Secondary Battery Vent Sealing for Directional Gas Discharge
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Solution Overview
Problem
Conventional secondary batteries face challenges in safely discharging gases generated during thermal propagation, leading to potential fires due to the difficulty in directing gas discharge in a specific direction.
Innovation Solution
Incorporating a vent member made of linear low-density polyethylene with a comonomer of 6 or more carbon number, integrated into a sealing portion with a narrower vent inducing region, which allows for easier gas discharge towards a specific direction, improving safety by reducing the sealing strength at high temperatures while maintaining strength at normal temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional sealing portion is used, then the battery maintains good sealing performance, but gas discharge cannot be directed in a specific direction during thermal propagation
Solution Approach 1:
The sealing portion is divided into a first sealing region and a second sealing region with different widths. The narrower second sealing region serves as a vent inducing region that directs gas discharge in a specific direction, while the broader first sealing region maintains overall sealing integrity. This segmentation allows the sealing portion to simultaneously achieve both sealing performance and controlled venting.
Solution Approach 2:
Different regions of the sealing portion are given different local properties: the first sealing region has a broader width for maintaining sealing strength, while the second sealing region has a narrower width for inducing directional gas discharge. This local differentiation enables the sealing portion to perform multiple functions in different areas.
2Ease of operation
If the sealing portion width is reduced to create a vent inducing region, then gas discharge is directed more easily, but the overall sealing strength may be compromised
Solution Approach 1:
The sealing portion is segmented into regions with different widths, where the narrower second sealing region provides venting functionality without compromising the overall sealing strength provided by the broader first sealing region.
Solution Approach 2:
The sealing portion has non-uniform width distribution, with the second sealing region being narrower to facilitate gas discharge while the first sealing region maintains adequate width to preserve sealing strength. This local quality variation resolves the contradiction between ease of gas discharge and sealing strength.
3Ease of operation
If a vent member with low melting point material is used, then gas discharge is facilitated at high temperature, but the vent member may fail to maintain sealing at normal temperatures
Solution Approach 1:
The vent member is made of linear low-density polyethylene with a comonomer having 6 or more carbon atoms, which has a melting point higher than conventional venting materials. This parameter change allows the vent member to maintain sealing reliability at normal temperatures while still facilitating gas discharge through melting at elevated temperatures during thermal propagation.
Solution Approach 2:
The vent member uses a composite material composition (linear low-density polyethylene with specific comonomers) that combines the properties of maintaining sealing at normal temperatures with the ability to melt and vent gas at high temperatures, resolving the contradiction between sealing reliability and gas discharge facilitation.
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 enhances the safety of secondary batteries by facilitating controlled gas discharge during thermal events, reducing the risk of fires and improving the overall safety of the battery.
Implementation Method 1
a vent member containing a linear low-density polyethylene having a comonomer with a carbon number of 6 or more
Implementation Method 2
directional venting characteristic is required to discharge the gas in one direction
Data Source
AI summary
Disclosed herein is a secondary battery having a vent member. The secondary battery may include an electrode assembly; an electrode lead attached to the electrode assembly; a case including an accommodation portion for accommodating the electrode assembly and a sealing portion containing a sealant resin and formed to seal the electrode assembly; a lead film formed to surround a part of an outer surface of the electrode lead and interposed between the electrode lead and the case; and a vent member containing a linear low-density polyethylene having a comonomer with a carbon number of 6 or more, wherein the sealing portion has a vent inducing region including the vent member, and a width of the vent inducing region is smaller than a width of the sealing portion other than the vent inducing region.