Metal-Air Button Cell Recess for Reliable Electrical Contact
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Solution Overview
Problem
Metal/air cells in button cell form often exhibit high variance in electrochemical properties, leading to elevated impedance values and increased rejection rates during production, primarily due to inadequate electrical connections between the collector structure and the cell cup.
Innovation Solution
The introduction of a recess on the outer side of the cell cup, which becomes a raised portion on the inner side, exerts pressure on the cathode disk periphery, enhancing the electrical connection and reducing impedance issues. This recess is made by impression in the cladding region of the cell cup, improving contact between the collector structure and the cell cup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cathode disk is positioned flat on the housing base to cover the inlet openings, then oxygen can enter the interior and contact the air cathode, but the electrical connection between the collector structure and the cell cup is inadequate, leading to high impedance values
Solution Approach 1:
The cell cup is designed with a localized raised portion at the specific location where the cathode disk periphery contacts the cell cup inner side. This localized structural modification creates enhanced contact pressure precisely at the electrical connection interface, improving electrical conductivity without affecting other areas of the cell structure.
Solution Approach 2:
The raised portion is pre-formed in the cell cup structure before assembly, ensuring that when the cathode disk is placed on the housing base, the electrical connection is immediately optimized through the pre-positioned contact enhancement. This preliminary structural preparation prevents poor electrical connection from occurring in the first place.
2Reliability
If the cathode disk periphery contacts the cell cup inner side, then electrical connection is established, but the contact pressure is insufficient, leading to variable electrochemical properties and high rejection rates
Solution Approach 1:
Instead of uniformly increasing pressure across the entire cell structure, the raised portion creates localized enhanced contact pressure only at the critical electrical connection interface between the cathode disk periphery and the cell cup. This targeted approach ensures consistent electrical connection quality, reducing variability in electrochemical properties and lowering rejection rates.
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 design significantly reduces the rejection rate of zinc/air cells by more than 90% in some cases, as it ensures a more reliable electrical connection, thereby improving the overall performance and consistency of the cells.
Implementation Method 1
the at least one recess is made in the outer side of the cladding region such that the raised portion exerts a pressure against the cathode disk periphery in the region of the contact zone
Implementation Method 2
Hydroxide ions that can migrate via the electrolyte to the anode are produced
Implementation Method 3
During discharging, the catalyst catalyzes reduction of atmospheric oxygen and, if applicable, also oxidation of hydroxide ions during charging of the cells
Implementation Method 4
the metal on which the anode is based is oxidized while releasing electrons. The metal ions produced react with the hydroxide ions
Data Source
AI summary
A metal/air button cell includes a cell cup having at least one inlet opening via which atmospheric oxygen can enter the interior, the cell cup has an inner side facing the interior, and an oppositely directed outer side, an air cathode is in the form of a cathode disk with a circumferential cathode disk periphery, the air cathode includes a metal collector structure, the cathode disk is arranged such that the cathode disk periphery bears along a circumferential contact zone against the inner side of a cladding region, the cell cup has, on its outer side, at least one recess made by impression and becomes visible as a raised portion on the inner side, and the at least one recess is made in the outer side such that the raised portion exerts a pressure against the cathode disk periphery in the region of the contact zone.