Pouch Case Foaming Activator Moisture Protection
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Solution Overview
Problem
Pouch type lithium secondary batteries face instability issues due to low physical and mechanical strength, leading to risks of explosion from external impacts, moisture permeation, and short circuits, which are exacerbated by the difficulty in forming a strong pouch case without increasing size, volume, and manufacturing costs.
Innovation Solution
A pouch case with an inner layer containing an isocyanate-based foaming activator, which generates a protective gas layer upon reaction with a foaming agent like water or carbon dioxide, enhancing the mechanical strength and preventing moisture permeation and separator cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin soft laminated sheet (pouch) is used as the battery case, then the battery can be manufactured with no restriction on shape and size and can be made thin, but the physical and mechanical strength, sealing reliability, and stability against external impact are reduced
Solution Approach 1:
The pouch case is constructed as a multi-layer composite structure comprising an inner layer (polymer material), a metallic layer (aluminum foil), and an outer layer (polymer material). This composite structure provides enhanced mechanical strength, puncture resistance, and stability while maintaining the thin profile required for mobile device applications.
2Strength
If the pouch case mechanical strength is increased by using a high strength pouch case, then stability against external impact is improved, but the difficulty of forming the pouch case increases
Solution Approach 1:
The multi-layer composite structure combines materials with different properties: the inner and outer polymer layers provide formability and flexibility for manufacturing, while the metallic aluminum layer provides structural strength and rigidity. This combination enables the pouch case to be formed into required shapes while maintaining high mechanical strength and stability.
3Strength
If a separate reinforcement layer is added on the surface of the soft pouch case to improve strength, then battery stability is improved, but the size, volume, and manufacturing costs increase
Solution Approach 1:
The reinforcement is integrated into the pouch case wall structure itself through the metallic layer, rather than adding a separate external reinforcement layer. The aluminum layer serves dual purposes: reinforcing the pouch case for puncture resistance and mechanical strength, and acting as a barrier layer. This integrated approach provides enhanced stability without significantly increasing battery volume.
Solution Approach 2:
The metallic layer in the composite structure performs multiple functions simultaneously: it reinforces the pouch case for mechanical strength, acts as a barrier layer against moisture and oxygen, and provides thermal conductivity. This multi-functionality eliminates the need for separate reinforcement layers, maintaining compact battery dimensions.
4Strength
If a separate reinforcement layer is added on the surface of the soft pouch case to improve strength, then battery stability is improved, but manufacturing costs increase
Solution Approach 1:
The multi-layer composite structure with integrated metallic reinforcement layer provides enhanced stability without requiring additional separate reinforcement components. The structure can be manufactured using existing lamination and sealing technologies, avoiding the need for complex assembly processes and additional materials that would increase manufacturing costs.
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 protective gas layer formed between the inner layer and the electrode assembly significantly increases the pouch case's resistance to external impacts, preventing explosions and ensuring stability by blocking moisture and preventing separator cracking and short circuits.
Implementation Method 1
the inner layer includes a foaming activator capable of forming a protective gas layer... the inner layer includes a foaming activator containing an isocyanate-based compound which generates a gas by a reaction with a foaming agent
Data Source
AI summary
A pouch case of the present disclosure includes an inner layer, a metallic layer, and an outer layer, wherein the inner layer includes a foaming activator containing an isocyanate-based compound which generates a gas by a foaming agent. Accordingly, since the pouch case includes the inner layer including the foaming activator, when moisture or the like is permeated thereto due to an external factor, a protective gas layer is formed between the inner layer and an electrode assembly in a short time, so that the pouch case and the electrode assembly may be protected, moisture which is permeable into the electrode assembly may be blocked, and separator cracking also may be prevented. Accordingly, explosion which may be caused by moisture permeation, separator cracking, or a short circuit by contact between the pouch case and the electrode assembly, or the like, may be prevented.