Fuel Cell Unit Cell Sealing With High-Viscosity Elastomers
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Solution Overview
Problem
Existing unit cell assembly designs for solid polymer electrolyte fuel cells face challenges in manufacturing efficiency, waste production, and material limitations due to the use of low viscosity elastomers for sealing, which can lead to alignment issues and reduced fuel cell lifetime.
Innovation Solution
The use of an elastomeric seal made from higher viscosity elastomers like polyisobutylene, ethylene propylene diene monomer, silicone, or polyolefin elastomer, applied via liquid injection molding, without penetrating the edges of gas diffusion layers, combined with an adhesive layer to bond the gas diffusion layers and catalyst coated membrane assembly, enhances manufacturing efficiency and reduces waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low viscosity elastomers are used for sealing in unit cell assemblies, then the elastomer can penetrate and seal the edges of gas diffusion layers effectively, but this limits elastomer material choices and reduces fuel cell lifetime due to material failures
Solution Approach 1:
The patent introduces an adhesive layer as an intermediary between the gas diffusion layer and the flow field plate assembly. This adhesive mediator eliminates the need for elastomer penetration into the GDL edges, allowing the use of higher viscosity elastomers that do not compromise membrane electrolyte lifetime while still achieving effective sealing through the adhesive interface.
2Reliability
If plastic film frames are used to provide electrical isolation and sealing, then sealing functions are achieved, but this results in large waste stream from discarded framing film
Solution Approach 1:
The patent extracts and eliminates the plastic film frame component from the unit cell assembly. Instead of using a separate framing film for electrical isolation and sealing, the design relies on the adhesive layer and elastomeric seal applied directly to the flow field plate assembly, thereby removing the source of framing film waste while maintaining necessary sealing functions.
3Reliability
If plastic film frames are used for sealing, then sealing is achieved, but the framing film is not rigid enough and causes alignment problems with increased space requirements for tolerance
Solution Approach 1:
The adhesive layer serves as a compliant intermediary that compensates for tolerance variations between components. By using the adhesive to bond the gas diffusion layer to the flow field plate assembly, the design achieves both sealing and alignment functionality without requiring the additional space and tolerance accommodation needed for flexible film frames.
4Reliability
If elastomeric seal is applied to the frame instead of the flow field plate assembly, then sealing between unit cell assemblies is achieved, but this still produces waste and has similar material limitations
Solution Approach 1:
The patent positions the elastomeric seal and adhesive layer as an integrated intermediary system between the gas diffusion layer and flow field plate assembly. This approach consolidates the sealing function into the primary bonding interface, eliminating the need for separate frame-based sealing and the associated waste production from framing materials.
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 allows for the use of higher viscosity elastomers, reducing waste and alignment issues, while maintaining assembly integrity and extending fuel cell lifetime by eliminating the need for low viscosity sealants that limit elastomer choices and cause material failures.
Implementation Method 1
an adhesive layer to bond the gas diffusion layers and catalyst coated membrane assembly
Data Source
Figure 1a
Figure 2a~2c
AI summary
Unique unit cell assemblies (20) for a solid polymer electrolyte fuel cell stack and improved methods for making them are disclosed in which the methods initially comprise bonding a single gas diffusion layer to a flow field plate assembly (6) using an elastomeric seal (17), e.g. a liquid injection mold seal. Sealing of the unit cell assembly (20) does not rely on penetrating the gas diffusion layer with elastomer. The method provides for reliable unit cell assemblies (20) while advantageously allowing for use of higher viscosity elastomers and reducing waste.