Foaming Activator Pouch Case for Battery Impact 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 resin layer and an outer resin layer, both containing a foaming activator comprising an isocyanate-based compound and a polyol compound, which reacts to form a protective urethane-based foam layer upon external impact, enhancing the battery's stability by preventing moisture permeation and short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a soft pouch case is used for the battery, then the battery can be manufactured with thin dimensions and flexible shape, but the physical and mechanical strength is insufficient leading to low stability against external impact
Solution Approach 1:
The pouch case includes a foaming agent and a blowing agent embedded within the resin layer before battery assembly. When external impact occurs, these agents rapidly generate gas bubbles that expand the resin layer, forming a protective foam structure that absorbs impact energy and prevents electrode damage, thus providing preliminary protective action against external forces
Solution Approach 2:
The pouch case employs a composite structure combining a resin base material with integrated foaming agents and blowing agents. This composite material system provides both the flexibility and thinness of soft pouch cases while adding impact resistance through the foam expansion mechanism, resolving the contradiction between softness and strength
2Strength
If a reinforcement layer is added to the pouch case surface to improve strength, then stability against external impact is enhanced, but the size, volume, and manufacturing costs increase
Solution Approach 1:
The reinforcement function is merged into the existing pouch case resin layer by embedding foaming agents and blowing agents within the resin itself. This eliminates the need for separate reinforcement layers, maintaining a simple two-layer structure (inner and outer resin layers) while providing impact protection through foam expansion when triggered by external impact
Solution Approach 2:
The pouch case performs self-reinforcement through the embedded foaming agents and blowing agents that automatically activate upon external impact. The resin layer itself transforms into a protective foam structure without requiring external reinforcement components, making the system self-sufficient and structurally simple
3Volume of moving object
If the pouch case is made thinner to reduce battery volume, then the battery is more suitable for mobile devices, but the sealing reliability and protection against moisture permeation deteriorate
Solution Approach 1:
The outer resin layer contains embedded foaming agents and blowing agents that serve as preliminary protective measures. When external impact or penetration attempts occur, these agents rapidly expand to form a foam barrier that prevents moisture ingress and maintains sealing integrity, providing reliable protection despite the thin overall structure
Solution Approach 2:
The pouch case utilizes parameter changes in the resin layer's physical state. The resin transitions from a compact thin-layer state during normal operation to an expanded foam state when triggered by external impact. This parameter change (density and volume expansion) provides enhanced sealing and protection only when needed, maintaining thin dimensions during normal use
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 formed urethane-based foam layer significantly increases the pouch case's resistance to external impacts, preventing explosions and ensuring stability by sealing the electrode assembly and preventing separator cracking, thus enhancing the overall stability of the pouch type secondary battery.
Implementation Method 1
the foaming activator includes an isocyanate-based compound and a polyol compound
Implementation Method 2
forming urethane-based foam
Implementation Method 3
preventing moisture permeation
Data Source
AI summary
A pouch case of the present disclosure includes an inner resin layer, a metallic layer, and an outer resin layer, wherein the resin layer(s) include(s) a foaming activator containing an isocyanate-based compound and a polyol compound. Accordingly, since the pouch case includes the inner resin layer and/or the outer resin layer including the foaming activator, when moisture or the like is permeated thereto due to an external factor, a protective layer including urethane-based foam is formed in the outer resin layer or between the inner resin 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, and stability of a pouch type secondary battery may thus be ensured.