Secondary Battery Vent Structure for Thin-Case Pressure Relief
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Solution Overview
Problem
Existing rechargeable batteries with safety devices in the bottom of the case face challenges in maintaining case thickness and weight without compromising safety features.
Innovation Solution
A rechargeable battery design featuring a multi-stepped vent hole in the side wall of the case allows for the integration of a vent member below the case without increasing the case thickness, utilizing a thinner metal plate by forming the side wall of the vent hole to be multi-stepped, enabling the vent member to protrude inwardly for pressure relief without external protrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vent member is provided below the case to prevent explosion, then safety is improved, but the thickness of the bottom plate of the case must be increased
Solution Approach 1:
The vent member is nested within the case structure by forming the vent hole to extend into the case body. The side wall of the vent hole is multi-stepped, creating nested levels that accommodate the vent member below the bottom plate surface without increasing external thickness. This allows the vent member to be positioned inside the case volume rather than adding to the external dimensions.
Solution Approach 2:
The vent hole is configured to extend in the thickness direction of the case, utilizing the internal volume of the case rather than adding external thickness. By creating a multi-stepped side wall structure, the vent member is positioned in a different spatial dimension (inside the case body) rather than outside, thus maintaining the external thickness while providing the safety function.
2Reliability
If a vent member is provided below the case to prevent explosion, then safety is improved, but the weight of the case increases
Solution Approach 1:
The vent member is nested within the existing case structure by forming the vent hole to extend into the case body. This utilizes the existing material volume of the case rather than adding separate protective structures, thereby providing safety enhancement without proportionally increasing the overall weight of the battery assembly.
Solution Approach 2:
The bottom plate of the case serves multiple functions: it provides structural support for the battery components and simultaneously houses the vent member for safety pressure relief. By integrating the vent function into the existing bottom plate structure rather than adding a separate safety component, the weight increase is minimized while achieving both structural and safety objectives.
3Length of stationary object
If the side wall of the vent hole is made multi-stepped to accommodate vent member, then the case thickness can be reduced, but the device complexity increases
Solution Approach 1:
The side wall of the vent hole is segmented into multiple steps at different levels, creating distinct zones within the vent hole structure. This segmentation allows the vent member to be positioned at a specific depth within the case while maintaining a compact external profile. The multi-stepped structure is formed through conventional molding or machining processes, making the added complexity manageable in manufacturing.
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
This design ensures the battery's safety without increasing thickness or weight, allowing for effective pressure relief through a vent member that can be easily broken when internal pressure exceeds a predetermined level, preventing explosion while maintaining a slim profile.
Implementation Method 1
a vent member (39) provided in a vent hole (34) formed in a bottom plate (274) of the case (27), wherein side walls of the vent hole (34) are multi-stepped... the vent member (39) can be easily broken when internal pressure exceeds a predetermined level, preventing explosion
Data Source
Figure 1
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Figure 4~5
AI summary
A rechargeable battery according to an exemplary embodiment of the present invention includes: an electrode assembly including a first electrode, a separator, and a second electrode; a case that accommodates the electrode assembly, and of which one side through which the electrode assembly is inserted is opened; a cap assembly provided in the opening of the case by being fixed thereto; a vent hole that is formed in a bottom plate of the case, and of which side walls are multi-stepped; and a vent member provided in the vent, wherein a depth of the vent is greater than a thickness of the bottom plate.