Lithium-Ion Battery Packaging Material Humidity Formability
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Solution Overview
Problem
Conventional packaging materials for lithium-ion batteries face challenges in formability due to humidity environments, particularly when using biaxially stretched polyamide or polyester films, which are not well-suited for maintaining satisfactory formability under varying humidity conditions.
Innovation Solution
A packaging material with a substrate layer made of a plastic film that has a specific water absorption rate and tensile stress values, ensuring excellent formability irrespective of humidity, comprising a 10-40 μm thick polyethylene terephthalate film with 2-30% thermoplastic polyester elastomer, and laminated with adhesive, metal foil, anti-corrosion, and sealant layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If biaxially stretched polyamide film or laminate film is used as substrate layer, then formability is improved, but formability becomes unsatisfactory in humidity environment
Solution Approach 1:
The patent changes the material parameters of the substrate layer by specifying a water absorption rate of 0.01-3% and tensile stress values of 70-110 MPa when stretched by 10%. These parameter specifications ensure that the packaging material maintains satisfactory formability regardless of the humidity environment during forming operations.
2Quantity of substance
If deeper recess is formed by cold forming, then energy density is increased, but pinholes or breakage occur in packaging material
Solution Approach 1:
The patent optimizes the mechanical parameters of the substrate layer by controlling tensile stress to be 70-110 MPa at 10% elongation. This parameter optimization allows the packaging material to withstand the stresses of deep recess forming without developing pinholes or breakage, thereby enabling higher energy density while maintaining manufacturing precision.
3Reliability
If aluminum foil layer is added to prevent corrosion, then corrosion resistance is improved, but device complexity increases
Solution Approach 1:
The patent employs a composite structure with multiple functional layers including substrate layer, adhesive layers, metal foil layer, anti-corrosion layer, and sealant layer. This composite material approach provides comprehensive corrosion protection while maintaining a systematic and manageable structure suitable for industrial fabrication.
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 packaging material exhibits improved formability and resistance to electrolytic solutions, maintaining consistent film characteristics across different humidity environments, thus enhancing the packaging material's performance during lithium-ion battery fabrication.
Implementation Method 1
a plastic film having a water absorption rate of from not less than about 0.01% to not larger than about 3% when determined by a test described in JIS K 7209:2000
Implementation Method 2
a first adhesive layer, a metal foil layer, an anti-corrosion layer, a second adhesive layer and a sealant layer which are successively laminated on one surface of the substrate layer
Data Source
AI summary
A packaging material for lithium-ion battery comprises a substrate layer made of a plastic film, and a first adhesive layer, a metal foil layer, an anti-corrosion layer, a second adhesive layer and a sealant layer successively laminated on one surface of the substrate layer. The plastic film has a water absorption rate of not less than about 01% to not larger than about 3% when determined by a method described in JIS K 7209:2000 and when the plastic film is subjected to a tensile test (wherein the sample of the plastic film is stored for 24 hours in an environment of 23° C. and 40% R.H., and subjected to a tensile test in the same environment as indicated above under conditions of a sample width of 6 mm, a gauge length of 35 mm and a tensile speed of 300 mm/minute), stress values in an MD direction of the sample and in a TD direction of the sample after stretching by about 10% relative to a length of the sample prior to the tensile test are both from not larger than about 110 MPa and at least one of the stress values in the MD direction of the sample and in the TD direction of the sample is not less than about 70 MPa.