Zinc-Air Button Cell Seal Design for Internal Volume Expansion
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Solution Overview
Problem
Zinc/air button cells have limited capacity due to constraints on external dimensions and passive cell components, necessitating a design that increases usable volume for the zinc energy source while minimizing mercury content and reducing gassing susceptibility.
Innovation Solution
The design features a novel seal configuration with a hollow-cylindrical jacket and a single-walled cell cover, reducing the double-walled segment's contribution to the cell's height, allowing for a shorter cell cover and increased internal volume, along with a mercury-free zinc anode and a gas diffusion electrode with a plastic-bonded catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional double-walled seal design is used, then sealing reliability is improved, but cell capacity is reduced due to increased housing material volume
Solution Approach 1:
The seal is divided into a first seal portion and a second seal portion that are electrically insulated from each other, allowing each portion to be optimized independently for sealing performance while minimizing overall volume
Solution Approach 2:
The seal design transitions from a conventional double-walled structure to a single-walled structure with a through-opening, changing the dimensional arrangement to reduce material volume while maintaining sealing integrity through the insulating bridge configuration
2Quantity of substance
If cell dimensions are enlarged to increase capacity, then energy storage is improved, but compliance with IEC standards is violated
Solution Approach 1:
The housing structure is optimized locally at critical areas (seal configuration, wall thickness distribution) to maximize internal volume for zinc storage while maintaining external dimensions that comply with IEC button cell standards
Solution Approach 2:
The single-walled seal structure with integrated first and second seal portions creates a nested configuration that maximizes internal usable volume within the constrained external dimensions specified by IEC standards
3Strength
If more housing material is used for robust construction, then mechanical strength is improved, but internal volume for zinc storage is reduced
Solution Approach 1:
The housing utilizes thin-walled construction with strategic reinforcement at critical stress points, allowing sufficient mechanical strength with minimized material usage to maximize internal volume for zinc storage
Solution Approach 2:
The seal combines electrically insulating material with conductive contact portions, creating a composite structure that provides both mechanical integrity and electrical isolation while minimizing overall volume
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 configuration achieves a significant increase in cell capacity by up to 6.4% and reduces gassing susceptibility, while saving housing material and maintaining low mercury content, enhancing the energy storage efficiency of zinc/air button cells.
Implementation Method 1
Gas diffusion electrodes are electrodes in which the substances involved in the electrochemical reaction (usually a catalyst, an electrolyte, and atmospheric oxygen) are present side by side in solid, liquid, and gaseous forms and can come into contact with each other
Implementation Method 2
a plastic binder (e.g., polytetrafluoroethylene, or PTFE) forms a porous matrix in which particles of an electrocatalytically active material are embedded
Implementation Method 3
The catalyst catalyzes the reduction of atmospheric oxygen during discharge and, if necessary, also the oxidation of hydroxide ions during charging of the cells
Implementation Method 4
the zinc anode and an air cathode are arranged... The catalyst catalyzes the reduction of atmospheric oxygen during discharge
Data Source
Figure 1
AI summary
A zinc-air button cell (100) comprises a liquid-tight closed housing made of a cell cup (101), a cell top (102), and a seal (103), which enclose an interior in which a zinc anode and an air cathode (105) are arranged in a manner separated by a separator (104). The cell cup (101) comprises a base (101a), a hollow-cylindrical casing region (101b) and an annular peripheral region (101c), which each have an inner side facing into the interior and an outer side facing in the opposite direction. The cell top (102) comprises a base (102a) and an annular peripheral region (102c), which each have an inner side facing into the interior and an outer side facing in the opposite direction. Arranged on the inner side of the base (101a) of the cell cup (101) are the air cathode (105) and the separator (104). The seal (103) comprises a hollow-cylindrical casing (103a) which bears against the inner side of the casing region (101b) and is delimited on the end side by an upper annular seal periphery (103b) facing away from the base (101a) and a lower annular seal periphery (103c) facing in the direction of the base (101a). The upper annular seal periphery (103b) has an annular gap (103f). The cell top (102) is configured in a single-wall manner - including the peripheral region (102c) - and comprises a terminal cut edge (102e). The peripheral region (102c) of the cell top (102) is curved radially outwards such that it forms a free-standing, circular region of radial extent, the outer periphery of which is formed by the cut edge (102e). The peripheral region (102c) of the cell top (102) is pushed with the cut edge (102e) first into the annular gap (103f) in the upper seal periphery (103b) and the peripheral region (101c) of the cell cup (101) is curved radially inwards in order to close the cell.