Cylindrical Li-Ion Battery Venting with Curved Can Floor Relief
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Solution Overview
Problem
Cylindrical lithium ion secondary batteries face challenges in maintaining the flatness of the can floor, which can lead to dimensional errors and reduced safety vent effectiveness due to excess metal accumulation and potential damage during the formation of the safety vent.
Innovation Solution
A cylindrical lithium ion secondary battery design that incorporates a curved portion on the can floor adjacent to the safety vent, allowing excess metal to be guided away from the vent, enhancing the flatness of the can floor and reducing damage. The safety vent is either covered with a resin plate or coated with a resin layer to prevent oxidation and ensure proper operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety vent is formed on the can floor, then battery safety is improved, but excess metal accumulation damages the safety vent and reduces flatness
Solution Approach 1:
The can floor is segmented into three distinct regions: a first region with the safety vent, a second region with the curved portion adjacent to the vent, and a third region as the remaining floor area. This segmentation allows excess metal to be directed to the curved portion rather than accumulating on the safety vent, resolving the contradiction between vent effectiveness and floor flatness.
Solution Approach 2:
The curved portion acts as an intermediary region between the safety vent and the rest of the can floor. It serves as a buffer zone that receives and contains excess metal, preventing direct contact between the metal and the safety vent, thus protecting the vent while maintaining overall floor flatness.
2Manufacturing precision
If the can floor is made flat, then manufacturing precision is improved, but safety vent damage from excess metal cannot be prevented
Solution Approach 1:
The curved portion is formed in advance on the can floor before the safety vent formation process. This preliminary action creates a predetermined path for excess metal flow, ensuring that when the safety vent is later formed, the excess metal is already directed away from the vent area, preventing damage while maintaining flatness.
3Device complexity
If the safety vent is exposed, then the structure is simple, but the vent is susceptible to oxidation and damage
Solution Approach 1:
A resin plate is positioned to cover the safety vent, forming a protective barrier. The resin plate acts as a flexible shell that protects the metal vent from oxidation and physical damage while allowing the vent to function. This adds minimal complexity while effectively addressing the harmful factors.
Solution Approach 2:
The safety vent structure becomes a composite system combining the metal vent material with the resin protective plate. This composite structure leverages the advantages of both materials: the metal provides structural integrity and venting function, while the resin provides oxidation resistance and damage protection.
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 design enhances the flatness of the can floor, reduces dimensional errors in manufacturing processes, and prevents damage to the safety vent, while the resin coverage protects the vent from oxidation and maintains functionality even at elevated temperatures.
Implementation Method 1
The safety vent is either covered with a resin plate or coated with a resin layer to prevent oxidation and ensure proper operation
Implementation Method 2
A resin plate melted at a temperature of 100° C. to 300° C. may be attached to the curved portion to cover the safety vent
Data Source
AI summary
An embodiment of the present invention relates to a cylindrical lithium ion secondary battery. The technical problem to be solved is to provide a cylindrical lithium ion secondary battery which is designed such that a safety vent is formed and at the same time or afterwards excess metal can be guided to a curved portion adjacent to the safety vent, thereby enhancing the flatness of a can floor and reducing damage to the safety vent. To this end, the present invention provides a cylindrical lithium ion secondary battery comprising: a cylindrical can; an electrode assembly accommodated in the cylindrical can; and a cap assembly for sealing the cylindrical can, wherein the cylindrical can comprises a circular floor portion, a curved portion curved from the floor portion towards the electrode assembly, and a safety vent formed on the curved portion.