Pouch Battery Case Laminate for Deep Cup Forming
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Solution Overview
Problem
Conventional pouch film laminates for secondary batteries face limitations in forming deeper cup portions, reducing the radius of filleting at the edges, and achieving a vertical outer wall, leading to increased dead space and decreased energy efficiency.
Innovation Solution
A pouch type battery case with a pouch film laminate comprising a sealant layer, a surface protection layer, and a gas barrier layer formed of an aluminum alloy film with specific thickness and grain size, along with optional drawing assistance layer, to enhance tensile strength, elongation, and puncture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional pouch film laminate is used, then the manufacturing process is simple, but the tensile strength and elongation are insufficient, leading to poor formability
Solution Approach 1:
The pouch film laminate is constructed as a composite material consisting of multiple layers including a polyolefin sealant layer, a metal foil layer (aluminum, stainless steel, or aluminum alloy), and a polyester surface protection layer. This composite structure combines the sealing properties of polyolefin, the strength and barrier properties of metal foil, and the surface protection of polyester, achieving high tensile strength and elongation while maintaining formability.
Solution Approach 2:
The pouch film laminate is divided into distinct functional layers: a sealant layer for heat sealing, a metal foil layer for mechanical strength and gas barrier, and a surface protection layer for durability. Each layer performs a specific function, and the segmented structure allows optimization of each layer's properties to achieve overall high tensile strength and elongation.
2Length of moving object
If a conventional pouch film laminate is used, then the structure is simple, but the elongation is insufficient, limiting the cup portion formation depth
Solution Approach 1:
The metal foil layer in the composite pouch film laminate provides high elongation capacity (10-50% for aluminum foil, 20-80% for stainless steel foil) that enables deep cup portion formation. The composite structure maintains stability by distributing stresses across different layers, with the metal foil accommodating deformation while the polymer layers maintain structural integrity.
Solution Approach 2:
The invention changes the material parameters of the pouch film laminate by selecting specific metal foils with high elongation properties (aluminum alloy with 10-50% elongation, stainless steel with 20-80% elongation) and optimizing their thickness (30-100 μm). This parameter optimization enables the cup portion to be formed to a depth of 10 mm or more while maintaining pouch film integrity.
3Volume of stationary object
If the pouch film laminate is made thinner to reduce dead space, then the volume efficiency improves, but the puncture resistance decreases
Solution Approach 1:
The metal foil layer in the composite pouch film laminate provides exceptional puncture resistance despite thin dimensions (30-100 μm). The metal foil's high tensile strength and elongation prevent pinhole formation and cracks during forming, while the composite structure with polymer layers adds dimensional stability and resistance to external pressures, maintaining reliability without increasing dead space.
Solution Approach 2:
The pouch film laminate applies different material properties to different functional requirements: the metal foil layer provides local puncture resistance and gas barrier properties where needed, while the polymer layers provide sealing and flexibility. This localized quality distribution achieves high puncture resistance in critical areas without uniformly increasing thickness throughout the entire pouch film.
4Productivity
If the cup portion is formed deeper to increase accommodation space, then the energy efficiency to volume improves, but the radius of filleting increases
Solution Approach 1:
The invention changes the material parameters by using metal foils with high elongation (10-50% for aluminum, 20-80% for stainless steel) and optimized thickness (30-100 μm) that enable deep cup formation with reduced filleting radius. The high elongation capacity allows the pouch film to accommodate sharp corners and deep formations without excessive material deformation, reducing the radius of filleting at the bottom and open portions.
Data Source
AI summary
The present invention relates to a pouch type battery case which includes a pouch film laminate including a sealant layer, a gas barrier layer, and a surface protection layer, wherein the sealant layer is formed of a first polymer as an innermost layer, the surface protection layer is formed of a second polymer as an outermost layer, and the gas barrier layer is laminated between the surface protection layer and the sealant layer and is formed of an aluminum alloy thin film having a thickness of 60 μm to 100 μm and a grain size of 10 μm to 13 μm.