Cylindrical Battery Can with Bent Portion for Rupture Prevention
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Solution Overview
Problem
Secondary batteries face the risk of circumferential surface rupture due to internal gas generation, which can lead to side-rupture propagation and successive explosions when excessive heat and gas are generated, as existing safety vent configurations are inadequate in managing sudden gas pressure.
Innovation Solution
A cylindrical can design featuring a first bent portion extending between a first and second region on its surface, with a 90° to 100° angle, and notches for easy separation of the cap assembly from the can, allowing gas to be exhausted before the surface ruptures, thereby preventing or reducing the risk of rupture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cylindrical can design is used, then the battery structure is simple and easy to manufacture, but the circumferential surface may rupture due to internal gas pressure
Solution Approach 1:
The can's circumferential surface is segmented into multiple regions (first region, second region, third region) connected by bent portions. This segmentation allows the structure to flex and deform locally at the bent portions when gas pressure builds up, preventing catastrophic rupture of the entire circumferential surface while maintaining overall structural integrity.
Solution Approach 2:
The bent portions are designed with specific geometric parameters (angles, curvature radii, thickness variations) that allow controlled deformation under pressure. By optimizing these parameters, the can can accommodate gas expansion through elastic and plastic deformation at the bent portions without rupturing, thus improving reliability while maintaining a relatively simple overall structure.
2Reliability
If the cap assembly is tightly sealed to the can, then sealing performance is improved, but the cap assembly cannot separate to release internal gas pressure
Solution Approach 1:
The bent portions are pre-formed with specific geometries that create controlled weak points or separation paths. When gas pressure builds up, these pre-designed features allow the cap assembly to separate from the can in a controlled manner before the circumferential surface ruptures, providing a safety release mechanism while maintaining strong bonding during normal operation.
3Reliability
If the can wall thickness is increased to prevent rupture, then rupture resistance is improved, but manufacturing complexity and material usage increase
Solution Approach 1:
Instead of uniformly increasing the entire can wall thickness, the design introduces localized structural features (bent portions with specific angles and curvature radii) at critical locations. These localized features provide enhanced rupture resistance where gas pressure is most likely to cause failure, while keeping the rest of the can wall thickness optimized for manufacturing efficiency and cost-effectiveness.
Data Source
AI summary
A secondary battery includes: a cylindrical can including a first region, a second region, and a first bent portion extending between the first region and the second region on a circumferential surface of the can; an electrode assembly accommodated in the can; and a cap assembly at a top end of the can and sealing the can. The first bent portion is bent such that an angle between the first region and the second region is in a range of about 90° to about 100°; the first region of the can partially covers a top surface of the cap assembly facing an exterior side of the can, and the second region of the can surrounds side surfaces of the cap assembly.