Crosslinked Polymer Insulator for Battery Cap Assembly Heat Resistance
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Solution Overview
Problem
Current interrupt devices (CIDs) in secondary batteries fail to maintain current interruption during heat generation due to insulator melting in short-circuit situations, leading to potential overcharging and explosion risks.
Innovation Solution
A cap assembly with a crosslinked polymer insulator, such as polypropylene or polyethylene resin, is used between the vent plate and middle plate, which is designed to maintain electrical isolation even under high temperatures, featuring a circular ring shape with anti-deformation ribs and protrusions for enhanced heat resistance and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional insulator is used in the CID, then the device structure is simple and manufacturing is easy, but the insulator melts due to heat in short-circuit situations, causing current interruption failure
Solution Approach 1:
The insulator is constructed as a composite structure comprising a base insulator and a heat-resistant insulator layer made of crosslinked polymer material disposed on the base insulator. This composite structure combines the electrical insulation properties of the base insulator with the high-temperature stability of the crosslinked polymer layer, preventing insulator melting during short-circuit conditions while maintaining current interruption reliability.
Solution Approach 2:
The insulator material undergoes a parameter change by using crosslinked polymer material with modified thermal properties. The crosslinked structure provides higher glass transition temperature and thermal stability compared to conventional insulator materials, enabling the insulator to withstand the heat generated during short-circuit situations without melting or deforming.
2Temperature
If the insulator material is changed to heat-resistant material, then heat resistance is improved, but manufacturing process complexity increases
Solution Approach 1:
The heat-resistant crosslinked polymer layer is disposed on the base insulator in advance before the CID assembly is finalized. This preliminary action ensures that the heat-resistant properties are pre-established in the insulator structure, allowing the rest of the CID assembly to proceed with standard manufacturing processes without requiring complex post-assembly heat treatment or material substitution.
3Stability of the object's composition
If the insulator structure is reinforced to prevent deformation, then structural integrity under heat is improved, but device complexity increases
Solution Approach 1:
The composite insulator structure combines a base insulator with a crosslinked polymer heat-resistant layer, where the crosslinked network provides dimensional stability and resistance to thermal deformation. This composite approach achieves structural reinforcement without requiring complex geometric designs or additional support elements, as the material itself provides the necessary stability.
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 cap assembly effectively stabilizes the performance of the current interrupt device by preventing re-flow of current during heat events, ensuring safe operation of secondary batteries by maintaining electrical isolation and preventing overheating or explosion.
Implementation Method 1
the insulator includes a crosslinked polymer
Implementation Method 2
designed to maintain electrical isolation even under high temperatures
Implementation Method 3
The vent plate is configured to deform in response to an increase in an internal pressure of the secondary battery
Implementation Method 4
an anti-deformation rib may extend along an outer periphery of the circular ring shape of the insulator and may protrude downward
Implementation Method 5
The plurality of protrusions may engage an upper portion of the lower bent portion to couple the vent plate to the insulator
Data Source
AI summary
A cap assembly for a secondary battery includes: a cap plate; a current interrupt device (CID); a middle plate; and an insulator. The CID includes: a vent plate under the cap plate and including a vent portion protruding downward; and a sub-plate under the vent plate and connected to the vent portion. The middle plate is between the vent plate and the sub-plate and is electrically connected to the vent plate via the sub-plate. The insulator is between the vent plate and the middle plate, and the insulator includes a crosslinked polymer.