Miniature Cell Lid Channels for Electrolyte Wetting
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Solution Overview
Problem
Miniature electrochemical cells with a volume less than 0.5 cc face challenges in electrolyte filling due to limited internal space and the cathode current collector blocking the electrolyte fill port, making it difficult for the electrolyte to effectively wet the active materials and promote desirable cell discharge.
Innovation Solution
The design incorporates an electrolyte fill port with radially extending channels on the lid, allowing for vacuum filling and ensuring that the electrolyte can adequately wet the anode and cathode active materials, even in small cells, by providing a pathway for electrolyte flow beyond the current collector's edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the cell size is reduced to less than 0.5 cc, then the cell becomes miniaturized for new medical device applications, but the internal space for electrolyte is severely limited making it difficult to effectively wet the active materials
Solution Approach 1:
The patent introduces a vertical dimension for electrolyte distribution by drilling channels through the lid thickness. Instead of relying solely on horizontal spreading in the limited internal space, the electrolyte is delivered from the top surface through vertical channels that extend downward, allowing efficient wetting of active materials stacked beneath the lid in the vertical direction.
Solution Approach 2:
The lid channels serve as an intermediary structure that mediates between the fill port and the active materials. The channels provide a dedicated pathway that bypasses the space constraints of the internal cavity, allowing electrolyte to reach the active materials directly through the lid structure rather than attempting to flood the limited internal volume.
2Reliability
If the cathode current collector is placed to cover the fill port, then electrical contact is established, but the electrolyte cannot flow into the casing to activate the electrode assembly
Solution Approach 1:
The lid is segmented into functional zones: a central fill port region for electrolyte introduction, radial channels for distribution, and peripheral areas for current collector placement. This segmentation allows the current collector to cover the fill port for electrical contact while the channels provide separate pathways for electrolyte flow, resolving the conflict between electrical connectivity and electrolyte access.
Solution Approach 2:
The channels act as an intermediary structure between the fill port and the internal cavity. They provide a dedicated fluid pathway that is spatially separated from the current collector's electrical contact function, allowing both functions to coexist without interference.
3Quantity of substance
If the channels extend to the peripheral edge of the lid, then maximum electrolyte distribution is achieved, but the structural integrity and sealing of the lid is compromised
Solution Approach 1:
The channels are positioned with specific local quality considerations: they extend radially outwardly beyond the current collector edge to ensure adequate electrolyte distribution, but they do not extend to the peripheral edge of the lid. This localized channel placement provides sufficient electrolyte access while preserving the peripheral lid structure for mechanical strength and sealing.
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 solution enables efficient activation of the electrode assembly in miniature cells, ensuring sufficient electrolyte distribution and promoting acceptable discharge without excess electrolyte, and is applicable to various electrochemical cell chemistries, including lithium-ion cells.
Implementation Method 1
electrolyte channels extending radially outwardly from the fill port... allowing for vacuum filling and ensuring that the electrolyte can adequately wet the anode and cathode active materials
Implementation Method 2
The fill port/fluid channel system allows the casing to be filled with electrolyte using a vacuum filling process
Data Source
AI summary
A miniature electrochemical cell of a primary or secondary chemistry with a total volume that is less than 0.5 cc is described. The cell has a casing comprising an annular sidewall supported on a lower plate opposite an upper lid. The lid has a sealed electrolyte fill port. At least one electrolyte channel in the inner surface of the lid extends radially from the fill port and outwardly beyond an outer peripheral edge of the current collector. A current collector contacts an inner surface of the lid with a first electrode active material contacting the current collector. An opposite polarity active material contacts the lower plate. A dielectric material coats the lower open end of the annular sidewall and a portion of the inner surface of the sidewall. A glass seals the dielectric material to the lower plate. An electrolyte activates the electrode assembly.