Battery Pouch Laminate Structure for High-Temperature Seal Strength
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Solution Overview
Problem
Existing exterior materials for electrical storage devices face challenges in maintaining high load resistance and sealing strength, particularly in high-temperature environments, which are necessary for advanced applications such as all-solid-state batteries.
Innovation Solution
A laminate structure comprising a base material layer, a barrier layer, and a heat-sealable resin layer, with specific tensile rupture strength and creep resistance characteristics, ensuring high load resistance and sealing strength at 150°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic exterior materials are used for electrical storage devices, then sealing strength is improved, but weight reduction and shape diversification are limited
Solution Approach 1:
The patent employs a composite laminate structure consisting of a base material layer, a barrier layer, and a heat-sealable resin layer. This composite construction combines the advantages of different materials: the base material provides structural strength, the barrier layer prevents permeation, and the heat-sealable resin layer enables sealing. This resolves the contradiction by achieving metallic-level sealing strength without the weight penalty of solid metal exteriors.
Solution Approach 2:
The patent uses a film-shaped laminate structure that can be formed into diverse shapes through cold molding. The flexible nature of the laminate allows for thin-walled constructions that reduce weight while maintaining sealing integrity. The heat-sealable resin layer enables reliable sealing in this flexible structure, overcoming the limitation of rigid metallic exteriors.
2Weight of moving object
If film-shaped laminate with heat-sealable resin layer is used, then shape diversification and weight reduction are improved, but load resistance and high-temperature sealing strength deteriorate
Solution Approach 1:
The patent uses a composite laminate where the base material layer provides high strength and load resistance, while the overall thin-walled structure maintains weight reduction benefits. The synergistic combination of layers allows the exterior to withstand mechanical loads without requiring thick metal walls.
Solution Approach 2:
The patent applies different material properties to different layers: the base material layer is optimized for strength and load bearing, the barrier layer for permeation resistance, and the heat-sealable resin layer for sealing. This localized functional assignment allows each layer to excel at its specific task, achieving high load resistance in a lightweight structure.
3Ease of manufacture
If conventional laminate structure is used, then ease of manufacture is improved, but high-temperature sealing strength at 150°C deteriorates
Solution Approach 1:
The patent specifies particular parameter ranges for the heat-sealable resin layer, including gel fraction (5-60%) and specific chemical composition ratios. These parameter optimizations ensure the resin maintains sealing properties at high temperatures up to 150°C while still being manufacturable through conventional heat-sealing processes.
Solution Approach 2:
The patent uses a heat-sealable resin layer that can be applied in thin amounts and sealed through simple heating processes. This approach prioritizes ease of manufacture and weight reduction over using extremely high-temperature resistant materials, accepting that the sealing layer is a consumable component that provides sufficient performance for the application lifecycle.
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 provides enhanced load resistance and sealing strength, enabling the construction of electrical storage devices that can withstand high temperatures and maintain integrity in demanding conditions.
Implementation Method 1
heat-sealable resin layers are heat-sealed to obtain an electrical storage device
Data Source
Figure 1~2
Figure 3~4
Figure 5(a)~5(d)
AI summary
Provided is an exterior material for a power storage device, the exterior material being formed from a laminate comprising at least a base material layer, a barrier layer, and a thermally-fusible resin layer in this order from the outside, and the exterior material having a tensile strength at break of 180 MPa or greater as measured by the method below, and having a creep resistance characteristic of 10 minutes or more as measured by the method below. <Measurement of tensile strength at break> Each tensile strength at break in the machine direction (MD) of the exterior material for the power storage device is measured by a method compliant with the provisions of JIS K7127:1999 by using a tensile tester. The measurement conditions are such that a dumbbell 7 shape is used for a sample shape, the distance between target lines is 10 mm, the tensile speed is 0.5 mm/min, the test environment is set to a temperature of 120°C, and the average value from three measurements is used. <Measurement of creep resistance characteristic> The exterior material for a power storage device is cut out so as to have a width of 60 mm in the transverse direction (TD) and a length of 150 mm in the MD direction and is then folded in half such that the thermally-fusible resin layer is positioned at the inside. The folded exterior material is then heat sealed using a 7 mm heat seal bar at a position 10 mm from the fold such that the thickness of the thermally-fusible resin layer is in a range of 60-95% the thickness prior to sealing. The resulting heat-sealed exterior material for a power storage device is then cut to a width of 15 mm to form a sample. Both of the mutually opposing ends of the sample are affixed to respective SUS plates (stainless steel plates) by using an adhesive, and a weight of 2 kg is applied to one side. The end on the opposite side is hung from the top of a thermostatic bath and stored in the thermostatic bath at 150°C. The creep resistance is evaluated using the time until the sealed part opens. The SUS plates that are used have a thickness of 2 mm, a width of 30 mm, a length of 100 mm, and a weight of 42.5 g, and one side of the SUS plates is S-shaped.