Battery Packaging Laminate With Oriented Polyester Film for Curl Control
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Solution Overview
Problem
Existing battery packaging materials face issues with curling and reduced moldability when thinned, particularly in large secondary batteries, affecting production efficiency and chemical resistance.
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
1Weight of stationary object
If the thickness of the battery packaging material is reduced, then the weight and thickness of the battery are reduced, but the peripheral edge of the concave portion curls and moldability deteriorates
Solution Approach 1:
The patent uses a laminate structure comprising a base material layer, a barrier layer, and a heat-sealable resin layer. This composite structure allows each layer to contribute different properties: the base material provides mechanical strength and moldability, the barrier layer prevents electrolyte penetration, and the heat-sealable resin layer enables sealing. This resolves the contradiction by maintaining overall structural integrity and moldability even when individual layers are thin.
Solution Approach 2:
The patent specifies different thickness requirements for different layers: the base material layer has a thickness of 5-25 μm, the barrier layer has a thickness of 2-10 μm, and the heat-sealable resin layer has a thickness of 10-30 μm. This local differentiation allows the base material to be thin for weight reduction while the heat-sealable resin layer maintains sufficient thickness to prevent curling and ensure proper sealing.
2Length of stationary object
If the thickness of the battery packaging material is reduced, then the thickness of the battery is reduced, but the peripheral edge of the concave portion curls and storage of battery elements is hindered
Solution Approach 1:
The laminate structure with multiple layers provides distributed mechanical support. The base material layer and heat-sealable resin layer work together to maintain the shape of the concave portion, preventing curling even when the overall thickness is reduced. The barrier layer in between provides additional structural stability.
Solution Approach 2:
The patent specifies that the heat-sealable resin layer should have a thickness of 10-30 μm, which is relatively thicker than the base material layer. This local thickness enhancement at the sealing portions provides sufficient rigidity to prevent curling of the concave portion peripheral edge while keeping the overall package thin.
3Reliability
If a stretched polyester film is used as the base material to improve chemical resistance, then the chemical resistance and electrolytic solution resistance are improved, but the moldability deteriorates due to higher hardness
Solution Approach 1:
The patent uses a laminate structure where the stretched polyester film base material provides chemical and electrolytic solution resistance, while the barrier layer and heat-sealable resin layer compensate for the reduced moldability. The barrier layer, being softer and more formable, can be molded effectively, and the heat-sealable resin layer ensures proper sealing.
Solution Approach 2:
The patent specifies a thin thickness range of 5-25 μm for the base material layer, which reduces the overall hardness and improves moldability while maintaining sufficient chemical resistance. The heat-sealable resin layer with thickness of 10-30 μm provides the necessary flexibility for molding and sealing 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 laminate structure effectively minimizes curling and improves moldability, allowing for thinner and more diverse battery designs while maintaining chemical resistance.
Implementation Method 1
the polyester film having a ratio in a range of 1.4 or more and 2.7 or less between a maximum value Ymax and a minimum value Ymin (degree of surface orientation: Ymax/Ymin), with the maximum value Ymax and the minimum value Ymin respectively representing a maximum value and a minimum value of a ratio between an absorption peak intensity Y1340 at 1340 cm−1 and an absorption peak intensity Y1410 at 1410 cm−1 (Y1340/Y1410) in infrared absorption spectra
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.