Spiral-Wound Button Cell Sealing Under Axial Load
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Solution Overview
Problem
Conventional button cells with stacked electrode-separator assemblies face issues such as complex and costly production, high scrap rates due to faulty connections, and susceptibility to leaks under axial mechanical loads, particularly in lithium-ion systems without a beaded-over cup edge.
Innovation Solution
A button cell design featuring a spiral winding of electrode-separator assemblies with electrodes aligned at right angles to the housing areas, using a metallic housing with a cylindrical winding core and an electrically insulating seal, which absorbs radial forces and prevents axial implosion, eliminating the need for additional electrical contacts and enhancing sealing characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If stacked electrode-separator assemblies are used in button cells, then the available area within the housing can be optimally utilized, but the production becomes complicated and expensive with high scrap rates due to faulty connections
Solution Approach 1:
The electrode-separator assembly is divided into multiple individual tablets stacked within the housing, with each tablet being a separate, pre-fabricated unit. This segmentation allows for optimized area utilization while simplifying production, as each tablet can be manufactured independently and assembled without complex connections between them.
Solution Approach 2:
The electrical connection function is extracted from the assembly process itself and implemented within each individual electrode tablet. This eliminates the need for complex inter-assembly connections during stacking, thereby reducing production complexity and scrap rates while maintaining optimal space utilization through the stacked configuration.
2Ease of manufacture
If button cells are manufactured without a beaded-over cup edge, then production is simplified, but the cells cannot be loaded as heavily in the axial direction and are more susceptible to leaks under axial mechanical loads
Solution Approach 1:
The sealing structure is enhanced locally at the interface between the cell cup and cell top by providing a sealing surface on the cell top that extends beyond the cell cup opening. This localized quality improvement at the critical sealing area provides the necessary mechanical strength and leak prevention without requiring the complex beaded-over cup edge structure, thus maintaining production simplicity while improving reliability.
Solution Approach 2:
The sealing arrangement creates an asymmetric structure where the cell top extends beyond the cell cup opening, providing an asymmetric load distribution that enhances resistance to axial mechanical loads. This asymmetric design allows the sealing surface to bear the axial loads effectively without requiring symmetric beading, thereby simplifying manufacture while improving reliability.
3Quantity of substance
If multiple electrode-separator assemblies are stacked to fill the housing, then capacity is increased, but the cells very quickly start to leak under axial mechanical loads
Solution Approach 1:
The sealing surface on the cell top is designed to extend beyond the cell cup opening, creating a localized reinforcement at the sealing interface. This local quality enhancement provides the necessary structural support to handle axial mechanical loads generated by multiple stacked electrode assemblies, preventing leaks while maintaining the high capacity enabled by the stacked configuration.
Data Source
AI summary
A method for producing a button cell includes providing a cell cup, a cell top and an electrode-separator assembly winding, the electrode-separator assembly winding having a positive electrode and a negative electrode. An electrically insulating seal is applied at least to an outer portion of the cell top casing. The electrode-separator assembly winding is inserted into the cell top. The cell top is inserted into the cell cup to form a housing. A pressure is applied in a radial direction perpendicular to an axis of the electrode-separator assembly winding so as to seal the housing.