Battery Pouch Sealing Structure for Stepwise Pressure Relief
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Solution Overview
Problem
Pouch-type batteries experience swelling and potential explosion due to gas generation, which reduces durability and safety, as existing sealing technologies either fail to manage pressure effectively or risk insulation failure.
Innovation Solution
A secondary battery pouch design with a sealing portion that alternates between a first fusion portion with high seal strength and a second fusion portion with low seal strength, allowing controlled expansion to manage internal pressure and prevent swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing force is increased to delay venting time or prevent venting, then the sealing durability is improved, but the internal pressure increases leading to swelling and potential explosion
Solution Approach 1:
The sealing portion is divided into multiple fusion portions with different thicknesses (first fusion portion with smallest thickness, second fusion portion with largest thickness). This segmentation creates zones of different sealing strengths, allowing the battery to release gas progressively through thinner sections while maintaining overall sealing integrity, thus reducing internal pressure without compromising sealing durability.
Solution Approach 2:
Different regions of the sealing portion are given different local properties through varying fusion thicknesses. The first fusion portion has smaller thickness providing weaker sealing for pressure relief, while the second fusion portion has larger thickness providing stronger sealing for durability. This local differentiation allows simultaneous achievement of both sealing reliability and pressure management.
2Reliability
If the sealing force is increased by thickening the PP layer, then the venting prevention is improved, but the battery deformation and short circuit risk increase
Solution Approach 1:
The sealing structure is segmented into fusion portions of varying thicknesses rather than uniformly thickening the PP layer. This allows selective pressure release at thinner sections, preventing the uniform swelling and deformation that would result from overall thickening, while still providing adequate sealing to prevent catastrophic venting.
3Reliability
If the sealing force is increased to delay venting time, then the battery stability is improved, but the internal pressure buildup promotes further decomposition
Solution Approach 1:
The sealing portion is divided into fusion portions with different thicknesses that create a progressive pressure release mechanism. This allows the battery to maintain stability through controlled, gradual gas release rather than sudden venting, preventing the pressure buildup that would accelerate electrolyte decomposition while still delaying catastrophic failure.
Solution Approach 2:
The alternating pattern of thick and thin fusion portions creates a periodic structure that enables staged pressure release. As pressure builds, it progressively overcomes the sealing at thinner sections first, then moves to thicker sections, creating a periodic, controlled venting process that maintains stability while managing decomposition.
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 design prevents swelling by gradually expanding the inner space to reduce pressure, maintaining safety and extending device lifespan while avoiding insulation failures.
Implementation Method 1
allow the space inside the pouch to gradually expand in a stepwise manner, thereby preventing a swelling phenomenon and increasing the stability of a battery
Data Source
AI summary
Embodiments provide a secondary battery pouch including a sealing portion formed at an outside of the secondary battery pouch constituting a battery cell and configured to seal an inner space of the secondary battery pouch. The sealing portion includes: a first fusion portion having a smallest thickness in the sealing portion; and a second fusion portion having a largest thickness in the sealing portion. The first fusion portion and the second fusion portion are continuously formed at least one time alternately in a direction from an innermost side of the sealing portion in contact with the inner space of the secondary battery pouch to an outer side of the sealing portion.