Battery Packaging Laminate With Oriented Polyester Film Against Curling
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Solution Overview
Problem
Battery packaging materials face issues with curling and reduced moldability when thickness is minimized, particularly in large secondary batteries, affecting production efficiency and electrolyte attachment, especially when using stretched polyester films.
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 surface orientation ratio (Y1340/Y1410) between 1.4 and 2.7, enhancing moldability and minimizing curling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of each layer in the battery packaging material is decreased to reduce battery size and weight, then the reduction in thickness and weight is achieved, but the peripheral edge of the concave portion becomes curled, hindering storage of battery elements and heat sealing operations
Solution Approach 1:
The patent applies parameter changes by controlling the crystallinity of the polyester film within a specific range of 30% to 70%. This crystallinity parameter control prevents curling of the peripheral edge during cold molding while enabling efficient heat sealing operations, thus resolving the contradiction between reduced thickness and manufacturing ease.
Solution Approach 2:
The patent uses a laminate structure comprising multiple layers including a polyester film layer, a polyolefin resin layer, and an adhesive layer. This composite material structure combines the advantages of each layer to prevent curling while maintaining thin profile and enabling efficient manufacturing operations.
2Reliability
If a stretched polyester film is used as a base material to improve chemical resistance and electrolytic solution resistance, then the resistance is improved, but the battery packaging material generates curling more easily and has reduced moldability
Solution Approach 1:
The patent changes the crystallinity parameter of the polyester film to a specific range of 30% to 70%, which optimizes both the electrolytic solution resistance and moldability. This parameter control prevents excessive curling while maintaining the chemical resistance benefits of polyester film.
Solution Approach 2:
The patent applies different functional layers with specific properties at different positions. The polyester film layer provides chemical resistance, while the polyolefin resin layer with specific crystallinity control provides moldability and reduces curling. Each layer has localized quality optimized for its specific function.
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.