Secondary Battery Sealed Vent Structure for Internal Pressure Release
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Solution Overview
Problem
Secondary batteries face safety concerns due to internal pressure buildup, which can lead to structural failure without adequate venting mechanisms.
Innovation Solution
A secondary battery design featuring a vent in the fusion-welded sealed portion between the case cover and case base, with a lower coupling force than the sealed portion, allowing it to break easily under increased internal pressure, thereby enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sealed portion is made with strong fusion welding to ensure structural integrity, then the strength and reliability of the case are improved, but the ability to vent internal pressure safely is reduced
Solution Approach 1:
The sealed portion is designed with non-uniform fusion welding characteristics: most of the sealed portion maintains strong fusion welding for structural integrity, while the vent region has reduced fusion welding strength to enable controlled breaking under internal pressure. This local differentiation resolves the contradiction by making different regions serve different functions.
Solution Approach 2:
The potential harmful effect of strong fusion welding (inability to vent pressure) is converted into a benefit by intentionally creating a controlled weakness in the vent region. This allows the sealed portion to safely break at the vent under internal pressure, transforming what would be a structural failure into a controlled safety mechanism.
2Reliability
If the case structure is designed to be completely sealed for protection, then the reliability and protection are improved, but the safety mechanism for pressure release is lost
Solution Approach 1:
The vent is pre-designed with reduced fusion welding strength in the sealed portion before the battery is assembled and sealed. This preliminary preparation ensures that when internal pressure builds up during battery operation, the vent will break at the predetermined weak point to release pressure, maintaining both protection and safety.
Solution Approach 2:
The vent acts as an intermediary element between the sealed case structure and the internal pressure. It provides a controlled pathway for pressure release while maintaining the overall sealed structure, mediating between the need for protection and the need for pressure relief.
3Ease of manufacture
If the fusion welded sealed portion is made uniformly strong, then the manufacturing simplicity is improved, but the safety venting capability is reduced
Solution Approach 1:
The fusion welding process is applied with local quality variation: the vent region receives reduced fusion welding strength compared to the rest of the sealed portion. This can be achieved by adjusting welding parameters (current, speed, pressure) in the vent region during the manufacturing process, allowing both ease of manufacture and pressure release capability.
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 improves safety by providing a controlled release mechanism for internal pressure, preventing structural failure and ensuring stability during pressure increases.
Implementation Method 1
a sealed portion sealed by fusion (fusion welding) on at least three sides of the case
Implementation Method 2
when the case including a metal layer expands by internal pressure
Data Source
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AI summary
A secondary battery having a structure in which a vent having a low coupling force due to fusion is provided in a sealed portion such that the vent is easily broken if a secondary battery made of stainless steel (SUS) or steel with a plating layer formed on the surface thereof is expanded by internal pressure, thereby improving safety. The secondary battery includes an electrode assembly having a positive electrode plate, a negative electrode plate, and a separator between the positive electrode plate and the negative electrode plate and a case configured to receive the electrode assembly. The case includes a metal layer and a sealed portion sealed by fusion on at least three sides. The sealed portion includes at least one vent.