Cylindrical Cell Contact Lug Expansion Section
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing safety solutions for button cells, such as lithium-ion cells, that incorporate contact lugs for fixation on printed circuit boards often compromise compactness due to the need for maintaining a minimum distance or preventing mechanical resistance, which can impede the rupture mechanism in case of excess pressure.
Innovation Solution
A cylindrical cell design featuring a second contact lug with an angled subsection that includes an expansion section, allowing it to extend predictably under tensile loading, thereby preventing blocking of the rupture mechanism and maintaining compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rupture cross is created in the end face for safety pressure release, then safety is improved, but the contact lug may block the rupture mechanism or require minimum distance from the printed circuit board, compromising compactness
Solution Approach 1:
The contact lug is designed with an expansion section that allows it to dynamically change its cross-sectional area. Under normal conditions, the contact lug maintains its original compact form. When excess pressure occurs, the contact lug expands in the longitudinal direction, increasing its cross-sectional area to prevent blocking of the rupture mechanism, thus resolving the contradiction between maintaining compactness and ensuring safety functionality.
Solution Approach 2:
The patent changes the geometric parameters of the contact lug by introducing an expansion section with specific dimensional relationships. The expansion section has a length L2 and width B2, where L2 is between 0.5-2 times B2, and the overall length L1 is between 2-5 times B2. These parameter changes enable the contact lug to transition from a compact state to an expanded state, allowing it to fulfill both compactness and safety requirements.
2Volume of moving object
If the end face with rupture cross is positioned close to the printed circuit board for compactness, then compactness is improved, but the rupture process may be impeded by mechanical resistance
Solution Approach 1:
The contact lug transitions from a static structure to a dynamic one that can change its dimensions. The expansion section allows the contact lug to increase its cross-sectional area when needed, creating sufficient clearance between the end face and the printed circuit board during rupture events, thus enabling the rupture mechanism to function properly while maintaining compactness in normal operation.
Solution Approach 2:
The expansion section is pre-designed with specific geometric parameters (length L2 between 0.5-2 times width B2, overall length L1 between 2-5 times B2) to ensure that when expansion is triggered by excess pressure, the contact lug will automatically achieve the necessary dimensions to prevent blocking, without requiring additional components or complex mechanisms.
3Strength
If contact lugs are made rigid for mechanical strength, then mechanical strength is improved, but they may provide mechanical resistance to housing parts sliding apart during pressure release
Solution Approach 1:
The contact lug is designed with an expansion section that provides controlled flexibility. The specific dimensional ratios (L2 between 0.5-2 times B2, L1 between 2-5 times B2) create a structure that is sufficiently strong for mechanical fastening but can expand to accommodate housing part displacement during pressure release, eliminating the need to choose between rigidity and flexibility.
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 design enables a controlled pressure release mechanism without compromising the compactness of the cell, ensuring safety and reliability by allowing the contact lug to expand under defined tensile loading, thus preventing mechanical resistance and maintaining the cell's compact form factor.
Implementation Method 1
the angled-away subsection includes an expansion section in which the second contact lug expands in the main direction of extent in a targeted and predictable manner under a defined tensile loading in its main direction of extent
Implementation Method 2
The contact lugs are usually flat sheet-metal strips applied, for example, by resistance welding to the end faces
Data Source
AI summary
A cylindrical cell includes a. a cylindrical housing enclosing an interior space and composed of a first and a second metal housing part, wherein the housing includes, at its axial ends, a first planar end face and a second planar end face connected to one another by an annular casing, b. a positive electrode and a negative electrode, at least one of which can intercalate and/or deintercalate lithium ions, wherein the positive electrode electrically connects to the first housing part directly or via a separate electrical conductor, and the negative electrode electrically connects to the second housing part directly or via a separate electrical conductor, c. a first contact lug configured as a sheet-metal part that is welded onto the first end face and which has a planar section extending in a plane parallel to the first end face, and d. a second contact lug configured as a sheet-metal part that is welded onto the second end face and has a planar subsection extending in a plane parallel to the second end face and has a subsection angled away from the plane and extends as far as into the plane of the planar section, wherein the angled-away subsection includes an expansion section in which the second contact lug expands in the main direction of extent in a targeted and predictable manner under a defined tensile loading in its main direction of extent.