Concave Safety Vent for Secondary Battery Pressure Relief
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Solution Overview
Problem
Existing secondary batteries face challenges in safely managing internal pressure to prevent explosions and fatigue fractures due to overcharging, particularly in designs lacking effective safety valves that can reliably open at specific pressures without being compromised by swelling.
Innovation Solution
A secondary battery design featuring a safety vent on the cap plate that protrudes inwardly with a concave shape and angled plates, including grooves of varying shapes (V, U, trapezoidal) to maintain consistent opening pressure and prevent fatigue fractures, ensuring the vent operates only at a predetermined internal pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a safety vent is designed with a flat shape, then manufacturing is simple, but it cannot effectively focus internal pressure to ensure reliable opening at specific pressure
Solution Approach 1:
The safety vent is designed with a concave shape that protrudes inwardly toward the interior of the case. This curved geometry focuses the internal pressure onto a specific narrow region, ensuring reliable opening at the predetermined pressure while maintaining manufacturing feasibility through standard molding processes.
2Reliability
If the safety vent protrudes inwardly with a concave shape, then pressure focusing capability is improved, but the thin part may be compromised by swelling and fatigue fractures
Solution Approach 1:
The safety vent is divided into distinct functional regions: a thin破膜部 (breaking portion) for pressure opening and a thicker support structure for mechanical strength. This segmentation allows the thin part to fail at the predetermined pressure while the surrounding structure prevents premature fatigue fractures and swelling.
Solution Approach 2:
The design incorporates a support structure with sufficient thickness around the thin breaking portion to prevent swelling and fatigue fractures before the predetermined pressure is reached. This cushioning effect ensures that only the intended breaking portion fails at the correct pressure.
3Strength
If grooves are added to the safety vent, then fatigue fracture resistance is improved, but manufacturing complexity increases
Solution Approach 1:
Grooves are strategically placed only in specific regions where stress concentration would occur, rather than throughout the entire safety vent structure. This localized approach provides fatigue fracture resistance where needed while minimizing manufacturing complexity and material usage.
Data Source
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AI summary
The present invention refers to a secondary battery, including a case defining an interior space. The case includes a safety vent, the safety vent having a concave shape such that a central portion of the safety vent protrudes toward the space. A region of the safety vent that protrudes farthest toward the space is being midway between peripheral edges of the safety vent.