprising at least an outer layer, a barrier layer, and a sealant layer structured in that order, wherein the sealant layer is formed by extrusion on the barrier layer, wherein the sealant layer has a glass transition temperature (Tg) of -10°C to -7°C, and wherein a crystallinity of the sealant layer is 28% to 32%, a preparation method thereof, a secondary battery using the cell pouch film, and a manufacturing method for the secondary battery. The sealing strength of the pouch film may be maintained or increased at high temperatures, thereby providing excellent high-temperature stability, which prevents electrolyte leakage during battery use in high-temperature environments and ensures battery safety with fewer defects.