Cylindrical Battery Cap Assembly for Delayed Safety Vent Opening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cylindrical secondary batteries experience premature opening of safety vents in high-temperature environments due to rapid internal pressure increases, leading to unexpected gas discharge.
Innovation Solution
The design includes a cap assembly with a cap-down portion and safety vent, where the elongation rate of the cap-down portion is higher than that of the safety vent, made from different aluminum alloys, connected by laser welding, to delay the opening time of the safety vent by ensuring the cap-down portion elongates before the safety vent opens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the safety vent is made from the same material as the cap-down portion, then the manufacturing process is simplified, but the safety vent opens prematurely in high-temperature environments
Solution Approach 1:
The patent applies local quality by using different aluminum alloys for the safety vent and cap-down portion. The safety vent uses an aluminum alloy with lower elongation rate (e.g., Al-Mn-based alloy) while the cap-down portion uses an aluminum alloy with higher elongation rate (e.g., pure aluminum or Al-Mg-based alloy). This localized material differentiation ensures that under high-temperature conditions, the cap-down portion elongates first while the safety vent maintains its structural integrity, delaying premature opening and improving reliability without significantly complicating the manufacturing process.
2Adaptability or versatility
If the elongation rates of the cap-down portion and safety vent are the same, then the material selection is simplified, but the safety vent opens before the cap-down portion is sufficiently elongated in high-temperature environments
Solution Approach 1:
The patent applies parameter changes by deliberately setting different elongation rate parameters for the safety vent and cap-down portion. The safety vent is designed with a lower elongation rate parameter while the cap-down portion has a higher elongation rate parameter. This parameter differentiation ensures that when temperature increases cause internal pressure buildup, the cap-down portion elongates sufficiently before the safety vent opens, maintaining the correct opening sequence and improving thermal characteristics.
3Speed
If the safety vent opens quickly in high-temperature environments, then gas discharge is rapid, but thermal characteristics are degraded due to premature opening
Solution Approach 1:
The patent applies preliminary action by designing the cap-down portion with higher elongation rate characteristics that allow it to elongate first in advance before the safety vent opens. This preliminary elongation of the cap-down portion absorbs some of the internal pressure buildup, delaying the opening of the safety vent until the appropriate time. This ensures that gas discharge occurs at the correct moment rather than prematurely, thereby improving thermal characteristics while still maintaining rapid gas discharge capability when needed.
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 effectively delays the opening of the safety vent in high-temperature environments, improving the thermal characteristics of the battery by maintaining internal pressure until the cap-down portion is sufficiently elongated, thereby preventing premature gas discharge.
Implementation Method 1
The safety vent and the cap-down portion may be connected to each other by laser welding.
Implementation Method 2
the elongation rates of the cap-down portion and the safety vent are different from each other. The elongation rate of the cap-down portion may be higher than that of the safety vent.
Data Source
AI summary
In order to solve a technical problem according to the present disclosure, provided is a cylindrical secondary battery capable of preventing the deformation of components during the manufacture or use thereof. To this end, the present disclosure provides a cylindrical secondary battery comprising: a cylindrical can; an electrode assembly accommodated in the cylindrical can; and a cap assembly for sealing the electrode assembly by covering the cylindrical can, wherein the cap assembly includes: a cap-up portion; a cap-down portion provided below the cap-up portion; and a safety vent provided between the cap-up portion and the cap-down portion, and the elongation rates of the cap-down portion and the safety vent are different from each other.