Laminate Battery Pouch With Through-Hole Venting and Moisture Barrier
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Solution Overview
Problem
The internal pressure of lithium secondary batteries increases due to gas generation, which affects battery life, and existing technologies do not effectively improve gas permeability to alleviate this issue.
Innovation Solution
A power storage device with an exterior body made of a laminate film that includes a metal layer with through holes of specific diameters and a resin portion, enhancing gas permeability while preventing moisture intrusion, by using a resin material with lower moisture permeability than the resin layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the exterior body is made of a laminate film with a metal layer, then moisture barrier performance is improved, but gas permeability deteriorates
Solution Approach 1:
The metal layer is segmented by forming through holes, dividing it into multiple regions. This segmentation allows gas to pass through the metal layer via the through holes while the remaining metal layer portions maintain the moisture barrier function, thus resolving the contradiction between moisture protection and gas permeability.
Solution Approach 2:
Different regions of the laminate film are given different properties: the through holes provide gas permeability, the resin portions filling the through holes provide moisture sealing, and the surrounding metal layer provides structural strength and moisture barrier. This local differentiation of properties allows simultaneous achievement of gas discharge and moisture prevention.
2Productivity
If through holes are provided in the metal layer to improve gas permeability, then gas discharge is improved, but moisture intrusion risk increases
Solution Approach 1:
Resin portions are introduced as intermediary materials to fill the through holes in the metal layer. These resin portions act as mediators that allow gas to pass through while blocking moisture intrusion. The resin portions effectively translate the through holes from potential moisture pathways into controlled gas discharge channels.
Solution Approach 2:
The exterior body uses a composite laminate structure combining metal layer, resin layer, and resin portions. The metal layer provides moisture barrier and strength, the resin layer provides sealing, and the resin portions in the through holes provide selective permeability. This composite material approach enables simultaneous gas discharge and moisture protection.
3Productivity
If the diameter of through holes is increased to improve gas permeability, then gas discharge efficiency is improved, but mechanical strength deteriorates
Solution Approach 1:
The diameter of the through holes is optimized within a specific range (3 mm or more and 10 mm or less) to balance gas discharge efficiency and mechanical strength. This parameter optimization ensures sufficient gas permeability while maintaining adequate structural integrity of the exterior body.
4Productivity
If multiple through holes are provided to ensure gas permeation rate, then gas discharge is improved, but manufacturing precision requirements increase
Solution Approach 1:
Instead of providing numerous small through holes that would require high positioning precision, the invention uses a limited number of through holes with diameters of 3 mm or more and 10 mm or less. This partial action approach achieves sufficient gas permeation rate while reducing the stringency of manufacturing precision requirements for hole positioning.
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 improves gas permeability and maintains mechanical strength, preventing electrolyte leakage and moisture intrusion, thereby extending battery life and ensuring reliable gas discharge.
Implementation Method 1
The resin portion may include a resin material having a lower moisture permeability than the material used for the resin layer. Accordingly, it is possible to more reliably suppress the moisture from entering the inside through the through hole.
Implementation Method 2
When the through hole is provided in the metal layer and the diameter of the through hole is set to be equal to or larger than 3 mm and equal to or smaller than 10 mm, it is possible to improve the gas permeability of the exterior body.
Data Source
AI summary
The power storage device includes an electrode body and an exterior body made of a laminate film that houses the electrode body. The laminate film has a barrier layer which is a metal layer, and a sealing layer laminated on a surface of the barrier layer facing the electrode body. In the barrier layer, a through hole that penetrates the barrier layer in the thickness direction is formed. The diameter of the through hole is 3 mm or more and 10 mm or less. The laminate film further includes a resin portion disposed in the through hole.