Wound Button Cell Housing Connection for Axial Stress Resistance
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Solution Overview
Problem
Button cells without crimping fail to withstand high axial stresses, particularly from volume changes during charging and discharging of lithium ion systems, leading to potential leaks and electrical contact issues with the metal housing.
Innovation Solution
A button cell design featuring a spiral-shaped electrode winding with metal foil conductors welded to the inner side of the housing halves, ensuring secure electrical connections and enhanced mechanical stability without crimping, using a method that includes forming an electrode assembly with current collectors, separator layers, and insulators, and welding the conductors to the housing parts after assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If button cells are manufactured without crimping the cell cup edge, then the manufacturing process is simplified and production efficiency is improved, but the button cell cannot withstand high axial stresses and is more prone to leaks
Solution Approach 1:
The sealing function is segmented from the mechanical fastening function. The plastic sealing ring handles the sealing task while the cell cup and cell top are joined by force-fit connection without crimping, allowing simplified manufacturing while maintaining sealing reliability under axial stress
Solution Approach 2:
A plastic sealing ring is introduced as an intermediary element between the cell cup and cell top. This sealing ring serves as a mediator that provides both sealing function and enhanced mechanical stability, allowing the button cell to withstand axial stresses without crimping the cup edge
2Ease of manufacture
If electrode layers are arranged stacked in parallel alignment with the plane bottom and top regions, then the manufacturing process is simpler, but radial forces during charging and discharging cannot be absorbed effectively
Solution Approach 1:
Instead of arranging electrode layers parallel to the plane bottom and top regions, the invention inverts the orientation by arranging them perpendicular to these planes. This orthogonal arrangement allows the electrode winding to effectively absorb radial forces during lithium ion charging and discharging while maintaining manufacturing simplicity
3Stability of the object's composition
If an axial cavity is left at the center of the winding, then the winding can expand freely, but electrical contact between electrodes and metal housing may be compromised
Solution Approach 1:
Metal foil conductors are introduced as intermediary elements that bridge the electrode winding and the metal housing. These conductors are welded to both the electrode assembly and the housing, ensuring reliable electrical contact even when the winding expands into the axial cavity during operation
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 solution provides improved axial force absorption and reduced risk of leaks, maintaining electrical contact integrity and simplifying production by welding conductors to the housing after assembly, enhancing the mechanical stability and reliability of button cells.
Implementation Method 1
welding the second portion of the first metal foil conductor to a first housing part
Data Source
AI summary
A button cell includes a metal cell cup, a cell top, a first electrode, and a second electrode. The first electrode includes a first current collector having an active material-free region, and the second electrode includes a second current collector. The button cell further includes a first metal foil conductor having a first portion attached to the active material-free region of the first current collector and an insulator applied to a rear side of the first metal foil conductor along a second portion of the first metal foil conductor. The first electrode and the second electrode form, along with a first separator layer and a second separator layer, an electrode assembly that is wound in a spiral to form an electrode winding. The second portion of the first metal foil conductor is welded to one of the metal cell cup or the cell top.