Fuel Cell Current Collector Extension Design
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Solution Overview
Problem
Current fuel cell stack assemblies face challenges in achieving efficient current collection while maintaining component tolerances and operational performance, due to variations in compressive load and material expansion, leading to increased costs and complexity, as well as potential component failure or reduced performance.
Innovation Solution
The design decouples contact pressure and sealing requirements from the fuel cell active areas by extending the current collector beyond the electrode and electrolyte perimeter, allowing electrical contact without compressive force on the electrodes or electrolyte, using an electrically conductive substrate and interconnect plate with non-conductive spacers for mechanical support and gas flow management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compressive force is applied to achieve good electrical contact between current collector and electrode, then electrical contact resistance is reduced, but component stress increases leading to potential failure
Solution Approach 1:
The patent divides the current collector into two functional zones: a first area that contacts the electrode for current collection, and a second area extending beyond the electrode perimeter for mechanical support and compression distribution. This segmentation allows the compressive force to be applied through the second area without directly stressing the electrode, while still achieving good electrical contact through the first area.
Solution Approach 2:
The current collector acts as an intermediary element between the compression system and the electrode. By extending the current collector beyond the electrode perimeter, it mediates the transmission of compressive force, distributing it through its extended structure rather than concentrating it on the electrode, thus protecting the electrode from excessive stress while maintaining electrical contact.
2Reliability
If tight component tolerances are enforced to minimize stress variations, then component reliability is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent changes the geometric parameters of the current collector by extending it beyond the electrode perimeter. This parameter change transforms the current collector from a simple contact element into a structural component that can accommodate tolerance variations in electrode thickness and flatness, thereby reducing the stringency of manufacturing tolerance requirements while maintaining stack reliability.
Solution Approach 2:
By segmenting the current collector into contact and extension areas, the patent allows the extension area to compensate for dimensional variations in the electrode. This segmentation enables the system to tolerate greater variations in component dimensions without compromising electrical contact or stack integrity, thus reducing manufacturing complexity.
3Reliability
If uniform compressive force is distributed across the stack, then electrical contact is maintained, but local stress concentrations occur due to component variations
Solution Approach 1:
The patent applies local quality by giving different parts of the current collector different functions: the first area is optimized for electrical contact with the electrode, while the second extended area is optimized for distributing compressive forces. This local differentiation allows the structure to handle both electrical and mechanical requirements simultaneously, preventing stress concentrations while maintaining contact consistency.
Solution Approach 2:
The patent extends the current collector into a new spatial dimension by projecting it beyond the electrode perimeter. This dimensional extension creates additional structural capacity to distribute compressive forces across a larger area, reducing local stress concentrations while maintaining uniform electrical contact through the original contact area.
4Ease of manufacture
If current collector extends beyond electrode perimeter, then manufacturing tolerances are relaxed, but device complexity increases
Solution Approach 1:
The extended current collector serves multiple functions: it provides electrical contact through the first area, distributes compressive forces through the second area, compensates for tolerance variations, and provides structural support. By making the current collector multi-functional, the patent achieves relaxed manufacturing tolerances without significantly increasing device complexity, as the same component performs multiple roles.
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 approach reduces the magnitude of stack compression load, relaxes component production tolerances, and enhances operating performance by minimizing contact pressure variations, resulting in a lower-cost, more efficient fuel cell stack assembly with improved reliability and efficiency.
Implementation Method 1
the current collector at least one extension is made to contact an adjacent electrically conductive interconnect plate in use such that good electrical contact is made from one fuel cell stack layer to an adjacent fuel cell stack layer
Implementation Method 2
compression means adapted to exert compressive force through said cover means upon said at least one fuel cell outside of said perimeter of each said first and second electrodes and each said electrolyte to effect good electrical contact
Implementation Method 3
an electrically non-conductive structure which in-use provides mechanical support for components placed on top of it
Data Source
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Figure 9
AI summary
The present invention is concerned with a fuel cell comprising : an electrolyte layer defining first and second faces and with said first face mounted on and in electrochemical contact with a first electrode and with said second face mounted on and in electrochemical contact with a second electrode, and an electrically conductive current collector joined to or mounted on or in said second electrode and in electrical contact with said second electrode, said electrically conductive current collector having an at least one extension extending outwards of a perimeter defined by said first and second electrodes and said electrolyte, fuel cell stack assemblies comprising same and methods of manufacture of same.