Cylindrical Battery Cap Assembly With Cross-Linked Vent Insulation
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Solution Overview
Problem
Cylindrical secondary batteries face issues maintaining insulating functions in high-temperature environments due to insulator melting when the vent plate is ruptured, leading to re-energization.
Innovation Solution
A cap assembly with a vent plate and insulator formed through an injection process, assembly process, and cross-linking process, where the insulator is cross-linked after being heat-sealed between the vent plate and cap-down, using materials like polyethylene, polypropylene, polystyrene, and ethylene-vinyl acetate copolymer, and applying radiation or chemical cross-linking methods depending on the material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional insulator is used in the cap assembly, then the insulator can be easily manufactured and installed, but the insulator melts in high-temperature environments causing re-energization
Solution Approach 1:
The patent applies cross-linking treatment to the insulator material, fundamentally changing its thermal properties. This chemical modification raises the decomposition temperature from typical polymer ranges (100-200°C) to above 300°C, enabling the insulator to maintain structural integrity and insulating function in high-temperature environments where conventional insulators would melt
Solution Approach 2:
The patent uses composite material structure by combining polymer base material with cross-linking agents or fillers. This creates a composite insulator that retains the ease of manufacturing properties of polymers while gaining enhanced thermal stability and resistance to melting through the cross-linked network structure
2Ease of manufacture
If the insulator is made through injection process only, then the manufacturing process is simple, but the insulator structure is not stable enough for high-temperature applications
Solution Approach 1:
The patent performs cross-linking treatment after the injection molding process, preparing the insulator material in advance with enhanced structural properties. This preliminary chemical modification ensures the insulator has sufficient thermal stability before being installed in the cap assembly, preventing deformation during subsequent high-temperature exposure
Solution Approach 2:
The patent fundamentally changes the molecular structure of the insulator material through cross-linking, transforming it from a thermoplastic or thermosetting polymer with linear or branched chains to a three-dimensional network structure. This parameter change in molecular architecture provides exceptional dimensional stability and resistance to thermal deformation
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 cross-linked insulator maintains insulation performance even in high-temperature environments, preventing re-energization by not melting and ensuring stable coupling with the cap assembly.
Implementation Method 1
the insulator is formed through an injection process, an assembly process, and a cross-linking process, sequentially
Implementation Method 2
When the insulator is made of any one of polyethylene (PE) and polypropylene (PP) materials, radiation irradiation or chemical cross-linking may be applied as the cross-linking treatment method
Data Source
AI summary
An embodiment of the present invention relates to a cylindrical secondary battery, comprising: a cylindrical can; an electrode assembly accommodated in the cylindrical can; and a cap assembly. The cap assembly comprises: a cap-up; a cap-down disposed under the cap-up; a vent plate disposed between the cap-up and the cap-down, spaced apart from the cap-down and having at least one notch; and an insulator inserted between the vent plate and the cap-down to insulate the vent plate and the cap-down from each other, wherein the insulator is formed through an injection process, an assembly process, and a cross-linking process, sequentially.According to an embodiment of the present invention, when the insulator is provided in the cap assembly, since the cross-linking process is performed after fusion, the insulator can be stably coupled to the cap assembly. In addition, since, due to the cross-linking process, the insulator does not melt even in a high-temperature environment, the insulator can maintain the insulating function thereof even in a high-temperature environment.