Battery Cell Weak Part Sealing for Gas Venting
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to decomposition and gas generation during abnormal operations, leading to potential fires or explosions, especially in large-sized battery packs, and existing solutions require additional components or processes that increase costs and reduce reliability.
Innovation Solution
A battery cell design with a weak part formed at the sealing region corresponding to an electrode lead with low flexibility, allowing for controlled gas discharge outside when internal pressure increases, thereby enhancing safety without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing part is formed by thermal welding to ensure sealability, then sealing reliability is improved, but gas discharge capability during abnormal conditions deteriorates
Solution Approach 1:
The sealing part has different properties at different locations: the first sealing region (without electrode leads) has strong sealing force for reliable sealing, while the second sealing region (with electrode leads) has weak sealing force to allow gas discharge. This local differentiation resolves the contradiction between overall sealing reliability and localized gas discharge capability.
2Reliability
If additional safety components are added to enable gas discharge, then safety is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The sealing part serves dual functions: it provides strong sealing at the first sealing region to maintain battery integrity, and provides weak sealing at the second sealing region to enable gas discharge during abnormal conditions. This multi-functionality eliminates the need for separate safety components, reducing device complexity while maintaining safety.
3Reliability
If the sealing force is increased to prevent leakage, then sealability is improved, but gas discharge capability during abnormal operations deteriorates
Solution Approach 1:
The sealing part exhibits locally differentiated sealing forces: strong sealing force at the first sealing region (without electrode leads) ensures leak prevention, while weak sealing force at the second sealing region (with electrode leads) enables easy gas discharge during abnormal operations. This resolves the contradiction between overall sealability and localized gas discharge ease.
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 effectively directs gas discharge during abnormal conditions, improving safety and reducing manufacturing costs by maintaining sealability during normal operations.
Implementation Method 1
the battery case is thermally welded along the edge of a receiving part thereof to form a sealing part
Implementation Method 2
the weak part being physically deformed, such that internal gas is discharged outside through the weak part, when predetermined pressure is applied to the weak part
Data Source
AI summary
Disclosed herein is a battery cell constructed in a structure in which an electrode assembly is mounted in a battery case made of a laminate sheet including a metal layer and a resin layer, and the battery case is thermally welded along the edge of a receiving part thereof to form a sealing part, wherein a weak part is formed at a portion of the sealing part ('an electrode lead correspondence portion') corresponding to one of electrode leads (a, b) connected to the electrode assembly, e.g., the electrode lead (a) having relatively low flexibility, the weak part being physically deformed, such that internal gas is discharged outside through the weak part, when predetermined pressure is applied to the weak part, and the weak part is not formed at an electrode lead correspondence portion of the other electrode lead (b).