Battery Sealant Vent Structure for Directional Gas Discharge
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Solution Overview
Problem
Conventional secondary batteries face challenges in safely discharging gases in a specific direction, leading to potential ignition and increased fire risk due to rapid thermal propagation.
Innovation Solution
Incorporating a thermal conductive layer within the sealant layer of the battery case, which includes thermally conductive particles and a vent member with a lower melting point than the sealant resin, to facilitate directional gas discharge and improve safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional sealant layer is used without thermal conductive layer, then the manufacturing process is simple, but the gas discharge directionality is poor and thermal propagation risk increases
Solution Approach 1:
The sealant layer is constructed as a composite material system comprising a base sealant resin combined with thermally conductive particles (such as aluminum oxide, boron nitride, or aluminum nitride). This composite structure enhances thermal conductivity to improve gas discharge directionality while maintaining the sealing function, thereby resolving the contradiction between safety improvement and structural complexity.
Solution Approach 2:
The vent member serves as an intermediary element with a lower melting point than the sealant resin. It is embedded within the sealant layer and acts as a preferential pathway for gas discharge. When thermal propagation occurs, the vent member melts first to create a controlled discharge channel, directing gas flow away from critical components while the surrounding sealant layer maintains structural integrity.
2Reliability
If thermal conductive layer is added to the sealant layer, then gas discharge directionality is improved, but the manufacturing complexity increases
Solution Approach 1:
The thermal conductive particles are not uniformly distributed throughout the entire sealant layer but are concentrated in specific regions to create thermal pathways. The vent member is positioned at specific locations within the sealant layer where gas discharge is most critical. This localized approach achieves effective gas discharge directionality while minimizing the overall manufacturing complexity compared to uniform distribution throughout the entire structure.
3Reliability
If vent member with lower melting point is used, then directional venting is achieved, but the sealing strength at high temperature is reduced
Solution Approach 1:
The vent member is designed with a melting point specifically lower than the sealant resin by a controlled amount (e.g., 20-50°C difference). This parameter difference ensures that during thermal events, the vent member melts at a lower temperature to create discharge pathways, while the sealant resin maintains its structural integrity and sealing strength at operating temperatures. The sealing strength is thus preserved under normal conditions while venting function is activated under thermal stress.
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 directs gas discharge during abnormal conditions, enhancing the safety of the battery by preventing local thermal damage and ensuring efficient venting of gases, thereby reducing the risk of fire.
Implementation Method 1
a thermal conductive layer is included in the sealant layer
Implementation Method 2
the vent member may have a lower melting point than the sealant resin
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 configured to accommodate the electrode assembly therein; 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, wherein the case contains a sealant layer, and a thermal conductive layer is included in the sealant layer.