Battery Packaging Laminate for Thin Pouches With Less Curling
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Solution Overview
Problem
Battery packaging materials face challenges in reducing thickness and weight while maintaining moldability and minimizing curling, especially in large secondary batteries, due to the limitations of metallic materials and existing film-based laminates.
Innovation Solution
A battery packaging material with a laminate structure comprising a barrier layer, a heat-sealable resin layer, and a polyester film, where the polyester film has a specific degree of surface orientation (1.4 to 2.7) and birefringence index (0.016 or more), optimizing its crystal orientation to enhance moldability and reduce curling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If the thickness of the battery packaging material is reduced to achieve weight reduction and thinness, then the weight and thickness are improved, but the peripheral edge of the concave portion curls and moldability deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the degree of orientation of the polyester film within a specific range (1.4 to 2.7) and adjusting the thickness ratio between the heat-sealable resin layer and polyester film (1/4 to 3/4). These parameter optimizations enable thin packaging materials to maintain proper moldability without edge curling, resolving the contradiction between thickness reduction and manufacturing precision.
2Length of stationary object
If the thickness of each layer is decreased to achieve thinner packaging, then the thickness is improved, but the peripheral edge curls and heat sealing becomes hindered
Solution Approach 1:
The patent optimizes the thickness ratio parameter between the heat-sealable resin layer and polyester film within the range of 1/4 to 3/4. This parameter control ensures that even when overall thickness is reduced, the heat-sealable layer maintains sufficient thickness for proper heat sealing while the polyester film provides structural support to prevent curling, thus resolving the contradiction between thinness and ease of manufacture.
3Reliability
If a stretched polyester film is used to improve chemical resistance and electrolytic solution resistance, then the resistance is improved, but the moldability deteriorates due to higher hardness
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the degree of orientation parameter of the stretched polyester film within the range of 1.4 to 2.7. This parameter optimization balances the film's crystallinity and molecular orientation, maintaining the chemical and electrolytic solution resistance provided by stretching while reducing excessive hardness to improve moldability.
Solution Approach 2:
The patent employs a composite laminate structure combining the heat-sealable resin layer and polyester film in specific thickness ratios. This composite structure allows the polyester film to provide chemical resistance while the overall laminate composition ensures proper moldability, resolving the contradiction between reliability and manufacturing precision.
4Adaptability or versatility
If the battery packaging material has a large size for use in large secondary batteries, then the application range is improved, but the impact of curling on productivity increases significantly
Solution Approach 1:
The patent applies parameter changes by controlling the degree of orientation of the polyester film within the specific range of 1.4 to 2.7 and optimizing the thickness ratio of layers. These parameter optimizations minimize edge curling even in large-sized packaging materials, ensuring that productivity is not significantly impacted while maintaining adaptability for large secondary battery applications.
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 effectively improves moldability and minimizes curling after molding, allowing for thinner, more versatile battery packaging that enhances production efficiency and product quality.
Implementation Method 1
a battery packaging material with a laminate structure comprising a barrier layer, a heat-sealable resin layer, and a polyester film, where the polyester film has a specific degree of surface orientation (1.4 to 2.7) and birefringence index (0.016 or more), optimizing its crystal orientation to enhance moldability and reduce curling
Data Source
AI summary
A battery packaging material including a laminate that is provided with a barrier layer, a heat-fusible resin layer positioned on one surface side of the barrier layer, and a polyester film positioned on the other surface side of the barrier layer. When the infrared absorption spectrum on the surface of the polyester film in 18 directions at intervals of 10° from 0° to 180° is obtained using the total reflection method of Fourier transform infrared spectroscopy, the ratio (surface orientation degree, Ymax/Ymin) of the maximum value Ymax and the minimum value Ymin of the ratio (Y1340/Y1410) of the absorption peak intensity Y1340 in 1340 cm−1 and the absorption peak intensity Y1410 in 1410 cm−1 in the infrared absorption spectrum is in the range of 1.4-2.7.