Battery Cap Assembly Hardness Layout for Pressure-Induced Shorts
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Solution Overview
Problem
Cylindrical secondary batteries face issues with safety vents and current interrupt devices penetrating the gasket due to their high hardness, leading to potential short circuits and increased risk of ignition or thermal runaway during stability tests and external pressure.
Innovation Solution
A cap assembly design featuring a safety vent made of aluminum or aluminum alloy with a lower hardness than the current interrupt device, positioned at an angle of 0° to 30°, where the safety vent is designed to deform and apply pressure to the current interrupt device, which is made of a softer material to absorb external pressure effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If safety vent and current interrupt device are made of high hardness material, then their structural strength is improved, but they penetrate the gasket without deforming under external pressure causing short circuit
Solution Approach 1:
The patent applies different material properties to different components: the safety vent is made of high hardness material (aluminum alloy with 60-80 HV) to maintain structural strength, while the current interrupt device is made of lower hardness material (aluminum alloy with 30-50 HV) to enable deformation and absorption of external pressure, preventing penetration of the gasket
Solution Approach 2:
The patent changes the physical parameter of hardness between two components: the safety vent has higher hardness (60-80 HV) for strength, while the current interrupt device has lower hardness (30-50 HV) for deformability, allowing each component to fulfill its specific function under external pressure
2Strength
If safety vent and current interrupt device are made of high hardness material, then their structural integrity is improved, but they cause deformation of cap assembly under external pressure
Solution Approach 1:
The patent assigns different material properties to different locations: the safety vent (higher hardness) maintains local structural integrity, while the current interrupt device (lower hardness) deforms locally to absorb external pressure, preventing overall cap assembly deformation
Solution Approach 2:
The softer current interrupt device acts as a cushioning element that deforms first under external pressure, absorbing the impact before it reaches the harder safety vent and the rest of the cap assembly, thereby preventing deformation propagation
Data Source
AI summary
A cap assembly has one side open and is configured to be coupled to an upper portion of a secondary battery can. The cap assembly includes a top cap to be coupled to the upper portion of the secondary battery can; a safety vent under the top cap and configured to be coupled to a distal end of the top cap; and a current interrupt device under the safety vent and having at least a portion that is in contact with the safety vent. The current interrupt device includes a material having a lower hardness than a hardness of the safety vent.