Battery Cell Vent Portion Hardness for Controlled Pressure Release
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Solution Overview
Problem
Lithium secondary batteries experience swelling and pressure increase during charging and discharging, leading to potential explosions or fires, necessitating effective internal pressure control measures.
Innovation Solution
A battery cell design with a vent portion having a lower hardness than other regions, featuring a notch portion recessed in the case surface, which is formed through heat treatment or laser etching, allowing controlled pressure release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the case is made with high strength and hardness to maintain structural integrity, then the case can withstand internal pressure, but the vent portion cannot break easily to release pressure when needed
Solution Approach 1:
The case is designed with non-uniform hardness: the vent portion has lower hardness than the main case body. This is achieved by forming the vent portion with reduced thickness or by applying heat treatment to create a hardness gradient, allowing the vent portion to break at a lower pressure while the main case maintains its structural integrity.
Solution Approach 2:
The case is segmented into two functional regions: a strong main body for structural support and a weak vent portion for pressure release. This segmentation allows each region to have optimized properties for its specific function, resolving the contradiction between overall strength and localized pressure release capability.
2Reliability
If the vent portion is made with low breaking pressure to enable easy pressure adjustment, then pressure can be released when needed, but the overall case strength is reduced
Solution Approach 1:
The case is designed with non-uniform hardness: the vent portion has lower hardness than the main case body. This is achieved by forming the vent portion with reduced thickness or by applying heat treatment to create a hardness gradient, allowing the vent portion to break at a lower pressure while the main case maintains its structural integrity.
Solution Approach 2:
The case is segmented into two functional regions: a strong main body for structural support and a weak vent portion for pressure release. This segmentation allows each region to have optimized properties for its specific function, resolving the contradiction between overall strength and localized pressure release capability.
3Object-affected harmful factors
If the vent portion breaks at low pressure to prevent explosions, then safety is improved, but the case structure is damaged
Solution Approach 1:
The vent portion is intentionally designed as a weak point that breaks under pressure to convert the harmful effect of pressure buildup into a beneficial pressure release mechanism. The controlled breakage of the vent portion prevents more catastrophic failures while the main case structure remains intact.
Solution Approach 2:
The case is designed with non-uniform hardness: the vent portion has lower hardness than the main case body. This is achieved by forming the vent portion with reduced thickness or by applying heat treatment to create a hardness gradient, allowing the vent portion to break at a lower pressure while the main case maintains its structural integrity.
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 provides improved stability by adjusting internal pressure, minimizing damage by breaking the vent portion before the electrode terminal, preventing additional energy supply and reducing overall case strength loss.
Implementation Method 1
The vent portion may be formed by performing heat treatment on an area of the case
Implementation Method 2
The forming the notch portion may be performed by press working, cutting, or laser etching
Data Source
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AI summary
A battery cell (100) according to an embodiment of the present disclosure includes a case receiving an electrode assembly, and an electrode terminal (130) electrically connected to the electrode assembly, wherein the case includes a vent portion (190) having a lower hardness than other regions of the case.