Button Cell Case Notch for Twist-Induced Safety Shorting
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Solution Overview
Problem
Conventional coin cells or button cells are prone to significant deformation and electrical sparks due to external twists, leading to increased risk of fire and short-circuiting, especially in wearable devices with high energy density and small size.
Innovation Solution
A notch is formed on the outer circumferential surface of the case to induce a short circuit between the electrodes when external pressure is applied, reducing current flow and minimizing the risk of explosion or fire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the case is made small and compact for wearable devices, then the battery size and energy density are improved, but the case becomes more prone to deformation and electrical sparks under external pressure
Solution Approach 1:
The notch is pre-formed in the case at a location that will collapse under external pressure to create a short circuit. This preliminary structural feature ensures that when pressure is applied, the case will deliberately collapse at the notch to penetrate the electrode assembly and trigger a short circuit, preventing fire or explosion without requiring real-time detection or response systems.
2Weight of moving object
If the case material is made thin and lightweight for small batteries, then the battery weight and size are reduced, but the case strength and resistance to external force are decreased
Solution Approach 1:
The notch creates a localized weak point in the case structure with specific geometric features (width, depth, position) that differ from the rest of the case. This local structural modification allows the case to maintain overall strength while having a predetermined collapse point that will fail in a controlled manner under external pressure to trigger the safety short circuit mechanism.
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 notch quickly reduces current within the cell upon external pressure, preventing deformation and potential ignition by allowing the case to collapse and penetrate into the electrode assembly, thereby enhancing safety.
Implementation Method 1
the notch is configured to penetrate into an inside of the case in response to external pressure and come into contact with the first electrode or the second electrode
Data Source
AI summary
The present disclosure relates to a secondary battery. The secondary battery includes: an electrode assembly configured to comprise a first electrode, a second electrode, and a separator disposed between the first electrode and the second electrode and wound therearound; a case configured to have an opening formed on one side thereof to accommodate the electrode assembly; and a cap assembly joined to the one side of the case to seal the opening of the case, and the case comprises a notch formed on a side portion of the case.