Battery Can Top Cap Venting Under Internal Pressure
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Solution Overview
Problem
The risk of fire or explosion in secondary batteries increases due to deteriorated thermal stability of positive electrode active materials, particularly when internal pressure or temperature rises, and existing methods to improve thermal stability are limited by cost and productivity constraints.
Innovation Solution
A secondary battery design featuring a battery can with an open upper portion and a top cap that includes a bent part to reduce the overlapping area when internal pressure exceeds a predetermined value, allowing the top cap to space apart from the battery can without fragmenting, facilitating gas discharge and maintaining safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the content of nickel contained in the positive electrode active material is increased to achieve larger capacity, then the battery capacity is improved, but the thermal stability of the positive electrode active material deteriorates
Solution Approach 1:
The top cap is divided into a bonding region and a non-bonding region, with the non-bonding region forming a protrusion that can deform independently under pressure to release internal stress and prevent catastrophic failure
Solution Approach 2:
The top cap structure transitions from a static rigid component to a dynamic component that can deform elastically under internal pressure, allowing the non-bonding region to move and reduce overlapping area with the bent part, thereby releasing pressure safely
2Reliability
If a compound is added to improve the thermal stability of the secondary battery, then the safety is improved, but the manufacturing cost and productivity are limited
Solution Approach 1:
The safety function is extracted from the chemical domain (adding compounds) and transferred to the structural domain (designing the top cap with non-bonding region), eliminating the need for additional materials while maintaining safety improvements
Solution Approach 2:
The design parameters of the top cap (bonding area ratio, protrusion shape, thickness) are optimized to achieve the desired pressure release characteristics without requiring material composition changes, thus avoiding increased manufacturing complexity
3Reliability
If the top cap is designed to allow gas discharge when internal pressure increases, then the safety is improved, but the structural integrity may be compromised
Solution Approach 1:
Different regions of the top cap have different properties: the bonding region maintains strong adhesion to ensure structural integrity, while the non-bonding region with protrusion is designed to deform and release pressure, achieving both strength and safety
Solution Approach 2:
The non-bonding region acts as a pre-designed pressure relief mechanism that activates before catastrophic failure can occur, cushioning the system against excessive pressure buildup and preventing explosive failures
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 optimized structure effectively reduces the risk of fire or explosion by ensuring safe gas discharge and maintaining structural integrity during increased internal pressure, balancing bonding force and deformation to prevent accidental fragmentation.
Implementation Method 1
a bent part that is bent inward toward the top cap to fix the top cap is disposed on an end of the upper portion of the battery can, and when an internal pressure of the battery can exceeds a predetermined value, a region (R) in which the top cap and the bent part overlap each other when viewed from above is reduced by deformation of the top cap or the bent part
Data Source
AI summary
According to one aspect of the present invention, a secondary battery has a bent part disposed on an end of an upper portion of the battery can. The bent part is bent inward toward a top cap to fix the top cap. The secondary battery is configured such that, when an internal pressure of the battery can exceeds a predetermined value, a region (R) in which the top cap and the bent part overlap each other when viewed from above is reduced by deformation of the top cap or the bent part to allow an entire region of the top cap to become spaced further from the battery can.