Button Cell Edge Coating for Thin, Strong Sealing Elements
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Solution Overview
Problem
Existing button cell sealing elements face challenges in achieving thin wall thicknesses without compromising mechanical strength and are prone to damage from cut edges, leading to gassing effects and capacity utilization issues.
Innovation Solution
A method involving a cup-shaped, metallic housing with a liquid plastic precursor coating forming the sealing element, where the inside and outside of the housing part are coated to create a solid plastic coating that is thicker at the opening edge for enhanced mechanical strength and sealing, avoiding the limitations of injection molding and film seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If injection molding is used to manufacture sealing elements, then mechanical strength and ease of manufacture are improved, but wall thickness cannot be reduced below 0.1 mm and device complexity increases
Solution Approach 1:
The patent changes the manufacturing method from injection molding to a coating process, allowing continuous control of wall thickness down to micrometer ranges. This parameter change enables achieving both thin walls and sufficient mechanical strength by optimizing coating thickness and material properties.
Solution Approach 2:
The patent replaces the mechanical injection molding process with a coating application system, substituting complex mechanical tooling with a simpler coating process that can achieve precise thickness control without the limitations of mold-based manufacturing.
2Volume of stationary object
If sealing element wall thickness is reduced to improve capacity utilization, then volume is reduced, but mechanical strength and processability deteriorate
Solution Approach 1:
By changing from injection molding to coating process, the patent enables wall thicknesses in the micrometer range while maintaining mechanical integrity through controlled material deposition and curing parameters.
Solution Approach 2:
The patent employs thin film coating technology to create sealing elements with walls as thin as a few micrometers, utilizing flexible coating materials that can provide sufficient mechanical strength at ultra-thin dimensions.
3Reliability
If PVD coating processes are used to coat housing parts, then electrical insulation is improved, but manufacturing cost and device complexity increase due to expensive equipment and masking requirements
Solution Approach 1:
The patent extracts the sealing and insulating function from complex PVD coating processes and implements it through a simpler liquid coating method, eliminating the need for expensive PVD equipment and complex masking procedures while achieving the same electrical insulation effect.
Solution Approach 2:
The patent replaces expensive, complex PVD coating systems with a cost-effective liquid coating process that uses simple, disposable coating materials, significantly reducing equipment investment and process complexity.
4Reliability
If coating processes are used on single-walled housing parts with cut edges, then electrical insulation is achieved, but the coating is easily damaged by cut edges causing gassing effects
Solution Approach 1:
The patent applies preliminary treatment to the cut edges before coating, such as rounding or chamfering, to prevent coating damage. This preliminary action eliminates the sharp edges that would otherwise cause coating failure and subsequent gassing effects during cell operation.
Solution Approach 2:
The patent provides beforehand protection by applying a primer or intermediate layer that cushions the coating from mechanical damage at cut edges, preventing direct contact between the coating and sharp edges that would cause coating failure.
5Reliability
If injection molded sealing elements are used, then electrical insulation and sealing are achieved, but capacity utilization is impaired due to thicker wall thickness
Solution Approach 1:
The patent changes the manufacturing approach from injection molding to coating, enabling wall thickness reduction from hundreds of micrometers to just a few micrometers while preserving electrical insulation properties through optimized coating material selection and thickness control.
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
This approach allows for the production of very thin and secure sealing elements with controlled thickness, preventing electrical shorts and mechanical damage, thereby improving capacity utilization and assembly efficiency.
Implementation Method 1
dried to form a solid plastic coating
Data Source
Figure 1a~1e
AI summary
A button cell (100) comprises a housing (101, 102) with an interior (104) in which a positive electrode, a negative electrode, and a separator are arranged. The housing comprises a cup-shaped, metallic first housing part (101) and a cup-shaped, metallic second housing part (102), as well as an electrically insulating sealing element (103) between the housing parts. Each housing part comprises a circular base (101a, 102a), a hollow cylindrical shell (101b, 102b), a circumferential transition region (101c, 102c) connecting the base and the shell, and an opening rim (101d, 102d) defining a circular opening. The bases and shells each have an inner surface facing the interior and an outer surface facing in the opposite direction, and the opening rims each lie in a plane parallel to the respective base.To manufacture the button cell (100), the inner and outer surfaces of the casing (101b) and the opening edge (101d) of the first housing part (101) are coated with a liquid plastic precursor (105). The liquid plastic precursor is dried and/or cured on the first housing part (101) to form a solid plastic coating, with the opening edge (101d) of the first housing part pointing downwards at least temporarily, either vertically or with a deviation of no more than 5° from the perpendicular. The housing is assembled from the first and second housing parts, with the plastic coating forming the sealing element 103. The plastic coating 103 is thicker in the area of the opening edge (101d) than in areas of the casing (101b) spaced away from the opening edge.