Battery Outer Packaging Material for Deep Drawing and Corrosion Resistance
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Solution Overview
Problem
Existing aluminum-plastic composite films for lithium-ion batteries suffer from poor deep drawing performance and poor resistance to electrolyte solution corrosion, leading to potential leakage and safety issues due to the formation of Li—Al alloys and corrosion of the aluminum foil.
Innovation Solution
An outer packaging material comprising a substrate layer, a first bonding layer, a barrier layer made of an aluminum alloy foil with specific compositions and properties, and a hot-melt connecting layer, with a corrosion-resistant treatment on the barrier layer to enhance deep drawing formability and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heat-treated 8021 or 8079 alloy aluminum foil is used to improve deep drawing formability, then the aluminum-plastic composite film achieves good deep drawing performance, but the aluminum foil is corroded by electrolyte solution to form Li-Al alloy, reducing corrosion resistance
Solution Approach 1:
The patent changes the chemical composition parameters of the aluminum alloy foil by adding specific amounts of Si (0.03-0.15%), Mn (0.05-0.20%), and Mg (0.05-0.15%), while controlling Fe content (0.8-1.5%). This compositional adjustment modifies the alloy's properties to achieve both good deep drawing formability and resistance to electrolyte solution corrosion, preventing Li-Al alloy formation.
Solution Approach 2:
The patent creates a composite aluminum alloy system by combining multiple elements (Al-Si-Mn-Mg-Fe) to achieve synergistic effects. The specific combination of these elements in controlled proportions provides both the formability needed for deep drawing and the corrosion resistance required to prevent electrolyte solution attack and Li-Al alloy formation.
2Reliability
If non-heat-treated 3003 or 3004 aluminum foil is used to improve corrosion resistance, then the aluminum foil has better resistance to electrolyte solution, but the deep drawing formability is poor
Solution Approach 1:
The patent applies heat treatment to the aluminum alloy foil containing Si, Mn, and Mg elements. This thermal processing parameter change modifies the microstructure and mechanical properties of the alloy, enabling it to achieve both good deep drawing formability and maintained corrosion resistance, overcoming the limitations of non-heat-treated alloys.
3Strength
If Fe content is increased to improve elasticity and deep drawing performance, then the aluminum foil has greater elasticity beneficial for deep drawing, but the precipitation of Fe promotes formation of intermediate compounds that act as recrystallization nuclei, potentially affecting material properties
Solution Approach 1:
The patent optimizes the Fe content to a specific range (0.8-1.5%) and combines it with controlled additions of Si (0.03-0.15%), Mn (0.05-0.20%), and Mg (0.05-0.15%). This balanced compositional approach ensures sufficient Fe for elasticity and deep drawing performance while the presence of other elements and heat treatment control the precipitation behavior and recrystallization, maintaining overall compositional stability.
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 solution effectively inhibits the formation of Li—Al alloys, improves deep drawing formability, and enhances the resistance of the packaging material to electrolyte solution, thereby preventing leakage and ensuring battery safety.
Implementation Method 1
after the aluminum alloy foil is annealed, a large amount of Mg is precipitated from the aluminum alloy foil, and a ratio of precipitated Mg to precipitated Al is 2-4
Implementation Method 2
with a corrosion-resistant treatment on the barrier layer to enhance deep drawing formability and corrosion resistance
Data Source
AI summary
An outer packaging material for a battery apparatus, the material comprising a base layer (1), a bonding layer (2), a barrier layer (5), another bonding layer (7), and a hot-melt adhesive layer (8); the bonding layer (2) is disposed between the base layer (1) and the barrier layer (5); the other bonding layer (7) is disposed between the barrier layer (5) and the hot-melt adhesive layer (8); the barrier layer (5) is composed of a single layer or multiple layers of aluminum alloy foil; the aluminum alloy foil composition and the mass percentage thereof comprises over 1.2% Fe content and over 1% Mg content; after undergoing annealing treatment, a large amount of Mg will precipitate out from within the aluminum foil, and the ratio of the precipitated Mg amount to a precipitated Al amount is between 2-4.