Fuel Cell Separator Plate Sealing with Metal Shim
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional corrugated cathode separator plates in fuel cell stacks experience intermittent connections with the underlying electrolyte layer, leading to potential leakage during thermal cycling, especially in smaller form stacks, where reducing corrugation pitch compromises air flow or increasing gasket width reduces active cell area and efficiency.
Innovation Solution
Incorporating a metal shim with higher stiffness than the gasket or membrane electrode assembly material, either as an integral part of the separator plate or as a separate component with engagement features, to provide uniform sealing pressure and prevent leakage without affecting air flow, and forming the shim and plate as a common unit to reduce components and material wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the corrugation pitch is made smaller to reduce gaps between contacts with the underlying layers, then the possibility of leakage is reduced, but the volume of air flow paths available across the cell is reduced
Solution Approach 1:
The separator plate is divided into two functional zones: corrugated regions that provide air flow paths and a peripheral sealing region that is substantially planar and provides continuous sealing contact. This segmentation allows the air flow paths to maintain sufficient volume while the sealing region ensures continuous contact with the gasket and underlying layers, preventing leakage without compromising air flow volume.
2Reliability
If the width of the gasketed region surrounding the active region is increased to reduce leakage possibility, then sealing is improved, but the proportion of the active area of the cell is reduced, thereby reducing efficiency
Solution Approach 1:
The separator plate exhibits different local qualities: the peripheral sealing region has a substantially planar configuration optimized for sealing contact, while the central region contains corrugations optimized for air flow. This local differentiation allows effective sealing at the periphery without compromising the active cell area, as the sealing function is localized to the edge region rather than requiring a wide gasketed zone around the entire active area.
3Speed
If conventional corrugated cathode separator plates are used to provide air flow paths, then air flow is achieved, but only intermittent connection with the underlying electrolyte layer is provided, leading to potential separation during thermal cycling
Solution Approach 1:
The separator plate is segmented into corrugated air flow regions and a peripheral sealing region that provides continuous contact. This segmentation ensures that while the corrugated portions facilitate air flow, the peripheral region maintains stable, continuous connection with the underlying layers during thermal cycling, preventing separation and leakage.
Solution Approach 2:
The peripheral sealing region is designed with appropriate flexibility to accommodate thermal expansion and contraction during cycling, maintaining continuous contact with the gasket and underlying layers. This flexible sealing region compensates for dimensional changes while preserving the intermittent corrugated structure needed for air flow in the central region.
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 metal shim ensures a more uniform sealing pressure, reducing the likelihood of leakage while maintaining air flow efficiency, and can be integrated into the manufacturing process to simplify assembly and reduce material waste.
Implementation Method 1
the material from which the shim is formed having a substantially higher stiffness than the gasket or MEA material, thereby allowing the intermittent pressure profile provided by the corrugated separator plate to be more uniformly applied
Implementation Method 2
a cathode separator plate having a series of corrugations extending, and providing air flow paths, between first and second opposing edges of the plate
Data Source
AI summary
The invention relates to fuel cell assemblies, and in particular to improvements relating to sealing of such assemblies, embodiments of which include a fuel cell assembly (200) comprising a membrane electrode assembly (104), a cathode separator plate (208) having a series of corrugations extending, and providing air flow paths, between first and second opposing edges of the plate, a gasket (105) providing a fluid seal around a peripheral edge of the membrane electrode assembly (104) between the separator plate (208) and the membrane electrode assembly (104) and a metal shim (107) disposed between the gasket (105) and the separator plate (208) over the peripheral edge of the membrane electrode assembly (104).