Battery Packaging Material Layer Adhesion via Aluminum Foil Roughness
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Solution Overview
Problem
Power storage devices, particularly lithium ion batteries, face challenges in compression tests due to the separation of packaging material layers, leading to inconsistent performance and reliability issues when used in applications requiring high reliability, such as in cars and motorcycles.
Innovation Solution
A packaging material structure comprising a cover layer, a barrier layer with an aluminum foil and anticorrosion treatment, a sealant adhesive layer, and a sealant layer, where the aluminum foil layer has specific glossiness and surface roughness characteristics to enhance adhesiveness and durability, ensuring effective separation resistance during compression tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packaging materials are used, then manufacturing cost and weight are reduced, but layer separation occurs during compression tests leading to poor reliability
Solution Approach 1:
The packaging material uses a composite multilayer structure comprising a polyolefin resin layer, a polyamide resin layer, and an aluminum foil layer with specific surface roughness. This composite structure combines the heat sealability of polyolefin, the strength and barrier properties of polyamide, and the moisture resistance of aluminum foil, achieving both high reliability in compression tests and compatibility with conventional manufacturing processes
Solution Approach 2:
The aluminum foil layer is engineered with specific local surface properties, having a surface roughness of 0.5 μm to 3.0 μm measured by arithmetic mean height Sa. This localized surface quality enhancement at the aluminum foil interface improves adhesion between layers without affecting the overall structure or requiring complex manufacturing changes
2Reliability
If layer adhesion is enhanced through surface treatment, then compression test performance improves, but manufacturing process complexity increases
Solution Approach 1:
The invention controls the surface roughness parameter of the aluminum foil layer within a specific range of 0.5 μm to 3.0 μm (arithmetic mean height Sa). By optimizing this physical parameter, the adhesion between the aluminum foil layer and adjacent layers is significantly improved, enhancing compression test performance without introducing complex surface treatment processes or additional structural elements
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 proposed packaging material structure improves the adhesiveness and durability of battery cells, resulting in better performance and reliability in compression tests, ensuring consistent energy density and extended lifespan of power storage devices.
Implementation Method 1
Different surface roughness leads to different strength of anchor effect accordingly, which is assumed to be the cause of change in adhesiveness of the sealant adhesive layer
Implementation Method 2
the barrier layer includes an aluminum foil layer and an anticorrosion treatment layer that is provided to a sealant-layer-side surface of the aluminum foil layer
Data Source
AI summary
A packaging material for a power storage device includes a structure made up of a cover layer, a barrier layer, a sealant adhesive layer, and a sealant layer laminated in this general order. In the packaging material, the barrier layer has an aluminum foil layer and an anticorrosion treatment layer that is provided to a sealant layer side surface of the aluminum foil layer and faces the sealant adhesive layer. The sealant layer side surface of the aluminum foil layer has a 60° glossiness that is 690 or less in both MD and TD, and has a difference in 60° glossiness between MD and TD that is 100 or less.