Cylindrical Battery Cap Assembly Degassing Mechanism
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Solution Overview
Problem
Cylindrical secondary batteries face limitations due to internal gas generation, which can deform the cap assembly and can, leading to performance deterioration.
Innovation Solution
A cylindrical secondary battery design featuring a cap assembly with a degassing hole and a sealing mechanism, including a resin or rubber pin, and a sealing member, allows for the removal of internal gas, preventing deformation and performance issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cap assembly is sealed to prevent gas leakage, then battery safety is improved, but internal gas accumulation causes deformation and performance deterioration
Solution Approach 1:
A degassing hole is pre-formed in the cap assembly before battery operation, allowing gas to be vented before pressure buildup causes deformation. This preliminary structural feature prevents the harmful effect of gas accumulation while maintaining sealed operation during normal use.
Solution Approach 2:
The degassing hole acts as an intermediary pathway that allows controlled gas release without compromising the overall sealed structure. It mediates between the need for sealing (safety) and the need to release gas (prevent deformation), enabling both functions to coexist.
2Shape
If a degassing hole is provided in the cap assembly, then internal gas can be removed preventing deformation, but the sealing structure becomes more complex
Solution Approach 1:
The cap assembly is segmented into functional zones: a sealed portion for safety and a degassing portion with the hole for gas release. This segmentation allows each zone to perform its specific function optimally without compromising the other, managing complexity through functional division.
Solution Approach 2:
The cap assembly has different local properties: most of the cap maintains sealed integrity while a specific localized region (the degassing hole) provides gas release capability. This local differentiation allows the structure to achieve both sealing and degassing functions without overall complexity increase.
3Strength
If the cap assembly is made robust to prevent deformation, then structural strength is improved, but gas pressure buildup cannot be relieved
Solution Approach 1:
The harmful gas pressure is extracted from the sealed system through the degassing hole in the cap assembly. This allows the cap to maintain robust structural strength for deformation prevention while the extracted gas pathway eliminates the harmful pressure buildup that would otherwise compromise the strong structure.
Data Source
AI summary
Provided is a cylindrical secondary battery. The cylindrical secondary battery includes a cylindrical can, an electrode assembly in which a first electrode plate, a second electrode plate, and a separator are wound and which is accommodated in the can, and a cap assembly which is insulated from the can and electrically connected to the electrode assembly and through which a degassing hole passes to communicate with the inside of the can. According to the embodiment, since a degassing function is applied to remove the gas generated before the product shipment, deformation of the can and the cap assembly may be reduced. In addition, swelling of the electrode assembly due to the generation of the internal gas may be prevented from occurring to reduce performance deterioration of the secondary battery.