Battery Cap Assembly Vent Structure for Short-Circuit Insulation
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Solution Overview
Problem
Existing secondary batteries face challenges in ensuring insulation safety, particularly due to the risk of short circuits when the gasket is melted or damaged.
Innovation Solution
The secondary battery design incorporates a cap assembly with a safety vent featuring a vent extension part and an insulation washer, where a thin welding area is formed in the safety vent to prevent the welding bead from contacting the insulation washer, thereby enhancing insulation safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gasket is used to seal between the cap assembly and case, then sealing performance is improved, but insulation safety deteriorates when the gasket is melted or damaged
Solution Approach 1:
An insulation washer is introduced as an intermediary component between the cap assembly and case. This washer provides a secondary insulation barrier that prevents short circuits even when the gasket fails, thus resolving the contradiction between maintaining sealing performance and preventing short circuit risks.
Solution Approach 2:
The insulation washer is installed in advance to cushion against the potential harmful effect of gasket failure. By preparing this protective layer beforehand, the system ensures that short circuits cannot occur even if the primary sealing component (gasket) is compromised.
2Strength
If laser welding is used to join the safety vent to the cap-up, then welding strength is improved, but the risk of welding bead contact with insulation washer increases
Solution Approach 1:
The vent extension part is designed with non-uniform thickness, featuring a thinner section specifically at the welding area. This local quality change allows the welding bead to be contained within the thicker portion, preventing contact with the insulation washer while maintaining strong welding in the critical joint area.
Solution Approach 2:
The problem is solved by introducing a dimensional variation in the vent extension part thickness. By creating a thickness gradient, the design provides spatial separation between the welding bead and insulation washer, preventing short circuits while maintaining welding integrity.
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 prevents short circuits between the cap assembly and the case, even if the gasket is compromised, thereby improving the overall safety of the secondary battery.
Implementation Method 1
A portion of the safety vent and a portion of the cap-up may be melted by laser welding to form a welding bead
Implementation Method 2
An oxide film may be formed on a surface of the insulation washer
Data Source
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AI summary
The present invention relates to a secondary battery capable of improving insulation safety. For example, the secondary battery includes: an electrode assembly; a case configured to accommodate the electrode assembly; and a cap assembly coupled to an upper portion of the case, wherein the cap assembly includes a cap-up, a safety vent installed below the cap-up and having a vent extension part extending to an upper side of the cap-up to surround an edge of the cap-up, and an insulation washer attached to upper portions of the vent extension part and the cap-up, and a welding area having a thickness less than that of surroundings is formed on the vent extension part.