Fluoroelastomer Fuel Cell Seals for Leak and Ion Leaching Control
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Solution Overview
Problem
Existing fuel cell assemblies face challenges in sealing bipolar plates to proton exchange membranes due to complex geometries and brittle materials, leading to leakage and ion leaching issues, which affect efficiency.
Innovation Solution
A water-based fluoroelastomer cross-linkable composition is applied as a seal between fuel cell components using traditional coating techniques, comprising vinylidene-fluoride based fluoropolymers, basic compounds, and pyridinium salts to form a resilient gasket that enhances leak resistance and reduces ion leaching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid injection molding techniques are used to mold LSR gaskets onto bipolar plates, then sealing capability is improved, but the process becomes difficult due to complex shape and brittle material
Solution Approach 1:
The patent replaces the mechanical injection molding process with a chemical curing process. The fluoroelastomer composition is applied as a coating and cured in-situ through chemical reaction, eliminating the need for complex mechanical molding equipment and processes while achieving reliable sealing on brittle bipolar plates with complex geometries
Solution Approach 2:
The patent changes the physical state and application method of the sealing material from molded solid LSR to a curable fluoroelastomer composition that can be applied in various forms (paste, coating, or injection-molded) and then cured in-situ. This parameter change enables sealing of complex geometries without the limitations of traditional molding
2Ease of manufacture
If traditional sealing materials are used, then manufacturing is simpler, but ion leaching occurs reducing fuel cell efficiency
Solution Approach 1:
The patent uses fluoroelastomer as a composite material that combines the manufacturing simplicity of traditional rubber sealing materials with superior ion leaching resistance. The fluoroelastomer's molecular structure provides both ease of application and resistance to ion leaching in the fuel cell environment
Solution Approach 2:
The patent changes the chemical composition of the sealing material from traditional hydrocarbon-based rubber to fluoroelastomer, which has different chemical properties including resistance to ion leaching. This material substitution maintains manufacturing simplicity while dramatically improving reliability
3Reliability
If fluoroelastomers are used with curing agents and heated to cure in situ, then seal performance is improved, but the process complexity increases
Solution Approach 1:
The patent employs self-service curing mechanisms where the fluoroelastomer composition cures through exposure to atmospheric moisture, UV radiation, or heat that is already present in the fuel cell assembly environment. This eliminates the need for separate curing equipment or complex multi-step processes while achieving high seal performance
Solution Approach 2:
The patent incorporates curing agents and initiators into the fluoroelastomer composition before application. The composition is prepared in advance with all necessary components for curing, so that when applied to the bipolar plates, it can cure in-situ without requiring additional materials or complex process steps
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 resulting fuel cell stack exhibits superior leak resistance and reduced ion leaching, improving overall efficiency and reliability.
Implementation Method 1
an aqueous cross-linkable composition for fuel cell seals that may be applied in latex form between the components of the fuel cell... comprising particles of at least one vinylidene-fluoride (VDF) based fluoropolymer... at least one basic compound; at least one pyridinium salt
Data Source
AI summary
The present invention relates to fuel cells that incorporate seal means, in particular seal means for sealing a bipolar plate to a membrane in a PEM fuel cell stack. The resulting fuel cell stack exhibits superior leak resistance and reduced ion leaching in water.