Multilayer Tab Sealant for Battery Pressure Relief and Adhesion
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Solution Overview
Problem
In power storage devices like lithium ion secondary batteries, the tab sealant's temperature control is critical to maintain sealing properties, as a low-melting-point layer can melt and release pressure, but excessive heat can cause it to flow and fail to adhere properly, leading to inconsistent sealing during production and potential packaging rupture due to internal pressure increases.
Innovation Solution
A tab sealant with a multilayer structure comprising a high-melting-point layer, a medium-melting-point layer, and a low-melting-point layer, where the low-melting-point layer melts to release pressure and the medium-melting-point layer ensures stable adhesion during production, with specific melting points and thicknesses to balance adhesion and pressure relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-melting-point layer is provided in the tab sealant to enable pressure release, then safety performance is improved, but manufacturing precision deteriorates due to difficulty in controlling adhesion during production
Solution Approach 1:
The tab sealant is divided into multiple layers with different melting points: a first sealant layer with low-melting-point material (100-135°C) for safety pressure release, a second sealant layer with medium-melting-point material (140-170°C) for stable adhesion during production, and optionally a third sealant layer with high-melting-point material. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between safety performance and manufacturing precision.
2Reliability
If the tab sealant temperature is increased to ensure adhesion, then sealing properties are improved, but the low-melting-point layer melts and flows causing production inconsistency
Solution Approach 1:
Different regions of the tab sealant (different layers) are given different thermal properties. The first sealant layer has low melting point (100-135°C) for safety function, while the second sealant layer has medium melting point (140-170°C) for production stability. This local differentiation of material properties allows the sealant to exhibit appropriate behavior at different temperatures and locations, resolving the contradiction between sealing properties and production consistency.
3Manufacturing precision
If the tab sealant temperature is decreased to prevent melting, then production consistency is improved, but adhesion to packaging material becomes insufficient
Solution Approach 1:
The tab sealant is segmented into layers with progressively higher melting points. The second sealant layer with medium-melting-point material (140-170°C) provides stable adhesion during production without melting at typical production temperatures, while the first sealant layer with low-melting-point material (100-135°C) remains intact during production but activates for pressure release. This segmentation resolves the contradiction between production consistency and adhesion reliability.
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 tab sealant effectively reduces internal pressure by releasing gas when the battery heats up, while maintaining stable sealing properties during production, preventing packaging rupture and ensuring consistent adhesion to both the metal terminal and packaging material.
Implementation Method 1
the low-melting-point layer melts, causing the internal gas to be released, whereby the internal pressure drops
Implementation Method 2
the power storage device body may suddenly generate heat for some reason and enter a high temperature state. When the internal pressure of the power storage device increases accordingly
Implementation Method 3
the medium-melting-point layer ensures stable adhesion during production
Implementation Method 4
the temperature at which the tab sealant is fused
Data Source
AI summary
A tab sealant disposed covering at least a part of an outer surface of metal terminals of a power storage device, the tab sealant including: a first sealant layer disposed facing the metal terminal; a high-melting-point layer containing a polyolefin resin; and a second sealant layer, which are laminated in this order, wherein each of the first sealant layer and the second sealant layer includes a low-melting-point layer containing acid-modified polyolefin resin and a medium-melting-point layer disposed between the low-melting-point layer and the high-melting-point layer, the low-melting-point layer has a melting point of 100°° C.to 135°° C., the high-melting-point layer has a melting point of 140°° C.to 170° C., and the melting point of the medium-melting-point layer is higher than the melting point of the low-melting-point layer by 10° C. or more and lower than the melting point of the high-melting-point layer by 10° C. or more.